SynopsisThermal analysis of cotton samples grafted with acrylamide, acrylonitrile, methyl acrylate, and methyl methacrylate individually and in mixture compositions has been carried out. Additional endothermic peaks in the DTA curves characteristic of the polymers grafted were observed. Graft copolymerization of acrylamide and acrylonitrile makes cotton thermally more stable, while in the case of methyl acrylate-and methyl methacrylate-grafted cottons, the initial decomposition starts a t higher temperatures, but subsequent decomposition is faster and the overall thermal stability is lowered. In the case of binary mixtures of acrylamide and acrylonitrile, inception of decomposition starts earlier, but subsequent decomposition takes place a t much higher temperatures than for individual monomer-grafted cottons. Interaction between monomers during grafting is indicated. When fabric samples containing polyacrylamide grafts are methylolated and subsequently crosslinked, there is a reduction in the thermal stability of the treated cotton.
Modification of poly(tetrafluoroethyleneco-ethylene), Tefzel (ETFE), film has been carried out by grafting methylmethacrylate (MMA) by radiation method including preirradiation and double-irradiation methods. Percentage of grafting has been determined as a function of the (i) total dose, (ii) monomer concentration, (iii) amount of liquor ratio, (iv) reaction time, and (v) temperature. The effect of different alcohols such as methanol, ethanol, 2-propanol, n-butanol, n-pentanol, and 2-ethoxy ethanol on percentage of grafting of MMA was also studied. The graft copolymers were characterized by IR spectroscopy and thermogravimetric analysis (TGA).Methylmethacrylate produces higher percentage of grafting by preirradiaton method than double-irradiation method. MMA-grafted ETFE films (S irr ), i.e., prepared by preirradiation involving single irradiation show better thermal stability than MMA-grafted ETFE films (D irr ), i.e., prepared by double irradiation and unmodified ETFE film.
Fabric samples were grafted with binary and ternary mixtures of selected vinyl monomers along with acrylamide onto cotton using ceric ammonium nitrate as catalyst from aqueous solution or emulsion, and subsequently polyacrylamide grafts were methylolated in situ and crosslinked. Except in the case of acrylamide-acrylonitrile treatment, finished fabrics show good wrinkle-recovery properties accompanied by satisfactory retention of breaking- and tear-strength and also very much improved resistance to abrasion. The finish is suitable for the deferred-cure process with minimum evolution of formaldehyde. When the above-mentioned uncrosslinked grafted samples are crosslinked through N-methylol crosslinking agents, improvement in wrinkle-recovery properties are accompanied by usual losses in strength and abrasion resistance. However, when ternary mixtures containing ethylacrylate, acrylamide, and acrylonitrile are grafted at higher polymer add-ons, and fabric is crosslinked through the conventional crosslinking agents, very good abrasion-resistance properties along with good strength retention are achieved. In the reverse process— i.e., where samples are first crosslinked through polyacrylamide grafts and then further grafted with ethylacrylate alone or in combination with other monomers—abrasion properties are markedly improved, while wrinkle-recovery properties are only moderate.
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