Noryl blends with polystyrene

Oxidative coupling of phenols was first reported by Hay and coworkers in 1959" and has since been developed to produce commercially useful polymers. In these reactions the parent compound, phenol, has a potential functionality of four, that is the two ortho and the one para position of the aromatic ring and the phenolic group. Not surprisingly, the commercially useful polymers are made from substituted phenols in which the potential functionality is reduced to two. Of these phenols 2,6-dimethylphenol or orf/zo-xylenol has been developed to a commercial polymer, poly(2,6-dimethyl-1,4-phenylene oxide) (54). The General Electric Company sells this as a blend with polystyrene under the trade name Noryl. 

Health and Safety Factors. Animal-feeding studies of DMPPO itself have shown it to be nontoxic on ingestion. The solvents, catalyst, and monomers that are used to prepare the polymers, however, should be handled with caution. Eor example, for the preparation of DMPPO, the amines used as part of the catalyst are flammable toxic on ingestion, absorption, and inhalation and are also severe skin and respiratory irritants (see Amines). Toluene, a solvent for DMPPO, is not a highly toxic material in inhalation testing the TLV (71) is set at 375 mg/m, and the lowest toxic concentration is reported to be 100—200 ppm (72). Toxicity of 2,6-dimethylphenol is typical of alkylphenols (qv), eg, for mice, the acute dermal toxicity is LD q, 4000 mg/kg, whereas the acute oral toxicity is LD q, 980 mg/kg (73). The Noryl blends of DMPPO and polystyrene have PDA approval for reuse food apphcations. 

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. 

To the range of engineering plastics were added polyethylene and polybutylene tereph-thalates (PET and PBT), as well as General Electric s polyethers, the PPO (polyphenylene oxide) produced through polymerization of 2,6-xylenol and the Noryl plastic produced by blending PPO with polystyrene. Other special polymers, derived like the polycarbonates from bisphenol A, were added to this range polyarylates, polysul-fones, polyetherimides. 

Many of the practical examples of miscible blends involve poly(vinylchloride) including those with butadiene-acrylonitrile copolymers2), possibly the first put into use, and various poly acrylates and vinyl acetate copolymers3,4) which are extensively used in PVC formulations at present. Others involve high performance engineering plastics such as blends of polystyrene with poly(2,6-dimethyl-1,4-phenylene oxide) (Noryl )5). In some cases a useful compromise or averaging of properties can be obtained whereas in others a useful combination of different desirable properties can be achieved. 

Noryl resins n. Blends of poly-(2,6-dimethyl-l,4-phenyl oxide) with polystyrene or with high impact polystyrene. 

The commercial PPO resins were developed by General Electric (Noryl) and defined as modified PPO. Their exact chemical nature is unknown. They may be polymer blends, likely with polystyrene or high-impact polystryene. In Europe PPO is recognized by a more generic name, polyphenylene ether (PPE). 

DMPPO with polystyrene and additives is marketed under the trade name of Noryl thermoplastic resin. Blends of DMPPO with nylon plus additives are sold as Noryl GTX resin. Other poly(phenylene oxide)s are also of commercial interest. For example, low molecular weight, imsubstituted poly(phenylene oxidels are of use as heat-transfer fluids and liquid phases for gas chromatography. Poly(2,6-diphenyl-l,4-phenylene oxide) is sold as a gas absorbent and for gas chromatography. 

PPO is completely miscible with polystyrene and blends of the two products have glass temperatures between those of the two polymers. This result led to the commercialization of NORYL resins, one of the class of engineering thermoplastics. The discoveries which led to the commercial product as well as the scope of the oxidative coupling reaction are the subject of this paper. 

Many miscible blends with single TgS are commercially available [6], the most interesting being Noryl 731 (General Electric Co.), which is a blend of polystyrene (PS) and poly(2,6-dimethyl-l,4-phenylene oxide) (PPO, 50% by weight). 

Noryl n Poly(phenylene oxide) Trade name for a family of blends of polyphenylene oxide (PPO) with much less costly styrenic polymers. These blends have the processability, low water absorption, and good dielectric properties associated with polystyrene, while the PPO contributes heat resistance. Glass-reinforced grades are available. Manufactured by General Electric, U.S. 

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. 

PPO is difficult to process due to its high melt viscosity, its methyl groups are sensitive to oxidation above 150 °C and its synthesis is relatively expensive. Therefore, the commercialization of neat PPO was not much successful, but PPO showed the unusual property to be miscible with polystyrene. Hence, PPO mainly serves as reinforcing component of polystyrene, and these blends were and are commercialized by GE under the Trademark Noryl [96]. 

The formation of poly (2,6-dimethyl-1,4-phenylene oxide) 2, later called PPO resin, represented a new method of polymerization which was termed polymerization by oxidative coupling. PPO was commercialized in 1964 and two year later blends of PPO with polystyrene, NORYL resins that are miscible blends of PPO and polystyrene, were commercially introduced. The scope and mechanism of the oxidative polymerization reaction and the historical development of PPO and its blends have been extensively reviewed previously... 

Noryl. Noryl engineering thermoplastics are polymer blends formed by melt-blending DMPPO and HIPS or other polymers such as nylon with proprietary stabilizers, flame retardants, impact modifiers, and other additives (69). Because the mbber characteristics that are required for optimum performance in DMPPO—polystyrene blends are not the same as for polystyrene alone, most of the HIPS that is used in DMPPO blends is designed specifically for this use (70). Noryl is produced as sheet and for vacuum forming, but by far the greatest use is in pellets for injection mol ding. 

The processing of blends of an amorphous material (polystyrene) and a crystalline material with a high melting point (PPO) reflects the nature of the constituent materials. The processing is mainly by injection moulding, and the major points to be considered when processing Noryl-type materials are ... 

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. 

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