Summary
With the project, we proposed novel thermoplastic elastomers (TPE) and rubber composites containing high added value wastes rubber (GTR). First, the dynamic vulcanization of PLA-based thermoplastic elastomers using GTR show a co-continuous morphology of PLA and rubber permitted by the encapsulation of the GTR into a fresh natural rubber phase. This allowed to obtain a PLA based TPE with highly improved toughening as well as good shape memory properties that are of interest for the design of eco-friendly high impact pieces in the automotive industry. Second, the vulcanization of natural rubber-based composites using GTR showed a nucleation ability of the GTR on the strain induced crystallization of the rubber matrix and consequently on its elastocaloric capacity. Such materials can be used as efficient elastocaloric material in a heating/cooling technology whose major interests are the low mechanical energy required to cyclically deform the material and its eco-friendly nature.
Result description
The project presents strategies of materials design incorporating wastes rubber as high added value. First, series of PLA (Polylactic Acid)/natural rubber (NR)/ground tire rubber (GTR) were melt-blended via dynamic vulcanization using dicumyl peroxide (DCP). Swelling, dissolution and SEM images of etched fracture surface reveal that vulcanized blends (>3 wt.% DCP) show co-continuous rubber/PLA morphology whose tensile toughness is increased of 12.5 as compared to those of the pristine PLA. A DCP content of 3-3.75 wt.% provide the same toughness, impact strength, shape memory properties as compared to equivalent binary PLA/NR blends. Second, vulcanized NR/GTR rubber blends were prepared and their elastocaloric (eC) properties analysed. Blends using 20 wt.% of GTR resulted in a slight improvement of heat exchanges (+10%), that we ascribed to a high thermoelastic effect and a high ability of the natural rubber matrix to crystallize due to a nucleation ability of the GTR. The materials coefficient of performance was found equal 3.8 for the blend containing 20 wt.% of wastes. Their eC abilities make these blends good candidates for application such as heating/cooling machines.
Addressing target audiences and expressing needs
- Grants and Subsidies
We developed scientific and technological R&D results such as experimental methods for the design of thermoplastic elastomers and rubber composites. We demonstrated proof of concepts for some of the targeted applications, such as the elastocaloric effect. We are looking for fellowship to advance our research, research and technology organisations and academic collaborations, private investors, public or private funding institutions, that would help us to further design of heating/cooling machines based on the elastocaloric performance of our materials.
- Public or private funding institutions
- Research and Technology Organisations
- Private Investors
R&D, Technology and Innovation aspects
Proof of concept: The experimental proof of concept has been achieved thanks to the processing of natural rubber-based composites using wastes and natural particles as well as the characterization of their elastocaloric effect. Natural/waste rubber composites with wastes content from 0 to 30 wt.% have been processed by physical blending and then vulcanized in a hot press. These composites have been cyclically deformed on a laboratory tensile test machine at high strain (3000 mm/min) and the temperature changes on the specimen surface have been measured by using an infrared camera. The results show that the composites containing 20 wt.% of wastes show the best heating/cooling performance with a maximum measured temperature at 32.0 °C and a minimum at 12.8 °C, i.e., around +10/-10 °C around room temperature, and hence showing great potential for heating/cooling/refrigerating (H/C/R) applications using eco-friendly materials.
Prototype: The validation of the technology is under development thanks to the current development of an autonomous prototype able to multi-axially deform a rubber specimen. The work is in progress about the integration of circulating fluid to permit heating/cooling exchange between the materials and the environment (room).
Published papers provide the full experimental methods and materials composition to make our results replicable by a laboratory owing similar materials and machines.
Result submitted to Horizon Results Platform by AGENCIA PER A LA COMPETITIVITAT DE LA EMPRESA
