1
|
Surisetty J, Sharifian M, Lucyshyn T, Holzer C. Investigating the Aging Behavior of High-Density Polyethylene and Polyketone in a Liquid Organic Hydrogen Carrier. Polymers (Basel) 2023; 15:4410. [PMID: 38006134 PMCID: PMC10674436 DOI: 10.3390/polym15224410] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2023] [Revised: 11/07/2023] [Accepted: 11/10/2023] [Indexed: 11/26/2023] Open
Abstract
Hydrogen is recognized as a significant potential energy source and energy carrier for the future. On the one hand, storing hydrogen is a challenging task due to its low volumetric density, on the other hand, a particular type of hydrogen in the form of a liquid can be used to store large quantities of hydrogen at ambient conditions in thermoplastic tanks. But storing hydrogen in this form for a long time in polymer tanks affects the physical and chemical properties of the liner. In the current automotive industry, high-density polyethylene (HDPE) has already been used in existing fuel tank applications. However long-term exposure to fuels leads to the permeation of hydrocarbons into the polymers, resulting in a loss of mechanical properties and reducing the efficiency of fuel cells (FC) in automotive applications. Additionally, facing material shortages and a limited supply of resin leads to an increase in the cost of the material. Therefore, an alternative material is being searched for, especially for hydrogen fuel tank applications. In this study, two semi-crystalline thermoplastics, HDPE and polyketone (POK), were compared, which were exposed to a selected liquid organic hydrogen carrier (LOHC) at 25 °C and 60 °C for up to 500 h in an enclosed chamber, to measure their fuel up-take. A short analysis was carried out using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), and mechanical testing to understand the influence of the LOHC on the polymer over time. Fuel sorption and tensile properties showed a plasticizing effect on HDPE. The material degradation was more pronounced for the aged samples of HDPE in comparison to POK. As expected, thermal aging was increased at 60 °C. The fuel absorption of POK was lower compared to HDPE. A slight increase in crystallinity was observed in POK due to the aging process that led to changes in mechanical properties. Both HDPE and POK samples did not show any chemical changes during the aging process in the oven at 25 °C and 60 °C.
Collapse
Affiliation(s)
- Jyothsna Surisetty
- Polymer Processing, Department of Polymer Engineering and Science, Montanuniversität Leoben, 8700 Leoben, Austria; (T.L.); (C.H.)
| | - Mohammadhossein Sharifian
- Chemistry of Polymeric Materials, Department of Polymer Engineering and Science, Montanuniversität Leoben, 8700 Leoben, Austria;
| | - Thomas Lucyshyn
- Polymer Processing, Department of Polymer Engineering and Science, Montanuniversität Leoben, 8700 Leoben, Austria; (T.L.); (C.H.)
| | - Clemens Holzer
- Polymer Processing, Department of Polymer Engineering and Science, Montanuniversität Leoben, 8700 Leoben, Austria; (T.L.); (C.H.)
| |
Collapse
|
2
|
Hentschel L, Petersmann S, Kynast F, Schäfer U, Holzer C, Gonzalez-Gutierrez J. Influence of the Print Envelope Temperature on the Morphology and Tensile Properties of Thermoplastic Polyolefins Fabricated by Material Extrusion and Material Jetting Additive Manufacturing. Polymers (Basel) 2023; 15:3785. [PMID: 37765639 PMCID: PMC10534743 DOI: 10.3390/polym15183785] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2023] [Revised: 09/04/2023] [Accepted: 09/12/2023] [Indexed: 09/29/2023] Open
Abstract
Additive manufacturing (AM) nowadays has become a supportive method of traditional manufacturing. In particular, the medical and healthcare industry can profit from these developments in terms of personalized design and batches ranging from one to five specimens overall. In terms of polymers, polyolefins are always an interesting topic due to their low prices, inert chemistry, and crystalline structure resulting in preferable mechanical properties. Their semi-crystalline nature has some advantages but are challenging for AM due to their shrinkage and warping, resulting in geometrical inaccuracies or even layer detaching during the process. To tackle these issues, process parameter optimization is vital, with one important parameter to be studied more in detail, the print envelope temperature. It is well known that higher print envelope temperatures lead to better layer adhesion overall, but this investigation focuses on the mechanical properties and resulting morphology of a semi-crystalline thermoplastic polyolefin. Further, two different AM technologies, namely material jetting (ARBURG plastic freeforming-APF) and filament-based material extrusion, were studied and compared in detail. It was shown that higher print envelope temperatures lead to more isotropic behavior based on an evenly distributed morphology but results in geometrical inaccuracies since the material is kept in a molten state during printing. This phenomenon especially could be seen in the stress and strain values at break at high elongations. Furthermore, a different crystal structure can be achieved by setting a specific temperature and printing time, also resulting in peak values of certain mechanical properties. In comparison, better results could be archived by the APF technology in terms of mechanical properties and homogeneous morphology. Nevertheless, real isotropic part behavior could not be managed which was shown by the specimen printed vertically. Hence, a sweet spot between geometrical and mechanical properties still has to be found.
Collapse
Affiliation(s)
- Lukas Hentschel
- Polymer Processing, Montanuniversitaet Leoben, 8700 Leoben, Austria
| | - Sandra Petersmann
- Materials Science and Testing of Polymers, Montanuniversitaet Leoben, 8700 Leoben, Austria
| | | | - Ute Schäfer
- Research Unit Experimental Neurotraumatology, Department of Neurosurgery, Medical University of Graz, 8036 Graz, Austria
- BioTechMed-Graz, 8010 Graz, Austria
| | - Clemens Holzer
- Polymer Processing, Montanuniversitaet Leoben, 8700 Leoben, Austria
| | | |
Collapse
|
3
|
Hubmann M, Schuschnigg S, Ðuretek I, Groten J, Holzer C. Enhancing High-Pressure Capillary Rheometer Viscosity Data Calculation with the Propagation of Uncertainties for Subsequent Cross-Williams, Landel, and Ferry (WLF) Parameter Fitting. Polymers (Basel) 2023; 15:3147. [PMID: 37514536 PMCID: PMC10385220 DOI: 10.3390/polym15143147] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Revised: 07/20/2023] [Accepted: 07/21/2023] [Indexed: 07/30/2023] Open
Abstract
Measuring the shear viscosity of polymeric melts is an extensive effort frequently performed in high-pressure capillary rheometers, where the pressures required to push the melt through a capillary at various temperatures and volumetric flow rates are recorded. Then, the viscosity values are obtained through Bagley and Weissenberg-Rabinowitsch corrections involving parameter fitting. However, uncertainties in those conversions due to pressure variations and measurement inaccuracies (random errors) affect the accuracy of the consequently calculated viscosities. This paper proposes quantifying them through a propagation of uncertainties calculation. This has been experimentally demonstrated for a polycarbonate melt. In addition, the derived viscosity uncertainties were used for the weighted residual sum of squares parameter estimation of the Cross-WLF viscosity model and compared with the coefficients obtained using the standard residual sum of squares minimization approach. The motivation was that, by comparison, individual poorly measured viscosity values should have a less negative impact on the overall fit quality of the former. For validation, the rheometer measurements were numerically simulated with both fits. The simulations based on the Cross-WLF fit, including the derived viscosity uncertainties, matched the measured pressures ~16% more closely for shear rates below 1500 1/s. Considering the uncertainties led to more precise coefficients. However, both fits showed substantial deviations at higher shear rates, probably due to substantial non-isothermal flow conditions that prevailed during these measurements. A capillary rheometer experiment was also simulated using arbitrarily chosen Cross-WLF parameters to exclude such systematic errors. A normally distributed error was then applied to the simulated pressures before re-fitting the parameters. Again, taking advantage of the derived viscosity uncertainties, the fit could recover the initial parameters better.
