Surface modification of polyamide 66 fabric by microwave induced grafting with 2-hydroxyethyl methacrylate

Microwave induced surface modification was used in grafting 2-hydroxyethyl methacrylate (HEMA) onto polyamide 66 (PA 66) fabric in order to improve its hydrophilicity and fire performance. Effects of reaction time, reaction temperature, initiator concentration and monomer concentration on the percentage of grafting (PG%) were investigated. It showed that the optimal reaction conditions were as follows: the reaction time was 60 min, the reaction temperature was 80°C, the initiator concentration was 0.5 wt.%, and the monomer concentration was 5 wt.%. The possible grafting mechanism was proposed and described. The chemical structure of grafted PA 66 fabric was characterized by attenuated total reflection infrared spectroscopy (ATR-FTIR), 13C nuclear magnetic resonance spectroscopy (13C NMR), and scanning electron microscopy (SEM). The results demonstrated that HEMA incorporated on the alkyl carbon site near amino-group of PA 66 chain through covalent bonds. Thermal behavior analysis indicated that the grafting treatment could decrease the decomposition temperature and increase the amount of char residue. The hydrophilicity of PA 66 fabric was also improved by the grafting treatment. The fire performance test showed that the limit oxygen index (LOI) values were decreased slightly, while the dripping tendency was reduced significantly. The mechanical property analysis showed that the elongation at break increased from 23.5% to 43.8%.