Elongational flow properties of thermoplastic polyvinyl alcohol/polypropylene from the melt spinning method

Abstract

In this investigation, the blend melts of thermoplastic polyvinyl alcohol (TPVA) and polypropylene (PP) were prepared through melt blending with various blending ratios. The melt spinning method was then adopted to determine and analyze the uniaxial elongational flow properties of the blend melts. First, a melt with a fixed blending ratio (TPVA/PP = 60/40) was selected as the sample to examine the effects of drawing ratios and spinning temperatures on the flow behavior. Experimental results demonstrate that the drawing ratio is the major determinant of elongational flow behavior, while temperature variation exerts little influence on flow behavior. Furthermore, the drawing ratio can also be altered through melt throughputs. The major differences between the samples with different melt throughputs were in the variations of thinning ability and the alteration of melt solidification points, leading to completely different elongation rate ranges. However, the elongation rate ranges increased with the drawing ratio. In addition, the elongation rates were initially close to each other, since the drawing ratio is changed by take up speed with same throughput. Moreover, the experimental data indicate that the elongational flow behavior of blend melts is also influenced by blending ratios. As the blending ratios converged, the elongational resistance decreased, and the elongation rate increased, suggesting a high deformation rate. Conversely, as the differences between blending ratios rose, the elongation rate decreased and the elongational resistance increased, such that the TPVA blending proportion was 20% or 80%. The elongational resistance of TPVA that increases with concave downward, and TPVA/PP blend melts exhibited an inflection in the profile of the elongational resistance versus the elongation rate.