Identifying Melt Processing Conditions for a Polyacrylonitrile Copolymer Plasticized with Water, Acetonitrile and their Mixtures

This paper discusses the feasibility of the melt spinning process of polyacrylonitrile (PAN) copolymer (acrylonitrile/methylacrylate 95.6/4.4 mol% ratio) plasticized with H2O acetonitrile (ACN) and their mixture. The objective is to use water only as a plasticizer to melt spin PAN under specific conditions (composition, temperature etc.). The melting point and theological measurements have been conducted by differential scanning calorimetry (DSC) and a modified capillary rheometer, respectively, for this plasticized system. The DSC results show that the melting point of the PAN copolymer can be reduced from over 300 degrees C to below 180 degrees C, which is the temperature for the onset of degradation (cyclization and crosslinking) of PAN. Rheological results show that the PAN copolymer can be extruded with a reasonable viscosity at 15 to 20 degrees C above its melting point, and also the stability and viscosity are strongly dependent on temperature and the plasticizer type and content. Furthermore, the results indicate that the most appropriate condition for PAN melt spinning is for the PAN/H2O mixture of 70/30 wt% ratio at a temperature of 180 degrees C for which the copolymer sample can remain stable without significant degradation for around 120 min and maintain its viscosity in the range of around 600 Pa s.