Microwave-initiated modification of polyamide 6.6 fabric surfaces for superior hydrophilic and flame retardant properties

Abstract

Microwave-assisted surface modification of polyamide 6.6 (PA6.6) fabrics was carried out in a grafting polymerization technique in the presence of acrylic acid (AA) monomer with an aim to enhance the extent of surface functional groups onto the PA6.6 fabric surfaces. In the next step, the surface modified fabric substrate was gone through a layer by layer (LbL) deposition process in the presence of some hybrid (organic/inorganic) polyelectrolytes in imparting hydrophylic and flame retardant properties and finally, the as prepared coating was subjected to a cross-linking treatment aided by hypo-phosphorus acid (HP) in enhancing the stability of the same. From the obtained results, it was revealed that the simultaneous microwave assisted grafting, LbL deposition and HP cross-linking left positive impacts in improving the flame retardant performance and hydrophilicity of PA6.6 fabrics along with the enhancement of coating stability in laundering. For example, acrylic acid grafted PA6.6 fabric sample with a 5-BL deposition and cross-linked with HP (i.e., PA6.6-g-AA-5BL-HP) attained a limiting oxygen index (LOI) value up to 23.5%, while exhibiting a significant level of reduction in the peak heat release rate (pHRR) by ca. 50 %. In line, a super-hydrophilic surface was obtained for this fabric sample as the water contact angle value declined to 0º. Furthermore, such kind of surface modification displayed a considerable level of coating stability during laundering as the anti-dripping properties still exist even after 10 home launderings.