Measuring cell: DSC821e with air cooling and automatic sample changer
Pan: Aluminum standard 40 μl, hermetically sealed
Sample preparation: Samples weighed in without pressing before sealing
DSC measurement: Heating from 35 to 150°C at 10 K/min to eliminate thermal history, quench-cooling in the sample changer. Second heating run 35 to 150 °C
Atmosphere: Static Air
The three measurements show the effect of the chlorine concentration on the glass transition. Higher concentrations of chlorine decrease the molecular mobility. As a result of this, the glass transition shifts to higher temperatures. The broadening of the glass transition with increasing chlorine content is particularly noticeable. The reason for this is the relatively large degree of inhomogeneity of the chlorine distribution. In chlorination, a hydrogen atom is replaced by a chlorine atom. This does not change the number of degrees of freedom of a monomer unit. The step height (Δcp) with respect to the molar mass therefore remains unaffected by chlorination. The decrease in the step height with increasing chlorination, which is apparent in the figure, is therefore due to the increase in size of the molar mass.
Glass Transition of PVC and Chlorinated PVC | Thermal Analysis Handbook No.HB223 | Application published in METTLER TOLEDO TA Application Handbook Thermoplastics