Study of Melt Spinning Processing Conditions for a Polyacrylonitrile Copolymer with a Water/Ethanol Mixture as a Plasticizer

Abstract

This paper is concerned with the feasibility of melt spinning of polyacrylonitrile (PAN) copolymer (acrylonitrile/methylacrylate 95.6/4.4 mol% ratio) plasticized with water-ethanol (EtOH) mixtures. The melting point and rheological and stability behaviors of PAN/water/ethanol mixture are reported. The objective is to determine whether this mixture is appropriate for allowing the PAN to be melt spun. The melting point results from differential scanning calorimetry show the T _m of PAN/water/ethanol (70/15/15 wt%) mixture can be reduced to 150 °C from 300 °C. The time-dependent viscosity results showed that this mixture can be processed at 170 °C for more than 100 min without degradation. The steady-shear viscosity results indicated the shear-thinning behavior is observed for this mixture at a temperature ranging from 170 °C to 190 °C. These rheological data are also highly similar to the reference condition and other potential conditions reported in our previous paper, which indicates PAN/water/ethanol (70/15/15 wt%) at 170 °C is a potential condition for PAN melt spinning. The scanning electron microscopy diagrams show the copolymer strand melt extruded from PAN/water (70/30 wt%) mixture contains many more voids and bubbles than the PAN/water/ethanol (70/15/15 wt%) system. In conclusion, PAN/water/ethanol (70/15/15 wt%) at 170 °C is the most benign set condition (i. e. the composition and temperature) for carrying out the PAN melt spinning process.