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By radical copolymerization, thermostable copolymers of N-(2-chlorophenyl)maleimide (ZCPMI), N-(3-chlorophenyl)maleimide (3CPMI) and N-(4-chlorophenyl)maleimide (4CPMI) with vinyl acetate were prepared. The values of reactivity ratios determined according to the Kelen-Tud6s method are: r2CPMI = 0,148 and rvA = 0,049; r3CpMI = 0,221 and rvA = 0,032; r&-pM, = 0,655 and rvA = 0,O. The position of the C1 atom in the phenyl ring of CPMI influences the copolymerization kinetics. 2CPMI exhibits the strongest tendency for cross propagation, 4CPMI has the highest ability for homopolymerization. Vinyl acetate in all the three systems forms inactive radicals. The thermostability of all three copolymers is higher than that of the vinyl acetate homopolymer and decreases in the order poly(3CPMI-co-VA) > poly(4-CPMI-co-VA) > poly(2CPMI-co-VA).CCC 0025-1 16)3/92/$05.00

ABSTRACT:Two new ultrafiltration membranes were obtained from a polymer mixture, containing 60% polyacrylonitrile (PAN) and 40% copolymer of methylmethacrylatedichlorophenylmaleimide (MMA-DCPMI). Membrane 1 (MB1) contains 40% DCPMI of the copolymer, and membrane 2 (MB2) contains 15% of the copolymer. The pore size, the specific surface, the water content, the water flux, and the selectivity were determined for the two membranes. The presence of dichlorophenylmaleimide in the copolymer ensures the preparation of membranes suitable for direct covalent enzyme immobilization without further modifications. These membranes were used for immobilization of glucose oxidase (GOD). High amount of bound protein was found on each of the membranes. High relative activities of the immobilized GOD were achieved, 72% for MB1 and 68% for MB2. The properties of the immobilized enzyme (GOD) were determined: optimum pH and temperature and pH, thermal, and storage stability, and then compared with the properties of the native enzyme. The kinetic parameters of the enzyme reaction, Michaelis constant (K m ) and maximum reaction rate (V max ), were also investigated. The results obtained showed that the ultrafiltration membranes prepared from the mixture of PAN and the copolymer MMA-DCPMI were suitable for use as carriers for the immobilization of GOD.

SynopsisA flocculant based on waste oligomers from the polycaprolactam production was synthesized by alkaline reduction with Ni/Al alloy. Both the reduced oligoamide and the sodium aluminate are precipitated by methanol. An oligomer, absorbed by a mineral carrier, is isolated as final product. The modified oligoamide was characterized by elemental analysis, IR spectra, and was shown to contain hydroxyl groups. The prepared flocculant may be used for the clarification of natural dilute (1%) clay suspensions and wastewaters. It accelerates the precipitation 35 times, giving a compact precipitate, which favors the decanting of the clarified liquid. The optimal concentration of the flocculant is 1.8 ghiter (corresponding to 0.06 g/liter oligomer).