Glass Transition and Cooperative Dynamics in PMMA/SAN/Clay Nanocomposite

Cooperative relaxation of blend of Poly(methyl methacrylate) and Poly(styrene-ran-acrylonitrile) and its nanocomposite containing 3wt% of organoclay (cloisite 30B) have been studied by differential scanning calorimetry (DSC). Heat capacity measurements have been employed to evaluate the effect of nanoconfinement on the glass transition cooperativity. The size of cooperatively rearranging regions, ξCRR, decreased from 2.64 for neat PMMA/SAN to 1.86 for the 50/50 PMMA/SAN/organoclay nanocomposite. The degree of thermodynamic fragility has been also appraised from ΔCP/CP,l at the glass transition temperature which ΔCP was normalized by the molecular weight of the structural units of systems. On the other hand, the slope in the Arrhenius diagram log τ vs Tg/T at Tg, dynamic fragility, was calculated from dynamic mechanical analysis (DMA). It observed that, the nanoconfinement decreased both thermodynamically and dynamically fragility.

کلیدواژه ها:

Polymer Blend ، Cooperatively Rearranging Regions ، Fragility