Poly Phenylene Oxide Based Blends

Blends of PPO with PS containing sulfonated and carboxylated groups have been reported in various studies [394-396]. The miscibility of sulfonated PS with PPO, sulfonated PPO with PS and blends of the sulfonated polymers was reported by Hseih and Peilfer [394]. Miscibility was maintained with sulfonation levels up to 2-4mol% for PS with sulfonated PPO and sulfonated PS with PPO. When both polymers were sulfonated, phase separation occurred at higher levels ( 10mol% sulfonation). The miscibility can be influenced by counter ion, as noted in a comparison of a Zn + neutralized sulfonic acid modified PS, which exhibited a larger miscibility window with PPO than the Na neutralized coimterpart [396]. Syndiotactic polystyrene was noted to be miscible over the entire composition range in amorphous blends with PPO, where the Tg versus composition followed the Fox equation predictions [397]. Isotactic polystyrene miscibility with PPO has also been observed, with crystallization and orientation data reported on the blend [398]. 

Biphenol based polysulfone (BPPSF) Poly(ether sulfone) (PES) 

Most of the variants of the PPO/PS blend studies have involved PS modifications. A PPO variant, poly(2,6-diphenyl-l,4-phenylene oxide)(DPPPO) was scaled-up as a developmental polymer byAkzo in the 1970s (Tenax), but not fuhy commercialized. DPPPO has been shown to be immiscible with PS [404]. Sulfonation of both DPPPO and PS did not yield miscible blends, although improved mechanical properties were noted. 

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Recent Developments in Poly Phenylene Oxide Based Blends and Composites and Their Applications... 

Phosphorus-based flame retardants are usually more suitable for engineering plastics that undergo charring than for commodity polymers. In some plastics, such as PC-ABS or poly(phenylene oxide)-HIPS blends, phosphorus-based flame retardants are more effective then halogenated flame retardants. Antimony trioxide, which is a part of halogen-containing formulations, is a Lewis acid and may destabilize some condensation polymers. Furthermore, the impact properties of engineering polymers may suffer due to the presence of powdery antimony trioxide. 

Alloys and blends are of great commercial significance. The archetype of "alloys" is the poly(phenylene oxide)—polystyrene resin discussed eadier. Important examples of blends based on immiscible resins are afforded by the polycarbonate—poly(butylene terephthalate) resins and polycarbonate—ABS blends. 

Miscible Blends. Both Components Amorphous. Certainly one of the most commercially important and publicized examples of a miscible polymer blend system is that based on polystyrene and poly(phenylene oxide), which is sold under the trade name Noryl by General Electric. Many fundamental studies of this system have been published, many of which were devoted to proving that these two components are miscible in a thermodynamic sense (see chapter 5 of Ref. 10 by MacKnight, Karasz, and Fried). Commercial interest in this system involves both... 

Poly(phenylene oxides) have been used as one component in blends because of their excellent physio-chemical properties. The best known example is that based on poly(styrene) and poly-(2,6-dimethy-l, 4-phenylene oxide) (PPO), sold under the trade name Noryl by General Electric. The addition of PPO to polystyrene raises the glass transition, improves mechanical properties and improves resistance to flammability. Detailed studies on the dynamic mechanical and dielectric properties of these blends and several similar systems have been performed by MacKnight et al, among others. 

Basically, polymer blends are divided into two large groups miscible on the molecular level and immiscible. Among commercial products based on miscible blends can be mentioned, for example, polystyrene (PS)- poly(phenylene oxide) (PPO), poly(vinylidene fluoride) (PVDF)-poly(methyl methacrylate) (PMMA),... 

A product range of increasing commercial importance is based on blends of PS with poly(phenylene oxide) (PPO). The latter is in fact the dimethyl... 

Pan, Y., Huang, Y., Cheng, M., Cong, G., Leung, L.M. (1998) Solution behavior of ionomer blends. U. Acid-base interactions in blends of poly(phenylene oxide) ionomers and poly(st5ftene-4-vinylpyridine). European Polymer Journal, 34, 213-217. 

A quantitative thermal method, based on the differential of heat capacity signal from modulated temperature differential scanning calorimetry, was described for determining the weight fraction of interface and the extent of phase separation in polymer materials. The interface was modelled as discrete fractions, each with its own characteristic increment of heat capacity. The materials used to demonstrate the range of the method were PS blended with poly(phenylene oxide) (PPO), pure PS, pure PPO, a styrene-isoprene-styrene triblock copolymer (SIS), SIS blended with PPO, PMMA/poly(vinyl acetate) blends and PVC sandwiched with poly(n-butyl acrylate). Two-phase and four-phase systems were used. The calculated results agreed well with experimental results for two- and four-phase systems. 20 refs. 

Cabasso, I., Yuan, Y., and Mittelstadt, C., Blend Membranes Based on Poly (phenylene oxide) for Enhanced Polymer Electrochemical Cells, US 5989742, 1999. (The Research Foundation of State University of New York)... 

Cabasso I, Yuan Y, Mittelsteadt C. Blend membranes based on sulfonated poly(phenylene oxide) for enhanced polymer electrochemical cells. US Patent 5,989,742 (1999). 

Compatible Polyblends. When the polymeric materials are compatible in all ratios, and/or all are soluble in each other, they are generally termed polyalloys. Very few pairs of polymers are completely compatible. The best known example is the polyblend of polyCphenylene oxide) (poly-2,6-dimethyl-l,4-phenylene oxide) with high-impact polystyrene (41). which is sold under the trade name of Noryl. It is believed that the two polymers have essentially identical solubility parameters. Other examples include blends of amorphous polycaprolactone with poly(vinyl chloride) (PVC) and butadiene/acrylonitrile rubber with PVC the compatibility is a result of the "acid-base" interaction between the polar substituents (1 ). These compatible blends exhibit physical properties that are intermediate to those of the components. 

A commercially important miscible polymer blend with low levels of polarity but high aromatic character is the basis of Noryl developed by General Electric [32]. It was based upon the miscibility of poly(2,6-dimethyl phenylene oxide) (PPO) and atactic polystyrene. 

Another example is poly p-phenylene oxide (PPO) and polystyrene. The General Electric Noryl is a blend of PPO with rubber modified polystyrene (i.e., high impact polystyrene, often known as HIPS) (see Section 6.8). HIPS is much tougher than glassy polystyrene but HIPS miscibility with PPO (Formula 5.13) is based upon HIPS polystyrene content. The improvement in toughness of the brittle PPO by HIPS makes this blend a commercial success. 

Similar equations based on free-volume arguments have been proposed for block copolymers. Again the agreement is quite satisfactory. For polymer blends, equations of the same sort have been successfully used to describe the change in with blend composition. For these latter systems, however, the experimental measurement of may dramatically affect the agreement obtained Figure 29 shows Tg vs. composition for mixtures of poly (2,6-dimethyl-1,4-phenylene oxide) (PPO) with polystyrene (PS) obtained by different experimental methods. As can be seen, the shape of the curve depends dramatically on the method of measurement. 

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