Evaluation of water repellency in bentonite filled polypropylene composites via physical and mechanical methods

With the advent of polymeric materials having dimensional stability, outdoor applications for polymer composites are increasing expeditiously. The employment of durable material in wet environments is the most effective means of water repellency. Silane modification was applied to bentonite clay for the donation of hydrophobicity on its surface. Surface functionalities of powder surfaces were confirmed by FTIR-ATR spectroscopy and SEM techniques. Polypropylene composities involving pristine and modified bentonite powders were produced in bulk and film forms at three different loading ratios. Water permeability of bulk and film samples was evaluated via water absorption test. In addition to water uptake values, optical microscopy was utilized in order to visualize the structural deterioration of composite samples after water immersion. Mechanical behaviours of composite materials before and after water absorption test were reported in order to analyze the effect of water aging. Based on the findings, in-depth discussions were performed by comparison with basic models postulated regarding migration of water molecules into polymer structure.