Poly thermoelasticity

Sperling, L. H., and A. V. Tobolsky Thermoelastic properties of poly (dimethyl siloxane) and poly (ethyl acrylate) as a function of temperature. J. MakromoL Sci. 1, 799 (1966). 

Using poly(oxytetramethylene)glycol as diol component, the subsequent polymerization of styrene led to a thermoplastic elastomer with properties similar to commercial thermoelastics . 

Static mechanical measurements to evaluate the stress-strain relationship in cholesteric sidechain LCEs have been described [71, 72]. In [72] it has been found, for example, thatfor0.94nominal stress Cn is nearly zero as the poly domain structure must be converted first into a monodomain structure. For deformations A < 0.94, the nominal stress increases steeply. Similar results have also been reported elsewhere [71]. The nominal mechanical stress as a function of temperature for fixed compression has also been studied for cholesteric sidechain elastomers [71]. It turns out that the thermoelastic behavior is rather similar as that of the corresponding nematic LCE [2, 5]. 

As seen in Figure 9B, at fixed extension of the y-irradiation-cross-linked elastic matrix comprised of poly[0.8(GVGVP), 0.2(GEGVP)], protonation of four carboxylates per 100 residues results in development of elastic force. A thermoelasticity characterization of this matrix at low pH gives the same result of dominantly entropic elasticity as found in curve b of Figure 6B for poly(GVGVP) in the absence of carboxyl moieties. 

Fig. 1.16. Thermoelastic results on poly(dimethylsiloxane) networks and their interpretation in terms of the preferred, -trans conformation of the chain [3, 6]. For purposes of clarity, the two methyl groups on each silicon atom have been deleted.

Wen J, Mark JE. Torsion studies of thermoelasticity and stress-strain isotherms of unimodal, bimodal, and filled networks of poly(dimethylsiloxane). Polym J 1994 26 151-7. 

McCrum [213, 214] recently suggested that the above approach is subject to large errors and based on an irrational premiss. He proposed a new method of thermoviscoelasticity . Smith and Mark [215] have demonstrated McCrum s analysis to be flawed and have shown that the classical thermoelasticity approach is soundly based on theory. Indeed, there is excellent agreement between thermoelastic and viscometric results for poly(l-pentene) [206, 211], polyethylene [151, 154, 155, 211, 216], poly(dimethyl siloxane) [205, 211, 217], poly(ethylene oxide) [211, 218], poly (isobutylene) [207, 211, 216, 219] and poly(H-butyl methacrylate) [220, 221] (Table 6). 

P. A. Botto, R. A. Duckett, and I. M. Ward, The Yield and Thermoelastic Properties of Oriented Poly(Methyl-Methacrylate) , Polymer 28, 257-262 (1987). 

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