Blends poly styrene/vinyl methyl

The experimental results that will be examined consist of studies that look at the ability of a random copolymer to improve the properties of mixtures of the two homopolymers relative to the ability of a block copolymer. The three different systems that are examined include copolymers of poly(styrene-co-methyl methacrylate) (S/MMA), poly(styrene-co-2-vinyl pyridine) (S/2VP), and poly(styrene-co-ethylene) (S/E) in mixtures of the two homopolymers. The experiments that have been utilized to examine the ability of the copolymer to strengthen a polymer blend include the examination of the tensile properties of the compatibilized blend and the determination of the interfacial strength between the two homopolymers using asymmetric double cantilever beam (ADCB) experiments. 

In addition to forming polymers with molecules of their own kind, many monomers can form copolymers with other monomers. The scale of possibilities is thus widely extended. In free radical polymerization, for example, styrene is converted to poly(styrene), methyl methacrylate to poly(methyl methacrylate), and vinyl acetate to poly(vinyl acetate). A mixture of styrene and methyl methacrylate gives poly(styrene-co-methyl methacrylate) even at the lowest conversions. From a mixture of styrene and vinyl acetate, on the other hand, practically pure poly(styrene) is first formed, and then, when the styrene is exhausted, almost pure poly(vinyl acetate). This is therefore a mixture (blend) and not a copolymer. Whereas stilbene, free-radically initiated, does not give a unipolymer, and maleic anhydride gives one of only low molecular weight, a mixture of both monomers leads to a copolymer of the composition 1 1. 

The utility of the DSC for studying polymer-polymer miscibility has been demonstrated for poly(vinyl chloride)/nitrile rubber polyfvinyl methyl ether)/poly-styrene and poly(2,6-dimethyl 1,4-diphenylene oxide)/poly(styrene-co-chloro-styrene)It has also been particularly useful for measuring the melting point depressions of crystalline polymers in blends Mn order to calculate the interaction parameter as will be discussed later. 

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... 

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. 

Arrighi, V., Cowie, J. M. G., Ferguson, R., McEwen, 1. J., McGonigle, E.-A., Pethrick, R. A., and Princi, E., Physical ageing in poly(4-hydroxy styrene)/poly(vinyl methyl ether) blends, Polym. Int., 55, 749-756 (2006). 

The apparatus is described and details given of its use with PETP homopolymer, PS/poly(vinyl methyl ether) miscible blend and styrene-styrenesulphonic acid copolymer/ethyl acrylate-4-vinylpyridine copolymer ionomer blend with ionic interactions. Orientation and relaxation curves were obtained for all three samples. It is concluded that the technique is very efficient for obtaining curves with high precision. For these three systems, the relaxation rate increases with temperature. 

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... 

Other polymers which have been the subject of thermal degradation studies include ethylene-vinyl acetate [29, 66, 67], ethylene-vinyl alcohol [68], poly(aryl-ether ketone) [69], poly-2-vinyl-naphthalene-co-methyl maleate [34], polyphenylenes based on diethyl-benzophenone [70], polyglycollide [71-73], poly(a-methylstyrene tricarbonyl chromium [74], polytetrahydrofuran [75], polylactide [76-78], poly(vinyl) cyclohexane [79], styrene-vinyl cyclohexane [80], isopropenylacetate-maleic dianhydride [80], polyethylene glycol containing a 1,3-disubstituted phenolic group [81], poly-2-vinyl naphthalene-co-methacrylate [34], collagen biopolymers [82], chitin graft poly (2-methyl-oxazoline - polyvinyl chloride blends [83], cellulose [32, 83-88] and side-chain cholestric elastomers [89, 90]. 

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... 

Figure 6.13 Height-mode atomic force microscopy images of poly(styrene-b-2-vinyl pyridine)/poly(methyl methacrylate) (PMMA) blend thin films with different compositions of PMMA (a) 10wt%, (h) 20wt%, (c) 30 wt%, (d) 40wt%, and (e) 50wt% at a fixed polymer concentration of 0.6 wt%.

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). 

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... 

Bonner examined poly(ethylene-covinyl acetate). Other relevant studies include phase transitions in styrene-butadiene copolymers and blends and measurement of glass transitions in polymers containing surface-active groups. An interesting recent application is the study of compatibility in mixtures of polystyrene and poly(vinyl methyl ether), reported by Su and Patterson. Guillet et have reported detailed studies of the use of inverse g.l.c. to... 

Kriisa, A., Park, S.S., and Roth, C.B. (2012) Characterization of phase separation of poly styrene/poly (vinyl methyl ether) blends using fluorescence. ]. Polym. Sci. Polym. Phys., 50 (4), 250-256. 

It is evident from the above discussion that the free volume data derived from positron lifetime measurements is incapable of providing information on the composition-dependent miscibility level of the blend. At this point, a new method based on the same free volume data measured from positron lifetime measurements was introduced to determine the miscibility of binary blends. The new method was based on hydrodynamic interactions (the mathematics required have been explained in detail earlier), and calculations of the y parameter derived from the hydrodynamic interaction approach were made for three selected polymer blends, namely poly(styrene-co-acrylonitrile) (SAN)/poly(methyl methacrylate) (PMMA) (completely miscible), poly(vinyl chloride) (PVC)/poly(methyl methacrylate) (PMMA) (partially miscible) and poly(vinylchloride) (PVC)/polystyrene (PS) (immiscible) (see Figure 27.13). As can be seen, this parameter behaves similar to the interchain interaction parameter /3, in the sense that it exhibits a complex behavior making it difficult to determine the composition-dependent miscibility of the blends. 

Raman spectroscopy has been used in structural studies of a wide range of homopolymers and copolymers [109-122] including crystalline PE [123], polyaniline [124], polystyrene-co-p-(hexafluoro-2 hydroxyisopropyl)-alpha methyl styrene/polypropylene carbonate blends [125], PE [126], PP [126], polylactide [127], polyacrylonitrile [128], Nylon-6 - polyvinyl alcohol blends [129], poly(4-vinyl pyridine cupric salt complexes [130] and regenerated cellulose [131]. 

This section will cover blends of polymers, both exhibiting water solubihty. Many of the water soluble polymers have been noted in earher sections in this chapter to exhibit misci-bihty with non-water soluble polymers. These water soluble polymers include poly(ethylene oxide), poly(N-vinyl pyrollidone), poly(vinyl amine), polyacrylamide, poly(N,N-dimethyl acrylamide poly(acryhc acid), poly(methacrylic acid), poly(ethyl oxazohne), poly(styrene sulfonic acid), poly(vinyl pyridine), poly(vinyl alcohol), hydroxyl ethyl ceUulose, hydroxy propyl cellulose, carboxy methyl ceUulose, poly(itaconic acid) and poly(ethyleneimine) (several structures shown below). 

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