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(acrylonitrileacrylic acid) copolymer, PA on thermal and rheological behavior has also been reported. Incorporation of CuSO 4 , FeSO 4 , ZnSO 4 , and Al 2 (SO 4 ) 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(SO 4 ) and Al 2 (SO 4 ) 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% FeSO 4 (on the weight of dope solids) and 690 Cps for Al 2 (SO 4 ) 3 and 906 cps for ZnSO 4 complex. However, for CuSO 4 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 N 2 atmosphere in case of neat polymer is 6.3 Jg Ϫ1 min Ϫ1 , which reduces to 5.5 Jg Ϫ1 min Ϫ1 in the case of the PA/Al complex, confirming the role of Al 2 (SO 4 ) 3 in retarding the rate of cyclization reaction.

SYNOPSISSolution copolymerization of acrylonitrile (AN) with various vinyl acids, i.e., acrylic acid (AA), methacrylic acid (MAA), and itaconic acid (IA), was carried out in DMF at 70°C using a,a'-azobisisobutyronitrile (AIBN) as an initiator with an acidic monomer of 0.012-0.092 mol %. Copolymers were characterized by FTIR, CHN analysis, 'H-and 13C-NMR, and viscometry. The reactivity ratios were calculated using Fineman-Ross and KelenTudos methods. In all three systems, the value of rl (AN) is much less than the value of r2. However, the rz (MAA) is higher than r2 of (AA) and (IA). The reactivity ratios were calculated using Q and e schemes also. The results are in good agreement with experimentally calculated data. The tacticity and sequence length distribution of these copolymers were calculated using 13C-NMR from C=N and CH signals. It was observed that the isotacticity of acrylonitrile-itaconic acid copolymer P(AN-IA) with 8.2 mol % of a comonomer is lower than that of P(AN-MAA) with 10.3 mol % and P(AN-AA) with 7.61 mol %. 0 1996 John Wiley & Sons, Inc.