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Candau N, Zimny A, Vives E, Maspoch ML. Elastocaloric Waste/Natural Rubber Materials with Various Crosslink Densities. Polymers (Basel) 2023; 15:polym15112566. [PMID: 37299363 DOI: 10.3390/polym15112566] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Revised: 05/23/2023] [Accepted: 05/30/2023] [Indexed: 06/12/2023] Open
Abstract
The characterization of the mechanical behavior of elastocaloric materials is essential to identify their viability in heating/cooling devices. Natural rubber (NR) is a promising elastocaloric (eC) polymer as it requires low external stress to induce a wide temperature span, ΔT. Nonetheless, solutions are needed to further improve DT, especially when targeting cooling applications. To this aim, we designed NR-based materials and optimized the specimen thickness, the density of their chemical crosslinks, and the quantity of ground tire rubber (GTR) used as reinforcing fillers. The eC properties under a single and cyclic loading conditions of the resulting vulcanized rubber composites were investigated via the measure of the heat exchange at the specimen surface using infrared thermography. The highest eC performance was found with the specimen geometry with the lowest thickness (0.6 mm) and a GTR content of 30 wt.%. The maximum temperature span under single interrupted cycle and multiple continuous cycles were equal to 12 °C and 4 °C, respectively. These results were assumed to be related to more homogeneous curing in these materials and to a higher crosslink density and GTR content which both act as nucleating elements for the strain-induced crystallization at the origin of the eC effect. This investigation would be of interest for the design of eC rubber-based composites in eco-friendly heating/cooling devices.
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Affiliation(s)
- Nicolas Candau
- Departament de Ciència i Enginyeria de Materials (CEM), Escola d'Enginyeria Barcelona-Est (EEBE), Universitat Politècnica de Catalunya BarcelonaTech (UPC), Av. Eduard Maristany 16, 08019 Barcelona, Spain
| | - Adele Zimny
- Departament de Ciència i Enginyeria de Materials (CEM), Escola d'Enginyeria Barcelona-Est (EEBE), Universitat Politècnica de Catalunya BarcelonaTech (UPC), Av. Eduard Maristany 16, 08019 Barcelona, Spain
| | - Eduard Vives
- Departament de Física de la Matèria Condensada, Facultat de Física, Universitat de Barcelona, Martí i Franquès 1-11, 08028 Barcelona, Spain
- Institute of Complex Systems (UBICS), University of Barcelona, Martí i Franquès 1-11, 08028 Barcelona, Spain
| | - Maria Lluïsa Maspoch
- Departament de Ciència i Enginyeria de Materials (CEM), Escola d'Enginyeria Barcelona-Est (EEBE), Universitat Politècnica de Catalunya BarcelonaTech (UPC), Av. Eduard Maristany 16, 08019 Barcelona, Spain
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Joseph L, Madhavan MK, Jayanarayanan K, Pegoretti A. High Temperature Performance of Concrete Confinement by MWCNT Modified Epoxy Based Fiber Reinforced Composites. MATERIALS (BASEL, SWITZERLAND) 2022; 15:9051. [PMID: 36556856 PMCID: PMC9788616 DOI: 10.3390/ma15249051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Revised: 12/09/2022] [Accepted: 12/13/2022] [Indexed: 06/17/2023]
Abstract
The conventional method of fiber reinforced polymer (FRP) wrapping around concrete columns uses epoxy as the binder along with synthetic or natural fibers such as carbon, glass, basalt, jute, sisal etc. as the reinforcement. However, the thermal stability of epoxy is a major issue in application areas prone to fire exposure. The current work addressed this major drawback of epoxy by modifying it with a nanofiller, such as multiwalled carbon nanotubes (MWCNT), and reinforcing it using basalt and sisal fibers. The effect of exposure to elevated temperature on the behavior of concrete cylinders externally confined with these FRP systems was analyzed. Three types of specimens were considered: unconfined; confined with sisal fiber reinforced polymer (SFRP); and confined with hybrid sisal basalt fiber reinforced polymer (HSBFRP) specimens. The test samples were exposed to elevated temperature regimes of 100 °C, 200 °C, 300 °C and 400 °C for a period of 2 h. The compressive strengths of unconfined specimens were compared with various confined specimens, and from the test results, it was evident that the mechanical and thermal durability of the FRP systems was substantially enhanced by MWCNT incorporation. The reduction in the compressive strength of the FRP-confined specimens varied depending on the type of the confinement. After two hours of exposure at 400 °C, the compressive strength corresponding to the epoxy-HSBFRP-confined specimens were improved by 15%, whereas a 50% increase in strength corresponding to MWCNT-incorporated epoxy-HSBFRP-confined specimens was observed with respect to unconfined unexposed specimens. The MWCNT-modified epoxy-incorporated FRP-confined systems demonstrated superior performance even at elevated temperatures in comparison to unconfined specimens at ambient temperatures.
