Poly vinyl methyl ether PVME Blends

The effect of electron beam irradiation on the miscible poly(styrene) and poly(vinyl methyl ether) (PVME) blend has been studied. The poly (styrene), being much more resistant to effects of irradiation, does not offer any protectimi to the poly(vinyl methyl ether). Gel content studies indicated significant crosslinking [199]. Further studies of this... 

The samples used are the polystyrene (PS) and poly(vinyl methyl-ether) (PVME) blends whose mechanical properties can be freely changed by controlling the blend ratio. In this case, in order to make the sample the measurement standard, the molecular weight of the polystyrene used is relatively low to avoid phase separation at room temperature. Ordinarily, the modulus of PS is on the order of GPa and PVME is on the order of MPa the moduli of blends can vary continuously in the range of these values as a function of the blend ratio. This is why this blend system was chosen as the standard of mechanical properties. The cantilever used is a V-shaped lever with thickness of 0.8 pm and length of 100 pm. At the tip, a very small Si3N4 scanning needle is fixed. The modulus of the cantilever is 0.68 N/m, which is stiffer than the one for ordinary contact measurement. Two different measurements were conducted. The first is the... 

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 ... 

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. 

The application of this technique as a morphological tool requites that there be a close coupling between polymer photophysics and polymer physics. In the photophysical studies described in this paper emphasis will be placed on the development of analytical models for electronic excitation transport (EET). The areas of polymer physics that we will consider involve the configurational statistics of Isolated chains and phase separation in multicomponent polymer systems. The polymer system of primary interest is the blend of polystyrene (PS) with poly(vinyl methyl ether) (PVME). 

The miscibility of different Cgo-containing polystyrenes with other polymers was studied in attempts to transfer the fullerene properties to the resulting polymer blends [71]. It was found that poly(2,6-dimethyl-l,4-phenylene oxide), PPO, is miscible with all the PS/Cgo samples investigated, whereas in the case of poly (vinyl methyl ether), PVME, PS/Cgo samples were miscible only for lower contents of Cgo [71]. 

Blends of polystyrene(PS) and poly(vinyl methyl ether) (PVME) have attracted much interest because of their compatibility over a wide range of blend composition . The compatibility of PVME with styrenic copolymers has also been extensively investigated. 

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.)... 

Charlesby-Pinner plot of pure poly(vinyl methyl ether) (PVME) (white triangle), pure poly(vinylpyrrolidinone) (PVP) (black triangle), and a 1 1 mixture (black circle electron beam white circle y-irradiation) s corresponds to the sol fraction and D to the radiation dose. (From Gottlieb, R., Schmidt, T., Arndt, K., Synthesis of temperature-sensitive hydrogel blends by high-energy irradiation. Nuclear Instruments and Methods in Physics Research Section B Beam Interactions with Materials and Atoms 2005,236,371-376. With permission.)... 

Experiments on temporally forcing of phase separation were performed using mixtures of poly(vinyl methyl ether) (PVME) and anthracene-labeled polystyrene (PSA). The phase diagram of this PSA/PVME blend is illustrated in Figure 1 together with the composition dependence of its glass transition... 

Miscible blends of poly(styrene) (PS) and poly(vinyl methyl ether) (PVME) show LCST behavior as presented in Figure 18. Phase separation occurs above 152 °C. This liquid-liquid phase separation, we may discuss in terms of Floiy-Huggins parameter given as a function of temperature. We see parameter i as a free-energy parameter comprising energy and entropy contribution, Xv Xs... 

The first comprehensive study of physical aging in a miscible blend system using enthalpy relaxation was reported by Cowie and Ferguson (1989) who followed the enthalpic relaxatirm in a series of blends of PS and poly(vinyl methyl ether), PVME. ComparisOTi of the blend behavior with that of the two components by analyzing the data oti the basis of both the P-M and C-F models led to the conclusions that the blends aged more slowly than PVME when aging was carried... 

