Tg, effect

The conformational entropies of copolymer chains are calculated through utilization of semiempirical potential energy functions and adoption of the RIS model of polymers. It is assumed that the glass transition temperature, Tg, is inversely related to the intramolecular, equilibrium flexibility of a copolymer chain as manifested by its conformational entropy. This approach is applied to the vinyl copolymers of vinyl chloride and vinylidene chloride with methyl acrylate, where the stereoregularity of each copolymer is explicitly considered, and correctly predicts the observed deviations from the Fox relation when they occur. It therefore appears that the sequence distribution - Tg effects observed in many copolymers may have an intramolecular origin in the form of specific molecular interactions between adjacent monomer units, which can be characterized by estimating the resultant conformational entropy. 

It was further found that an upstream heat treatment also helps to improve the Tg effect in milk with the casein present in micellar form, in addition to integrating the whey proteins in the gel. The increased Tg effect in milk, which was heat treated at higher levels above pasteurisation level. The same applies for milk which was UHP treated, as shown by Lauber (2002). This can be explained by the heat inactivation of a so-called Tg-inhibitor substance present in milk (De Jong et al. 2003). BOnisch et al. (2006) also proved that the inhibitor substance is located in the milk serum and demonstrated the effect of heat treatment for systems, where only the miUc serum... 

Tg. Effects of stress relaxation, aging, and thermal cycling can also be quantified. 

Schmidt SP, Osbom TG. Effects of endophyte-infected tall fescue on animal performance. Agric Ecosys Environ 44 233-262, 1993. 

Tg effects of low vinyl content SSBR / high vinyl content SSBR (75/25) blends... 

PK co- and terpolymer Tg effects can be detected by DSC both on dry, non-aged virgin powder and on fused samples. The results of the DSC Tg(onset)-value determinations on (virgin) powder samples proved to scatter, however, considerably due to the too strong influence of the crystalline phase on the shape of the Cp/T curve. Thus, a real DSC Tg(onset)-value determination of PK co- and terpolymer samples is only possible on non-aged, dry and one time fused samples. The reproducibility of this DSC Tg(onset)-value determination proved to be + 3°C. The average DSC Tg(onset)-value of a series of PK co- and terpolymer samples proved to be 4°C. 

FIGURE 9.10A The (DSC) Tg effect for a PK terpolymer dried, non-aged powder sample... 

Evans MJ, Livesey JH, Ellis MJ, Yandle TG, Effect of anticoagulants and storage temperatures on stability of plasma and serum hormones, Clin. Biochem. 2001 34 107-112. 

Hall TG. Effect of methylprednisolcne on cyclosporine blood levels. Pharmaco req y (1990)10,248. 

FIGURE 3 Kinetic, T, and potential, V, energies of the bonding g and antibonding u orbitals for H+. Note that even though Vg is unstable, the Tg effect compensates to create a bonding state. 

Desbonnet L, Garrett L, Clarke G, Kiely B, Cryan JF, Dinan TG. Effects of the probiotic Bifidobacterium infantis in the maternal separation... 

The purpose of the present communication is to provide experimental support for the idea that Tp (TTg) are all issued from a unique relaxation kinetics which is primary responsible for the Tg effect The suggestion that Tp is a precursor of Tg is not new 2.4 the idea that T// behaves like a classical kinetic transition, i.e., like a sort of Tg is not new eitfaer. > Frenkel in the USSR suggests that the 7 transition merges with the Tg transition on a log frequency vs. 1/7 plot at a temperature which corresponds to 7//. These observations all concur separately with our own attempt to reconcile into a unique relaxation mechanism the 7 Tg, and Tn "transitions." Atactic polystyrene is chosen here for the experimental data because the physical properties relevant to our discussion are well-documented in the literature for this particular polymer, representative of the class of amorphous polymers. Furthermore, TSC (Thermally Stimulated Current) and DSC results on rheomolded polystyrene samples can be systematically compared since the influence of the rheomolding parameters (frequency of vibration during molding, amplitude of vibration, and post treatment armealing effects) are simultaneously studied and analyzed by both techniques. " ... 

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