Collapse
Affiliation(s)
- Martin Hubmann
- Polymer Processing, Department of Polymer Engineering and Science, Montanuniversitaet Leoben, 8700 Leoben, Austria
| | - Stephan Schuschnigg
- Polymer Processing, Department of Polymer Engineering and Science, Montanuniversitaet Leoben, 8700 Leoben, Austria
| | - Ivica Ðuretek
- Polymer Processing, Department of Polymer Engineering and Science, Montanuniversitaet Leoben, 8700 Leoben, Austria
| | - Jonas Groten
- Joanneum Research Forschungsgesellschaft mbH, Franz-Pichler Str. 30, 8160 Weiz, Austria
| | - Clemens Holzer
- Polymer Processing, Department of Polymer Engineering and Science, Montanuniversitaet Leoben, 8700 Leoben, Austria
| |
Collapse
|
4
|
Momeni V, Shahroodi Z, Gonzalez-Gutierrez J, Hentschel L, Duretek I, Schuschnigg S, Kukla C, Holzer C. Effects of Different Polypropylene (PP)-Backbones in Aluminium Feedstock for Fused Filament Fabrication (FFF). Polymers (Basel) 2023; 15:3007. [PMID: 37514397 PMCID: PMC10385633 DOI: 10.3390/polym15143007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Revised: 07/06/2023] [Accepted: 07/07/2023] [Indexed: 07/30/2023] Open
Abstract
The current study presents the effect of the backbone as an important binder component on the mechanical, rheological, and thermal properties of Aluminium (Al) alloy feedstocks. A thermoplastic elastomer (TPE) main binder component was blended with either polypropylene (PP), grafted-maleic anhydride-PP (PPMA), or grafted-maleic anhydride-PPwax (PPMAwax) plus PP, as the backbone. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) tests were performed to investigate the thermal properties of binder systems and feedstocks. Fourier-transform infrared (FTIR) spectroscopy was used to study the chemical interaction between the binder and the Al alloy. After making feedstock filaments, tensile tests, scanning electron microscopy (SEM), and fused filament fabrication (FFF) printing were done. The results showed that although the PP printability was acceptable, the best mechanical properties and printed quality can be achieved by PPMA. TGA test showed that all binder systems in the feedstocks could be removed completely around 500 °C. From FTIR, the possibility of chemical reactions between Al alloy particles and maleic anhydride groups on the grafted PP backbone could explain the better dispersion of the mixture and higher mechanical properties. Tensile strength in PP samples was 3.4 MPa which was improved 1.8 times using PPMA as the backbone.
Collapse
Affiliation(s)
- Vahid Momeni
- Polymer Processing, Montanuniversitaet Leoben, 8700 Leoben, Austria
| | - Zahra Shahroodi
- Polymer Processing, Montanuniversitaet Leoben, 8700 Leoben, Austria
| | - Joamin Gonzalez-Gutierrez
- Polymer Processing, Montanuniversitaet Leoben, 8700 Leoben, Austria
- Functional Polymers Research Unit, Materials Research and Technology (MRT) Department, Luxembourg Institute of Science and Technology (LIST), L-4940 Hautcharage, Luxembourg
| | - Lukas Hentschel
- Polymer Processing, Montanuniversitaet Leoben, 8700 Leoben, Austria
| | - Ivica Duretek
- Polymer Processing, Montanuniversitaet Leoben, 8700 Leoben, Austria
| | | | - Christian Kukla
- Industrial Liaison Department, Montanuniversitaet Leoben, 8700 Leoben, Austria
| | - Clemens Holzer
- Polymer Processing, Montanuniversitaet Leoben, 8700 Leoben, Austria
| |
Collapse
|
5
|
Raguž I, Berer M, Fleisch M, Holzer C, Brancart J, Vanderborght B, Schlögl S. Soft dielectric actuator produced by multi‐material fused filament fabrication
3D
printing. POLYM ADVAN TECHNOL 2023. [DOI: 10.1002/pat.6024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/09/2023]
Affiliation(s)
- Ivan Raguž
- Polymer Competence Center Leoben GmbH Leoben Austria
| | - Michael Berer
- Polymer Competence Center Leoben GmbH Leoben Austria
| | | | - Clemens Holzer
- Department of Polymer Engineering and Science, Montanuniversitaet Leoben Leoben Austria
| | - Joost Brancart
- Physical Chemistry and Polymer Science Vrije Universiteit Brussel Brussels Belgium
| | | | | |
Collapse
|
6
|
Momeni V, Hufnagl M, Shahroodi Z, Gonzalez-Gutierrez J, Schuschnigg S, Kukla C, Holzer C. Research Progress on Low-Pressure Powder Injection Molding. Materials (Basel) 2022; 16:379. [PMID: 36614718 PMCID: PMC9822315 DOI: 10.3390/ma16010379] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Revised: 12/25/2022] [Accepted: 12/28/2022] [Indexed: 06/17/2023]
Abstract
Powder injection molding (PIM) is a well-known technique to manufacture net-shaped, complicated, macro or micro parts employing a wide range of materials and alloys. Depending on the pressure applied to inject the feedstock, this process can be separated into low-pressure (LPIM) and high-pressure (HPIM) injection molding. Although the LPIM and HPIM processes are theoretically similar, all steps have substantial differences, particularly feedstock preparation, injection, and debinding. After decades of focusing on HPIM, low-viscosity feedstocks with improved flowability have recently been produced utilizing low-molecular-weight polymers for LPIM. It has been proven that LPIM can be used for making parts in low quantities or mass production. Compared to HPIM, which could only be used for the mass production of metallic and ceramic components, LPIM can give an outstanding opportunity to cover applications in low or large batch production rates. Due to the use of low-cost equipment, LPIM also provides several economic benefits. However, establishing an optimal binder system for all powders that should be injected at extremely low pressures (below 1 MPa) is challenging. Therefore, various defects may occur throughout the mixing, injection, debinding, and sintering stages. Since all steps in the process are interrelated, it is important to have a general picture of the whole process which needs a scientific overview. This paper reviews the potential of LPIM and the characteristics of all steps. A complete academic and research background survey on the applications, challenges, and prospects has been indicated. It can be concluded that although many challenges of LPIM have been solved, it could be a proper solution to use this process and materials in developing new applications for technologies such as additive manufacturing and processing of sensitive alloys.
Collapse
Affiliation(s)
- Vahid Momeni
- Polymer Processing, Montanuniversitaet Leoben, 8700 Leoben, Austria
| | | | - Zahra Shahroodi
- Polymer Processing, Montanuniversitaet Leoben, 8700 Leoben, Austria
| | - Joamin Gonzalez-Gutierrez
- Polymer Processing, Montanuniversitaet Leoben, 8700 Leoben, Austria
- Functional Polymers Research Unit, Materials Research and Technology (MRT) Department, Luxembourg Institute of Science and Technology (LIST), L-4940 Luxembourg, Luxembourg
| | | | - Christian Kukla
- Industrial Liaison Department, Montanuniversitaet Leoben, 8700 Leoben, Austria
| | - Clemens Holzer
- Polymer Processing, Montanuniversitaet Leoben, 8700 Leoben, Austria
| |
Collapse
|
7
|
Bascucci C, Duretek I, Lehner S, Holzer C, Gaan S, Hufenus R, Gooneie A. Investigating thermomechanical recycling of poly(ethylene terephthalate) containing phosphorus flame retardants. Polym Degrad Stab 2022. [DOI: 10.1016/j.polymdegradstab.2021.109783] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
|
8
|
Katschnig M, Wallner J, Janics T, Burgstaller C, Zemann W, Holzer C. Biofunctional Glycol-Modified Polyethylene Terephthalate and Thermoplastic Polyurethane Implants by Extrusion-Based Additive Manufacturing for Medical 3D Maxillofacial Defect Reconstruction. Polymers (Basel) 2020; 12:E1751. [PMID: 32764496 PMCID: PMC7465993 DOI: 10.3390/polym12081751] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2020] [Revised: 07/28/2020] [Accepted: 08/03/2020] [Indexed: 11/16/2022] Open
Abstract
This work addresses the topic of extrusion-based additive manufacturing (filament-based material extrusion) of patient-specific biofunctional maxillofacial implants. The technical approach was chosen to overcome the shortcomings of medically established fabrication processes such as a limited availability of materials or long manufacturing times. The goal of the work was a successful fabrication of basic implants for defect reconstruction. The underlying vision is the implants' clinic-internal and operation-accompanying application. Following a literature search, a material selection was conducted. Digitally prepared three-dimensional (3D) models dealing with two representative mandible bone defects were printed based on the material selection. An ex-vivo model of the implant environment evaluated dimensional and fitting traits of the implants. Glycol-modified PET (PETG) and thermoplastic polyurethane (TPU) were finally selected. These plastics had high cell acceptance, good mechanical properties, and optimal printability. The subsequent fabrication process yielded two different implant strategies: the standard implant made of PETG with a build-up rate of approximately 10 g/h, and the biofunctional performance implant with a TPU shell and a PETG core with a build-up rate of approximately 4 g/h. The standard implant is meant to be intraoperatively applied, as the print time is below three hours even for larger skull defects. Standard implants proved to be well fitting, mechanically stable and cleanly printed. In addition, the hybrid implant showed particularly cell-friendly behavior due to the chemical constitution of the TPU shell and great impact stability because of the crack-absorbing TPU/PETG combination. This biofunctional constellation could be used in specific reconstructive patient cases and is suitable for pre-operative manufacturing based on radiological image scans of the defect. In summary, filament-based material extrusion has been identified as a suitable manufacturing method for personalized implants in the maxillofacial area. A further clinical and mechanical study is recommended.
