Improving the Mechanical Properties of Polyamide 6-Nanosilica Nanocomposites by Combining Masterbatch Technique within situPolymerization

Qijie Xu,Zhijun Zhang,Fangfei Chen,Xiaohong Li

doi:10.5935/0103-5053.20140099

Abstract

A reactive polyamide 6 (PA6)/SiO2 masterbatch (MA) containing 20% (mass fraction) of nano-SiO2 was prepared readily. Furthermore, the as-prepared reactive MA was used as a filler to prepare PA6/SiO2 nanocomposites (RA). The structure of RA was analyzed by means of Fourier transform infrared spectrophotometry (FTIR), transmission electron microscopy (TEM), powder X-ray diffractometry (XRD), scanning electronic microscopy (SEM) and polarizing microscopy (POM). Thermal stability and crystallization behaviors of RA were evaluated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Findings indicated that the PA6 molecular chains were anchored on the surface of nano-SiO2 through chemical bonding between the surface amino groups of nano-SiO2 and e-caprolactam monomer or prepolymer of PA6. As a result, a flexible interfacial layer was formed, thereby improving the compatibility of nano-SiO2 with PA6 matrix. Moreover, the enhancement effect of nano-SiO2 led to the improved mechanical properties of RA. Besides, due to the hindering effect of nano-SiO2 particles to the movement of PA6 molecular chains, the size of the PA6 spherocrystal was smaller, and its crystalline form was also affected. Furthermore, the molecular weight of the PA6 matrix tended to decrease gradually with increasing nano-SiO2 content.

Highlights

Polymer-matrix composites (PMCs) continually grasp human’s interest for decades, because they possess markedly improved mechanical properties
Fourier transform infrared spectrophotometry (FTIR) spectra are measured to verify whether nano-SiO2 is chemically bonded with polyamide 6 (PA6) molecular chains
That is because that the chemical bonding can result in greatly improved compatibility of nano-SiO2 with PA6 matrix, significantly increased interfacial strength between the inorganic filler and the polymer matrix

Summary

Introduction

Polymer-matrix composites (PMCs) continually grasp human’s interest for decades, because they possess markedly improved mechanical properties The weight loss of CRA is higher than that of PA6-matrix composites prepared by other methods, such as molten mixing method and only in situ polymerization method.[12,19] It illustrates that the surface of nano-SiO2 can form more strong interfacial strength by using the method of this paper that is beneficial to improve the mechanical properties of PA6.

Results

Conclusion