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Affiliation(s)
- Lakshmi Joseph
- Department of Civil Engineering, Amrita School of Engineering, Amrita Vishwa Vidyapeetham, Coimbatore 641112, India
| | - Mini K. Madhavan
- Department of Civil Engineering, Amrita School of Engineering, Amrita Vishwa Vidyapeetham, Coimbatore 641112, India
| | - Karingamanna Jayanarayanan
- Department of Chemical Engineering and Materials Science, Amrita School of Engineering, Amrita Vishwa Vidyapeetham, Coimbatore 641112, India
- Center of Excellence in Advanced Materials and Green Technologies (CoE-AMGT), Amrita School of Engineering, Amrita Vishwa Vidyapeetham, Coimbatore 641112, India
| | - Alessandro Pegoretti
- Department of Industrial Engineering, University of Trento, Via Sommarive 9, 38123 Trento, Italy
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Candau N, Fernandes JPC, Vasmer E, Maspoch ML. Cellulose nanocrystals as nucleating agents for the strain induced crystallization in natural rubber. SOFT MATTER 2022; 18:8663-8674. [PMID: 36349700 DOI: 10.1039/d2sm01291j] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Vulcanized natural rubber (NR)/cellulose nanocrystals (CNC) composites with a CNC content of up to 5 wt% using physical blending and dicumyl peroxide crosslinking were prepared. The tensile properties were investigated at slow and high strain rates. The slow strain rate tests revealed an increase of the elastic modulus concomitant with a decrease of strain at the crystallization onset while increasing the CNC fraction. The high strain rate tests performed near adiabatic conditions demonstrated the ability of the CNC to improve the elastocaloric properties of the NR matrix, with an increase of 30% and 15% of heating and cooling capacities, respectively, in the presence of 3 wt% CNC. Such results were ascribed to (i) a higher thermoelastic effect, due to strain amplification in the NR matrix in the presence of CNC and (ii) a nucleating effect of the CNC on strain induced crystallization. This series of materials can be proposed as a promising eco-friendly alternative to conventional carbon black filled rubber as potential green elastocaloric materials (heating pump, cooling machines).
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Affiliation(s)
- Nicolas Candau
- Centre Català del Plàstic (CCP) - Universitat Politècnica de Catalunya Barcelona Tech (EEBE-UPC), Av. D'Eduard Maristany, 16, 08019, Spain.
| | | | - Emilien Vasmer
- Centre Català del Plàstic (CCP) - Universitat Politècnica de Catalunya Barcelona Tech (EEBE-UPC), Av. D'Eduard Maristany, 16, 08019, Spain.
| | - Maria Lluisa Maspoch
- Centre Català del Plàstic (CCP) - Universitat Politècnica de Catalunya Barcelona Tech (EEBE-UPC), Av. D'Eduard Maristany, 16, 08019, Spain.