Collapse
Affiliation(s)
| | - Juergen Wallner
- Department of Oral and Maxillofacial Surgery, University Clinic of Dental Medicine and Oral Health, Medical University of Graz, 8036 Graz, Austria;
- Department of Cranio-Maxillofacial Surgery, AZ Monica and the University Hospital Antwerp, 2018 Antwerp, Belgium
| | | | | | - Wolfgang Zemann
- Department of Oral and Maxillofacial Surgery, University Clinic of Dental Medicine and Oral Health, Medical University of Graz, 8036 Graz, Austria;
| | - Clemens Holzer
- Chair of Polymer Processing, Montanuniversitaet Leoben, 8700 Leoben, Austria;
| |
Collapse
|
9
|
Cano S, Lube T, Huber P, Gallego A, Naranjo JA, Berges C, Schuschnigg S, Herranz G, Kukla C, Holzer C, Gonzalez-Gutierrez J. Influence of the Infill Orientation on the Properties of Zirconia Parts Produced by Fused Filament Fabrication. Materials (Basel) 2020; 13:ma13143158. [PMID: 32679838 PMCID: PMC7411807 DOI: 10.3390/ma13143158] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Revised: 07/07/2020] [Accepted: 07/13/2020] [Indexed: 11/16/2022]
Abstract
The fused filament fabrication (FFF) of ceramics enables the additive manufacturing of components with complex geometries for many applications like tooling or prototyping. Nevertheless, due to the many factors involved in the process, it is difficult to separate the effect of the different parameters on the final properties of the FFF parts, which hinders the expansion of the technology. In this paper, the effect of the fill pattern used during FFF on the defects and the mechanical properties of zirconia components is evaluated. The zirconia-filled filaments were produced from scratch, characterized by different methods and used in the FFF of bending bars with infill orientations of 0°, ±45° and 90° with respect to the longest dimension of the specimens. Three-point bending tests were conducted on the specimens with the side in contact with the build platform under tensile loads. Next, the defects were identified with cuts in different sections. During the shaping by FFF, pores appeared inside the extruded roads due to binder degradation and or moisture evaporation. The changes in the fill pattern resulted in different types of porosity and defects in the first layer, with the latter leading to earlier fracture of the components. Due to these variations, the specimens with the 0° infill orientation had the lowest porosity and the highest bending strength, followed by the specimens with ±45° infill orientation and finally by those with 90° infill orientation.
Collapse
Affiliation(s)
- Santiago Cano
- Department of Polymer Engineering and Science, Institute of Polymer Processing, Montanuniversitaet Leoben, Otto Gloeckel-Straße 2, 8700 Leoben, Austria; (P.H.); (S.S.); (C.H.); (J.G.-G.)
- Correspondence: (S.C.); (T.L.); Tel.: +43-3842-402-3529 (S.C.); Tel.: +43-3842-402-4111 (T.L.)
| | - Tanja Lube
- Department of Materials Science, Chair of Structural and Functional Ceramics, Montanuniversitaet Leoben, Franz Josef-Straße 18, 8700 Leoben, Austria
- Correspondence: (S.C.); (T.L.); Tel.: +43-3842-402-3529 (S.C.); Tel.: +43-3842-402-4111 (T.L.)
| | - Philipp Huber
- Department of Polymer Engineering and Science, Institute of Polymer Processing, Montanuniversitaet Leoben, Otto Gloeckel-Straße 2, 8700 Leoben, Austria; (P.H.); (S.S.); (C.H.); (J.G.-G.)
| | - Alberto Gallego
- INEI-ETSII, University of Castilla-La Mancha, Av. Camilo José Cela s/n, 13071 Ciudad Real, Spain; (A.G.); (J.A.N.); (C.B.); (G.H.)
| | - Juan Alfonso Naranjo
- INEI-ETSII, University of Castilla-La Mancha, Av. Camilo José Cela s/n, 13071 Ciudad Real, Spain; (A.G.); (J.A.N.); (C.B.); (G.H.)
| | - Cristina Berges
- INEI-ETSII, University of Castilla-La Mancha, Av. Camilo José Cela s/n, 13071 Ciudad Real, Spain; (A.G.); (J.A.N.); (C.B.); (G.H.)
| | - Stephan Schuschnigg
- Department of Polymer Engineering and Science, Institute of Polymer Processing, Montanuniversitaet Leoben, Otto Gloeckel-Straße 2, 8700 Leoben, Austria; (P.H.); (S.S.); (C.H.); (J.G.-G.)
| | - Gemma Herranz
- INEI-ETSII, University of Castilla-La Mancha, Av. Camilo José Cela s/n, 13071 Ciudad Real, Spain; (A.G.); (J.A.N.); (C.B.); (G.H.)
| | - Christian Kukla
- Industrial Liaison, Montanuniversitaet Leoben, Franz-Josef-Straße 18, 8700 Leoben, Austria;
| | - Clemens Holzer
- Department of Polymer Engineering and Science, Institute of Polymer Processing, Montanuniversitaet Leoben, Otto Gloeckel-Straße 2, 8700 Leoben, Austria; (P.H.); (S.S.); (C.H.); (J.G.-G.)
| | - Joamin Gonzalez-Gutierrez
- Department of Polymer Engineering and Science, Institute of Polymer Processing, Montanuniversitaet Leoben, Otto Gloeckel-Straße 2, 8700 Leoben, Austria; (P.H.); (S.S.); (C.H.); (J.G.-G.)
| |
Collapse
|
10
|
Godec D, Cano S, Holzer C, Gonzalez-Gutierrez J. Optimization of the 3D Printing Parameters for Tensile Properties of Specimens Produced by Fused Filament Fabrication of 17-4PH Stainless Steel. Materials (Basel) 2020; 13:ma13030774. [PMID: 32046236 PMCID: PMC7040736 DOI: 10.3390/ma13030774] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Revised: 02/03/2020] [Accepted: 02/05/2020] [Indexed: 11/16/2022]
Abstract
Fused filament fabrication (FFF) combined with debinding and sintering could be an economical process for three-dimensional (3D) printing of metal parts. In this paper, compounding, filament making, and FFF processing of feedstock material with 55% vol. of 17-4PH stainless steel powder in a multicomponent binder system are presented. The experimental part of the paper encompasses central composite design for optimization of the most significant 3D printing parameters (extrusion temperature, flow rate multiplier, and layer thickness) to obtain maximum tensile strength of the 3D-printed specimens. Here, only green specimens were examined in order to be able to determine the optimal parameters for 3D printing. The results show that the factor with the biggest influence on the tensile properties was flow rate multiplier, followed by the layer thickness and finally the extrusion temperature. Maximizing all three parameters led to the highest tensile properties of the green parts.
Collapse
Affiliation(s)
- Damir Godec
- Faculty of Mechanical Engineering and Naval Architecture, University of Zagreb (UNIZAG FSB), 10000 Zagreb, Croatia
- Correspondence: ; Tel.: +385-1-6168-192
| | - Santiago Cano
- Polymer Processing, Montanuniversitaet Leoben, 8700 Leoben, Austria; (S.C.); (C.H.); (J.G.-G.)
| | - Clemens Holzer
- Polymer Processing, Montanuniversitaet Leoben, 8700 Leoben, Austria; (S.C.); (C.H.); (J.G.-G.)
| | | |
Collapse
|
11
|
Spoerk M, Holzer C, Gonzalez‐Gutierrez J. Material extrusion‐based additive manufacturing of polypropylene: A review on how to improve dimensional inaccuracy and warpage. J Appl Polym Sci 2019. [DOI: 10.1002/app.48545] [Citation(s) in RCA: 88] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Martin Spoerk
- Polymer ProcessingMontanuniversitaet Leoben, Otto Gloeckel‐Straße 2 Leoben 8700 Austria
| | - Clemens Holzer
- Polymer ProcessingMontanuniversitaet Leoben, Otto Gloeckel‐Straße 2 Leoben 8700 Austria
| | | |
Collapse
|
12
|
Zitzenbacher G, Huang Z, Holzer C. Experimental study and modeling of wall slip of polymethylmethacrylate considering different die surfaces. POLYM ENG SCI 2018. [DOI: 10.1002/pen.24727] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Gernot Zitzenbacher
- Department of Materials Technology, School of Engineering; University of Applied Sciences Upper Austria; Wels Austria
| | - Zefeng Huang
- Department of Materials Technology, School of Engineering; University of Applied Sciences Upper Austria; Wels Austria
| | - Clemens Holzer
- Department Polymer Engineering and Science; Chair of Polymer Processing, Montanuniversitaet Leoben; Leoben Austria
| |
Collapse
|
13
|
Gonzalez-Gutierrez J, Cano S, Schuschnigg S, Kukla C, Sapkota J, Holzer C. Additive Manufacturing of Metallic and Ceramic Components by the Material Extrusion of Highly-Filled Polymers: A Review and Future Perspectives. Materials (Basel) 2018; 11:E840. [PMID: 29783705 PMCID: PMC5978217 DOI: 10.3390/ma11050840] [Citation(s) in RCA: 88] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/26/2018] [Revised: 05/11/2018] [Accepted: 05/16/2018] [Indexed: 11/21/2022]
Abstract
Additive manufacturing (AM) is the fabrication of real three-dimensional objects from metals, ceramics, or plastics by adding material, usually as layers. There are several variants of AM; among them material extrusion (ME) is one of the most versatile and widely used. In MEAM, molten or viscous materials are pushed through an orifice and are selectively deposited as strands to form stacked layers and subsequently a three-dimensional object. The commonly used materials for MEAM are thermoplastic polymers and particulate composites; however, recently innovative formulations of highly-filled polymers (HP) with metals or ceramics have also been made available. MEAM with HP is an indirect process, which uses sacrificial polymeric binders to shape metallic and ceramic components. After removing the binder, the powder particles are fused together in a conventional sintering step. In this review the different types of MEAM techniques and relevant industrial approaches for the fabrication of metallic and ceramic components are described. The composition of certain HP binder systems and powders are presented; the methods of compounding and filament making HP are explained; the stages of shaping, debinding, and sintering are discussed; and finally a comparison of the parts produced via MEAM-HP with those produced via other manufacturing techniques is presented.
