Study On Processing Behavior Of Poly(Lactic Acid)

In recent years, biodegradable polymer has attracted great interest for its gomerod degradation and biocompatibility. As an aliphatic polyester, poly(lactic acid)(PLA) has some disadvantages such as low melt strength, poor thermal stability and brittleness which blocks its wide application as general plactics. Aiming at these disadvantages of PLA, in this paper, we studied the method to modify PLA by means of chain extension, crosslinking, nanocomposite and melting blend with other polymers, which will widen the common use of PLA. This study consists of three systems. PLA system, PLA/poly(butylenes succinate)(PBS) blends and PL A/grafts/PBS blends, where the grafts are PLA-g-GMA and PBS-g-GMA, as the compatibilizers of PLA/PBS blends.The effects of several factors, such as the content of the additives and the compatibilizers on the mechanical, rheological and thermal properties of the materials were systematically investigated. The relationship between phase morphology and properties of the materials were also studied by SEM. DMA. DSC, TGA and FTIR.In the system of PLA, the mechanical and rheological properties have been improved with the addition of TPP. TDI. DCP and OMMT. and maintained a good heat resistance. The experiment results also showed that the addition of TPP and TDI could increase the melt viscosity of PLA. TGA results showed that2phr OMMT can improve the thermal decomposition temperature, and low content of OMMT significantly improved the tensile strength and elongation at break of PLA. nanocomposites exhibit the characteristics of strong and tough.In the system of PLA/PBS blends, the mechanical and rheological properties have been improved with the addition of DCP and OMMT, and maintained a good heat resistance. The results showed that, the addition of DCP improved the equilibrium torque of PLA/PBS blends. MFR test indicated that with the increase of DCP content, the MFR of PLA/PBS blends decreased, the melt viscosity was improved. The addition of OMMT significantly improved the elongation at break of PLA/PBS blends, at the same time the tensile strength did not decrease a lot. The elongation ar break was increased about1500%. and narrow neck could be seen obviousely during the tensile test.In the system of PLA/grafts/PBS blends, the compatibilizers, PLA-g-GMA and PBS-g-GMA were prepared by melt-grafting. FTIR analysis and back titration confirmed the presence of graft reaction. The largest graft ratio of PLA-g-GMA and PBS-g-GMA were2.53%and2.81%respectively. Comparing the properties of neat PLA, PLA/PBS blends, PLA/PLA-g-GMA/PBS and PLA/PBS-g-GMA/PBS, the addition of PLA-g-GMA and PBS-g-GMA improved the compatibility of PLA and PBS.