Microstructure and properties of PA6/HDPE/CNTs blends of different mixing sequences under normal stress dominated flow field

Abstract

Melt blending method dominated by normal stress for polymer-based composite was realized via a self-developed vane mixer. Effects of mixing sequences and mixing time on the microstructure, rheological properties, thermal properties and tensile strength of PA6/HDPE/CNTs ternary blend were experimentally investigated. SEM results show that the normal stress flow field can realize the uniform dispersion of PA6 and CNTs in a short time. Compared with the other two mixing sequences, the blend of the mixing sequence that HDPE and CNTs are firstly mixed to form the masterbatch, and then the masterbatch is mixed with PA6 (HDPE/CNTs+PA6) has the smallest PA6 particle size; DSC results show that Xc is significantly affected by the mixing sequence; mechanical properties show that the better tensile strength is obtained when the mixing sequence is HDPE/CNTs+PA6 and proper mixing time can further improve the tensile strength of the blend.The results aforementioned indicate that the normal stress flow field provides enough energy for the CNTs to overcome the energy barrier of the HDPE/PA6 two-phase interface and migrate into the PA6 phase, which proves that the normal stress flow field has higher dispersion efficiency.

Keywords

• normal stress dominated
• carbon nano-tubes (cnts)
• high-density polyethylene (hdpe)
• polyamide 6 (pa6)
• mixing sequence