Collapse
Affiliation(s)
- Joamin Gonzalez-Gutierrez
- Polymer Processing, Department of Polymer Engineering and Science, Montanuniversitaet Leoben, Otto Gloeckel-Strasse 2, 8700 Leoben, Austria.
| | - Santiago Cano
- Polymer Processing, Department of Polymer Engineering and Science, Montanuniversitaet Leoben, Otto Gloeckel-Strasse 2, 8700 Leoben, Austria.
| | - Stephan Schuschnigg
- Polymer Processing, Department of Polymer Engineering and Science, Montanuniversitaet Leoben, Otto Gloeckel-Strasse 2, 8700 Leoben, Austria.
| | - Christian Kukla
- Industrial Liaison Department, Montanuniversitaet Leoben, Peter Tunner Strasse 27, 8700 Leoben, Austria.
| | - Janak Sapkota
- Polymer Processing, Department of Polymer Engineering and Science, Montanuniversitaet Leoben, Otto Gloeckel-Strasse 2, 8700 Leoben, Austria.
| | - Clemens Holzer
- Polymer Processing, Department of Polymer Engineering and Science, Montanuniversitaet Leoben, Otto Gloeckel-Strasse 2, 8700 Leoben, Austria.
| |
Collapse
|
14
|
Spoerk M, Gonzalez-Gutierrez J, Lichal C, Cajner H, Berger GR, Schuschnigg S, Cardon L, Holzer C. Optimisation of the Adhesion of Polypropylene-Based Materials during Extrusion-Based Additive Manufacturing. Polymers (Basel) 2018; 10:E490. [PMID: 30966524 PMCID: PMC6415401 DOI: 10.3390/polym10050490] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2018] [Revised: 04/24/2018] [Accepted: 04/27/2018] [Indexed: 11/16/2022] Open
Abstract
Polypropylene (PP) parts produced by means of extrusion-based additive manufacturing, also known as fused filament fabrication, are prone to detaching from the build platform due to their strong tendency to shrink and warp. Apart from incorporating high volume fractions of fillers, one approach to mitigate this issue is to improve the adhesion between the first deposited layer and the build platform. However, a major challenge for PP is the lack of adhesion on standard platform materials, as well as a high risk of welding on PP-based platform materials. This study reports the material selection of build platform alternatives based on contact angle measurements. The adhesion forces, investigated by shear-off measurements, between PP-based filaments and the most promising platform material, an ultra-high-molecular-weight polyethylene (UHMW-PE), were optimised by a thorough parametric study. Higher adhesion forces were measured by increasing the platform and extrusion temperatures, increasing the flow rate and decreasing the thickness of the first layer. Apart from changes in printer settings, an increased surface roughness of the UHMW-PE platform led to a sufficient, weld-free adhesion for large-area parts of PP-based filaments, due to improved wetting, mechanical interlockings, and an increased surface area between the two materials in contact.
Collapse
Affiliation(s)
- Martin Spoerk
- Polymer Processing, Montanuniversitaet Leoben, Otto Gloeckel-Straße 2, 8700 Leoben, Austria.
- Centre for Polymer and Material Technologies, Department of Materials, Textiles and Chemical Engineering, Ghent University, Technologiepark 915, 9052 Zwijnaarde, Belgium.
| | | | - Christof Lichal
- Polymer Processing, Montanuniversitaet Leoben, Otto Gloeckel-Straße 2, 8700 Leoben, Austria.
| | - Hrvoje Cajner
- Faculty of Mechanical Engineering and Naval Architecture, University of Zagreb, Ivana Lučića 1, Zagreb 10002, Croatia.
| | - Gerald Roman Berger
- Injection Moulding of Polymers, Montanuniversitaet Leoben, Otto Gloeckel-Straße 2, 8700 Leoben, Austria.
| | - Stephan Schuschnigg
- Polymer Processing, Montanuniversitaet Leoben, Otto Gloeckel-Straße 2, 8700 Leoben, Austria.
| | - Ludwig Cardon
- Centre for Polymer and Material Technologies, Department of Materials, Textiles and Chemical Engineering, Ghent University, Technologiepark 915, 9052 Zwijnaarde, Belgium.
| | - Clemens Holzer
- Polymer Processing, Montanuniversitaet Leoben, Otto Gloeckel-Straße 2, 8700 Leoben, Austria.
| |
Collapse
|
15
|
Mostafa A, Lucyshyn T, Holzer C, Flachberger H, Oefner W, Riess G, Fritz B. Influence of filler treatment on the behavior of blast furnace slag filled polypropylene compounds. J Appl Polym Sci 2018. [DOI: 10.1002/app.46535] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- A. Mostafa
- Polymer Competence Center Leoben GmbH (PCCL); Leoben Austria
| | - T. Lucyshyn
- Chair of Polymer Processing, Montanuniversitaet Leoben; Leoben Austria
| | - C. Holzer
- Chair of Polymer Processing, Montanuniversitaet Leoben; Leoben Austria
| | - H. Flachberger
- Chair of Mineral Processing, Montanuniversitaet Leoben; Leoben Austria
| | - W. Oefner
- Chair of Mineral Processing, Montanuniversitaet Leoben; Leoben Austria
| | - G. Riess
- Chair of Chemistry of Polymeric Materials, Montanuniversitaet Leoben; Leoben Austria
| | - B. Fritz
- Voestalpine Stahl GmbH; Linz Austria
| |
Collapse
|
16
|
Zitzenbacher G, Dirnberger H, Längauer M, Holzer C. Calculation of the Contact Angle of Polymer Melts on Tool Surfaces from Viscosity Parameters. Polymers (Basel) 2017; 10:polym10010038. [PMID: 30966072 PMCID: PMC6415194 DOI: 10.3390/polym10010038] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Revised: 12/21/2017] [Accepted: 12/22/2017] [Indexed: 11/18/2022] Open
Abstract
It is of great importance for polymer processing whether and how viscosity influences the wettability of tool surfaces. We demonstrate the existence of a distinct relationship between the contact angle of molten polymers and zero shear viscosity in this paper. The contact angle of molten polypropylene and polymethylmethacrylate on polished steel was studied in a high temperature chamber using the sessile drop method. A high pressure capillary rheometer with a slit die was employed to determine the shear viscosity curves in a low shear rate range. A linear relation between the contact angle and zero shear viscosity was obtained. Furthermore, the contact angle and the zero shear viscosity values of the different polymers were combined to one function. It is revealed that, for the wetting of tool surfaces by molten polymers, a lower viscosity is advantageous. Furthermore, a model based on the temperature shift concept is proposed which allows the calculation of the contact angle of molten polymers on steel for different temperatures directly from shear viscosity data.
