Research On The Improvement Of Heat Resistance Of Poly Lactic Acid Material

With the aim to improve the heat-resistant property of the polylactic acid, this paper mainly carries on the research from the following three aspects:(1) The polylactic acid is blended with CD A which has rigid chain structure to improve its heat resistance. Because the blends is incompatible, CDA-g-PLA is prepared as a compatibilizer and the preparation process of it is also be investigated. The results shows that, with the addition of compatibilizer, the interface energy of the blends is reduced and the interfacial adhesion of the blends is increased,the compatibility of the blends is improved, tensile strength and impact strength is enhanced. The tensile strength increased from32.73MPa to41.12MPa, the impact strength was increased from4.23kJ/m2to5.44kJ/m2,Vicat softening temperature of PLA/CDA blends is increased from56℃to68℃,thermal properties is improved obviously.(2) The influence on resistant performance of poly lactic acid by the change of crystallization is researched in this paper, two methods were employed:adding different kinds of nucleating agent and adding trace plasticization agent. In this way, we studied the influence of different nucleating agent on the crystallization properties of polylactic acid, and the effect of different heat treatment conditions on the Vicat softening point of PLA. Using the New amide nucleating agent, TMC300, TMC306as the nucleating agent of PLA respectively, the results shows that, under the same temperature of110℃for10min, the crystallization of polylactic acid is increased to the maximum at18.6%by the addition of New amide nucleating agent. TCG is used as trace plasticizer of polylactic acid when their content are lower than2%, the result shows that, the Vicat softening point temperature of PLA is increased to the maximum at64.4℃when the plasticizer content is0.2%, which is much higher than that of pure PLA.(3) The influence of crosslinking reaction on the resistant performance of poly lactic acid is researched in this paper, the effect of the crosslinking and surface crosslinking poly lactic acid on the heat resistance of poly lactic acid are investigated respectively. With crosslinking, the melt index of poly lactic acid is significantly smaller, the hardness is increased from16.6HBW to21.3HBW, mechanical strength and size stability is improved obviously. After surface crosslinking, the Vicat softening temperature of poly lactic acid is137.21℃, which has been greatly improved compared with the pure polylactic acid(57.73℃).