Blends of polystyrene

The uses of blends of polystyrene with the so-called polyphenylene oxide polymers are discussed in Chapter 21. 

These results demonstrate some interesting chemical principles of the use of acrylic adhesives. They stick to a broad range of substrates, with some notable exceptions. One of these is galvanized steel, a chemically active substrate which can interact with the adhesive and inhibit cure. Another is Noryl , a blend of polystyrene and polyphenylene oxide. It contains phenol groups that are known polymerization inhibitors. Highly non-polar substrates such as polyolefins and silicones are difficult to bond with any technology, but as we shall see, the initiator can play a big role in acrylic adhesion to polyolefins. 

Zink et al. used a blend of polystyrene (hPS) and its deuterated counterpart (dPS), both of molecular weight 1.95 x 106 (abbreviated 1.95 M). The average volume fraction (4>dPS) of deuterated polystyrene was 30%. The polymers were dissolved in toluene and spin cast on thin silicon wafers (about 10 x 10 mm), the resulting film thickness being about 300 nm. The samples were annealed at 245°C for 8 days, and the measurement of the resulting depth profiles was conducted by NRA using a monoenergetic 700 keV 3He beam. The nuclear reaction employed can be written ... 

One of the most important outcomes of these efforts was impact-resistant polystyrene, which was obtained by modifying the brittle material with rubber. The first products were blends of polystyrene and synthetic rubbers recourse was soon made, however, to a principle that Ostromislensky (29) had suggested as early as 1927 styrene monomer was polymerized in the presence of rubber dissolved in it. 

Koberstein and coworkers121 have examined the effects of a polydimethylsiloxane-polystyrene (PDMS-PS) block copolymer on the interfacial tensions of blends of PDMS and polystyrene. As little as 0.002 wt% of the copolymer, added to the siloxane phase, was sufficient to lower the interfacial tension by 82% in the case of a blend of polystyrene (Afn = 4,000) and PDMS (Mn = 4,500). No further reduction in interfacial tension was observed at higher copolymer levels due to micelle formation. Riess122 has polymerized styrene in the presence of a silicon oil and a polydimethylsiloxane-polystyrene block copolymer to obtain a polystyrene in which 0.1-1 pm droplets of silicone oil are dispersed. This material displayed a lowered coefficient of kinetic friction on steel compared to pure polystyrene. 

Volume of Mixing. In general terms, exothermic interaction effects tend to diminish the volume of a mixture whereas entropic effects act in the opposite way. For miscible polymers, therefore, one expects a negative volume of mixing. This has been confirmed experimentally for different miscible polymers with LCST behavior, e.g. for miscible 50/50 blends of polystyrene and poly(2-chloro-styrene) the volume change AVM/V at 130°C has been reported to be about... 

Physical Properties of Blends of Polystyrene with Poly(methyl Methacrylate) and Styrene/ (methyl Methacrylate) Copolymers... 

Figure 1. Room-temperature miscibility diagrams for blends of polystyrene with poly(methyl methacrylate) and styrene/(methyl methacrylate) copolymers. Shaded area is compatible region.

Figure 2. Differential scanning calorimetry curves (10°C/min) for blends of polystyrene, PS-600 with PMMA (upper) 34 wt% PS-600 (lower) 42 wt% PS-600.

Blends of polystyrene and poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) can be mixed in the melt as both polymers have reasonable thermal stability. There has however been much discussion as to whether the blends are truly one phase. Some techniques suggest homogeneity while others suggest a heterogeneous structure. On balance it appears that the two polymers are in fact thermodynamically miscible in all proportions but completely efficient mixing is difficult to achieve... 

Evidence from spectral studies for interactions other than the above hydrogen bonds is not very plentiful. Polystyrene/poly(2,6 dimethyl-l,4-phenylene oxide) blends have been studied by infra-red and ultraviolet spectroscopy . Interactions involving the aromatic rings of the two polymers were proposed. Studies of low molecular weight ethers with aromatic compounds have shown evidence for specific interactions and this has recently been extended to blends of polystyrene with poly(methyl vinyl ether)... 

Odor in Blends of Polystyrene with K-Resin SB Copolymers, Plastics Technical Center Report 410, Chevron Phillips Chemical Co., Bartlesville, OK. 

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. 

Plasticizers perform this function if a single plasticizer solvates the dissimilar major components of a blend. Phthalate esters help to stabilize mixtures of poly(vinyl chloride) and poly(melhyl methacrylate) for example. These materials are also plasticizers for polystyrene, and stable blends of this polymer with poly(vinyl chloride) can be made by adding dioctyl phthalate to a blend of polystyrene and rigid PVC. 

Fig. 6. Sorption kinetics of n-hexane in a SO/SO blend of polystyrene and polyphenylene oxide illustrating C se 11 sorption kinetics. Note that Mt/M is proportional to time rather than to the square root of time in the initial stages of sorptimi ...

In the range of frequencies low enough that the interfacial terms become important, one can usually assume that both components of the blend are in their terminal regimes, and thus behave as Newtonian liquids. Following this reasoning, Gramespacher and Meissner (1992) divided the linear viscoelastic response of a blend of polystyrene (PS) and poly(methylmethacrylate) (PMMA) into bulk and interfacial terms, as in Eq. (9-35). The interfacial contributions were taken from the Choi-Schowalter theory for Newtonian liquids. Eq. f9-37h with ju, T], and Xj from Table 9-1. while the bulk contributions were obtained from Eq. (9-41), With these expressions for G ui and Gramespacher and... 

Figure 6. Photolysis of 4 1 blends of polystyrene with polystyrene 5% vinyl ketone copolymers...

Blends of polystyrene/poly(2,6-dimethyl-l,4-phenylene oxide) and polystyrene/poly(vinyl methyl ether) were investigated by IGC over wide composition and temperature ranges. Flory-Huggins free energy parameters were obtained and are discussed as the criterion for thermodynamic miscibility. From the temperature variation of the free energy parameter, phase diagrams for both blends were obtained. 

Figure 4. Temperature dependence of X23 i-n blends of polystyrene/poly(2,6-dimethyl-l,4-phenylene oxide)...

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).

Mixtures are systems consisting of two or more different chemical species. Binary mixtures consist of only two different species. An example of a binary mixture is a blend of polystyrene and polybutadiene. Mixtures with three components are called ternary. An example of a ternary mixture is a -solution of polystyrene and polybutadiene in toluene. If the mixture is... 

The appropriate use of sample preparation procedures to expose the interior (bulk) of a blend of interest is in many cases required. In addition, selective solvent treatments may assist to unequivocally identify the different phase, as illustrated in Fig. 3.59 [133]. In this example, the polystyrene phase in a blend of polystyrene and poly (n-butyl methacrylate) was identified by selective removal of the PS using cyclohexane. Thus the protrusion seen in the height image in panel (a), which are attributed to PS domains, are no longer detectable in panel (b). 

Polymer blend studies have attracted much less interest. Strong excimer formation in blends of polystyrene with l,4-bis(4-a-cyano-styryl)-2,5-dio-... 

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