This work investigates the function of an oxygenated additive on improving both the drawability and stabilization of polyacrylonitrile (PAN) polymer. Mechanical, thermal, and structural changes of PAN polymer are analyzed in both film and fiber form. The PAN films with 1wt% additive showed a 100% increase in both tensile strength and elongation at break of films, attributed to strain-induced chain orientation and compaction of PAN chains. Pristine PAN film samples showed 3.9% shrinkage, while additive-modified PAN films showed 9.8% extension along the applied prestress axis, with modulated thermomechanical analysis (MT-TMA) revealing the major cause of change is irreversible dimension change (+ 5.7% (with 1% additive) Vs − 5% (pristine PAN)). Similarly, the X-ray diffraction analysis of post-MT-TMA films showed an increase in crystallinity (17.4–31.8%), which indicates the strain-induced crystallization in films caused by the plasticizing effect. In a pilot-scale wet spinning of 1 K filament fibers, the modified PAN fibers showed increased draw ratio (8.4 to 10.9), resulting in higher tensile strength (770 MPa) and modulus (15 GPa). Even during stabilization at 250 °C, the effect of improved crystalline structure can be observed in terms of higher tensile strength (243 Vs 190 MPa). The thermal analysis showed higher (+ 80 kJ/kg) exothermic enthalpy, indicating the higher nitrile cyclic formation during stabilization, resulting in an increase in residual weight of ~ 5 wt% at higher temperatures.
Chandel et al. (Wed,) studied this question.