Determination of polymer transitions and investigations into molecular structure

2 Determination of polymer transitions and investigations into molecular structure 

Its sensitivity is such that it can also detect the more minor transitions that occur in plastics and rubbers at lower temperatures. These transitions are referred to as 3 and -y peaks in the tan 8 plot and are due to movements within the structure of the polymer 

DMA was used by Khonakdar etal [35] to study miscibility and the a, p and y transitions in blends of ethylene-vinyl acetate (EVA) with LDPE and HDPE. The results showed that the presence of the EVA reduced the temperature of all three types of transition. Increasing the level of the EVA was also found to broaden the peak of the tan 8 and this was thought to be due to a reduction in the level of crystallinity of the materials. 

The sensitivity of DMA to the glass transition temperature of polymers can be exploited for a number of different applications  

The identification of two polymers in a blend, even when one of the components is present at a low, e.g. 5%, level. 

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