HER/HQEE blends

To study the eutectic nature of the HER/HQEE blends, freezing point determinations were made. HER/HQEE blends were prepared at different weight ratios and melted at elevated temperatures. Then the melt was allowed to cool slowly under controlled conditions. The temperature at which the first crystallisation was observed was considered to be the freezing point of the melt corresponding to that particular HER/ HQEE composition. 

The plot of freezing point versus HER/HQEE blend is shown in Figure 8.13. As can be seen from the plot, HQEE melting can be considerably reduced with the help of an HER extender. 

Figure 8.13 Apparent freezing points of HER/HQEE blends...

In the case of poly(ester urethanes), HER and HQEE extended elastomers showed comparable tensile, tear, glass transition temperature (T ) and hysteresis (tan 8) properties. Compared to HER, HQEE extension produced elastomer with about 2 Shore-D units higher hardness. An improvement in the tensile strength value was observed for the HER/HQEE blend at 25 75 weight ratio. In general, all the physical and mechanical properties were slightly affected or lowered with HER/HQEE blends compared to either HER or HQEE extended material. 

DMA properties of HER and HQEE extended elastomers are similar. All the other physical and mechanical properties of the elastomers from the HER/HQEE blends were lower than the HER or HQEE extenders. 

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