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Hydroxyterminated polybutadiene (HTPB) was reacted with 2,4-toluene diisocyanate (TDI) followed by the addition of a diamine chain extender (prepared by the condensation reaction of 4,4′ ′diaminodiphenylsulfone and terepthalaldehyde) to prepare an imine containing polyurethaneurea (PIUU). The prepared polyurethaneurea was caste in order to obtain polymer film. The new polyurethaneurea film showed high phenol selectivity as pervaporation membrane. About 88% phenol was obtained in condensed permeate when pervaporation was performed at 50°C with 7% aqueous phenol solution as feed and permeate side pressure was maintained at 5 mm of Hg.

Hydroxyterminated-polybutadiene-based prepolyurethanes were prepared with two different catalysts, dibutyltindilaurate (DBTDL) and triethylamine (TEA); chain extension of the prepolyurethanes followed with two different aromatic diamines, oxydianiline and 4,4Ј-diaminodiphenylsulfone, in various concentrations. The prepolyurethane synthesis followed second-order kinetics, with the DBTDL catalyst showing better efficiency for urethane formation than TEA. TEA-catalyzed synthesis suffered from the self-association of isocyanates as a major side reaction, following second-order kinetics with respect to isocyanate concentration. Although there was a gradual increase in the intrinsic viscosity during prepolyurethane synthesis in the presence of DBTDL, the intrinsic viscosity remained almost constant with the progress of the reaction in the presence of TEA. The tensile properties of prepolyurethane and polyurethaneureas synthesized in DBTDL-catalyzed reactions were higher than the properties of those synthesized in TEA-catalyzed reactions. The variation of the tensile strength with the diamine concentration was correlated with the crosslink density and sol fraction. The solubility of the hard segment of polyurethaneurea in the reaction medium appeared to be important in influencing the tensile properties. The effects of the diamine concentration (chain extender) on the diffusion coefficient and activation energy of diffusion of toluene in polyurethaneureas were studied.

Hydroxy-terminated polybutadiene-based prepolyurethanes and diamine chain extended polyurethane-ureas were prepared and treated with various organic solvents in the moisture-cured state in order to modify their ultimate strength. FTIR studies with solvent-treated polyurethanes and polyurethane-ureas confirmed that organic solvents penetrated inside the polyurethane hard segments and affected hydrogen bonding. The polar and non-polar solvents showed different abilities to penetrate into polyurethane hard segments. Solvent treatment after moisture curing increased the tensile strength of these polyurethanes and polyurethane-ureas with respect to control samples. The stress-strain behaviour of solvent-treated polyurethane follows the constrained junction model. The change in hard segment crystallinity on solvent treatment has been explained by wide-angle X-ray diffraction study. The better orientation in polybutadiene soft segments evidenced from SEM (scanning electron microscopy) pictures is believed to be the main reason behind the improved tensile properties of solvent-treated polyurethane samples. The effect of solvent treatment, as well as stretching, on the diffusion coefficient of hexane in polyurethanes was investigated.

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ABSTRACT:A new method of edge correction has been formulated to calculate the near true diffusion coefficient of hexane in thin polyurethane and polyurethaneurea sheets. The method involves the calculation of time-average thickness during the diffusion of hexane in hydroxyterminated polybutadiene-based polyurethane and polyurethaneurea sheets. The precision of the method has been tested by the iteration of data. The diffusion coefficient increases with the increase of diamine chain extender in polyurethaneureas. The variation of activation parameters and enthalpy of diffusion of hexane with diamine chain extender in polyurethaneurea also have been studied.