Dynamically vulcanized polylactic acid/natural rubber/waste rubber blends: effect of the rubber content

The reduction in the production of conventional polymers based on crude oil by using bio-based plastics and by valorizing rubber wastes is an essential route to reverse the negative impact of the polymer industry on the environment. To contribute to this challenge, we prepared polylactic acid (PLA)/natural rubber (NR)/ground tyre rubber (GTR) blends via dynamic vulcanization. The PLA/NR/GTR blends with a rubber content and above 30 wt% show a continuous rubber phase (NR/GTR) where the GTR particles are encapsulated into the NR matrix as shown by dissolution experiment in dichloromethane and microscopy images on etched samples. PLA/NR/GTR blends with 30 wt% of rubber show a tensile modulus of 1.3 GPa, a tensile toughness of 8.3 MJ m(-3) and an impact strength of 260 kJ m(-2) higher than 1.1 GPa, 4.2 MJ m(-3) and 160 kJ m(-2), respectively, for the binary PLA/NR blend. The presence of reinforcing carbon black particles in the GTR as well as their partially vulcanized state of the GTR before dynamic vulcanization may result in a higher cross-linking level of the rubber phase in the ternary blends as compared to binary blends that likely contribute to concomitantly improve tensile modulus, toughness and impact tensile strength. [GRAPHICS] .

Automated summary

Reducing the production of conventional polymers based on crude oil through the use of bio-based plastics and valorizing rubber wastes is crucial for mitigating the negative environmental impact of the polymer industry. In this study, PLA/NR/GTR blends were prepared, with GTR particles encapsulated in the NR matrix, resulting in improved mechanical properties.