Thermal Behaviour Research Of PLA/OMMT Composites

Poly(lactic acid)is one of current polymer materials,which comes from reproducible plant resouces and can be processed by ways like conventional plastics,and also has excellent degradation property what conventional plastics donot have;lactic acid have a extensive source,it can be obtained from some fully renewable materials such as sugarbeet,sugarcane and so on,while conventional plastics can only be got from fossil fuels.However,there still have aspects that need improvements,such as mechanical properties,thermal stability and crystalline properties.In this paper,PLA/OMMT composite has been prepared by means of masterbatch method.First,masterbatch in which OMMT percentage is10%was prepared through melt intercalation by twin-screw extruder,then specimen PM1,PM3and PM5was prepared in the same way as masterbatch while OMMT percentage are1%,3%and5%,respectively.Pure PLA was also prepared as reference specimen PMO.Through the characterization of mechanical properties of composites,it was learned that,the mechanical strength of specimen PM1,PM3and PM5are higher than PMO,respectively.The flexural strength of PM1,PM3and PM5are all higher than PMO with the value of48.8%,107.7%and3.3%,respectively.The improvement of mechanical properties is owing to OMMT working as nucleating agent,which increased crystallinity of PLA and refined crystalline grain.DSC test results revealed that cold crystallization phenomena of PLA appeared in heating process,and there were no crystallization in cooling process after melting points.The crystallinity of PMO,PM1,PM3and PM5were3.2%,4.6%,5.6%and4.8%,respectively.Thermal decomposition of PLA revealed that the decomposed temperature of PM1,PM3and PM5are obviously higher than pure PLA.The increased thermal decomposed temperature meant that OMMT can improve the thermal stability of PLA. Non-isothermal kinetic research of PLA revealed that with the increase of heating rate the thermal decomposition temperature of PLA moved to a higher degree.The kinetic parameters of decomposition have been calculated by employing OFW and Friedman methods.These data of initial values had been optimized,and the reaction model had been derived by means of linear regression,finally.The resoults showed that the decompotision mode of PLA and composites all were Cn mode,Aâ†'B.The prediction of service life of PLA and PLA composites revealed that the service lives of sample PM0were outclassed by PM1,PM3and PM5,and the comparation result of composites were PM1>PM5>PM3.