Dependence of transition temperatures and enthalpies of fusion and crystallization on composition in polyaniline/nylon blends

The properties of blends, cast from hexafluoro-2-propanol; of nylon 6 and o f nylon 12 with polyaniline doped with various functionalized organic acids were investigated using differential scanning, calorimetry and microscopy. The glass transition temperature of the as-cast and dried blends;ls of pol yaniline with either nylon displayed a composition-independent relationship indicative of a phase-separated morphology irrespective of the functionali zation of the sulfonic acid dopant. Although electron microscopy data also showed phase-separated morphologies, the PANI domain size within the nylon matrix was found to be dependent upon the functionalized acid dopant. A dec rease in the melting transition temperatures of nylon 6 and associated enth alpies with blend composition is attributed to the effects of dissociation and degradation processes occurring during thermal analysis. We suggest tha t the effusion of the resulting thermally induced species from within the p olyamide domain disrupts the crystalline structure, leading to depression i n the melting point and heat of fusion. Changes in other thermal transition s, such as melt and cold crystallizations and their enthalpies, were attrib uted similarly to products of PANI dissociation and degradation formed duri ng thermal analysis.