Collapse
Affiliation(s)
- Gernot Zitzenbacher
- Department of Materials Technology, School of Engineering, University of Applied Sciences Upper Austria, 4600 Wels, Austria.
| | - Hannes Dirnberger
- Department of Materials Technology, School of Engineering, University of Applied Sciences Upper Austria, 4600 Wels, Austria.
| | - Manuel Längauer
- Department of Materials Technology, School of Engineering, University of Applied Sciences Upper Austria, 4600 Wels, Austria.
| | - Clemens Holzer
- Department Polymer Engineering and Science, Chair of Polymer Processing, Montanuniversitaet Leoben, 8700 Leoben, Austria.
| |
Collapse
|
17
|
Gooneie A, Holzer C. Reinforced local heterogeneities in interfacial tension distribution in polymer blends by incorporating carbon nanotubes. POLYMER 2017. [DOI: 10.1016/j.polymer.2017.07.077] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
|
18
|
Mostafa A, Pacher G, Lucyshyn T, Holzer C, Krischey E, Flachberger H, Fritz B, Laske S. Influence of Melt Compounding on Blast Furnace Slag Filled PP Compounds: A Comparative Study. INT POLYM PROC 2017. [DOI: 10.3139/217.3365] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Abstract
In the current study, an assessment of the melt-compounding approach upon the behavior of blast furnace slag (BFS) filled polypropylene (PP) is reported. Two melt-compounding technologies are compared in terms of thermodynamic considerations as well as final behavior of the produced compounds. For this comparison, three PP-BFS formulations are introduced, where non-treated BFS is melt-mixed with PP via (1) internal lab mixer (IM) and (2) co-rotating twin-screw compounder (TSC). PP-BFS compounds from both processes are formed into plates via compression molding, characterized and tested for rheological, thermal and mechanical behavior. Processing parameters were evaluated for both processes such as specific shear work, residence time and shear rates. In addition, the rheological, thermal and mechanical behavior of comparable compounds are evaluated. The calculated specific shear work values for IM and TSC are 0.15 and 0.1 kW · h · kg−1. Calculated residence time for TSC is 55 s. Regarding the rheological behavior, it was found that melt mixing via both technologies did not show major differences in complex viscosity or storage- and loss moduli values. DSC findings show that crystallization and melting temperatures of IM- and TSC formulations are comparable. Decreased strain values are noticed for TSC compounds, while tensile modulus is found to be independent of process variation.
Collapse
Affiliation(s)
- A. Mostafa
- Polymer Competence Center Leoben GmbH (PCCL) , Leoben , Austria
| | - G. Pacher
- Polymer Competence Center Leoben GmbH (PCCL) , Leoben , Austria
| | - T. Lucyshyn
- Chair of Polymer Processing , Montanuniversitaet Leoben, Leoben , Austria
| | - C. Holzer
- Chair of Polymer Processing , Montanuniversitaet Leoben, Leoben , Austria
| | - E. Krischey
- Chair of Mineral Processing , Montanuniversitaet Leoben, Leoben , Austria
| | - H. Flachberger
- Chair of Mineral Processing , Montanuniversitaet Leoben, Leoben , Austria
| | - B. Fritz
- voestalpine Stahl GmbH , Linz , Austria
| | - S. Laske
- Research Center Pharmaceutical Engineering GmbH , TU Graz, Graz , Austria
| |
Collapse
|
19
|
Spoerk M, Arbeiter F, Cajner H, Sapkota J, Holzer C. Parametric optimization of intra- and inter-layer strengths in parts produced by extrusion-based additive manufacturing of poly(lactic acid). J Appl Polym Sci 2017. [DOI: 10.1002/app.45401] [Citation(s) in RCA: 126] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Martin Spoerk
- Institute of Polymer Processing; Montanuniversitaet Leoben; Leoben 8700 Austria
| | - Florian Arbeiter
- Institute of Materials Science and Testing of Polymers; Montanuniversitaet Leoben; Leoben 8700 Austria
| | - Hrvoje Cajner
- Faculty of Mechanical Engineering and Naval Architecture; University of Zagreb; Zagreb 10002 Croatia
| | - Janak Sapkota
- Institute of Polymer Processing; Montanuniversitaet Leoben; Leoben 8700 Austria
| | - Clemens Holzer
- Institute of Polymer Processing; Montanuniversitaet Leoben; Leoben 8700 Austria
| |
Collapse
|
20
|
|
21
|
Abstract
Abstract
Beside the surface properties of the tool material, its temperature is an important parameter influencing the wettability of the tool surface by polymer melts in extrusion technology and injection molding. The temperature and time dependence of the contact angle of a polypropylene and a polymethylmethacrylate melt on polished tool steel was studied in this work at close to process conditions. The experiments were conducted by placing the polymeric sample on the hot tool material substrate in a high temperature chamber and recording the drop shape dependence on time. Based on the experimental results, a novel model was developed which allows a description of the contact angle dependent on temperature and time. The contact angle of the investigated polymer melts exhibits a linear decrease with rising temperature, which means that the wettability of the tool material by the polymer melt is improved with increasing temperature. Furthermore, the model proposed herein enables a complete mathematical description of the contact angle of polymer melts on the tool material dependent on temperature and time. The parameters of this function are the initial contact angle θ0, the contact angle when time approaches infinity θ∞ and a characteristic material time B. The time dependency is incorporated by an exponential function. The characterizing contact angle parameters (θ0, θ∞) follow a linear decrease with rising temperature. The characteristic material time B obeys an exponential law dependent on the reciprocal value of temperature similar to Arrhenius' law.
Collapse
Affiliation(s)
- G. Zitzenbacher
- Department of Materials Technology , School of Engineering, University of Applied Sciences Upper Austria, Wels , Austria
| | - M. Längauer
- Department of Materials Technology , School of Engineering, University of Applied Sciences Upper Austria, Wels , Austria
| | - C. Holzer
- Department Polymer Engineering and Science , Chair of Polymer Processing, Montanuniversitaet Leoben, Leoben , Austria
| |
Collapse
|
22
|
Gooneie A, Schuschnigg S, Holzer C. A Review of Multiscale Computational Methods in Polymeric Materials. Polymers (Basel) 2017; 9:E16. [PMID: 30970697 PMCID: PMC6432151 DOI: 10.3390/polym9010016] [Citation(s) in RCA: 113] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Revised: 12/07/2016] [Accepted: 12/22/2016] [Indexed: 11/17/2022] Open
Abstract
Polymeric materials display distinguished characteristics which stem from the interplay of phenomena at various length and time scales. Further development of polymer systems critically relies on a comprehensive understanding of the fundamentals of their hierarchical structure and behaviors. As such, the inherent multiscale nature of polymer systems is only reflected by a multiscale analysis which accounts for all important mechanisms. Since multiscale modelling is a rapidly growing multidisciplinary field, the emerging possibilities and challenges can be of a truly diverse nature. The present review attempts to provide a rather comprehensive overview of the recent developments in the field of multiscale modelling and simulation of polymeric materials. In order to understand the characteristics of the building blocks of multiscale methods, first a brief review of some significant computational methods at individual length and time scales is provided. These methods cover quantum mechanical scale, atomistic domain (Monte Carlo and molecular dynamics), mesoscopic scale (Brownian dynamics, dissipative particle dynamics, and lattice Boltzmann method), and finally macroscopic realm (finite element and volume methods). Afterwards, different prescriptions to envelope these methods in a multiscale strategy are discussed in details. Sequential, concurrent, and adaptive resolution schemes are presented along with the latest updates and ongoing challenges in research. In sequential methods, various systematic coarse-graining and backmapping approaches are addressed. For the concurrent strategy, we aimed to introduce the fundamentals and significant methods including the handshaking concept, energy-based, and force-based coupling approaches. Although such methods are very popular in metals and carbon nanomaterials, their use in polymeric materials is still limited. We have illustrated their applications in polymer science by several examples hoping for raising attention towards the existing possibilities. The relatively new adaptive resolution schemes are then covered including their advantages and shortcomings. Finally, some novel ideas in order to extend the reaches of atomistic techniques are reviewed. We conclude the review by outlining the existing challenges and possibilities for future research.
Collapse
Affiliation(s)
- Ali Gooneie
- Chair of Polymer Processing, Montanuniversitaet Leoben, Otto Gloeckel-Strasse 2, 8700 Leoben, Austria.
| | - Stephan Schuschnigg
- Chair of Polymer Processing, Montanuniversitaet Leoben, Otto Gloeckel-Strasse 2, 8700 Leoben, Austria.
| | - Clemens Holzer
- Chair of Polymer Processing, Montanuniversitaet Leoben, Otto Gloeckel-Strasse 2, 8700 Leoben, Austria.
