| Abstract: | The influence of acrylic, methacrylic, and itaconic acid comonomers in the nitrile oligomerization of acrylonitrile copolymers has been studied by DSC and DSC‐FTIR in air and nitrogen atmospheres. Addition of metal salts in poly(acrylonitrile–acrylic acid) copolymer, PA on thermal and rheological behavior has also been reported. Incorporation of CuSO4, FeSO4, ZnSO4, and Al2 (SO4)3 (1 to 5 wt %) salt in the polymer solution affects its solubility in DMF. The complexes of PA with zinc sulphate, took a longer time to dissolve in DMF, whereas the complexes with Fe(SO4) and Al2(SO4)3 are almost insoluble in DMF, perhaps due to intermolecular crosslinking. Addition of these metal salts to the PA solution also affects its Brookfield viscosity. The viscosity of 10 wt % polymer solution increases from 400 centipoise (Cps) to 1090 Cps for complex with 5% FeSO4 (on the weight of dope solids) and 690 Cps for Al2 (SO4)3 and 906 cps for ZnSO4 complex. However, for CuSO4 salt complex this value is 770 Cps. FTIR spectra shows the participation of COOH and CN group in the complex formation, which is responsible for enhanced Brookfield viscosity. Thermal behavior of the polymer–metal salt complex showed that these salts also affect the exothermic reaction. The initiation of cyclization reaction takes place at a lower temperature compared to neat acrylonitrile–acrylic acid copolymer. However, the heat liberated per unit time in N2 atmosphere in case of neat polymer is 6.3 Jg?1 min?1, which reduces to 5.5 Jg?1 min?1 in the case of the PA/Al complex, confirming the role of Al2 (SO4)3 in retarding the rate of cyclization reaction. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 567–582, 1999 |
