Effects of Three Different Injection-Molding Methods on the Mechanical Properties and Electrical Conductivity of Carbon Nanotube/Polyethylene/Polyamide 6 Nanocomposite.

Dashan Mi,Wenli Zhu,Zhongguo Zhao

doi:10.3390/polym11111779

Abstract

Morphological evolution under shear, during different injection processes, is an important issue in the phase morphology control, electrical conductivity, and physical properties of immiscible polymer blends. In the current work, conductive nanocomposites were produced through three different injection-molding methods, namely, conventional injection molding, multi-flow vibration injection molding (MFVIM), and pressure vibration injection molding (PVIM). Carbon nanotubes in the polyamide (PA) phase and the morphology of the PA phase were controlled by various injection methods. For MFVIM, multi-flows provided consistently stable shear forces, and mechanical properties were considerably improved after the application of high shear stress. Shear forces improved electrical property along the flow direction by forming an oriented conductive path. However, shear does not always promote the formation of conductive paths. Oscillatory shear stress from a vibration system of PVIM can tear a conductive path, thereby reducing electrical conductivity by six orders of magnitude. Although unstable high shear forces can greatly improve mechanical properties compared with the conventional injection molding (CIM) sample, oscillatory shear stress increases the dispersion of the PA phase. These interesting results provide insights into the production of nanocomposites with high mechanical properties and suitable electrical conductivity by efficient injection molding.

Highlights

IntroductionCarbon nanotubes (CNTs) are representative examples of nanofillers
Nanocomposites are attracting considerable interest in applied and fundamental research [1].Carbon nanotubes (CNTs) are representative examples of nanofillers
CNTs have satisfactory mechanical properties, only small fractions of their stiffness and strength are translated into a matrix, in which CNTs are embedded by aggregation, twisting, and curling [2]

Summary

Introduction

Carbon nanotubes (CNTs) are representative examples of nanofillers. They have exceptional aspect ratios, elastic moduli, strength, electrical properties, thermal conductivity, and chemical stability. CNTs have satisfactory mechanical properties, only small fractions of their stiffness and strength are translated into a matrix, in which CNTs are embedded by aggregation, twisting, and curling [2]. Well-dispersed nanotubes are efficiently interconnected and decrease the amount of fillers for electrical percolation [3,4,5]. Other studies demonstrated that the poor dispersion of nanotubes in a matrix results in the formation of agglomerates and significantly increases the percolation threshold [6]

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Results

Conclusion