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One modi®ed poly(ethylene terephthalate) (m-PET) containing 16 mol % of isophthalic acid content and three kinds of isotactic polypropylene (i-PP) with different molecular weights were melt blended in various volume ratios by a twin screw extruder. The dynamic viscosity of the i-PP=m-PET blend showed positive deviation at lower volume content of i-PP and negative deviation at higher volume content of i-PP. The size of dispersed phase increased with an increase of the minor component. Also, the less difference between the viscosities of two polymers caused the smaller particle size in the blend and the smaller critical Weber number. After melt spinning of these binary polymer blends, m-PET and i-PP micro staple ®ber, whose diameter was about 0.13 to 2.75 mm, could be obtained by extracting the continuous phase with a proper solvent. The less the minor component in the blend, the better the spinnability of the blended polymers and the physical properties of the ®ber. Also, when i-PP was the continuous phase, the spinnability and the physical properties of the ®bers were better than the opposite case. Molecular weight of i-PP and the blend ratio had a marked in¯uence on the diameter of micro®bers. The micro ®ber obtained from i-PP which has similar viscosity with m-PET showed the smallest diameter than those obtained from other two i-PPs.

ABSTRACT:The linear viscoelastic behavior of acrylonitrile-butadiene-styrene (ABS) polymers in the molten state, with different degrees of grafting, was investigated within the framework of Palierne's emulsion model. The main aim of the present study is to quantitatively analyze the effect of grafting degree on the storage modulus GЈ of the polybutadiene (PB) rubber core dispersed in ABS polymers. According to our model calculations, the degree of grafting significantly affects the GЈ values of the PB core and, hence, the viscoelastic properties of ABS polymers. Our calculations showed that the Palierne model is very useful to calculate the storage modulus of the rubber particles dispersed in rubber-modified polymeric materials, at least in the high-frequency region.

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