Modification Of Polylactide Material On Toughening And Heat Resistant

In recent years, with the increasing depletion of oil resources, it’s significant to find an alternative materials instead of petroleum-based products. Researchers have paid more attention on polylactic acid (PLA) material, which is biodegradable material. PLA is used to the field of degradable plastics since1990s. PLA is now mainly used in household goods, industrial and agricultural supplies and biomedical products. Now, as general plastics, PLA still subject to certain restrictions, mainly due to its drawbacks, the most crucial two points:PLA is brittle with low elongation and poor impact resistance; thermal stability is insufficient, it will decrease the molecular weight even the process under the temperature of thermal decomposition.PLA has a high strength and modulus, but It is difficult to keep both toughness and transparency for modified PLA without compromising its tensile strength and biocompatibility. This paper introduced a new method that poly (L-lactide)(PLLA)/Methyl MQ Silicone Resin (Me-MQ) blends were prepared via a simple solvent evaporation method at various Me-MQ loadings in this research. Me-MQ, which is applied to the field of adhesives and personal care product, is a silane coupling agent with high transparency, strength and decomposition temperature. PLA blends with a low content of Me-MQ achieving toughness of PLA.Tensile test showed that the elongation at break of PLLA blends increased to67.9%and217.7%at the loadings of1and2wt%Me-MQ respectively. Meanwhile, the blend just decreased strength slightly, the amplitude of reducing are less than6%.The thermal property test showed that Me-MQ is helpful to enhance the decomposition temperature of the blend material. For the PLLA/Me-MQ blends, the onset of decomposition temperature (at weight loss of5%) are improved by about5,15,24and26℃w ith increasing the Me-MQ loading at1,2,4,6wt%, respectively.Besides, Me-MQ increases the storage modulus of the material, and the cold crystallization temperature is lower with the add of Me-MQ. UV-vis test showed the light transmittance of the films at the loadings of lwt%Me-MQ is almost the same as neat PLLA.Subsequently, in order to enhance the thermal stability of PLA material, stereocomplex of PLA is neened. The paper designed the modification of Me-MQ, and then modified Me-MQ reacts with L/D lactide through the ring-opening copolymerization. The branched copolymer of poly lactic acid polymer is prepared. At last, in order to get a stereocomplex of modified PLLA and PDLA, mixing L/D type and other quality. The melting point of material is reinforced through the test results of DSC. The melting point of Me-MQ-PLLA was170.4℃, Me-MQ-PDLA was167.8℃, while the stereocomplex (1:1) was224.6℃.Themelting point improved56℃.In addition, strength testing showed elongation at break of stereoregular composites is improved, increasing from the original3.47%to7.19%, the enhancement of breaking strength increased from60.3MPa to78.6MPa, the amplitude of increasing are more than30%.