Paper Information

Journal:   IRANIAN POLYMER JOURNAL (ENGLISH)   2008 , Volume 17 , Number 3; Page(s) 227 To 235.
 
Paper: 

DESIGNING INDEX OF VOID STRUCTURE AND TENSILE MODULUS IN WET-SPUN POLY(ACRYLONITRILE) PROTO-FIBRES. PART II: SYNERGISTIC EFFECT OF DOPE NON-SOLVENT CONCENTRATION AND JET DRAW RATIO

 
 
Author(s):  ARBAB SH., MOHAMMADI N.*, NOURPANAH P.
 
* LOGHMAN FUNDAMENTAL RESEARCH GROUP, POLYMER ENGINEERING DEPARTMENT
 
Abstract: 

Synergistic effects of dope non-solvent concentration and jet draw ratio of poly(acrylonitrile) on as-spun fibre void structure and tensile properties were investigated and rationalized based on a modified designing index, namely CXh-1. The notations C, X, and η are the non-solvent diffusion coefficient normalized by the solvent diffusion coefficient through the proto-fibre, a parameter defined by solubility differences among the system components and jet elongation viscosity, respectively. An increase of dope non-solvent concentration enhanced CXh-1 leading to minute porosity decrease. On the other hand, the simultaneous dope non-solvent concentration and draw ratio increases up to 5 vol% and 4, led to reduction of CXh-1 and therefore to severe fibre porosity. The modulus-porosity relationship of the free drawn fibres were best fitted with the Wang's second order equation E = E0e-(ap+bp2) (R2=0.96) and hence assigned to liquid-liquid de-mixing as the governing phase separation mechanism. On the other hand, the mechanical behavior/porosity of proto-fibre containing non-solvent in their dope and drawn with the draw ratio value of 4 was best fitted with the Eshprieg's first order equation, E =E0e-ap (R2=0.97) and accordingly assigned to the solid-liquid based phase separation. Where E0 and p are modulus of the virgin sample and its porosity, respectively, while a, and b are the Eshprieg's and Wang's equation constants.

 
Keyword(s): WET-SPINNING, POROSITY, MECHANICAL PROPERTIES, NON-SOLVENT, PHASE SEPARATION
 
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