Effects of loading and silane treatment of Alumina nanoparticles in CFRP composite

In this work, the effects of loading and silane treatment of alumina nanoparticle fillers on the mechanical properties of the carbon fibre-reinforced polymer composite were investigated. The nanoparticles were introduced into the polymer matrix at three different mass fractions, namely 1 wt%, 2 wt%, and 3 wt% of epoxy weight. The nanoparticles increased the average elastic modulus of the composite by more than 80% with a considerable reduction in its tensile strength of close to 29%. The fillers were then treated using three different silane coupling agents, namely (3-Aminopropyl)triethoxysilane, (3-Glycidyloxypropyl)trimethoxysilane, and 3-(Trimethoxysilyl)propylmethacrylate, before their introduction into the matrix at 2 wt% loading. It was found that the silane treatment further enhanced the elastic modulus of the composite and compromised the tensile strength of the composite. This experiment shows that silane treatment augmented the effect of alumina particle loading on the mechanical properties of carbon fibre-reinforced polymer composite, and it has negligible impact on the nanocomposite hardness. 3-(Trimethoxysilyl)propylmethacrylate caused the greatest augmentation whereas (3-Aminopropyl)triethoxysilane the least. Scanning electron microscopy showed the appearance of voids, microcracking, and agglomeration of nanoparticles at 1 wt% to 2 wt%. At 3 wt%, a significantly different matrix rupture was observed. At 1 wt%, the nanoparticles were most uniformly dispersed, which concurred with the greatest enhancement in elastic modulus. However, nanoparticles served as stress concentration sites, reducing the tensile strength. On the other hand, silane treatment seemed to have prevented agglomeration but at the cost of inducing air bubbles that weaken the composites considerably.