Study On The Moisture Permeability And Migration Properties Of Plasticized Polylactide Acid Film

With the rapid economic development, resource and environment issues have become increasingly prominent. polylactide acid (PLA) As a fully biodegradable biomass materials which attracted more and more people's attention. PLA is natural Poor flexibility that difficult processing into flexible film. so carry out effective plasticizer to modification PLA is particularly important. And requires plasticizers must be efficient, non-toxic, low migration rate, etc. In this work chose the citric ester, with the solution casting method, prepared PLA-4060D/citric ester and PLA-4032D/citric ester plasticized system as two kinds of film. The changes of phase structure and grass transition temperature were tested by SEM and DSC. The results showed that all film samples were Homogeneous structure, the Tg of plasticized film linearly decreased by the increased of plasticizer contents. Then focused studying on the water vapor transpermition ratio (WVTR) and migration ratio of plasticized PLA films. The study found that WVTR linearly increased by the plasticizer contents increasing. Moreover, the high temperature migration ratio of plasticizers relation to the molecular weight, the larger migration ratio was, as well as the migration speed do. the higher molecular weight was, the lower migration ratio was. At high temperature, the migration ratio of PLA-4032D/citric ester plasticized system was higher than that of PLA-4060D/citric ester system, the reason was at the temperature 100℃PLA-4032D would be crystalline. Moreover, this work studied the plasticizers influence on the hydrophilicity, the result was contact angle of PLA-4060D/citric ester system decreased obviously, but not the PLA-4032D/citric ester system. At last, simply study the influence of draw ratio on the WVTR of blowing PLA film,I also found that WVTR was inverse relationship to the draw ratio.