The nucleation effect of N,N '-bis(benzoyl) alkyl diacid dihydrazides on crystallization of biodegradable poly(L-lactic acid)

Five N,N'-bis(benzoyl) alkyl diacid dihydrazides were synthesized from benzoyl hydrazine and alkyl diacyl dichloride which were derived from alkyl diacid via acylation. PLLA/N,N'-bis(benzoyl) alkyl diacid dihydrazide samples were prepared by melt blending and hot-press forming process. The nucleation effect of N,N'-bis(benzoyl) alkyl diacid dihydrazide on crystallization of biodegradable poly(l-lactic acid) (PLLA) was investigated using differential scanning calorimetry (DSC) and vicat softening analysis. The results showed that five N,N'-bis(benzoyl) alkyl diacid dihydrazides acted as powerful nucleating agent for PLLA; with incorporation of N,N'-bis(benzoyl) alkyl diacid dihydrazide, the crystallization peak became sharper and shifted to higher temperature as the degree of supercooling decreased at a cooling rate of 1 degrees C/min from melt. The nucleation activities of five N,N'-bis(benzoyl) alkyl diacid dihydrazides were quantitatively determined. It is shown that N,N'-bis(benzoyl) suberic acid dihydrazide has higher nucleating activity than the other N,N'-bis(benzoyl) alkyl diacid dihydrazides. In the presence of N,N'-bis(benzoyl) alkyl diacid dihydrazide, the melting behavior of PLLA is affected significantly. In addition, the thermal stability of PLLA/0.8 % N,N'-bis(benzoyl) alkyl diacid dihydrazide is tested and reported. Compared to the neat PLLA, the onset degradation temperature of PLLA/0.8 % N,N'-bis(benzoyl) alkyl diacid dihydrazide samples has been decreased significantly