Effect of Bentonite on the Electrical Properties of a Polylactide-Based Nanocomposite

In this paper, a novel polylactide-based nanocomposite with the addition of bentonite as a filler, Fusabond, and glycerine as a compatibilizer and plasticizer, were prepared and investigated. Four samples with different contents of bentonite (1, 5, 10, and 15 wt.%), as well as three samples without fillers, were prepared with an easily scalable method: melt blending. The electrical properties of all prepared samples were investigated with broadband dielectric spectroscopy in the frequency range between 0.1 Hz and 1 MHz. Measurements were conducted at nine temperatures between 293.15 and 333.15 K (20 to 60 °C) with steps of 5 K. It was found that the increase in the content of bentonite in polylactide has a significant effect on the electrical properties of the prepared nanocomposites.

The Influence of Selected Fillers on the Functional Properties of Polycarbonate Dedicated to 3D Printing Applications

Additive manufacturing is still the fastest-developing technology in the modern world. Three-dimensional printing has become popular due to the method's numerous advantages, such as its short time and low cost, compared to conventional methods such as injection molding. Therefore, the demand for new materials and material systems that will be characterized by the desired functional properties is clearly growing. As part of this work, work was carried out on the development and preparation of new polymer composites dedicated to 3D printing applications, especially in FDM/FFF/MEM technologies. The influence of the content and amount of fillers, such as silica modified with alumina (S) and bentonite modified with a quaternary ammonium salt (B), on the functional properties of a commercially available fiber made of traditional plastic, such as polycarbonate, obtained in the form of a filament (PCF), was determined. It was found that the addition of B significantly increased the fluidity of the polymer, the introduction of a filler in the amount of 1.5% allowed to obtain a result that was 6% higher compared to PCF (16.8 g/10 min), while the amount of 3% was 20% higher. The obtained mass melt flow rate (MFR) results were confirmed by determining the viscosity of the produced polymer composites. Satisfactory results of mechanical properties were obtained, including the following: it was found that the introduced modified fillers increased the elasticity of the material. The introduction of modified silica resulted in a reduction in Young's modulus by 10.02% at the content of 0.5% S and at 1% S by 8.64% compared to the polymer. The introduced modified filler S significantly increased the thermostability of polycarbonate (T5% equal to 449 °C) by 23 °C for PCF/0.5% S and 14 °C for PCF/1% S, respectively. The SEM and WAXS results confirmed the appropriate dispersion of the fillers in the polymer matrix, which indicates well-selected conditions for the homogenization process of the components and the subsequent production of samples. Detailed characterization of the influence of selected fillers on the functional properties of the polymer matrix-polycarbonate allowed for an increase in the range of polymer composites and their use in rapid prototyping technologies, as well as supplementing the literature on databases regarding the characteristics of the obtained materials.

Polymer Composites Based on Polycarbonate/Acrylonitrile-Butadiene-Styrene Used in Rapid Prototyping Technology

As part of this work, polymer composites based on polycarbonate/acrylonitrile-butadiene-styrene (PC/ABS) were obtained and used in 3D printing technology, particularly Melted Extrusion Modeling (MEM) technology. The influence of selected fillers on the properties of the obtained composites was investigated. For this purpose, modified fillers such as silica modified with alumina, bentonite modified with a quaternary ammonium salt, and hybrid lignin/silicon dioxide filler were introduced into the PC/ABS matrix. In the first part of this work, polymer blends and their composites containing 1.5-3 wt. of the filler were used to obtain the filament using the proprietary technological line. Moldings for testing the performance properties were obtained using additive manufacturing techniques and injection molding. In the subsequent part of this work, rheological properties (mass flow rate (MFR) and viscosity curves) and mechanical properties (Rockwell hardness and static tensile strength with Young's modulus) were examined. The structures of the obtained composites were also determined by scanning electron microscopy (SEM/EDS). The obtained results confirmed the results obtained from a wide-angle X-ray scattering analysis (WAXS). In turn, the physicochemical properties were characterized on the basis of the results of tests using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Based on the obtained results, it was found that the introduced modified additives had a significant impact on the processing and functional properties of the tested composites.

