Glass transition double

The blends of polysulfone with the a-methyl styrene polymers are immiscible, as evidenced by the double glass-transition temperatures in Table II. To improve the miscibility characteristics, polysulfone was modified in two ways. First, 25% of the bisphenol A was replaced by monomer I which contains a pendant ester group and, when no improvement resulted, the whole 50% of the bisphenol A was replaced. Again, the blends remain immiscible as evidenced from Figures 4 and 5 and from Table II. Further, the presence of the pendant ester group in polymer C does not improve the miscibility picture even though one would expect a favorable contribution from the carbonyl group on account of the miscibility of polycarbonate with the a-methyl styrene polymers. 

Blends of poly(pentamethylene 2,6-naphthalate) with poly(heptamethylene 2,6-naphthalate) have been prepared by solution blending [53]. Blends in a ratio of 1 9 and 9 1 show a single glass transition, which commonly indicates a homogeneous phase. However, intermediate blends exhibit double glass transitions, which suggest the existence of two phases. 

Immiscibility dominates polymer blends. It reveals itself as opacity, delamination, double glass transition, or combination of these properties. Most immiscible polymer blends require compatibilization and toughening. 

PLA/PVAc blends were miscible systems for the entire composition range, but for the blends with even 10% hydrol5 ed PVAc copol5mier the phase separation and double glass transition are observed. 

Zhou, Z., Chudnovsky, A. and Bodnyak C.P (1995) Cold-drawing (necking) behavior of polycarbonate as a double glass-transition. Polym. Eng. Sci., 35, 304. 

FIG. 2 The double glass transition, T g(L) and Tg(JJ), and the Ty amorphous relaxation in linear polyethylene. The size of the circles indicate the intensity of the two Tg. Intensity of the Ty transition increases continuously with decreasing crystallinity. (Reproduced from the review paper of Boyer [2] with the permission of ACS Publication Division.)... 

In other systems, double glass transitions have already been reported. For instance, the double glass transition phenomenon in aqueous tetraalkylammonium halide solutions is... 

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