synopsisThe accelerated rate of diffusion of disperse dyes into synthetic fibers caused by various dyebath additives ("carriers") has been correlated with their plasticizing action. The rate of change in length of Acrilan filaments with temperature under dyebath conditions enabled the effects of the carrier on the To of the filaments to be measured, and the results for different concentrations of carrier a t one temperature could be superimposed on a common curve by employing suitable shift factors. The shift factors, BS well as the variations of the diffusion coefficients of dyes with temperature and carrier concentration, bothmatched a WLF relationship, confirming that the dyeing process is controlled by the segmental mobility of the polymer. Indirect experimental evidence suggests that the same relation will describe the effect of carriers on the dyeing of poly(ethy1ene terephthalate) substrates with disperse dyes. INTRODUCTIONEarlier diificulties associated with the coloration of synthetic fibers made from polyacrylonitrile and poly(ethy1ene terephthalate) , using nonionic dyes, were due to the unacceptably slow rate of diffusion of the dyes into the fiber. These practical problems were eventually overcome by applying the dyes in specially developed pressurized machines which operate at temperatures greater than 100°C, or by the addition to the dyebath of organic compounds such as phenols, primary amines, hydrocarbons, and esters, which have the effect of increasing the rate of diffusion of the dyes in the fibers to an acceptable level of temperatures below 100°C. The latter compounds are referred t o as "carriers" and their mode of action is discussed in this report.Various aspects of the action of "carriers" have already been examined in an attempt to elucidate the mechanism by which they operate and various theories have been put forward. Some workers' suggest that the enhanced rate of dyeing is a result of an increase in the low solubility of the disperse dyes in the dyebath, while others2 claim the action of water-insoluble carriers to be due to the formation of a surface layer of carrier around the fiber in which the dye is very soluble and from which movement into the fiber is rapid due to the intimate contact between dye and fiber.It has also been noted that some carriers cause swelling of the fibers, and this leads to the theory that a more vigorous movement of the fibrous 3733

SynopsisHigh-density polyethylene up to about 30% by weight was melt-mixed with polypropylene and short-glass-fiber-reinforced polypropylene. The presence of high-density polyethylene and glass fibers in the polypropylene matrix affects its crystallization characteristics, which were studied with the help of differential scannihg calorimetry. The blend and composite samples have a large number of polypropylene domains apparently due to an abundance of surface nuclei; as a result, the tensile strength, tensile modulus, and toughness are enhanced. The temperature dependence of shear modulus and logarithmic decrement indicate that high-density polyethylene can have plasticizing effect below the glass transition temperature of polypropylene. The scanning electron micrographs of fractured ends show the presence of dispersed domains in the composite samples.

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The equilibrium constant K = [OEt-] [H,O]/[OH-] [EtOH] has been calculated for mixtures of water and ethanol containing up to 35% by volume of ethanol by measuring the simultaneous rates of hydrolysis and ethanolysis of various solutes. The values of K vary as the solvent composition is changed, and also from one solute to another.

SynopsisThe melting and crystallization behavior of poly(tetramethy1ene terephthalate) and its copolymers with tetramethylene sebacate (> 20 mol%) has been studied using differential scanning calorimetry (DSC). The effect of the sebacate concentration on equilibrium melting temperature and crystallization behavior is discussed in terms of the theory of equilibrium crystallization of random copolymers. The multiple-melting behavior of these systems is described and interpreted in terms of the theory of equilibrium melting of chain-folded crystals, together with molecular fractionation during crystallization and melting and recrystallization during the DSC scan.