Radiation-induced graft copolymerization to polyester, 17

For the purpose of making polyester(polyethylene terephthalate) fabric hydrophilic grafting of polyethyleneglycol-dimethacrylates (PEGma) and -diacrylates (PEGMA-A) were carried out; the degree of polymerization, n of PEG-block of the PEG-esters were 2, 3, 4, 9, 14 and 23. The fabric was impregnated with aqueous or acetic acid solution of PEGMA or PEGMA-A and irradiated at room temperature with electron beams from a Van de Graaff accelerator for the grafting. Grafting up to 10% was obtained at a dose of 1 to 4 Mrad with monomer utilization higher than 90%. Grafting with irradiation in a frozen state at -650C was also carried out, resulting in nearly the same grafting rate and monomer utilization with that at room temperature. The grafting reaction in a frozen state took place smoothly in the presence of air, while that at room temperature was seriously inhibited with air. Hydrophilic properties of the graft fabrics such as frictional electricity, absorption rate of a water droplet in fabric (wicking test) and moisture regain were measured. Both PEGMA's and PEGMA-A's of n=14, 23 were effective, wherein PEGMA-A's being more effective, but those of smaller n's exhibited fas less effect for the purpose of making polyester hydrophilic. Several percent grafting of PEGMA or PEGMA-A of n=14, 23 was sufficient to improve the hydrophilicity of the polyester fabric. At about 2 to 5% graft the electrostatic charge by friction dropped to the same level as that of cotton fabric, independent on the grafting temperature. Wicking test showed that the time required for a droplet of water to be absorbed in fabric dropped to less than one tenth of the value for the original fabric. The characteristic of the water droplet-absorption rate of the graft fabric irradiated in a frozen state was superior to that irradiated at room temperature, particularly for the fabric with large amount of grafting. The fabric grafted with PEGMA (n=14) up to 33% graft exhibited nearly the same dyeability with dispersed dyes as that of original fabric. Tensile and tearing strengths of polyester fabric were not changed with grafting of PEGMA (n=14). Both PEGMA and PEGMA-A graft polyester showed excellent resistance to alkali as compared to acrylic acid or methacrylic acid graft fabrics. From these experimental results it is considered that the most of PEGMA or PEGMA-A does not enter into the fiber and is deposited on the surface of the fibers as insoluble polymer due to cross-linking. (auth.)