Melting temperature, concentration and cooling rate dependent nucleating ability of a self assembly aryl amide nucleator on poly(lactic acid) crystallization
Abstract The self assembly behavior of N,N',N' tricyclohexyl 1,3,5 benzenetricarboxylamide (BTCA) and its nucleating effect on poly(lactic acid) (PLA) crystallization were studied by differential scanning calorimetry and polarized optical microscopy. The effect of melting temperatures (Tf) from 190 to 240 degC, BTCA concentrations from 0 to 0.5 wt% and cooling rates from 2.5 to 20 degC/min was investigated. It was found that, when Tf was 240 degC, BTCA could dissolve completely in PLA matrix, and then self assemble into supermolecular frameworks upon decreasing temperature. The core findings are as follows: (1) for the two step crystallization, the half crystallization time of PLA showed a bell shaped dependence on the pre crystallization temperatures of BTCA, which was higher than that without pre treatment; (2) for nonisothermal crystallization, the crystallization peak temperature of PLA presented a bell shaped dependence on the concentration of BTCA at each rate. Meanwhile, the BTCA concentration, which corresponded to the maximum crystallization rate of PLA, shifted to higher value with the increase of cooling rate. The observations were discussed in term of the effective nucleating surface area of BTCA.
Polymer