Green Biodegradable Thermoplastic Natural Rubber Based on Epoxidized Natural Rubber and Poly(butylene succinate) Blends: Influence of Blend Proportions

Abstract

Green biodegradable thermoplastic natural rubber based on epoxidized natural rubber (ENR) and poly(butylene succinate) (PBS) blends was prepared via simple blend (SB) or via dynamic vulcanization (DV). Influence of blend proportions of ENR and PBS on morphological, dynamic, mechanical, dynamic mechanical, thermal properties, and water absorption together with biodegradability were investigated. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were also used to assess phase morphologies in the ENR/PBS blends. It was found that the ENR/PBS simple blend had co-continuous phase structure, while the dynamically cured ENR/PBS blend (DV) has spherical micron-sized crosslinked ENR particles dispersed in the PBS matrix. In addition, the particle size of vulcanized ENR domains of DV and the grain size of ENR and PBS phases in the simple blend decreased with increasing PBS content up to 50 wt%. This might be caused by interfacial adhesion effects between the phases. However, increasing the ENR fraction to 70 wt% caused increasing of elasticity in terms of shear viscosity, shear modulus, storage modulus, together with elongation at break, and tension set. It was also found that mechanical and thermal properties as well as biodegradability of dynamically cured ENR/PBS blends were better than for the simple blend counterparts, That is, the lowest biodegradability, as indicated by the least weight loss, is seen for the 50/50 ENR-25/PBS simple blend (about 1.2%) and dynamic vulcanizate (about 0.6%).