Improving The Flame Retardancy Of Nylon 66 Fabric By Microwave Induced Grafting

Nylon 66 fabric/fiber has become one of the widely industrial production of synthetic fibers in our country and widely used in the daily life and military aspects because the excellent mechanical properties and wear resistance, however, nylon 66 fabric/fiber has a the limiting oxygen index of only 20-22 and produce serious dripping problems during combustion, which cannot meet the requirements in many industrial and domestic applications.Microwave induced grafting has low damage to fabric surface, high efficiency, energy saving compared with plasma, photo and chemical grafting technology. The main contributions of this work are as follows:Firstly, acrylamide (AM) was grafted onto nylon 66 fabrics surface under microwave irradiation. Effects of initiator/monomer concentration, reaction time and reaction temperature on PG% were investigated. The structure of grafted PA66 fabric was characterized by Attenuated total reflection infrared spectroscopy (ATR-FTIR) and scanning electron microscopy (SEM), and the results have demonstrated that AM has been successfully grafted onto PA66 fabric surface. The thermal behavior and flammability were characterized by thermogravimetric analysis (TGA), limiting oxygen index (LOI), vertical burning tests. It proves that microwave induced grafting AM can increase the flame retardancy of PA66 fabric. The LOI is increased from 20.2 to 27.0 when PG% is 24.6%, the damaged length is decreased from 17.0 cm to 11.5 cm when PG% is 23.5%. The mechanical property analysis shows that the presence of grafted chains can increase the breaking strength and the elongation at break of PA66 fabric. When PG% is 27.3%, the breaking strength is increased from 503 N to 617 N and the elongation at break is increased from 26.56% to 45.32%.Secondly, thiosinamine (ATU) was grafted onto nylon 66 fabrics surface under microwave irradiation. Effects of initiator/monomer concentration, pre-irradiation, reaction time and reaction temperature on PG% were investigated. The structure of grafted PA66 fabric was characterized by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM), and the results have demonstrated that thiosinamine has been successfully grafted onto PA66 fabric surface. The thermal behavior and flammability were characterized by thermogravimetric analysis (TGA), limiting oxygen index (LOI), vertical burning tests, and cone calorimetric test (CONE). It proves that microwave induced grafting can significantly increase the flame retardancy of PA66 fabric. When PG% is 2.1%, the LOI is increased from 20.2 to 27.6, the damaged length is decreased from 17.0cm to 7.0 cm, no melt dripping and without after-flame times, pHRR is decreased from 480.0 kw/m2 to 250.6 kw/m2 and TSP is decreased from 1.13 m2/m2 to 0.32 m2/m2. The mechanical property analysis shows that the breaking strength will decrease slightly with presence of grafted chains (decreased from 1061 N to 1021 N, when PG% is 2.2%) and the elongation at break of PA66 fabric increase to around 29.11%.Thirdly, AM-VTMS in association with thiourea were introduced onto PA66 by a dip-padding process. Effects of the concentration of VTMS, AM and thiourea on the stability of aqueous colloidal system were investigated, and the flame retardancy, mechanical properties and washable properties of modified fabric were characterized. The advantages and disadvantages of dip-padding treatment and grafting modification were compared and summarized.