The Performance Investigation of PLLA/PPAPH: The Influence of PPAPH as Heterogeneous Crystal Nuclei

Abstract

To overcome PLLA�s poor crystallization capability, using nucleating agent as crystallization improvement strategy was performed in this study. PPAPH as PLLA�s an organic nucleating agent was firstly synthesized, and then PLLA was blended with different PPAPH loading through melting blend method, the resulting influences of PPAPH on PLLA�s performances were investigated using the relevant testing instruments. Melt-crystallization revealed that PPAPH played important role in promoting PLLA�s crystallization through providing effective sites of heterogeneous nucleation, and effect of PPAPH loading on PLLA�s melt-crystallization was very poor, indicating that low PPAPH loading could cause PLLA to possess powerful crystallization capacity. In addition, the relative low final melting temperature was beneficial for PLLA/PPAPH�s crystallization. However, an increase of cooling rate during cooling stage weakened PLLA/PPAPH�s crystallization capacity. PLLA/PPAPH�s cold-crystallization suggested that PPAPH had an inhibition effect on cold-crystallization process to some extent. Melting behaviors depended on heating rate and previous crystallization including melt-crystallization at various cooling rates and isothermal crystallization at various crystallization temperatures. PPAPH enhanced PLLA�s fluidity, tensile modulus and tensile strength. Unfortunately, PLLA�s transmittance was seriously weakened as PPAPH loading increased, as well as the elongation at break continuously decreased.