PVME/poly blends

Fig. 12. Flory-Huggins y/v0 parameters for deuterated polystyrene/poly(vinyl methyl ether) and protonated polystyrene/poly(vinyl methyl ether) interactions. The first one was obtained from binary (PSD/PVME) mixtures (50%/50% weight fraction) and the second one from ternary (PSD/PVME/PSH) blend mixtures (23.8%/25.6%/50.6%)...

PS is miscible with several polymers, viz. polyphenyleneether (PPE), polyvinylmethylether (PVME), poly-2-chlorostyrene (PCS), polymethylstyrene (PMS), polycarbonate of tetramethyl bisphenol-A (TMPC), co-polycarbonate of bisphenol-A and tetramethyl bisphenol-A, polycyclohexyl acrylate (PCHA), polyethylmethacrylate (PEMA), poly-n-propyl methacrylate (PPMA), polycyclohexyl methacrylate (PCHMA), copolymers of cyclohexyl methacrylate and methyl methacrylate, bromobenzylated- or sulfonated-PPE, etc. Other miscible blends are listed in Appendix 2. 

Temperature dependence of dielectrically determined relaxation times "c of monomeric segments of poly(2-chlorostyrene) (P2CS) and poly(vinyl methyl ether) (PVME) in P2CS/PVME miscible blends with various P2CS volume fractions ( )p2cs as indicated. (Data taken, with permission, from Urakawa, O., Y. Fuse, H. Hori, Q. Tran-Cong, and O. Yano. 2001. A dielectric study on the local dynamics of miscible polymer blends Poly(2-chlorostyrene)/poly(vinyl methyl ether). Polymer 42 765-773.)... 

It is known for a long time (Wetton et al. 1978) that the relaxation function measured for a miscible blend is considerably broadened compared to the spectra of the pure polymers (Colmenero and Arbe 2007). To be more precise the broadening is more or less symmetric. As an example this is shown for a miscible blend of polystyrene (PS) and poly(vinyl methylether) (PVME) in Fig. 12.15 (Colmenero and Arbe 2007 Katana et al. 1992 Zetsche and Fischer 1994). Compared to PVME the dipole moment of PS is weak, and therefore, the contribution of PS to the dielectric loss of the blend is negligible. In other words the fluctuations of PVME are selectively monitored by dielectric spectroscopy, whereas the fluctuations of the PS segments are dielectrically invisible. For the blend (see Fig. 12.15b), the loss peak is much broader than that for the single component PVME (see Fig. 12.15a). Moreover, the loss peak narrows as temperature increases. For the PVME/PS blend system, it was proven by a combination... 

PVF2 is immiscible with PCL, poly(vinyl methyl ether) (PVME), poly(vinyl propionate), poly(vinyl butyrate) [217, 219], poly(isopropyl methacrylate), and poly(isobutyl methacrylate) and poly(isopropyl acrylate) [220]. Lest behavior was noted for PVF2 blends with PEA, PVMK, PEMA, PMAc and PMMA with a relationship noted between the lest and the interaction parameter [220]. Miscibility of poly(vinyl pyrrolidone)(PVP) and PVF2 has been reported [221] with elimination of PVF2 crystallinity above 40 wt% PVP in the time scale of the experimental protocol employed. 

One of the main goals of experimental studies carried out on polymer blends is to resolve the dynamics of the individual components. For dielectric measurements this can be achieved when one of components has a high dipole moment, for example, PVME, poly(chlorostyrene), or poly(tetramethyl-Bisphenol-A-polycarbon-ate) (TMPC) [163,164], compared to the second polymer, for example, polystyrene. 

Figure 10.7 The phase diagram (a) and the glass transition temperatures (b) of a PSC/PVME mixture obtained, respectively, by light scattering and differential scanning calorimetry (DSC). Irradiation experiments were performed in the miscible region at 127 C indicated by (X) in the figure of trans-cinnamic acid-labeled polystyrene/poly(vinyl methyl ether) blends.

Fig. 14 Creation of a single specimen polymer blend phase diagram from orthogonal polymer composition and temperature gradients. The polymers are polystyrene and poly(vinyl methyl ether) (PVME) a composition library placed orthogonal to a temperature gradient b completed gradient library polymer blend phase diagram. White points are data derived from traditional measurement for comparison. See text for details, (b reproduced with permission from [3])...

