Analysis of mechanical property degradation in polymer nanoclay composites

Abstract

Polymers are used in various industrial applications due to their ease of production, light weight and ductility. Fillers such as nanoclays are added to polymers to improve a range of factors such as material processing, thermal properties, fire retardance and cost. However, adding nanoclays may negatively impact the mechanical performance, affecting the strength, stiffness and impact resistance of the composite. There are two important ways to mitigate this degradation in mechanical properties. The first is to improve the chemical adhesion between the polymer and the filler by adding an appropriate compatibiliser, and the second is to control the amount of nanoclay added. There have been several studies in literature that investigated both options to understand the interaction between the polymer matrix, nanoclay and compatibiliser and the resulting influence on the mechanical performance. These studies generally aim to find a composition ratio which results in improved properties (processing, thermal, chemical, fire resistance, low weight, etc.) and a good enough mechanical performance for a desired application. When designing such a composite without severely impacting the mechanical performance, an understanding of the mechanical property degradation due to increased weight loading of nanoclay is beneficial. This study aims to define the problem of determining an upper limit for nanoclay inclusions. Commercial nanoclay particles are compounded with high density polyethylene (HDPE) at weight loadings of 2.5%, 5%, 7.5%, 10%, 15% and 20%. The effect of inclusion fraction on strength, stiffness and elongation to failure are investigated.