Glass transition behavior of poly(trimethylene 2,6-naphthalate) in nanoclay confinement

The glass transition behavior of poly(trimethylene 2,6-naphthalate) (PTN)/nanoclay composites was investigated using differential scanning calorimetry and dynamic mechanical analysis. The incorporation of two different types of nanoclays in the PTN matrix resulted in intercalation of the PTN chains in the narrow space of the clay intergalleries (d 001(clay)) and constrained the polymer chains in the vicinity of the nanoclay layers. Despite being in constrained regions, the glass transition temperature of the PTN/nanoclay composite was decreased as compared to neat PTN. Moreover, the characteristic length of the polymer chains (ξa) at T g was evaluated by employing the cooperatively rearranging region theory. The glass transition of the PTN chains depended on the correlation between ξa and the interlayer gallery distance (d 001(clay)). The decrease in T g of PTN/nanoclay composites is ascribed to the development of local free volume owing to the confining effect of the chain intercalation.