Mechanical Properties and Orientation of Atactic Poly(methyl methacrylate): Sub‐Tg Annealing and Stereocomplex Formation

The mechanical properties and orientation behavior of atactic poly(methyl methacrylate) films cast from acetone (A‐aPMMA films) and chloroform (C‐aPMMA films), with subsequent sub‐T_g annealing, have been studied. The formation of a stereocomplex in sub‐T_g‐annealed A‐aPMMA films and C‐aPMMA films was demonstrated by means of differential scanning calorimetry. Stereocomplex in A‐aPMMA films is more pronounced than in C‐aPMMA films at each annealing temperature. It is proposed that stereocomplex formation can process at temperatures below T_g, leading to enhanced yield stress and higher orientation.