Effect of 1,3,5-trialkyl-benzenetricarboxylamide on the Crystallization of Poly (lactic acid)

A series of 1,3,5-trialkyl-benzenetricarboxylamides (BTA-Rs) with different side-chain lengths of n-alkyl are synthesized to use as nucleating agents of poly (lactic acid) (PLA). Crystallization rate of PLA is detailed discussed in nonisothermal melt-crystallization with addition of the synthesized nucleating agents. Among these BTA-Rs, BTA-n-butyl (BTA-nBu) shows the most excellent nucleation ability for PLA. The influences of BTA-nBu on the nonisothermal melt-crystallization and cold-crystallization from the glassy state, isothermal crystallization, crystalline structure, and spherulite morphology of PLA are investigated. It is found that 0.8 wt % is the optimal weight fraction of BTA-nBu to improve the crystallization of PLA. In the case of isothermal melt-crystallization from melt, the addition of BTA-nBu shortens the crystallization half-time and speeds up the crystallization rate of PLA with no discernible effect on the crystalline structure. Besides, BTA-nBu nucleated PLA exhibits smaller spherulites size and larger nucleation density than that of pure PLA