The Modification Research Of PLA/PBS Blends

Polylactic acid (PLA) which is a kind of the biodegradable plastics is derived from renewable agricultural resources (such as corn starch), and it has a wide application potential in the field of the environmentally friendly packaging. However, PLA has some deficiencies that are the poor crystallization ability and the poor toughness. Blending with poly butylene succinate (PBS) which is another biodegradable plastics is one way to improve the toughness of PLA. But, due to the weak compatibility of the blends of PLA/PBS, the mechanical performance of the blends of PLA/PBS is not satisfactory. In this thesis, we respectively studied the effect of the properties of the blends of PLA/PBS adding the compatibilizer or the cross-linking agent.First, we prepared a series of different compositions of PLA/PBS blends by melt blending, and we studied their compatibility, rheological and mechanical properties. In order to improve the compatibility for the next step, we choose a benchmark component that had the better overall performance.Next, this paper introduced the triphenyl phosphite (TPPi) to the PLA/PBS blends. And we studied the effect of compatibility,the crystallization and mechanical properties of the blends with different amounts.Finally, we studied the effect of the performance of the PLA/PBS blends through introduction of the dicumyl peroxide(DCP) which was a kind of the cross-linking agents. And we had a deeper study, we added talcum to improve defects of the blends system which were unevenly distributed and slow crystallization rate, and studied the impact of the blends system on the crystallization rate and mechanical properties with the combined effect of Talc and DCP.The following conclusions were gotten by studying of this subject:(1) The result that the PLA/PBS blend was the incompatible system was verified, and we confirmed the base composition 75/25(wt%) which had better flow properties, processing and mechanical properties. (2) By comparison, we found that adding TPPi could improve two dispersion phase(the average size of the dispersed phase and uniformity),but it also made processing properties and mechanical performance worse; adding DCP could not improve two dispersion phase, but it could make processing properties and mechanical performance better, and it made the elongation at break of blends was improved greatly.(3) Adding DCP could occur chemical reaction between the matrix, and the reaction made chain longer that slowed down the crystallization rate. When we added the nucleating agent(Talc),it accelerated the crystallization rate of the blends and improve the elongation at break, but it was almost no impact on the bending properties.