Structured polymer blends

The morphol. of model incompatible HDPE fiber-polystyrene blends was studied as functions of processing conditions and processing aids. Modeling of extrusion processes and continuous mixers yielded expressions for the shear rate and shear stress as well as the limited residence time and no. of reorientation. These results could be combined with knowledge of distributive and dispersive mixing process to predict morphol. development. Morphol. of nylon 6 blends with LDPE and ethylene-vinyl alc. copolymer including the effect of electron beam was also studied. [on SciFinder (R)

The measurement of interfacial tension in polymer/polymer systems : the breaking thread method

When blending incompatible polymers in the melt, the resulting morphology is strongly dependent on the interfacial tension. One stage of the mixing process is now used to determine this interfacial tension: in the absence of an overall flow field, extended liquid threads in a liquid matrix exhibit sinusoidal disturbances which cause the threads to disintegrate into lines of droplets. From the growth rate of these disturbances, the interfacial tension between the thread phase and the matrix phase is calculated. For molten polymers, this so-called ``breaking thread method'' is relatively fast and simple since it does not require density data for the two phases. Upon addition of a diblock copolymer to the thread phase, a considerable decrease in interfacial tension is measured