Glass transition temperature, effect molecular weight

Block resistance - wet/dry - ink to ink and ink to substrate The exposure time, pressure, and temperature are specified by the end use requirement (i.e. 3 min at 1034 bar, 50 °C for surface print ink (5.4) - The ink surface s resistance to heat and pressure is subjectively measured. Ink properties that effect blocking results are hardness , adhesion, cohesion, and slip. The polymer glass transition temperature (Tg), molecular weight, and surface compatibility effect the block resistance test... 

In Figure 2.4 the pressure-volume isotherm is shown at 25°C for polystyrene using the FOV equation of state. The characteristic parameters were obtained from Table 2.2. The EOS does not explicitly account for molecular weight and glass transition temperature effects. 

T is the glass-transition temperature at infinite molecular weight and is the number average molecular weight. The value of k for poly(methyl methacrylate) is about 2 x 10 the value for acrylate polymers is approximately the same (9). A detailed discussion on the effect of molecular weight on the properties of a polymer may be found in Reference 17. 

On comparison of the yield strengths and elastic moduli of amorphous polymers well below their glass transition temperature it is observed that the differences between polymers are quite small. Yield strengths are of the order of 8000 Ibf/in (55 MPa) and tension modulus values are of the order of 500 000 Ibf/in (3450 MPa). In the molecular weight range in which these materials are used differences in molecular weight have little effect. 

Effect of varying polyol molecular weight on the glass transition temperature of polyurethanes... 

Figures 2-5 depict the effects of CL content upon number-average molecular weight, glass transition temperature(Tg) and crystallization characteristics for those copolyesters derived from oligomeric PCL-diols.

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