Dynamic-mechanical study of molecular motions in solid polyoxymethylene copolymers from 4 to 315°K

Variations in four mechanical relaxations in polyoxymethylene copolymers in the temperature range from 4 to 315°K are described as a function of comer size and amount. The 6 relaxation at 50°K is interpreted as being due to limited motions in defect crystals; the γ2 relaxation, at ca. 175°K, is also associated with defect motion in the crystal; the γ1 relaxation, at ca. 205°K, is suggested to involve motion of short segments in disordered regions; aad the β relaxation, at ca. 270°K, involving motion of long segments, can be considered to be the glass transition.