| |
Collapse
|
23
|
|
24
|
Modarresi A, Strondl C, Holzer C, Ataimisch N. Modellierung und dynamische Simulation von Ruths-Dampfspeichern. CHEM-ING-TECH 2016. [DOI: 10.1002/cite.201650215] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
|
25
|
Gooneie A, Schuschnigg S, Holzer C. Dissipative Particle Dynamics Models of Orientation of Weakly-Interacting Anisometric Silicate Particles in Polymer Melts under Shear Flow: Comparison with the Standard Orientation Models. MACROMOL THEOR SIMUL 2016. [DOI: 10.1002/mats.201500086] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Ali Gooneie
- Chair of Polymer Processing; Department of Polymer Engineering and Science; Montanuniversität Leoben; Otto Glöckel-Straße 2 8700 Leoben Austria
| | - Stephan Schuschnigg
- Chair of Polymer Processing; Department of Polymer Engineering and Science; Montanuniversität Leoben; Otto Glöckel-Straße 2 8700 Leoben Austria
| | - Clemens Holzer
- Chair of Polymer Processing; Department of Polymer Engineering and Science; Montanuniversität Leoben; Otto Glöckel-Straße 2 8700 Leoben Austria
| |
Collapse
|
26
|
Zitzenbacher G, Huang Z, Längauer M, Forsich C, Holzer C. Wetting behavior of polymer melts on coated and uncoated tool steel surfaces. J Appl Polym Sci 2016. [DOI: 10.1002/app.43469] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Gernot Zitzenbacher
- Department of Materials Technology School of Engineering and Environmental Sciences; University of Applied Sciences Upper Austria; Stelzhamerstr. 23 4600 Wels Austria
| | - Zefeng Huang
- Department of Materials Technology School of Engineering and Environmental Sciences; University of Applied Sciences Upper Austria; Stelzhamerstr. 23 4600 Wels Austria
| | - Manuel Längauer
- Department of Materials Technology School of Engineering and Environmental Sciences; University of Applied Sciences Upper Austria; Stelzhamerstr. 23 4600 Wels Austria
| | - Christian Forsich
- Department of Materials Technology School of Engineering and Environmental Sciences; University of Applied Sciences Upper Austria; Stelzhamerstr. 23 4600 Wels Austria
| | - Clemens Holzer
- Department Polymer Engineering and Science; Chair of Polymer Processing, Otto Gloeckel-Straße 2, Leoben, 8700, Austria, Montanuniversitaet Leoben
| |
Collapse
|
27
|
Gooneie A, Schuschnigg S, Holzer C. Coupled Orientation and Stretching of Chains in Mesoscale Models of Polydisperse Linear Polymers in Startup of Steady Shear Flow Simulations. MACROMOL THEOR SIMUL 2016. [DOI: 10.1002/mats.201500060] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Ali Gooneie
- Department of Polymer Engineering and Science; Montanuniversität Leoben; Otto Glöckel-Straße 2 8700 Leoben Austria
| | - Stephan Schuschnigg
- Department of Polymer Engineering and Science; Montanuniversität Leoben; Otto Glöckel-Straße 2 8700 Leoben Austria
| | - Clemens Holzer
- Department of Polymer Engineering and Science; Montanuniversität Leoben; Otto Glöckel-Straße 2 8700 Leoben Austria
| |
Collapse
|
28
|
Mostafa A, Laske S, Pacher G, Holzer C, Flachberger H, Krischey E, Fritz B. Blast furnace slags as functional fillers on rheological, thermal, and mechanical behavior of thermoplastics. J Appl Polym Sci 2015. [DOI: 10.1002/app.43021] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
| | - Stephan Laske
- Chair of Polymer Processing, Montanuniversitaet Leoben; Leoben Austria
| | - Gernot Pacher
- Polymer Competence Center Leoben GmbH (PCCL); Leoben Austria
| | - Clemens Holzer
- Chair of Polymer Processing, Montanuniversitaet Leoben; Leoben Austria
| | | | - Elke Krischey
- Chair of Mineral Processing, Montanuniversitaet Leoben; Leoben Austria
| | | |
Collapse
|
29
|
Affiliation(s)
- Stephan Laske
- Department of Polymer Engineering and Science, Polymer Processing; Montanuniversitaet Leoben; Otto Gloeckel-Strasse 2 Leoben 8700 Austria
| | - Wolfgang Ziegler
- Department of Polymer Engineering and Science, Chemistry of Polymeric Materials; Montanuniversitaet Leoben; Otto Gloeckel-Strasse 2 Leoben 8700 Austria
| | - Markus Kainer
- IM Polymer GmbH; Peter Tunner Strasse 19 Leoben 8700 Austria
| | | | - Clemens Holzer
- Department of Polymer Engineering and Science, Polymer Processing; Montanuniversitaet Leoben; Otto Gloeckel-Strasse 2 Leoben 8700 Austria
| |
Collapse
|
30
|
Witschnigg A, Laske S, Holzer C, Patel R, Khan A, Benkreira H, Coates P. Near Infrared Investigation of Polypropylene-Clay Nanocomposites for Further Quality Control Purposes-Opportunities and Limitations. Materials (Basel) 2015; 8:5730-5743. [PMID: 28793532 PMCID: PMC5512652 DOI: 10.3390/ma8095272] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/17/2015] [Revised: 08/12/2015] [Accepted: 08/24/2015] [Indexed: 11/24/2022]
Abstract
Polymer nanocomposites are usually characterized using various methods, such as small angle X-ray diffraction (XRD) or transmission electron microscopy, to gain insights into the morphology of the material. The disadvantages of these common characterization methods are that they are expensive and time consuming in terms of sample preparation and testing. In this work, near infrared spectroscopy (NIR) spectroscopy is used to characterize nanocomposites produced using a unique twin-screw mini-mixer, which is able to replicate, at ~25 g scale, the same mixing quality as in larger scale twin screw extruders. We correlated the results of X-ray diffraction, transmission electron microscopy, G′ and G″ from rotational rheology, Young’s modulus, and tensile strength with those of NIR spectroscopy. Our work has demonstrated that NIR-technology is suitable for quantitative characterization of such properties. Furthermore, the results are very promising regarding the fact that the NIR probe can be installed in a nanocomposite-processing twin screw extruder to measure inline and in real time, and could be used to help optimize the compounding process for increased quality, consistency, and enhanced product properties.
Collapse
Affiliation(s)
- Andreas Witschnigg
- Department of Polymer Engineering and Science, Chair of Polymer Processing, Montanuniversitaet Leoben, Otto Gloeckel Strasse 2, Leoben 8700, Austria.
| | - Stephan Laske
- Department of Polymer Engineering and Science, Chair of Polymer Processing, Montanuniversitaet Leoben, Otto Gloeckel Strasse 2, Leoben 8700, Austria.
| | - Clemens Holzer
- Department of Polymer Engineering and Science, Chair of Polymer Processing, Montanuniversitaet Leoben, Otto Gloeckel Strasse 2, Leoben 8700, Austria.
| | - Raj Patel
- School of Engineering, Design and Technology, University of Bradford, Richmond Road, Bradford BD7 1DP, UK.
| | - Atif Khan
- School of Engineering, Design and Technology, University of Bradford, Richmond Road, Bradford BD7 1DP, UK.
| | - Hadj Benkreira
- School of Engineering, Design and Technology, University of Bradford, Richmond Road, Bradford BD7 1DP, UK.
| | - Phil Coates
- School of Engineering, Design and Technology, University of Bradford, Richmond Road, Bradford BD7 1DP, UK.
| |
Collapse
|
31
|
Stloukal P, Pekařová S, Kalendova A, Mattausch H, Laske S, Holzer C, Chitu L, Bodner S, Maier G, Slouf M, Koutny M. Kinetics and mechanism of the biodegradation of PLA/clay nanocomposites during thermophilic phase of composting process. Waste Manag 2015; 42:31-40. [PMID: 25981155 DOI: 10.1016/j.wasman.2015.04.006] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Revised: 03/20/2015] [Accepted: 04/09/2015] [Indexed: 06/04/2023]
Abstract
The degradation mechanism and kinetics of polylactic acid (PLA) nanocomposite films, containing various commercially available native or organo-modified montmorillonites (MMT) prepared by melt blending, were studied under composting conditions in thermophilic phase of process and during abiotic hydrolysis and compared to the pure polymer. Described first order kinetic models were applied on the data from individual experiments by using non-linear regression procedures to calculate parameters characterizing aerobic composting and abiotic hydrolysis, such as carbon mineralization, hydrolysis rate constants and the length of lag phase. The study showed that the addition of nanoclay enhanced the biodegradation of PLA nanocomposites under composting conditions, when compared with pure PLA, particularly by shortening the lag phase at the beginning of the process. Whereas the lag phase of pure PLA was observed within 27days, the onset of CO2 evolution for PLA with native MMT was detected after just 20days, and from 13 to 16days for PLA with organo-modified MMT. Similarly, the hydrolysis rate constants determined tended to be higher for PLA with organo-modified MMT, particularly for the sample PLA-10A with fastest degradation, in comparison with pure PLA. The acceleration of chain scission in PLA with nanoclays was confirmed by determining the resultant rate constants for the hydrolytical chain scission. The critical molecular weight for the hydrolysis of PLA was observed to be higher than the critical molecular weight for onset of PLA mineralization, suggesting that PLA chains must be further shortened so as to be assimilated by microorganisms. In conclusion, MMT fillers do not represent an obstacle to acceptance of the investigated materials in composting facilities.
