Surface Modification of Coarse Wool Fabric Using Malic Acid <i>via</i> RSM Approach for Enhanced Physico-Mechanical Properties of Wool-Natural Rubber Composites

In the reported work, medium coarse wool fabric was coated with natural rubber latex to form flexible composites. To enhance the interfacial adhesion between the hydrophilic wool and hydrophobic rubber, malic acid was used as a compatibilizer. The coating process was optimized using a three-factor, four-level Box-Behnken response surface methodology. The effects and interactions of three process parameters viz. dry rubber content, concentration of malic acid, and applied pressure on the mechanical properties of the composite were analyzed. The composites were further characterized with Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), and X-ray diffraction (XRD) analysis. The physical properties of the composites such as thickness, areal density, rubber uptake, tear strength, and hardness were also estimated. Further, thermal aging and accelerated soil degradation properties of the developed composites were evaluated. It is found that most of the mechanical properties of the composites have a positive correlation with the Dry Rubber Content (DRC). The SEM images confirmed the percolation of rubber throughout the wool fabric and a corresponding hike in the crystallinity was observed in XRD analysis. The high rubber content in the composites causes a reduction in tear strength and rate of soil degradation.