Processing and Mechanical Properties of Natural Rubber/Chitosan/Poly(3-hydroxybutyrate) Blends

In an attempt to improve the properties of natural rubber-based medical products, natural rubber (NR) was blended with chitosan (CS) and poly(3-hydroxybutyrate) (PHB) in an laboratory type internal mixer, with the total amount of CS and PHB is of 1, 3, 5, 10, 15 and 20 parts per hundred rubber (phr) , and CS and PHB is of a ratio of 1:1. The testing for processing properties of NR/CS/PHB compounds showed that the Mooney viscosity of NR/CS/PHB compounds increased with the addition of 1.0 phr CS/PHB and then decreased with increase in CS/PHB content, but the Mooney viscosity of each NR/CS/PHB compound was higher than that of NR compound; the minimum torque (ML) increased only slightly, while the maximum torque (MH) increased gradually, with increase in NR/CS/PHB content; the scorching tendency of NR/CS/PHB compounds increased with the increase in CS/PHB content; the optimum cure time (t90) decreased firstly, then increased with increase in CS/PHB content, and was not greatly different from that of NR compound. The results of mechanical properties of NR/CS/PHB vulcanizates showed that the tensile strength and elongation at break deceased, whereas the 300% and 500% moduli, tear strength and hardness increased, with increase in CS/PHB content.