A series of new copolymers with desired thermal stability and mechanical properties for applications in leather industry were synthesized from various substituted maleimides and alkyl acrylates. Polymerization was carried out by a free‐radical polymerization using benzoyl peroxide (BPO) as initiator. The monomers and polymers synthesized were characterized by elemental analysis, IR, and nuclear magnetic resonance (NMR). Interestingly, these polymers were soluble in common organic solvents. Copolymer composition and reactivity ratios were determined by 1H‐NMR spectra. The molecular weights of the polymers were determined by gel permeation chromatography. The homo‐ and copolymer of maleimide showed single‐stage decomposition (ranging from 300–580°C). The initial decomposition temperatures of poly[N‐(phenyl)maleimide] [poly(PM)], poly[N‐4‐(methylphenyl)maleimide] [poly(MPM)] and poly[N‐3‐(chlorophenyl)maleimide] [poly(CPM)] were higher compared to those of the copolymers. Heat‐resistant adhesives such as blends of epoxy resin with phenyl‐substituted maleimide‐co‐glycidyl methacrylate copolymers with improved adhesion property were developed. Different adhesive formulations of these copolymaleimides were prepared by curing with diethanolamine at two different temperatures (30°C and 60°C). © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1870–1879, 2001

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4-Chlorophenyl acrylate (CPA) was prepared by reacting 4-chlorophenol and acryloyl chloride in the presence of triethylamine in ethyl acetate solution. Poly(4-chlorophenyl acrylate) and copoly(4-chlorophenyl acrylate-methyl acrylate) were synthesized by the free radical polymerization in ethyl acetate at 70°C. All the polymers were characterized by infrared (IR) and nuclear magnetic resonance (NMR) spectroscopic techniques. The composition of the copolymers was determined by the 1 H-NMR spectroscopic technique, that is, by integrating the aromatic peaks corresponding to the 4-chlorophenyl acrylate unit against the carbomethoxy group in the methyl acrylate unit. The reactivity ratios were calculated by Fineman-Ross, Kelen-Tudos (K-T), and the extended Kelen-Tudos methods. The values of r 1 and r 2 obtained by these methods were in close agreement with each other; that is, r 1 (CPA) ϭ 0.64 and r 2 (MA) ϭ 0.13 by the K-T method. The number-average molecular weight (M n ϭ 1.55 ϫ 10 3 ), the weight-average molecular weight (M w ϭ 8.39 ϫ 10 3 ), and the polydispersity index (M w /M n ϭ 5.42) of poly(CPA) were determined by gel permeation chromatography (GPC). Thermal properties of the polymers were studied in a nitrogen atmosphere using thermogravimetric analysis (TGA). As the CPA increases in the copolymer, thermal stability of the copolymer increases (e.g., 90% weight loss occurs at 480°C for 20 mol % CPA, whereas the same weight loss occurs at 571°C for 80 mol % CPA). Acrylic binders, based on the CPA-MA-BA terpolymer, of different glass transition temperatures were prepared for applications in leather industry as top coat and base coat materials. These acrylic emulsions were cast into thin films, and their characteristics were tested for physical properties. These acrylic emulsions were applied as a base coat on leather, and the compositions having T g values of 1.08 and 9.25°C were found to have excellent properties as base coats for leather when compared with commercial samples.

Tannin, a natural polymer belonging to the polyphenolic group of compounds, is widely used in the leather industry, specifically as a tanning agent for the conversion of putrescible collagen fibers into leather matrix during the leather-manufacturing process. Unspent tannin poses a serious environmental threat to the public because it has a very high half-life, leading to groundwater pollution when discharged into soil. Attempts have been made to separate tannins through chemical means and recovered tannin needs to be encapsulated for its safe disposal. In the present study the recovered tannin was impregnated in phenol-formaldehyde (PF) resin. Spectroscopic and thermogravimetric (IR, NMR, TGA and DSC) studies revealed that the modified polyphenol was held physically in the impregnate. The impregnated matrix showed resistance to mineral acids, strong alkalis and organic solvents and was tested for its adhesive property on leather sheets. The leather that bonded with PF-modified polyphenol impregnate (PFT) had a 27% increase in peel strength and a 40% increase in lap shear strength as compared to the sample bonded with PF resin. The corrosive resistance result of the PFT resin shows it has potential application as an anticorrosive paint in the paint industry.

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