The Effect of Rubber on Morphology, Thermal Properties and Mechanical Properties of PLA/NR and PLA/ENR Blends

The biodegradable thermoplastic poly(lactic acid) (PLA) that has restricted its application due to its high brittleness and poor crystallization behavior. Toughness properties of PLA can be developed by blending with natural rubber (NR) and epoxidized natural rubber (ENR). Blending PLA with NR and ENR were prepared at various compositions from 0-30% by weight. Morphology, crystallization behavior, thermal stability and mechanical properties of blends were investigated. The rubber phase of NR was dispersed in the continuous PLA matrix with small droplet. Increasing of NR content, the large droplet size of rubber will be resulted. However, the partially compatible between PLA and ENR was responsible for coarse surface, i.e. very fine particles of ENR dispersion. Incorporation of NR would enhance the crystallization ability of PLA better than ENR but thermal stability was decreased with both rubbers. The ductility of PLA has been significantly improved by blending with NR. The amount of NR at 10% weight seems to give optimum property. At high content of NR, it seems to suffer tensile properties. In the case of the addition of ENR, it reduced crystallization ability, thermal resistance and tensile properties of the blend.