Glass-transition temperature increase

Films containing about 10% CIRh(PPh3)3 in PMMA were prepared and subjected to oxygen index, TGA, and DSC measurements. The oxygen index, bottom ignition (1 1), increases from about 14 for pure PMMA to about 20 for the rhodium compound in PMMA. TGA analysis indicates that about 25% of the sample is non-volatile at 600°C and the glass transition temperature increases by about 15°C by DSC. 

Glass Transition Temperature Increases with the presence of bulky pendant groups stiffening groups as 1,4-phenylene chain symmetry polar groups cross-linking... 

Glass Transition Temperature. Tables III and IV list the glass transition temperature (Tg) of both chlorinated PMS and P-p-MS respectively. A plot of Tg as a function of chlorine content is shown in Figure 13. The glass transition temperature increases with degree of chlorination as a result of increasing polarity (21). This increase in Tg is a linear function of the extent of chlorination. 

Reduction in the water holding capacity of the corneum can also make the corneocyte proteins brittle and vulnerable to cracking. Keratins in the corneum have a glass transition temperature just below the body temperature28 and this is sensitive to humidity levels. Glass transition temperature is the point below which the material is brittle. As the humidity/water content of the SC decreases, glass transition temperature increases to values above the body temperature thus making the corneocytes brittle at body temperature. 

The rates of relaxation and retardation processes above the glass temperature are strongly dependent on the viscosity and thus on the fraction of free volume present. Because the viscosity not only depends on temperature but also on static pressure (the glass transition temperature increases approximately 1 °C per 20 bar of pressure) it is not surprising that pressure also affects the viscoelastic processes. A qualitatively relation analogous to Eq. (13.121) can be readily derived (Ferry, 1980) ... 

About 40% of the monomer is used to produce heat-resistant ABS. For styrenic polymers containing 20wt% of AN, the glass transition temperature increases by about 0.4 °C for every 1 % of styrene that is replaced with aMeS. 

Before BASF investigated this product, Quirk and Hsieh [1], Yuki and coworkers [2,3] and Fischer [4] carried out investigations with this monomer. The first two used the anionic polymerization mechanism and Fischer tried to copolymerize this monomer using free radical polymerization. In the latter case the yields were very low. The use of S/DPE blocks in thermoplastic elastomers [5] has also been briefly described. Some of the work carried out at BASF has been published in a recent review article [6], Owing to the enhanced thermal properties of this copolymer in comparison with atactic polystyrene - the glass transition temperature increases up to 180 °C, depending... 

Several investigators (30, 45) found that the glass transition temperature increases with an increase in the concentration of ions in linear poljmiers. 

Several examples of ethylene/cyclopentene co-polymers prepared with metallocene catalysts have been reported.596,603,604 As is the case of many other co-polymers, for ethylene/cyclopentene co-polymers, the glass transition temperature increases linearly with the cyclopentene content,605 in the range 25-50 mol% of cyclopentane units. 

When the degree of cross-linking is low (H, is large), the glass transition temperature increases slightly as cross-linking proceeds. As approaches values in the hundreds, T becomes a sensitive measure of cure. Equation 10 can be derived in its essential features from the kinetic theory of rubber elasticity (62). giving... 

Polyphosphazenes with ferrocenyl substituents 35 have also been synthesized via the functionalization of poly-(methylphenylphosphazene) and related polymers by means of a deprotonation-electrophilic addition strategy (e.g., see Equation (10)). This versatile reaction sequence has yielded materials with, for example, degrees of substitution of 45% and 36% for polymers 35 (R = H and Me), respectively. The molecular weights of the polymers were M = Z.O x 10 and 1.5 x 10 for 35 (R = H and Me), respectively (with PDI values of 1.4-2.0). The glass transition temperatures increased in comparison with the unsubstituted polymer (Tg = 37°G) for 35 with values of 92 °C (R = H) and 87 °G (R = Me). 

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