Blends with Poly(vinyl methyl ether) (PVME). 189... 

Thin films of blended deuterated polystyrene (dPS) and poly(vinyl methyl ether) (PVME) were imaged as a fimction of the dPS PVME ratio. Near the critical composition of 35% dPS, an imdulating, spinodal-like structure was observed, whereas for compositions away from the critical mixture ratio, regular mounds or holes (< dPS < < crit and < dPS > (pent, respectively) were present. These variations were assigned to surface tension effects (120). Blends of PBD, SBR, isobutylene-brominated p-methylstyrene, PP, PE, natural rubber, and isoprene-styrene-isoprene block rubbers were imaged (Fig. 18). Stiff, styrenic phases and rubbery core-shell phases were evident as the authors utilized force-modulated afm to determine detailed microstructure of blends, including those with fillers such as carbon-black and silica (121). 

To test this prediction of the crossover from mean-field to Ising-t5q)e behavior, very precise small-angle neutron scattering measurements were completed on blends of deuterated polystyrene (d-PS) and poly(vinyl methyl ether) (PVME) at the critical concentration for a series of temperatures as the one-phase mixture approaches the temperature of phase separation (ie, the critical point Tc in Fig. 7) (61). The data were analyzed by fitting the measured I (q) to the random phase approximation to estimate l(g=0) for each temperature, where the temperature is controlled to 0.01 K... 

The characterization of surface structure for miscible blends is a more formidable task, requiring techniques that are sensitive to the composition of the blend within several nanometers of the surface. X-ray photoelectron spectroscopy (xps) provided the first direct and quantitative evaluation of surface composition and surface composition gradients for miscible polymer blends of poly(vinyl methyl ether) (PVME) and polystyrene (PS) (22,23). Since that time, the situation has changed dramatically with the advance of theory and the application of exciting new experimental techniques to this problem. In addition to xps and pendant drop tensiometry (22,23), forward recoil spectroscopy (28), neutron (29) and x-ray reflectivity (30), secondary ion mass spectroscopy (either dynamic or time-of-flight-static) (31,32), and attenuated total reflectance Fourier transform infrared spectroscopy (33-35), have been applied successfully to study surface segregation. The advent of these new tools has enabled a multitechnique experimental approach toward careful examination of the validity of current surface segregation theories (36-39). 

Higher amounts of AN raise this curve to above the decomposition temperature however, at 13% or more AN the SAN copolymers are not miscible with MPC. Polystyrene forms miscible blends with poly-(vinyl methyl ether), PVME, that phase separate at quite low temperatures. Copolymerization of very small amounts of acrylic acid with styrene dramatically elevates the phase separation... 

It has been proved that the nature of solvent used for casting in the preparation of the blend influences the compatibility and related properties of PS-poly(vinyl methyl ether) (PVME) mixtures." Clear films of PS-PVME mixtures were obtained on casting from solvents like benzene, toluene, etc., while visually incompatible films result upon casting from trichloroethylene and chloroform. Blends of PVC and LNR/epoxidized liquid natural rubber (ELNR) were prepared using a common solvent, 2-butanone. ° Another research group prepared PVC/NR blends using THE as the solvent. ... 

Figures 9.4 and 9.5 show G and G" for two linear polymers, a poly(vinyl methyl ether) (PVME) with a molecular weight of 138,000 and a polystyrene (PS) with a molecular weight of 123,000, respectively. The data for each polymer have been moved horizontally along the frequency axis until they form a single curve. There is a substantial region of overlap, extending over three decades of frequency, so the superposition is clearly established. The shift factors needed to obtain overlap of the curves are shown as inserts. The reference temperature for each case was taken to be 84 °C this temperature has no significance other than being a convenient value for the particular application for which the data were obtained, which was a study of phase separation in blends of the two polymers. One of the significant uses of time-temperature superposition is made evident by focusing on the open and closed symbols in the PVME curves. The dynamic moduli are available over five orders...

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