The glass transition and molecular motions of poly(chlorotrifluoroethylene)

Abstract

Molecular motions in poly(chlorotrifluoroethylene) have been studied over the range −150 to +200°C by thermal/mechanical techniques with the specific intent of clarifying the glass transition ( T g) of this polymer. An extremely broad Γ relaxation, centred at ≈ −15°C and associated with an activation energy of 17 kcal mol −1, is proposed to be a predominantly amorphous phenomenon involving small scale motions. A β relaxation peak at ≈ 95°C with an activation energy of 64 kcal mol −1 represents the amorphous segmental mobility and its onset at 75 ± 2°C is assigned as the T g. This value for the T g of poly(chlorotrifluoroethylene) is supported by dynamic mechanical, thermomechanical and differential scanning calorimetric techniques. We are unable to support the existence of an α relaxation at 140–150°C, i.e. T g < T < T m, occasionally cited in the literature.