Effect of Temperature on the Conformation Changes of Structural and Thermophysical Characteristics in Composite Cellulose-Acetate Films

Аннотация

The effect of temperature on the conformation changes of the structural and the thermophysical characteristics in the UAM-50, UAM-100, and MGA-95 composite films of cellulose acetate are studied. An interphase layer appears at the phase interface in the UAM-50 and the UAM-100 samples according to the data of differential scanning calorimetry. An exothermic effect appears in the calorimetry data curves for water-saturated samples in the temperature range of ΔT = 125–226°C with ΔH = 20.7 kJ/kg for the UAM-50 and 27.95 kJ/kg for the UAM-100; this indicates hydration of the polar groups of cellulose acetate and polyamide in the interphase layer of the composite films. When composite films in the air-dried and the water-saturated samples were studied with differential scanning, there was a redistribution of the ratio between the quantities of perfect crystalline structures in crystallites with different melting enthalpies. The melting enthalpy decreases from 6.06 to 0.99 kJ/kg for the MGA-95 low-temperature phase, from 1.99 to 1.72 kJ/kg for the high-temperature phase; from 3.04 to 1.38 kJ/kg for the UAM-50 low-temperature phase, from 8.12 to 1.76 kJ/kg for the high-temperature phase; from 4.99 to 1.5 kJ/kg for the UAM-100 low-temperature phase, and from 2.33 to 0.77 kJ/kg for the high-temperature phase. The total melting enthalpy of the endothermic peaks also decreases for all three samples; this is an indication of decreased crystallinity in the water-saturated samples of the composite films.