Study On Preparation And Properties Of LDPE Composite Film

In this paper, by means of melt blending and extrusion blowing film forming process, the low density polyethylene (LDPE)/thermoplastie elastomer (TPE) blend films and LDPE/inorganic particle composite films were prepared. The melt rheological properties, mechanical properties and moisture permeability of films were investigated.The varieties of spherulite morphology of composite films were observed by polarizing microscope (POM). Meanwhile, the crystallization properties were investigated by differential scanning calorimeter (DSC), and the relationship between moisture permeation and crystallization properties was analyzed. The details were as follows:By respectively selecting and blending the zeolite molecular sieve (ZMS), SiO2with LDPE, the LDPE composite films were prepared. The results show that with increasing content of ZMS, the mechanical properties of the composite films present a little bit increasing initially and then decreasing, the capacity of moisture permeability increases gradually. When adding Coupling agent in the composite films, the profile of the mechanical properties are similar to the system without coupling agent treated; The moisture permeability are relatively smaller than the system without coupling agent treated. When adding the dispersing agent in the composite films, the tensile strength and tear strength of the composite films present a little bit increasing initially and then decreasing, meanwhile the0.3phr content of dispersing agent is better. As the amount of SiO2(partile size3μm) increasing, the mechanical properties reduce. However adding SiO2with coupling agent treated, the profile of the mechanical properties of the LDPE composite films show the peak shape, and reach the maximum at SiO2content9phr. Comparison SiO2with different particle size, with the particle size of SiO2increasing, the mechanical properties of LDPE composite film increase initially then decrease. The particle size of SiO2around7μm is appropriate.By selecting with the ethylene vinyl acetate(EVA) and ethylene methacrylic acid(EMAA) copolymer respectively, the LDPE blend films were prepared. The results show that with increasing content of EVA, the tensile strength are decreased, however the elongation at break, tear strength and moisture permeability are increased gradually; The mechanical properties and the moisture permeability of LDPE/EMAA films are similar to the performance of LDPE/EVA blend films.With adding the POE-g-MAH, the mechanical properties and moisture permeability of the LDPE/EVA blend films showed peak profile, meanwhile the appropriate content of POE-g-MAH is around2phr.With adding of the LDPE-g-MAH. the mechanical properties and moisture permeability of the LDPE/EMAA blend membranes showed peak profile, meanwhile the content of LDPR-g-MAH is around1phr.The observation of POM shows that with the addition of ZMS, SiO2EVA or EMAA, the formation of spherulite size getting smaller, but more quantity, which can help enhance moisture permeability of LDPE film.By means of DSC method, the non-isothermal crystallization kinetics of LDPE composite films was investigated. By selecting data processing method of Mo ZS and modified Jeziorny, the results indicate that the ZMS, SiO2EVA or EMAA play a role of heterogeneous nucleation agent in the process of crystallization and increased the crystalline rate of LDPE. Especially the LDPE/ZMS composite film with Dispersing agent, there was outstanding heterogeneous nucleation effect and faster crystalline rate, which is corresponding to the result in properties with higher moisture permeability.