Poly(vinyl methyl ether), PVME, is a thermo-sensitive polymer. The aqueous solution has a Lower Critical Solution Temperature (LCST) of 37 °C. Therefore, PVME is soluble in water below its LCST, but insoluble above its LCST. When an aqueous solution of PVME is irradiated with y-rays the solution becomes PVME hydrogel [18, 19]. The gel shows thermo-sensitivity similar to the solution, and swells below 37 °C and shrinks above this temperature. It is important to form a fine porous gel structure to obtain quick response gels. There are two methods for the purpose. One is a method using micro-phase separation by heating. The other is a method using micro-phase separation by blending of polymer solutions. 

Consider a binary polymer blend [43] of deuterated polystyrene, PSD, (Mw = 1.95 x 10s g/mole, Mw/Mn = 1.02) and poly(vinyl methyl ether), PVME, (Mw = 1.59 x 10s g/mole, Mw/M = 1.3) with a composition of 48.4% PSD (volume fraction). SANS data were taken at various temperatures ranging from ambient to 160°C. De Gennes s RPA formula ... 

Fig. 13. Single-chain PS(Q), interchain P,(Q) and total PT(0) structure factors for a blend mixture of deuterated and protonated polystyrene (PSD, PSH) in poly(vinyl methy ether) (PVME). The total PVME fraction was 51% and the PSD fractions were varied from 49% to 24%. The three curves correspond to sample pairs 1-2, 2-3 and 1-3 in each case...

Miscible blends of poly(vinyl methyl ether) and polystyrene exhibit phase separation at temperatures above 100 C as a result of a lower critical solution temperature and have a well defined phase diagram ( ). This system has become a model blend for studying thermodynamics of mixing, and phase separation kinetics and resultant morphologies obtained by nucleation and growth and spinodal decomposition mechanisms. As a result of its accessible lower critical solution temperature, the PVME/PS system was selected to examine the effects of phase separation and morphology on the damping behavior of the blends and IPNs. 

After the examination of the PS photooxidation mechanism, a comparison of the photochemical behavior of PS with that of some of its copolymers and blends is reported in this chapter. The copolymers studied include styrene-stat-acrylo-nitrile (SAN) and acrylonitrile-butadiene-styrene (ABS). The blends studied are AES (acrylonitrile-EPDM-styrene) (EPDM = ethylene-propylene-diene-monomer) and a blend of poly(vinyl methyl ether) (PVME) and PS (PVME-PS). The components of the copolymers are chemically bonded. In the case of the blends, PS and one or more polymers are mixed. The copolymers or the blends can be homogeneous (miscible components) or phase separated. The potential interactions occurring during the photodegradation of the various components may be different if they are chemically bonded or not, homogeneously dispersed or spatially separated. Another important aspect is the nature, the proportions and the behavior towards the photooxidation of the components added to PS. How will a component which is less or more photodegradable than PS influence the degradation of the copolymer or the blend We show in this chapter how the... 

PHOTOOXIDATION OF BLENDS OF POLYSTYRENE AND POLY(VINYL METHYL ETHER) (PVME-PS)... 

The materials analyzed were blends of polystyrene (PS) and poly(vinyl methyl ether) (PVME) in various ratios. The two components are miscible in all proportions at ambient temperature. The photooxidation mechanisms of the homo-polymers PS and PVME have been studied previously [4,7,8]. PVME has been shown to be much more sensitive to oxidation than PS and the rate of photooxidation of PVME was found to be approximately 10 times higher than that of PS. The photoproducts formed were identified by spectroscopy combined with chemical and physical treatments. The rate of oxidation of each component in the blend has been compared with the oxidation rate of the homopolymers studied separately. Because photooxidative aging induces modifications of the surface aspect of the material, the spectroscopic analysis of the photochemical behavior of the blend has been completed by an analysis of the surface of the samples by atomic force microscopy (AFM). A tentative correlation between the evolution of the roughness measured by AFM and the chemical changes occurring in the PVME-PS samples throughout irradiation is presented. 

Figure 6. Temperature dependence of X23 in blends of polystyrene/poly(vinyl methyl ether) (x 15 wt-% PS/85 wt-% PVME, V 25 wt-% PS/75 wt-% PVME, A 50 wt-% PS/50 wt-% PVME, o 75 wt-% PS/25 wt-% PVME).

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