Physical properties of epoxidized natural rubber/chitosan blends

The objective of this study was to develop natural rubber/chitosan (NR/CS) films from rubber latex and CS solution at different rubber to CS ratios of 100/0, 90/10, 80/20, 70/30, 60/40, and 50/50 using a solution plating method. The study was divided into two parts. In the first part, the NR/CS films were prepared from pristine NR latex with and without sulfur curing agents. The study showed the cured NR/CS films showed higher swelling resistance and tensile strength (TS) than the uncured films. After thermal aging, the TS of the uncured NR/CS films decreased while that of the cured ones increased. This might be due to the further thermal curing during aging. Both uncured and cured NR/CS films showed two decomposition peaks. One at low temperature was attributed to the decomposition of CS whereas the one at higher temperature was due to the decomposition of NR. The NR/CS film had higher oxygen permeability (OP) than the pure NR and CS film. For the second part, the films were prepared from epoxidized NR latex (ENR) with 22% epoxidation in the presence of maleic anhydride (MA). The result showed that the ENR/CS film can be obtained only when adding MA. It was believed that MA did not only crosslink ENR chains but also chemically bonded ENR and CS chains, thus dismissing phase separation. The ENR/CS film at the ratio of 90/10 with MA of 2 phr showed highest TS. After thermal aging, the films at the ENR/CS ratios of 70/30, 60/40 and 50/50 with MA of 3 phr had higher TS. This might be due to the further thermal curing during aging. Thermal decomposition testing showed that the ENR/CS film without phase separation showed only one decomposition peak. Moreover, it was found that the ENR/CS film had lower OP than the pure ENR and CS film.