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Candau N, Vives E, Fernández AI, Maspoch ML. Elastocaloric effect in vulcanized natural rubber and natural/wastes rubber blends. POLYMER 2021. [DOI: 10.1016/j.polymer.2021.124309] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Nambiathodi V, Varghese S, Varghese N. Effect of latex reclaim on physico-mechanical and thermal properties of carbon black filled natural rubber/butadiene rubber composite. J RUBBER RES 2021; 24:641-650. [PMID: 34566496 PMCID: PMC8451391 DOI: 10.1007/s42464-021-00121-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Accepted: 09/09/2021] [Indexed: 11/04/2022]
Abstract
As a material having high rubber content, latex reclaim (white reclaim) has been used in the production of premium grade rubber products like tyres, retreading materials, etc. Introduction of latex reclaim (LR) is also an ideal method to reduce the cost of rubber products. In the present work, natural rubber (NR), butadiene rubber (BR), and latex reclaim (LR) combinations were prepared to develop cost efficient tread materials. LR was mixed with NR/BR at various proportions to produce tread materials which will comply with national specifications. The blends were prepared and the cure and mechanical properties were investigated. Results have indicated that the scorch time and cure time had decreased with the increase of reclaim loading. The mechanical properties like tensile strength, tear strength, abrasion resistance decrease with the increase in the LR content. It was found that 70–80% of the mechanical properties were retained even after addition of 30 phr of LR. The thermal behaviour and activation energy of NR/BR/LR system was investigated using thermogravimetry TGA analysis and increased activation energy showed that the thermal stability has increased when the amount of LR is high. SEM studies had indicated the morphology change due to the viscosity mismatch between NR and BR especially in the presence of LR.
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Affiliation(s)
- Vaishak Nambiathodi
- Technical Consultancy Division, Rubber Research Institute of India, Rubber Board P.O., Kottayam, 686009 Kerala India
| | - Siby Varghese
- Technical Consultancy Division, Rubber Research Institute of India, Rubber Board P.O., Kottayam, 686009 Kerala India
| | - Neethu Varghese
- Technical Consultancy Division, Rubber Research Institute of India, Rubber Board P.O., Kottayam, 686009 Kerala India
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Detailed Study on the Mechanical Properties and Activation Energy of Natural Rubber/Chloroprene Rubber Blends during Aging Processes. J CHEM-NY 2020. [DOI: 10.1155/2020/7064934] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Selection of a suitable thermal aging process could render desirable mechanical properties of the rubbers or blended rubbers. In this work, the effect of the aging processes on the mechanical properties and activation energies of natural rubbers (NR) and NR/chloroprene rubbers (CR) blends with low CR contents (5–10%) was investigated. Three aging processes including heat aging (at 110°C for 22 hours), mechanical aging (under dynamic loading to 140% strain for 16000 cycles), and complex aging (heat and mechanical aging) were studied. The results revealed that the compatibility of CR in natural rubber matrix had a significant effect on the dynamic properties of the blended rubber and negligible effect on the static properties. The changes in activation energies of the blended rubber during aging processes were calculated using Arrhenius relation. The calculated changes (ΔUc, ΔUd, and ΔUT) in activation energies were consistent with the results of mechanical properties of the blended rubber. Interestingly, the change in activation energies using complex aging conditions (ΔUc) was mostly equal to the total changes in activation energies calculated separately from heat aging (ΔUT) and mechanical aging (ΔUd) conditions. This indicates that, in complex aging conditions, the heat and dynamic loading factors act independently on the properties of the blended rubber.
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The effect of metal oxide on the cure, morphology, thermal and mechanical characteristics of chloroprene and butadiene rubber blends. Polym Bull (Berl) 2020. [DOI: 10.1007/s00289-019-02964-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Abstract
This paper discusses the role of metal oxides (MeO) in the cross-linking process and useful properties of chloroprene and butadiene rubber (CR/BR) blends. Iron(III) oxide (Fe2O3), iron(II,III) oxide (Fe3O4), silver(I) oxide (Ag2O) or zinc oxide were used. It has found that every proposed metal oxide can be used as a cross-linking agent of the CR/BR blends. The degree of cross-linking was evaluated by means of vulcametric parameters, equilibrium swelling in selected solvents and Mooney–Rivlin elasticity constants. The properties of the cured CR/BR products, such as tensile strength, stress at elongation, tension set under constant elongation and compression set, were also investigated. The results revealed that all CR/BR/MeO vulcanizates were characterized by a high cross-linking degree and satisfying mechanical properties. The most important advantage of obtained rubber goods is very high resistance to flame. The increase in the oxygen index value for the CR/BR/Fe2O3, CR/BR/Fe3O4 and CR/BR/Ag2O vulcanizates compared to the standard cross-linked chloroprene rubber showed that presented metal oxides provided a positive effect on the resistance to flame of the new CR/BR/MeO composites. Satisfactory properties of the studied blends are related to the presence of the interelastomer bonding of both rubbers in the compositions.
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