Modulated temperature DSC studies on the phase transitions of poly(ethylene oxide). Effect of temperature step

摘要

Phase behaviour of poly(ethylene oxide) (PEOX) was investigated by modulated temperature differential scanning calorimetry (DSC) - step scan alternating, DSC at different temperature steps. Additional features of reversible and non-reversible components during phasae transitions can be found. By increasing the temperature step between subsequent isothermal segments the reversible component of the melting process was decreasing. This effect is due to a shift of the equilibrium state of melting-recrystallization reversible processes towards higher degree of conversio that hinders molecular nucleation and recrystallization. Analysis of the non-reversible component during crystalization showed that an increase in the step caused a very distinct increase in the non-reversible component signal due to enhanced crystallizaiton of the less-defected structures which was facilitated by larger temperature gradient.