Study On Biodegradable Films Of Poly(lactic Acid) Modified Materials

This paper adopts A, ESO, ATBC as plasticizers, PBAT, PBS, PPC as flexibilizers, Talc, MMT CaCO₃ as fillers and PLA to molten blending in mixer. Then the blend conduct hot-pressing by plate vulcanizing machine. The tensile properties, impact properties, thermal properties, fracture surface morphology and crystal morphology were tested by electronic tensile machine, e-impact testing machine, TGA / DSC thermal analysis, scanning electron microscopy, harper torque rheometer, X-ray diffraction, hot stag polarized optical microscope. The relationships between toughened PLA stress-strain behaviors,thermal properties, crystallization properties, microstructure and the kinds and content of plastieizers, flexibilizers , inorganic fillers were studied in order to optimize the processing technology of the flexible PLA film. Secondly, some film mechanical properties tests(tensile strength, elongation at break, tensile modulus, tearing strength) were carried out to discover that the PLA film manufactured by blowing molding in single-screw extruder satisfies requirements of mechanical properties in practical application.The conclusions were summarized from this paper as following:(1) ESO, ATBC and A have different degrees plasticization effects on PLA. Compared with the ESO and ATBC, A not only greatly enhance the PLA's elongation, but also has good thermal stability and resistance to migration. A reduced the PLA's glass transition temperature, cold crystallization temperature and melting point, improved the PLA's crystallinity and made the crystal of the material more stable.(2) PBAT,PBS and PPC have different degrees toughen effects on PLA, The elongation at break and notched impact strength of toughed PLA have different degrees improvements, and PBAT has the best toughening effect on the PLA. PBAT, PBS and the PPC all have poor compatibility with the PLA. Relatively, PBAT's compatibility is better with the PLA, but PPC is the worst one.(3) The elongation at break of PLA mixed with CaCO₃, MMT and Talc reduced, respectively. Compared with the MMT and CaCO₃, Talc's distribution is more uniform in the PLA matrix. Talc improved the tensile strength of PLA, greatly reduced the cold crystallization temperature of PLA, significantly increased the melting point and crystallinity of PLA. Relative to the other two filled PLA blends,the PLA / Talc blend has higher melt viscosity.(4) Compared with the PBS and PPC, PBAT significantly reduced the tensile modulus of PLA films, but improved the tear strength of the film. PBS can still make the PLA film maintain a high tensile strength. Talc can make the tensile strength, tear resistance and flexible of PLA film deteriorate. When its content is not high, it can improve the elongation at break of PLA films. Talc reduced the PLA film plasticizer migration rate, improved weight loss temperature of the films.(5) The thermal stability of PLA film become poor after adding ESO and ATBC, but the thermal stability of A plasticized PLA film is good. Among the three plasticizers, A has the best resistance to migration. Talc can improve the stability and durability of plasticizers in PLA film, meanwhile, improving the thermal stability of PLA films.(6) The biodegradable PLA film manufactured by this study could partly replace the general polyolefin film and could be widely used as daily package film or bags.