Preparation of natural rubber (NR) latex/low density polyethylene (LDPE) blown film and its properties

Heat-shrink composite films based on LDPE and NR latex blends were prepared. The effect of varying the NR latex content on the physical, mechanical and dynamic properties and the heat-shrinkability of the composite films were investigated. The addition of NR latex into the LDPE films at up to 7.5 phr did not affect the clarity of the film but affected the color due to the β-carotene content of the NR latex. The degree of crystallinity of the LDPE/NR composite films increased with increasing NR latex content up to 7.5 phr, as did the tear strength and impact resistance up to a NR latex content of 5 phr. However, the tensile strength and hardness of the LDPE/NR composite films decreased with increasing NR latex content. The heat-shrinkability of LDPE films was improved by adding NR latex. A mechanism for the strain-induced crystallization of the LDPE/NR composite films during the blown film process is proposed.