On the specific heat and mass loss of thermochemical transition

Abstract

Poly(vinyl alcohol) PVA is a synthetic polymer used in a variety of applications and exhibits unusual thermal behavior. In this work, differential scanning calorimetry (DSC), isothermal and non-isothermal thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), optical microscopy, viscometry and kinetic modeling were used to study the thermal behavior of PVA for providing further insights about the thermochemical transition. It is shown that the value of specific heat of thermochemical transition is comparable to theoretical values derived from chemical bond dissociation energy values. Activation energy's contribution to the specific heat of thermochemical transition seems to be low. Contradictions among the conclusions from various analytical techniques, regarding the glass transition of PVA, are discussed and interpreted. Settlement of these contradictions leads to the conclusion that like PVA's melting point, its glass transition is also a thermochemical transition but with no detectable mass loss.