Thesis (M.Sc.)--Chulalongkorn University, 2010

In this study, the shrink film based on LDPE and NR (reclaimed rubber (RR) and natural rubber (NR) latex) blends was prepared by internal mixer. The effect of NR types and NR contents to shrink film properties were investigated. The results indicated that the RR was not suitable to use for shrink film because RR/LDPE films were rough surface, while the NR/LDPE films were smooth surface. Various properties of NR/LDPE films i.e., physical, crystallinity, morphology, dynamic mechanical, mechanical, thermal properties and shrinkability were also investigated. The results indicated that the increasing NR latex contents did not affect the clarity but affected the color of NR/LDPE films. The crystallization temperature (Tc) of NR/LDPE films was lower than that of neat LDPE, resulting in the increase ability of crystallization of NR/LDPE film. The increase of crystallinity, the increase of shrinkability of NR/LDPE film was obtained. The tensile strength and hardness of NR/LDPE films showed decreased with increasing NR latex contents. However, the impact resistance and tear strength increased with the increase of NR latex content up to 5 phr and then their values decreased beyond this content. These results indicated that the phase separation was occurred between LDPE and NR in the blend. These results could be confirmed by measuring dynamic mechanical analysis (DMA) and scanning electron microscopy (SEM).