One-step grafting onto commercial poly (ethylene terephthalate) (PET) fabrics was studied by use of the emulsion which consisted of vinyl monomer, benzoyl peroxide, monochlorobenzene, emulsifier and water. Acrylic acid (AA) and methacrylic acid (MAA) were used as vinyl monomers.
When a polyoxyethylene alkyl ether type nonionic surfactant was used as the emulsifier, a gum-like material deposited remarkably on the grafted PET. This material was considered to be a product formed by the association of the polycarboxylic acid with the surfactant polyoxyethylene. The formation of the gum-like material was distinctly reduced by addition of an anionic surfactant to the nonionic surfactant or by use of a nonionic-anionic surfactant instead of the nonionic surfactant.
As the monomer for the grafting, the mixture of AA and MAA was examined. The mixing ratio of AA/MAA affected grafting per cent and gave the highest grafting per cent when the ratio was about 2.5/7.5(mol./mol.). Over the whole range of the mixing ratio of the two monomers, the grafting per cent of the one-step grafting was 1.5_??_3 times higher than that of the two-step grafting reported previously.
Efficient graft polymerization proceeded above 80°C and the maximum grafting percent was attained by the reaction at 100_??_110°C for 1hour.
The apparent activation energy of the AA/MAA (2.5/7.5) grafting was calculated as 7.9kcal./mol.
The grafting was affected by pH of the grafting emulsion. With an increase in pH which was adjusted with Na
2CO
3, grafting per cent increased gradually to reach the maximum at pH 3.1_??_3.3 and then decreased. However, with increasing monomer concentration, increasing degree of grafting per cent became smaller. When monomer concentration was 6%, grafting per cent decreased monotonically by addition of Na
2CO
3.
The effect of heat treatment of PET fibers on the grafting was similar to that of heat treatment of PET on the dyeability with a disperse dye. As the treating temperature rose, grafting per cent decreased gradually to reach the minimum and then, above 200°C, began to increase.
From a microscopic observation of the AA/MAA grafted PET, it became clear that the surface of the grafted PET fiber was clean and grafting took place uniformly from the surface to the center of the fiber.
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