POSSIBILITIES OF THE CALORIMETRIC METHODS OF STUDYING THERMOPHYSICAL CHARACTERISTICS OF BIOPOLYMERS
The results of research enhanced calorimetry for determination the thermophysical properties of plant powders as biopolymers presented. The maximum temperature range of calorimetric scanning for biopolymers with natural humidity is chosen within their glass transition temperatures, for hydrated biopolymers with 20% humidity is chosen within the dehydration temperature of polymer decomposition or before the formation of a polymer network that suppresses its hydrophilicity. We found that the final scanning temperature depends linearly from the humidity level. The dependence of phase transition temperatures from particle size, molecular weight and active humidity of biopolymers was established. We have identified that the freezing temperature of amorphous powder with active humidity below 0,926 is shifted below zero. Dry powders with low glass transition temperatures below 150 °C after hydration are characterized by freezing temperatures below 0 °C. Powders with high glass transition temperatures above 153 °C after hydration are characterized by freezing temperatures of 0 °C. As a result of this work we found that maximum dehydration temperatures of 120 °C and 153 °C are typical for amorphous powders with natural humidity and glass transition temperatures not exceeding these dehydration temperatures very much, which can characterize these temperatures also as temperatures responsible for the preservation of the hydrophilic structure.