Hybrid Polymer Composites Based on Polystyrene (PS) Used in the Melted and Extruded Manufacturing Technology

As part of the work, innovative hybrid polymer composites dedicated to rapid prototyping, especially for 3D printing with the melted and extruded manufacturing (MEM) technique, were developed. For this purpose, the influence of modified fillers, such as alumina-modified silica, bentonite modified with quaternary ammonium salt, and lignin/silicon dioxide hybrid filler, on the functional properties of polystyrene-based composites was investigated. The introduced additives were selected to improve the processing properties of polystyrene (PS), in particular its thermal stability, while maintaining good mechanical properties. In the first part of the work, using the proprietary technological line, filaments from unfilled PS and its composites were obtained, which contain modified fillers in the amount of 1.5% to 3.0% by weight. Samples for testing functional properties were obtained by 3D printing in MEM technology and injection technique. The rheological properties-mass melt flow rate (MFR), viscosity, and mechanical properties-are presented in the further part of the work. The size and the respective dispersion in the polystyrene polymer matrix of the fillers used were determined by scanning electron microscopy with energy dispersion spectroscopy (SEM/EDS). The correct dispersion of additives in PS was also confirmed by wide-angle X-ray analysis (WAXS). A significant improvement in the thermal stability of the obtained composites after the introduction of fillers into the polymer matrix was confirmed on the basis of thermogravimetric analysis (TGA). The remaining tests of physicochemical properties, differential scanning calorimetry (DSC), and infrared spectroscopy with Fourier transform (FT-IR) allowed us to state no significant changes in relation to polystyrene. The obtained test results allowed us to conclude that the amount and type of fillers used in the PS polymer matrix significantly affect the performance properties of the tested hybrid composites. The composites obtained as part of the work can be successfully used in rapid prototyping technologies, especially for the production of details originally designed from PS, which are required to have higher thermal stability than is guaranteed only by the polymer matrix.

Quality improvement of gear wheels obtained from polymer materials by shaving process

The geometric accuracy of gears obtained by injection molding before and after finishing by shaving process has been compared. Significant assumptions in the application of this method to the finishing of polymer gears are presented. There is a clear influence of the applied technology on the dimensional stability improvement of the tested gears rim made of composite PA66 matrix containing 35 wt % glass fibers. The tested gears made of the composite materials used in some drive systems can successfully replace this type of machine elements made of metals.

Hybrid Polymer Composites Used in the Arms Industry: A Review

Polymer fiber composites are increasingly being used in many industries, including the defense industry. However, for protective applications, in addition to high specific strength and stiffness, polymer composites are also required to have a high energy absorption capacity. To improve the performance of fiber-reinforced composites, many researchers have modified them using multiple methods, such as the introduction of nanofillers into the polymer matrix, the modification of fibers with nanofillers, the impregnation of fabrics using a shear thickening fluid (STF) or a shear thickening gel (STG), or a combination of these techniques. In addition, the physical structures of composites have been modified through reinforcement hybridization; the appropriate design of roving, weave, and cross-orientation of fabric layers; and the development of 3D structures. This review focuses on the effects of modifying composites on their impact energy absorption capacity and other mechanical properties. It highlights the technologies used and their effectiveness for the three main fiber types: glass, carbon, and aramid. In addition, basic design considerations related to fabric selection and orientation are indicated. Evaluation of the literature data showed that the highest energy absorption capacities are obtained by using an STF or STG and an appropriate fiber reinforcement structure, while modifications using nanomaterials allow other strength parameters to be improved, such as flexural strength, tensile strength, or shear strength.

High AC and DC Electroconductivity of Scalable and Economic Graphite-Diamond Polylactide Nanocomposites

Two types of graphite/diamond (GD) particles with different ash content was applied to prepare new electroconductive polylactide (PLA)-based nanocomposites. Four samples of nanocomposites for each type of GD particles with mass fraction 0.01, 0.05, 0.10, and 0.15 were prepared via an easily scalable method—melt blending. The samples were subjected to the studies of electrical properties via broadband dielectric spectroscopy. The results indicated up to eight orders of magnitude improvement in the electrical conductivity and electrical permittivity of the most loaded nanocomposites, in reference to the neat PLA. Additionally, the influence of ash content on the electrical conductivity of the nanocomposites revealed that technologically less-demanding fillers, i.e., of higher ash content, were the most beneficial in the light of nanofiller dispersibility and the final properties.

Torsional strength tests of spline connections made of polymer materials (Rapid communication)

This work is a continuation of the publication [1], in which the torsional strength tests of samples made of polymer materials, loaded with torsional moment, which more and more often can be made with the use of incremental technologies, were carried out. The designed proprietary test stand, which was described in the publication [1], was used. A series of preliminary studies on the torsion of fittings with spline connections obtained using additive techniques were carried out. It was found, that a additive technologies have a clear impact on the torsional strength of the tested machine components, including the placement of the prototype relative to the 3D printing plane or the method of processing polymer material.