Thermal Stability Of Copolymers Research Articles

Graft copolymerization of poly(vinyl chloride) with styrene. II. Thermal behavior

AbstractThermal behavior of graft copolymers of polyvinyl chloride with polystyrene prepared by using a cationic initiator (AlCl3) was evaluated by measurement of rates of dehydrochlorination in nitrogen atmosphere. With increase in the extent of grafting the rates were found to decrease. Dynamic thermogravimetric analysis revealed an overall improvement in thermal stability of copolymers. Development of polyene sequences in degraded polymer samples was evaluated by measurement of electronic absorption spectra. In comparison to PVC, graft copolymer samples had fewer conjugated double bonds.

Copolymers of vinylcyclohexane with styrene: Peculiarity of thermal behavior, parameters of crystal structure, and structural transitions

AbstractThermal behavior, the parameters of crystal structure, and the structural transitions of copolymers of vinylcyclohexane with styrene were studied. Heating in air of the copolymers and of mechanical mixtures of homopolymers results in thermooxidative destruction. For all samples, the oxidation starts at 210–220°C. The antioxidant effect on thermal stability of copolymers was studied. Differential thermal analysis (DTA) data were used to determine the melting points of homopolymers and crystal copolymers. The method of x‐ray diffraction on large scattering angles was used to determine the dimensions and type of unit cells, the degree of crystallinity, the dimensions of the coherent scattering regions (the dimensions of crystallites) of copolymers of various compositions, and to compare them to the parameters of the structure of polyvinylcyclohexane and polystyrene. Information on molecular motion intensity and structural transitions in homopolymers and copolymers with changing temperature was obtained by the spin‐probe technique.

Free-Radical Copolymerizations of N-Phenyl Maleimide

Abstract Free radical-initiated copolymerization of N-phenyl maleimide (NPMI) with styrene (St), vinyl acetate (VAc) and methyl meth-acrylate (MMA) at 35°C in benzene solution initiated by AIBN was studied. The copolymerization of NPMI and St yields a “nearly equimolecular” alternating copolymer, irrespective of monomer feed. Reactivity ratios of NPMI with St, VAc, and MMA were determined by a curve-fitting method which has the advantage of delivering values not involving personal judgement. Q1 and e1 values of NPMI were also calculated. Tentative explanations have been proposed to Interpret the “nearly alternating” copolymerization between NPMI and St. In addition, thermal stabilities of copolymers were studied by using a programmed thermo-gravimetric analysis technique. Copolymers of St, VAc, and MMA show a considerable increase in thermal stability with increasing content of NPMI. The glass transition temperatures of copolymers of NPMI with MMA and St were measured by differential scanning calorimetry....

Thermal stability of copolymers of isobutylene with certain ?-methylstyrene derivatives

1. Viscosity-index improvers have been obtained by modification of polyisobutylene, specifically, by copolymerizing isobutylene with o-, m-, and p-isopropenyltoluenes and isopropenyl-p-xylene. The thermal stability of the homopolymers and copolymers has been studied by heating samples of these materials and of their solutions in Turbine Oil L, the changes being followed by viscometry and thermogravimetry. It has been established that the viscosity loss upon heating solutions of these copolymers in oil is substantially less than that for a polyisobutylene solution. 2. When the copolymers are heated in air or in argon, volatile products are formed in greater amounts than from polyisobutylene under similar heating conditions.

Thermal stability of copolymers of isobutylene with styrene derivatives

Thermal stability of copolymers of isobutylene with styrene derivatives