Breakage of carbon nanotube agglomerates within polypropylene matrix by solid phase die drawing

Abstract

Melt blending of polyolefin/carbon nanotube (CNT) composites always leads to serious agglomeration of CNTs and hence inferior properties. Thus, well-dispersed CNTs within matrix are urgently required during processing. In this work, effective breakage of CNT agglomerates was achieved by solid-phase die drawing at a temperature below but near to the melting temperature of the matrix. Experimental results indicate that the incurred extensional stress provides a high orientation degree on the polypropylene (PP) matrix and consequently helps rupture CNT agglomerates, leading to improved alternating current（AC） conductivity by ~5–6 orders in magnitude. The reduced agglomerate ratio, the altered CNT networks (3D→2D), and the improved interfacial morphology between CNT and matrix are suggested to be responsible for the viscoelasticity variation of the composite melt and the improved property of PP/multiwalled CNTs (MWCNTs) composite. The initial loss of tensile ductility by the incorporation of MWCNTs is recovered by nearly 100%, which was attributed to the low agglomeration rate and improved interfacial morphology. This article provided the potential inspiration for the melt blending of polymer melt and CNTs.