Preparation And Properties Of LLDPE/Modified Nano-ZnO Composite Films

LLDPE is widely used in film field, but because of its low strength, the application of LLDPE is limited, and nano-ZnO can show outstanding effect on the enhancing strength, toughness, heat resistance of polymer, and have the high antibacterial performance and UV-resistances. Thus LLDPE and nano-ZnO were mixed according to a certain proportion, the comprehensive properties of LLDPE films will be improved and the composite films show a good development prospects.In the paper, titanate coupling agent was used as modification agent and water as solvent, LLDPE and nano-ZnO were mixed according to a certain proportion and composite films were prepared through melt blowing by Brabender extruder. The optimum conditions were determined through researching the influence of modification conditions of the nano-ZnO on the mechanics properties of the composites. The dispersion of modified nano-ZnOparticles in LLDPE matrix was observed by SEM, the influence of the content of modified nano-ZnO on the crystallization behavior, mechanical properties of composite films, rheological properties of composites and vicat softening point were separately studied by POM, DSC, universal test machine controlled by an electronic computer, capillary rheometer, rotational rheometer, HAAKE torque rheometer and vicat softening point tester. The antibacterial performance and the UV-resistances of composite films were separately studied, and the processing technology conditions were optimized.The results for surface-modification of the nano-ZnO indicated that the modification effects of the nano-ZnO is best, when the titanate coupling agent content was 4wt%, the modified temperature was 60℃, the modified time was 1h, water acted as solvent and the ratio of water/nano-ZnO was 13/1.For the composite films, the results show that when the nano-ZnO’s content was 0.3wt%, nano-ZnO uniformly dispersed in LLDPE matrix. The appropriate amount of nano-ZnO acted as nucleators in the LLDPE matrix and improved the crystallinity of LLDPE. The mechanical properties and vicat softening temperature of the composite films can be improved effectively with an appropriate amount of nano-ZnO, but the addition of modified nano-ZnO slightly reduced flowability of the composites. The antibacterial rate and absorbance of the composite films increased with an increase of the content of d nano-ZnO. At the same time, adding a certain amount of nucleating agent and properly extending the mixing time of the master batch, properly rising the temperatures of blowning films all could enhance the mechanical properties of the composite films.