Bio-based thermoplastic vulcanizates from natural rubber (bioplastic/NR)

Abstract

Thermoplastic vulcanizates (TPV) is a class of thermoplastic elastomer of which generally consists of polyolefin phase, mainly PP or PE, with dynamically cured elastomer phase such as EPDM. The elastomer should be well dispersed in the polyolefin matrix which facilitates thermoplastic like processing of elastomer. The properties of TPV are mainly governed by properties of thermoplastic matrix and vulcanized rubber phases including curing system used for dynamic vulcanization. As environmental problem has been an important issue, application of bioplastic in thermoplastic elastomer is an interesting issue. The blending of NR with various has been studied in our work and the system should classify as bioplastics/NR. Dynamic vulcanization of NR during melt blending of NR with various bioplastics was also studied. In this report, the melt blending system of PBAT/NR; PCL/NR and PBS/NR were carried out. The batch melt blending in an internal mixer were performed with various NR and bioplastics compositions. Dynamic vulcanization of NR phase, using Luperox® 101 as curing agent, was also occurred in the mixer during melt blending. Except for PBS/NR TPV system where dicumyl peroxide was used as curing agent. This will advantage for foam preparation in further foaming step. The results showed that PBAT/NR TPV with NR content as high as 70% possessed tension set less than 20% and elongation at break under tension was higher than 600%. For PCL/NR system at the same composition, the tension set was also found at 20%, elongation at break under tension was as high as 1000%. The TPV system of PBAT/NR and PCL/NR were also extrudable. Tension set for NR/PBS TPV system was found at about 30% and the elongation at break under tension was about 600%. From the mentioned basic properties of biobased TPV in our researches, it presents that they could propose the promising qualified TPV, in term of reprocess ability and advantage for the sake of biodegradability. Note: PBAT, PCL and PBS stand for poly(butylene adipate-co-terepthalate, polycarprolactone, and poly(butylene succinate) respectively.