Abstract:  High performance carbon fibers for polymer matrix composites are currently derived from Polyacrylonitrile (PAN) copolymer fiber precursors via careful �stabilization� and carbonization. Polyacrylonitrile homopolymer degrades before it melts and is hence copolymerized with a small amount of comonomer to aid in depression of its melting point. All commercial PAN precursor fibers are presently wet or dry spun using expensive and environmentally harmful solvents and at slower rates than melt processed fibers could be produced1. Melt-spun fibers have been successfully generated when the copolymers were plasticized with water2.The water plasticized systems however require high pressures for extrusion, since the boiling point of water is below the extrusion temperature. Glycerin, a high boiling non-toxic plasticizer was earlier discovered to have somewhat similar plasticizing effects to water3. Glycerin, ethylene glycol , glycerin/water combinations and high molecular weight ethylene-vinyl alcohol copolymers have been investigated as potential plasticizers for high molecular weight (~240,000 g/mol), high acrylonitrile(93-96 wt%) content poly(acrylonitrile-co-methylacrylate) random copolymers. Equal weight mixtures of water and glycerin have been successfully extruded into fibers. Pure glycerin (25 wt %) induces an apparent crystallization followed by a reduced �Tm� of about 213 0C via DSC. However, this composition did not process well. A lower MW (~100K) copolymer was extruded with no apparent degradation. Our hypothesis is that the hydroxyl groups in glycerin (or water) disrupt the strong dipole-dipole interactions between the chains enabling the copolymer endothermic transition (�Tm�) to be reduced and melt before it degrades. Evidence for this is seen in the FT-IR which confirms specific interaction between the hydroxyl group of glycerin and the copolymer.References:D. D. Edie, Carbon 1998  , 36(4), 345-362James E. McGrath, Donald G. Baird, Sue J. Mecham, Susan Beck, Priya Pisipati, Jianhua Huang, Melt Processible Acrylonitrile Copolymers Via Free Radical or RAFT Controlled Radical Copolymerization and Processing Aids Based on Water and/or Glycerin, SAMPE Preprints, May 7,2013Alves,N.P.; Brito, C.A.; Garcia, E., Revista Plastico Moderno 2009,  n.412

Melt processible polyacrylonitrile/methyl acrylate (PAN/MA) statistical copolymers and plasticized blends as polymers for carbon fiber precursors

248th National Meeting (2014)

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