Polystyrene near-melt

Guenet JM, Picot C. BnUc crystaUization of isotactic polystyrene near its melting-point - A nentron-scattering study of the chain trajectory. Macromolecnles 1983 16 205-210. 

Poly(styrene-fc-butadiene) copolymer-clay nanocomposites were prepared from dioctadecyldimethyl ammonium-exchanged MMT via direct melt intercalation [91]. While the identical mixing of copolymer with pristine montmorillonite showed no intercalation, the organoclay expanded from 41 to 46 A, indicating a monolayer intercalation. The nanocomposites showed an increase in storage modulus with increasing loading. In addition, the Tg for the polystyrene block domain increased with clay content, whereas the polybutadiene block Tg remained nearly constant. 

Fig. 4.6 Relaxation modulus for nearly monodisperse polystyrene melts. Molecular weight ranges from Mw = 1.67 x 10 (F2) to M-w = 4.22 x 10 (F40). Reproduced from Ref. 6(b).

Pig. 4.12 Steady-state compliance of nearly monodisperse polystyrene melts at 160°C. The dashed line represents the result of the Rouse model. Reproduced, with permission, from Ref. 11. 

The convolution integral Eq. (4.73) may be solved nmnerically by the method of Hopkins and Hamming. The method is discussed in Appendix 4.A. Shown in Fig. 4.13 is the comparison of the G i) and curves of a nearly monodisperse polystyrene melt with = 4.69 x 10 obtained at 114.5°C (detailed in Chapter 14). The G t) line shape has more features — meaning different processes are better separated or resolved — than the curve, which are smeared by the con-... 

Fig. 9.1 Relaxation modulus 0 X,t) in the linear (A 0 ooo) and nonlinear (A = 5 aaa) regions of a nearly monodisperse polystyrene melt (Mw = 4.22 x 10 ). The G(A = 5, t) curve was measured at a temperature different from the reference temperature (127.5° C) of the shown G(A — 0, f) master curve as shown the G(A = 5,t) curve has been shifted along both the time axis and the modulus axis to superpose on the G(A — 0,t) curve in the terminal region. (See Fig. 12.3 for the results of G(A = 0.2, t) and G(A = 5, t), both measured at the same temperature.)...

Fig. 11.1 /C( a) for the nearly monodisperse (polystyrene) melts (from Ref. llb sameas...

This universality has also been illustrated by Watanabe et al. in another way. They compared the line shapes of the viscoelastic spectra of a nearly monodisperse polystyrene melt (sample L161 with = 1.72 x 10 and Myj/Mn = 1.07) and a blend solution (consisting of two nearly monodisperse polystyrene polymers L407 with Miu = 4.27 x 10 and M /Mn = 1.05 as component two and sample LIO with = 1.05 x 10 and Mw/Mn = 1.08 as component one the weight-fraction ratio of the blend is... 

As the glass transition temperature Tg is approached, the friction coefficient C sharply increases [3] and hence becomes too small to be measured. Thus, self-diffusion measurements on undiluted polymers are usually made at temperatures far above Tg. For example, all the reported data on polystyrene melts (Tg 100°C) were taken in the range 150 - 250° C. Working at such high temperatures, however, is not simple for various technical reasons including polymer degradation. It is therefore advantageous to study polymers with Tg far below room temperature if nearly monodisperse samples are available (use of polydisperse samples should be avoided for basic research). Extimples of such polymers are poly(isoprene) and polybutadiene. 

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