Biodegradable thermoplastic natural rubber based on natural rubber and thermoplastic starch blends

Biodegradable thermoplastic elastomer was prepared by blending natural rubber (NR) and thermoplastic starch (TPS) blends by both dynamic vulcanization (DV) and simple blend (SB) techniques. The main purpose was to enhance the biodegradability, physical properties and heat stability of this type of TPNR. The NR/TPS blends were dynamically cured with three alternative sulfur curing systems: conventional, semi-efficient and efficient vulcanization systems. The results showed that the dynamic curing gave NR/TPS blends superior modulus, tensile strength, thermal resistance and higher dynamic properties together with lower tension set when compared with the SB with no added vulcanizing agent. Furthermore, the dynamically cured natural rubber/thermoplastic starch with semi-efficient cure system showed higher mechanical, dynamic and thermal properties than the blends cured by the conventional and efficient systems. It is attributed to the best balance for crosslinking reactions with thermal breakdown of the sulfidic linkages during preparation. Moreover, the smallest dispersed NR domains were observed in the DV cured with semi-efficient system. Also, finely dispersion crosslinked networks in rubber particles in the TPS main constituent of DV gave comparatively higher resistance to biodegradation and accelerated weathering.

Automated summary

Biodegradable thermoplastic elastomer was prepared by blending natural rubber and thermoplastic starch using dynamic vulcanization and simple blend techniques. The dynamic curing process resulted in NR/TPS blends with superior mechanical, thermal, and dynamic properties compared to the simple blend. Among three alternative sulfur curing systems, the semi-efficient cure system showed the highest performance, attributed to the balanced crosslinking reactions and thermal breakdown of sulfidic linkages. The DV process with semi-efficient system also achieved the smallest dispersed NR domains and finely dispersed crosslinked networks, providing higher resistance to biodegradation and accelerated weathering.