Collapse
Affiliation(s)
- Petr Stloukal
- Centre of Polymer Systems, Tomas Bata University in Zlín, nám. TGM Sqr. 5555, 760 01 Zlín, Czech Republic; Department of Environmental Protection Engineering, Faculty of Technology, Tomas Bata University in Zlín, nám. TGM 5555, 760 01 Zlin, Czech Republic.
| | - Silvie Pekařová
- Department of Environmental Protection Engineering, Faculty of Technology, Tomas Bata University in Zlín, nám. TGM 5555, 760 01 Zlin, Czech Republic
| | - Alena Kalendova
- Polymer Engineering, Faculty of Technology, Tomas Bata University in Zlín, nám. TGM 5555, 760 01 Zlin, Czech Republic
| | - Hannelore Mattausch
- Department of Polymer Engineering, Chair of Polymer Processing, Montanuniversitaet Leoben, 8700 Leoben, Austria
| | - Stephan Laske
- Department of Polymer Engineering, Chair of Polymer Processing, Montanuniversitaet Leoben, 8700 Leoben, Austria
| | - Clemens Holzer
- Department of Polymer Engineering, Chair of Polymer Processing, Montanuniversitaet Leoben, 8700 Leoben, Austria
| | - Livia Chitu
- Materials Center Leoben GmbH, 8700 Leoben, Austria
| | | | | | - Miroslav Slouf
- Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Heyrovského nám. 2, 162 06 Praha 6-Břevnov, Czech Republic
| | - Marek Koutny
- Centre of Polymer Systems, Tomas Bata University in Zlín, nám. TGM Sqr. 5555, 760 01 Zlín, Czech Republic; Department of Environmental Protection Engineering, Faculty of Technology, Tomas Bata University in Zlín, nám. TGM 5555, 760 01 Zlin, Czech Republic
| |
Collapse
|
32
|
Janko M, Spiegl B, Kaufmann A, Lucyshyn T, Holzer C. Weld line improvement of short fiber reinforced thermoplastics with a movable flow obstacle. J Appl Polym Sci 2015. [DOI: 10.1002/app.42025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Marian Janko
- Department of Polymer Engineering and Science; Chair of Polymer Processing, Montanuniversitaet Leoben; 8700 Leoben Austria
| | | | | | - Thomas Lucyshyn
- Department of Polymer Engineering and Science; Chair of Polymer Processing, Montanuniversitaet Leoben; 8700 Leoben Austria
| | - Clemens Holzer
- Department of Polymer Engineering and Science; Chair of Polymer Processing, Montanuniversitaet Leoben; 8700 Leoben Austria
| |
Collapse
|
33
|
Geissler B, Feuchter M, Laske S, Walluch M, Holzer C, Langecker GR. Tailor-Made High Density PLA Foam Sheets - Strategies to Improve the Mechanical Properties. Cellular Polymers 2014. [DOI: 10.1177/026248931403300502] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
In this study, different strategies to improve the mechanical properties of physically foamed high density polylactic acid (PLA) sheets were examined to produce PLA foam sheets with tailor-made mechanical properties. The first part was the determination of the influence of the blending of PLA with polybutylene succinate (PBS) on the properties of the high density foam sheets. Additionally, the influence of the PBS on the rheological properties was investigated with a cone plate rheometer. The second part was to manufacture multilayer films with a physically foamed middle layer and highly filled skin layers. The foamed sheets were characterized in terms of mean cell size, cell density, density and surface roughness. The experiments were carried out on lab scale multi-layer extrusion line.
Collapse
Affiliation(s)
- Bernd Geissler
- Polymer Competence Center Leoben GmbH, Roseggerstraße 12, 8700 Leoben, Austria
| | - Michael Feuchter
- Chair of Material Science and Testing of Plastics, Department of Polymer Engineering and Science at the Montanuniversitaet Leoben, Otto Glöckel-Strasse 2, 8700 Leoben, Austria
| | - Stephan Laske
- Chair of Polymer Processing, Department of Polymer Engineering and Science at the Montanuniversitaet Leoben, Otto Glöckel-Strasse 2, 8700 Leoben, Austria
| | - Matthias Walluch
- Polymer Competence Center Leoben GmbH, Roseggerstraße 12, 8700 Leoben, Austria
| | - Clemens Holzer
- Chair of Polymer Processing, Department of Polymer Engineering and Science at the Montanuniversitaet Leoben, Otto Glöckel-Strasse 2, 8700 Leoben, Austria
| | - Günter R. Langecker
- Chair of Polymer Processing, Department of Polymer Engineering and Science at the Montanuniversitaet Leoben, Otto Glöckel-Strasse 2, 8700 Leoben, Austria
| |
Collapse
|
34
|
Geissler B, Feuchter M, Laske S, Fasching M, Holzer C, Langecker GR. Strategies to improve the mechanical properties of high-density polylactic acid foams. J CELL PLAST 2014. [DOI: 10.1177/0021955x14538274] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
In this study, different strategies to improve the mechanical properties of physically foamed high-density polylactic acid sheets were examined to produce polylactic acid foam sheets with tailor-made mechanical properties. The first part was the determination of the effect of different blowing agents (CO2 and N2) on the foam morphology. The second part of the study was the modification of the formulation. For this purpose, both a linear and a branching chain extender and a thermoplastic elastomer were used to improve the elongational properties (tensile modulus and strain at break) of the polylactic acid foam sheets. Additionally, the effect of the addition of cellulose fibers on the foam morphology and the mechanical properties was investigated. All experiments were carried out on a laboratory flat-film line. This extrusion line consists of a 30-mm single-screw extruder attached with a 250-mm flat sheet die. The results show a strong influence of the material formulation on the mechanical properties of the high-density foam sheets. Both the mechanical properties and foam morphology could be improved by the right material formulation. The addition of the thermoplastic elastomer leads to a better foam morphology and also to a reduced brittleness of the foam sheets. Furthermore, it could be demonstrated that cellulose fiber can be used as a nucleating agent for polylactic acid but causes a further decrease in the strain at break.
Collapse
Affiliation(s)
| | - Michael Feuchter
- Chair of Material Science and Testing of Plastics, Department of Polymer Engineering and Science, Montanuniversitaet, Leoben, Austria
| | - Stephan Laske
- Chair of Polymer Processing, Department of Polymer Engineering and Science, Montanuniversitaet, Austria
| | | | - Clemens Holzer
- Chair of Polymer Processing, Department of Polymer Engineering and Science, Montanuniversitaet, Austria
| | - Günter R Langecker
- Chair of Polymer Processing, Department of Polymer Engineering and Science, Montanuniversitaet, Austria
| |
Collapse
|
35
|
Müller F, Kukla C, Lucyshyn T, Harker M, Rath G, Holzer C. Wireless in-mold melt front detection for injection molding: A long-term evaluation. J Appl Polym Sci 2014. [DOI: 10.1002/app.40346] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Florian Müller
- Department of Polymer Engineering and Science, Chair of Polymer Processing; Montanuniversitaet Leoben; Otto Gloeckel-Strasse 2 8700 Leoben Austria
| | - Christian Kukla
- Department of Industrial Liaison; Montanuniversitaet Leoben; Peter Tunner Strasse 27 8700 Leoben Austria
| | - Thomas Lucyshyn
- Department of Polymer Engineering and Science, Chair of Polymer Processing; Montanuniversitaet Leoben; Otto Gloeckel-Strasse 2 8700 Leoben Austria
| | - Matthew Harker
- Department of Product Engineering, Chair of Automation; Montanuniversitaet Leoben; Peter-Tunner-Straße 25 8700 Leoben Austria
| | - Gerhard Rath
- Department of Product Engineering, Chair of Automation; Montanuniversitaet Leoben; Peter-Tunner-Straße 25 8700 Leoben Austria
| | - Clemens Holzer
- Department of Polymer Engineering and Science, Chair of Polymer Processing; Montanuniversitaet Leoben; Otto Gloeckel-Strasse 2 8700 Leoben Austria
| |
Collapse
|
36
|
Haubenwallner S, Katschnig M, Fasching U, Patz S, Trattnig C, Andraschek N, Grünbacher G, Absenger M, Laske S, Holzer C, Balika W, Wagner M, Schäfer U. Effects of the polymeric niche on neural stem cell characteristics during primary culturing. J Mater Sci Mater Med 2014; 25:1339-1355. [PMID: 24577943 DOI: 10.1007/s10856-014-5155-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2013] [Accepted: 01/12/2014] [Indexed: 06/03/2023]
Abstract
The polymeric niche encountered by cells during primary culturing can affect cell fate. However, most cell types are primarily propagated on polystyrene (PS). A cell type specific screening for optimal primary culture polymers particularly for regenerative approaches seems inevitable. The effect of physical and chemical properties of treated (corona, oxygen/nitrogen plasma) and untreated cyclic olefin polymer (COP), polymethymethacrylate (PMMA), PP, PLA, PS, PC on neuronal stem cell characteristics was analyzed. Our comprehensive approach revealed plasma treated COP and PMMA as optimal polymers for primary neuronal stem cell culturing and propagation. An increase in the number of NT2/D1 cells with pronounced adhesion, metabolic activities and augmented expression of neural precursor markers was associated to the plasma treatment of surfaces of COP and PMMA with nitrogen or oxygen, respectively. A shift towards large cell sizes at stable surface area/volume ratios that might promote the observed increase in metabolic activities and distinct modulations in F-actin arrangements seem to be primarily mediated by the plasma treatment of surfaces. These results indicate that the polymeric niche has a distinct impact on various cell characteristics. The selection of distinct polymers and the controlled design of an optimized polymer microenvironment might thereby be an effective tool to promote essential cell characteristics for subsequent approaches.
