Poly , heat capacity

SolubiHty parameters of 19.3, 16.2, and 16.2 (f /cm ) (7.9 (cal/cm ) ) have been determined for polyoxetane, po1y(3,3-dimethyl oxetane), and poly(3,3-diethyloxetane), respectively, by measuring solution viscosities (302). Heat capacities have been determined for POX and compared to those of other polyethers and polyethylene (303,304). The thermal decomposition behavior of poly[3,3-bis(ethoxymethyl)oxetane] has been examined (305). 

Fig. 4 Partial heat capacity functions of poly(NVCl-co-NVIAz) synthesized at 65 °C from the feeds with initial molar ratios of comonomers equal to a 85 15 and b 90 10 (the data from [26,27,42])...

Figure 11.7 Experimental and calculated heat capacities of solid and liquid PTT [49], From Heat capacity of poly(trimethylene terephthalate), Pyda, M., Boiler, J., Grebowicz, J., Chuah, H., Lebedev, B. V. and Wunderlich, B., J. Polym. Sci., Polym. Phys. Ed., 36, 2499-2511 (1998), Copyright (1998 John Wiley Sons, Inc.). Reprinted by permission of John Wiley Sons, Inc...

Lebedev, B.V. and Rabinovich, LB. Heat capacities and thermodynamic functions of methyl methacrylate and poly(methyl methacrylate), Tr. Khim. Khim. Teknol, 1 8-11, 1971. 

Figure 18.4. Heat capacity curves for poly(styrene) cooled at different rates. Adapted from Richardson (1989). Reproduced by permission of Elsevier, Ltd.

Changing a heat capacity, Cp, in above-mentioned equations into the residual electrical resistivity, p, they can be reduced to the corresponding kinetics models as applied to describe the results of residual resistivity measurements [5] for LuHo.igo and LuHo.254- Experimental [5] and theoretical [7], [8] results of investigation of the short-range order relaxation in LuHq.iso and LuHo.254 poly crystals were obtained from data about measurements of residual-resistivity-time dependence and are presented in Fig. 1 (b). These results we described within the framework of the first- and second-order kinetics models as well (see Fig. 1(b)). Migration energies for LuHq.iso and LuHo.254 solid solutions were evaluated and are listed in Table 1. 

Such a process is called polytropic. The equation is analogous to the isentropic equation (7.20) but the poly tropic exponent n is different from the heat capacity ratio k. 

Apart from the determination of heat capacities of a wide variety of materials, the other most common use of tmDSC is to determine the thermal behavior of synthetic polymers. A tmDSC analysis of poly(ethyle-neterephthalate) has been described by Haines et al. l... 

FIGURE 4.9 Apparent heat capacity and optical microscopy measurement (% light transmission) of a 75/25 poly(oxyethylene)/poly(ether sulfone) blend. (From Dreezen, G., Groen-inckx, G., Swier, S., and Van Mele, B., Polymer, 42, 1449, 2001. With permission.)... 

COM Comelli, F., Bigi, A., Vitahni, D., Rubini, K., and Francesconi, R., Densities, viscosities, refractive indices, and heat capacities of poly(propylene glycols) or poly(ethylene glycol)-poly(propylene glycol)-poly(ethylene yco )-block-copolymers + 2-methyltetrahydrofuran at (298.15 and 313.15) K and at atmospheric pressure, J. Chem. Eng. Data, 53, 1302, 2008. 

Glass transitions involve mainly the onset or freezing of cooperative, large-amplitude motion and can be studied using thermal analysis. Temperature-modulated calorimetry, TMC, is a new technique that permits to measure the apparent, fiequency-dependent heat capacity. The method is described and a quasi-isodiermal measurement method is used to derive kinetic parameters of the glass transitions of poly(ethylene terephthalate) and polystyrene. A first-order kinetics expression can describe the approach to equilibrium and points to the limits caused by asymmetry and cooperativity of the kinetics. Activation energies vary from 75 to 350 kJ/mol, dependent on thermal pretreatment. The preexponential factor is, however, correlated with the activation energy. 

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