Noryl mechanical

Physical or chemical vapor-phase mechanisms may be reasonably hypothesized in cases where a phosphoms flame retardant is found to be effective in a noncharring polymer, and especially where the flame retardant or phosphoms-containing breakdown products are capable of being vaporized at the temperature of the pyrolyzing surface. In the engineering of thermoplastic Noryl (General Electric), which consists of a blend of a charrable poly(phenylene oxide) and a poorly charrable polystyrene, experimental evidence indicates that effective flame retardants such as triphenyl phosphate act in the vapor phase to suppress the flammabiUty of the polystyrene pyrolysis products (36). 

Polyphenylene oxide (PPO) or Polyphenylene ether (PPE) is an amorphous polymer with a softening temperature of about 210 °C. To improve its processability it is mostly blended with PS (modified PPE, e.g. Noryl ), which is at the cost of its heat distortion temperature. The properties are excellent the applications are mainly in fine-mechanical construction, in automotive parts, in household equipment etc. 

Perhaps the best known member of the "heat-resistant" styrene plastics family is General Electric s Noryl (34). Noryl is an alloy of poly(phenylene oxide) and high-impact polystyrene. Heat deflection temperatures for Noryl range as high as 300 °F. The balance of mechanical properties is excellent, although processability is more difficult than for conventional styrene plastics. 

The first commercial blend of two dissimilar polymers was Noryl, a miscible polyblend of poly(phenylene oxide) and polystyrene, introduced by General Electric in the 1960s. Since that time a large number of different blends have been introduced. A number of technologies have been devised to prepare polyblends these are summarized in Table 4.34. For economic reasons, however, mechanical blending predominates. 

Other thermoplastic resins can be added to produce a polymer blend in order to achieve a desirable balance of mechanical/thermal properties and cost (e.g. PPO/PS, Noryl from GE). Most blends are two phase systems, where no stress transfer to the dispersed phase is possible. PPO/PS is a special case and forms a single blend Tg between the values of the PPO (210°C) and PS (100°C) depending on the relative proportion of the two polymers (e.g. about 150°C for Noryl). 

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. 

Polyvinylidene fluoride/Noryl (improved physico-mechanical properties)... 

A modified form of PPO is available with the trade name Noryl (General Electric Company). This is cheaper than PPO and has excellent mechanical properties over the range -40 to 120 °C. This polymer is used extensively in food contact applications where an impact strength slightly inferior to that of PPO is acceptable. 

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... 

The stress-whitening of the neighboring material, that was produced when the crack was opened up, suggested that the material was not degraded. Mechanical testing of samples, machined from a number of seats, verified this. Tensile modulus was 340 ksi, yield sfress - 4800 psi, strain at break - 38%, and Notched Izod impact strength of 4.2 ft-lb/in (with some minor variations, depending on the color of the seat material - these values are for the compounded materials, not pure Noryl). 

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