Effect of chemical structure of hydrazide compounds on nucleation effect in isotactic polypropylene

Abstract

A series of hydrazide compounds were synthesized and employed as nucleating agents for isotactic polypropylene (iPP). The effect of different structures of hydrazide compounds on the crystallization and melting behaviour of iPP was studied by differential scanning calorimetry (DSC). The results demonstrate that almost all nucleating agents are α-nucleating agents, some of which are highly efficient nucleating agents. In the case of the same substituent, the greater the number of hydrazide groups, the better the nucleation effect. The crystallization peak temperature (Tc) of iPP nucleated with dihydrazide is 3–4 °C higher than that of monohydrazide. When the substituent of the dihydrazide compound is hydrogen, ethyl and nonyl, their nucleating ability is relatively weak, but in the state of phenyl and cyclohexyl substitution, the Tc of iPP nucleated with dihydrazide nucleating agent is 8.5 °C than pure iPP. When the intermediate group of the dihydrazide compound is a long-chain alkyl, a phenyl, a cyclohexyl, and a naphthyl group, the phenyl group and the cyclohexyl group still exhibit an excellent effect, the Tc of nucleated iPP is raised by about 10 °C.