Improving The Dripping Resistance And Hydrophilicity Of Nylon66Fabric By Surface Grafting Modification

Nylon66fabric has been widely used for its excellent properties such as good mechanical property, wear resistance, shrinkage resistance and so on. However, its combustibility and serious dripping problems during combustion are still inadequate for many applications, moreover, compared with cotton, its inferior hydrophilicity property makes it uncomfortable to be used in civil life, therefore, it is very important to improve the flame retardancy and hydrophilicity property of nylon66fabric.Grafting method was used in this work to graft flame retardant monomers and to make a surface modify of nylon66fabric, which combined the flame retardant monomers onto nylon66surface through covalent bonds, and proved to be a durable modification comparing to physical treatment. It was suggested that the grafting process had minimal effect on the handle feeling and mechanical property of the fabric within the optimal percentage of grafting (PG%), which had great potential to be used commercially.The first part of this paper employed chemical grafting method to graft2-acryloylamino-2-methyl-l-propanesulfonic (AMPS) onto nylon66fabric surface, however, AMPS is difficult to be grafted on the hydrophobic nylon66because of its strong hydrophilicity.2-hydroxyethyl methacrylate (HEMA) was then used as a common grafting monomer for its amphipathy. Effects of monomer concentration, reaction time, reaction temperature on the percentage of grafting (PG%) were investigated and the optimal reaction conditions were determined as follows:monomer concentration was15wt.%, initiator concentration was0.5wt.%, reaction temperature was80℃and reaction time was2h. It was demonstrated that the chemical grafting modification could improve the thermal stability and the hydrophilicity of the samples, and could reduce the dripping tendency of the fabric significantlyIn the second part of this paper, microwave induced grafting was firstly introduced to surface modify nylon66fabric. Microwave can penetrate into the molecular inside and accelerate the reaction. Reactions under microwave irradiation proved to be more rapid, uniform and efficient, and the low PG%can protect the fabric from damage. HEMA was used as grafting monomer and potassium peroxydisulfate (KPS) was used as initiator. Effects of reaction time, reaction temperature, initiator concentration and monomer concentration on PG%were investigated, and the optimal reaction conditions were as follows:the fabric was pre-reacted in0.5wt.%initiator solution at80℃for20min then removed to the5wt.%monomer solution to react at80℃for60min, and all the reaction were conducted under the microwave irradiation (400W). Attenuated total reflection infrared spectroscopy (ATR-FTIR) and13C nuclear magnetic resonance spectroscopy (13C NMR) showed that the grafting reaction occurs on the alkyl carbon near amino-group. The fire performance tests showed that the limit oxygen index (LOI) values decreased slightly, while the dripping tendency was reduced significantly. The wetting time of the grafted sample reduced to22.5s from417.3s of pure nylon66. The breaking force improved slightly while the elongation at break increased from23.5%to43.8%.The third part of this paper compared the difference of combustion behaviors of the modified fabric treated with two treatments (chemical grafting and pad-dry physical treatment). Maleic anhydride (MA) and HEMA were used as the flame retardant monomer.3D TGA-FTIR spectra analysis, and the morphology observation of the char residue showed that pure nylon66fabric and physical treated samples firstly went through a process and then decomposed from the surface to release the inflammable gas during the combustion, while during the combustion of grafted samples the molten contraction process was almost disappeared, and began to decompose from grafting chains directly to form carbonaceous char, which can prevent the inside fabric from further decomposition. The physical treated samples had a better fire performance than the pure sample, while the grafted samples only showed a better anti-dripping property than the pure sample.