Linear polymers glass transition temperature

A second class of polarizers uses dichroism to produce linearly polarized light. Techniques to produce dichroic polarizing sheets were pioneered by Land [52], These are made by dissolving a strongly dichroic, small molecule into an amorphous, transparent polymer. The dichroic molecules are then oriented by a uniaxial stretching of the polymer matrix. Since this is accomplished below the polymers glass transition temperature, this ori-... 

The plotted according to the experimental data dependencies of elasticity modulus E on macromolecular entanglements cluster network density (Figs. 2.5 and 2.6) break down into two linear parts, the boundary of which serves loosely packed matrix glass transition temperature which is lower on about 50K of polymer glass transition temperature [50]. Below the value E is defined by the total contribution of both clusters and loosely packed matrix and above - only by clusters contribution. It becomes clear, if to taken into consideration, that above the elasticity modulus value of devitrificated loosely packed matrix has the order of 1 MPa [51], that is, negligible small. It is an extremely interesting the observation, that loosely packed matrix in the value E, determined by the plot E (v, ) extrapolation to = 0, is independent on temperature. Such situation is not occasional and deserves individual consideration. 

Mechanical properties of these linear polymers can be varied within wide limits by proper selection of the diol or mixture of diols. This is illustrated in Fig. 2 which shows variation in the glass transition temperature of the polymer as a function of diol composition... 

The heat distortion temperature of impact-resistant polystyrene may also be improved by polymer blends. Those of impact-resistant polystyrene with poly-2,5-dimethylphenylene-1,4-oxide (PPO) are particularly interesting (90). Polystyrene and PPO are molecularly compatible and mixtures of them have glass transition temperatures which vary virtually linearly with composition. A further advantage of these compositions which should not be under-estimated is their better flame resistance. 

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