Surface modification of nylon fabric and its optimization for improved adhesion in rubber composites

Abstract

Nylon-6,6 fabric was treated with formic acid for surface roughening and was subjected to Resorcinol Formaldehyde Latex treatment for making rubber composites. Physicochemical effects of surface roughening of nylon were evidenced using scanning electron microscope (SEM), Fourier Transform Infrared spectroscope (FTIR) and differential scanning calorimeter (DSC). Further, the treatment effect on interfacial adhesion was quantified through peel strength test. The process parameters of the formic acid treatment were optimized using Box-Behnken method through geometrical surface roughness obtained through Kawabata evaluation system for micro-surface roughness of nylon to ensure good interfacial adhesion with rubber. Surface modification conditions of 11.2% formic acid concentration, 70 °C temperature and 30 min time were found to yield optimum condition at which surface roughness (SMD) was found to be of 20.1 μm. SEM analysis confirmed the presence of heterogeneous appearance like cracks, etches and micro-rough surfaces on the treated Nylon-6,6 fibre surface. FTIR analysis showed changes in –C = O stretching and –N–H stretching. No significant change was noted in the DSC curve. The peel strength between the rubber and treated fabric was improved to 150% in warp and 124% in weft directions, respectively with reference to the control fabric.