Collapse
Affiliation(s)
- Stefan Haubenwallner
- Research Unit for Experimental Neurotraumatology, Department of Neurosurgery, Medical University of Graz, Auenbruggerplatz 2/2, 8036, Graz, Austria
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
37
|
Laske S, Witschnigg A, Selvasankar RK, Holzer C. Measuring the residence time distribution in a twin screw extruder with the use of NIR-spectroscopy. J Appl Polym Sci 2013. [DOI: 10.1002/app.39919] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Stephan Laske
- Montanuniversitaet Leoben; Chair of Polymer Processing; Otto Glöckel-Strasse 2 8700 Leoben Austria
| | - Andreas Witschnigg
- Montanuniversitaet Leoben; Chair of Polymer Processing; Otto Glöckel-Strasse 2 8700 Leoben Austria
| | - Ramesh Kumar Selvasankar
- Montanuniversitaet Leoben; Chair of Polymer Processing; Otto Glöckel-Strasse 2 8700 Leoben Austria
| | - Clemens Holzer
- Montanuniversitaet Leoben; Chair of Polymer Processing; Otto Glöckel-Strasse 2 8700 Leoben Austria
| |
Collapse
|
38
|
Müller F, Rath G, Lucyshyn T, Kukla C, Burgsteiner M, Holzer C. Presentation of a novel sensor based on acoustic emission in injection molding. J Appl Polym Sci 2013. [DOI: 10.1002/app.38083] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
|
39
|
Witschnigg A, Laske S, Kracalik M, Holzer C. Influence of induced shear work on the properties of polyolefine nanocomposite pipes. POLYM ENG SCI 2012. [DOI: 10.1002/pen.22146] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
|
40
|
Laske S, Duretek I, Witschnigg A, Mattausch H, Tscharnuter D, Holzer C. Influence of the degree of exfoliation on the thermal conductivity of polypropylene nanocomposites. POLYM ENG SCI 2012. [DOI: 10.1002/pen.23121] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
|
41
|
Kracalik M, Laske S, Witschnigg A, Holzer C. Effect of the Mixture Composition on Shear and Extensional Rheology of Recycled PET and ABS Nanocomposites. ACTA ACUST UNITED AC 2012. [DOI: 10.1002/masy.201000122] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
|
42
|
Lucyshyn T, Knapp G, Kipperer M, Holzer C. Determination of the transition temperature at different cooling rates and its influence on prediction of shrinkage and warpage in injection molding simulation. J Appl Polym Sci 2011. [DOI: 10.1002/app.34591] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
43
|
Lucyshyn T, Kipperer M, Kukla C, Langecker GR, Holzer C. A physical model for a quality control concept in injection molding. J Appl Polym Sci 2011. [DOI: 10.1002/app.35590] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
|
44
|
|
45
|
Witschnigg A, Laske S, Kracalik M, Feuchter M, Pinter G, Maier G, Märzinger W, Haberkorn M, Langecker GR, Holzer C. In-line characterization of polypropylene nanocomposites using FT-NIR. J Appl Polym Sci 2010. [DOI: 10.1002/app.32024] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
|
46
|
Rosenberg M, Meyer W, Herndon D, Holzer C, Rosenberg L, Huddleston V. Comparison of the epidemiology of burns of Mexican and American children. Burns 2007. [DOI: 10.1016/j.burns.2006.10.235] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
47
|
Blakeney P, Meyer W, Holzer C, Thomas C. Final report and future questions regarding a social skills training program for burned adolescents. Burns 2007. [DOI: 10.1016/j.burns.2006.10.088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
48
|
Weidler C, Holzer C, Harbuz M, Hofbauer R, Angele P, Schölmerich J, Straub RH. Low density of sympathetic nerve fibres and increased density of brain derived neurotrophic factor positive cells in RA synovium. Ann Rheum Dis 2005; 64:13-20. [PMID: 15608299 PMCID: PMC1755208 DOI: 10.1136/ard.2003.016154] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
OBJECTIVE To investigate the correlation between density of nerve fibres and the presence of BDNF(+) cells. METHODS Densities of nerve fibres and BDNF(+) cells were detected by quantitative immunohistochemistry in fresh synovial tissue from 52 patients with RA, 59 with OA, and 26 controls (Co). BDNF was also detected by in situ hybridisation. RESULTS Sympathetic nerve fibre density was similar in Co and OA but markedly reduced in RA (p = 0.002), whereas density of substance P positive (SP(+)) sensory nerve fibres was lower in OA than in Co and RA (p = 0.002). The ratio of sympathetic/SP(+) sensory nerve fibre density was highest in OA and Co, followed by RA. The correlation between density of sympathetic nerve fibres and SP(+) sensory nerve fibres in OA (R = 0.425, p = 0.001) was strongly positive, had a positive trend in Co (R = 0.243, NS), but was negative in RA (R = -0.292, p = 0.040). In RA and OA tissue the density of BDNF(+) cells was high in sublining areas but markedly lower in Co (p = 0.001). BDNF(+) cell density correlated positively with the ratio of sympathetic/SP(+) sensory nerve fibre density in Co (R = 0.433, p = 0.045) and in OA (R = 0.613, p = 0.015), but not in RA (R = 0.101, NS). Immunohistochemical double staining demonstrated that some macrophages and fibroblasts were positive for BDNF. CONCLUSIONS The correlation of density of SP(+) sensory with sympathetic nerve fibres was positive in Co and OA but negative in RA. BDNF may have a stimulatory role on growth of sympathetic in relation to SP(+) sensory nerve fibres in Co and OA, but not in RA.
Collapse
Affiliation(s)
- C Weidler
- Department of Internal Medicine I, University Hospital, 93042 Regensburg, Germany
| | | | | | | | | | | | | |
Collapse
|
49
|
Abstract
This study assessed long-term psychosocial sequelae of young adult pediatric burn survivors. Subjects were 101 young adults (43 females and 58 males) between the ages of 18 and 28 years who were at least 2 years (average, 14 years) postburn at least 30% TBSA (mean = 54 +/- 20%). Educational status was 25% high school dropouts, 28% high school graduation only, 32% some college, and 5% completed college. Seventy-seven percent either worked or attended school; 28% had had a long-term partner. When assessed by Achenbach's Young Adult Self-Report (YASR) scale and compared with its published reference group, the males reported differences only in the somatic complaints, but the females endorsed significantly more externalizing and total problems, specifically withdrawn behaviors, somatic complaints, thought problems, aggressive behavior, and delinquent behavior. Despite these problems suffered by some female pediatric burn survivors, the overall outcome revealed that most pediatric burn survivors are making the transition into adulthood with minimal unexpected difficulty.
Collapse
Affiliation(s)
- W J Meyer
- Department of Psychiatry and Behavioral Science, University of Texas Medical Branch, Galveston, Texas 77550, USA
| | | | | | | | | | | | | |
Collapse
|
50
|
Felthous AR, Hempel AG, Heredia A, Freeman E, Goodness K, Holzer C, Bennett TJ, Korndorffer WE. Combined homicide-suicide in Galveston County. J Forensic Sci 2001; 46:586-92. [PMID: 11372993] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/16/2023]
Abstract
Combined homicide-suicides have been classified based on the psychopathology of the perpetrator and the nature of the relationship between perpetrator and victim(s). To further understand the nature of this tragic phenomenon and to test the validity and practicality of a previously suggested classification system, investigators systematically collected data on all combined homicide-suicide events that occurred in Galveston County, Texas over a continuous 18-year period (n = 20). The most common psychopathological finding for perpetrators was high serum alcohol levels that suggested intoxication. Most combined homicide-suicides fell into one of the relational categories and most of these, as predicted, were of the consortial type, possessive subtype. As expected, due to the small sample size, the less common types of combined homicide-suicide were not represented in this sample.
Collapse
Affiliation(s)
- A R Felthous
- Department of Psychiatry, Southern Illinois University School of Medicine, USA.
| | | | | | | | | | | | | | | |
Collapse
|