Processing of styrenic PPOs

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  

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The second case we describe here is the polymerization of styrene to polystyrene in the presence of polyphenylene oxide. Poly-2,6-dimethyl-l,4-phenylene oxide (PPE) is an orange-red polymer with a glass transition temperature of 220°C and it is completely miscible with PS. Although strictly speaking the system consists of two components, the mutual complete miscibility of all components (monomer as well as both polymers) permits to treat this polymerization as a one-component reactive extrusion process. From product point of view the addition of PPE to PS results in a polymer blend with a higher glass transition temperature (6) than polystyrene. From process point of view the increased viscosity of PPO... 

The nozzle meets the demands associated with processing of all semi-crystalline plastics, as well as CAB, PMMA, PPO, PVC, TPU and styrene plastics. 

Flame-retardant polystyrene is used primarily in expanded foam for building insulation. Rubber-modified styrenic polymers are flame retarded for use in a number of applications, such as enclosures for electronics and business equipment. By far the largest volume flame-retardant HIPS application is television enclosures (Figure 29.1) these are made primarily from flame-retardant HIPS [3]. Flame-retardant HIPS has an attractive balance of mechanical properties, processability and cost. Flame-retardant styrenic blends such as HIPS-PPO and PC-ABS also find utility in a number of electrical applications such as printers, computers and monitors. These blends have received increasing attention recently because of their ability to be flame retarded with nonhalogen flame retardants (see Section 7). 

Styrene polymers, with ease of processing and well-established impact modification, balance the refractory nature of PPO resins. 

Poly(phenylene ether or oxide) (PPE), A thermoplastic produced by catalytic polymerization of 2,6-dimethyl phenol (Fig. 1.3). For the sake of better processability, styrene copolymer-modified PPO is generally used in industrial practice. The service temperature of injection moulded and extruded parts in modified PPE is up to... 

The first major industrial use of thermoplastics (a filled blend of polycarbonate [PC] and acrylonitrile-butadiene-styrene [ABS]) in an automotive exterior door panel, rocker panel, and rear panel was introduced by The Dow Chemical Company in a special process developed for the General Motors Saturn line of vehicles. A formulated blend of nylon 6,6 and polyphenylene oxide (PPO), known as Noryl GTX, also was introduced at the same time in those same Saturn vehicles by General Electric Plastics (now SABIC) using a special assembly line procedure (Figures 9 and 10). 

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. 

Here the different steps of the preparation of the nanocomposites are briefly summarized. First, PPO (a low molar mass polymer powder supplied by Sabic-IP, the Netherlands] was end-capped by acetylation in order to avoid inhibition of the styrene polymerization by phenolic OH groups. It was subsequently mixed with styrene and hexadecane. Then the mixture was added to an aqueous solution of 4-dodecylbenzenesulfonic acid (SDBS). This mixture of SDBS/ hexadecane was chosen as a stabilization system since it is suitable to achieve and guarantee efficient stabilization of polymer particles of sizes smaller than 1 ymP The emulsification process was split up into two steps, namely, a first pre-emulsification step performed by ultra-high shear stirring, followed by ultrasonication in order to obtain submicron particles. Finally, the polymerization was initiated and carried out at 80°C under inert atmosphere (final monomer conversion of 90 %]. The latex obtained had a solid content of 23.6 wt% and contained 10 wt% of PPO dissolved in PS and had a particle size of 100 nm. At the end of the polymerization, the PS molar mass was about... 

The majority of the early work involving the layer-by-layer process involved inorganic substrates such as quartz and silicone since it was thought that the process required flat clean surfaces. Later on polymer films and other organic materials were used as substrates. Some of the most studied polymers include poly(propylene) (PP), poly(isobutylene) (PIB), poly(styrene) (PS), poly(methyl methacrylate) (PMMA), poly(ethylene terephthalate) (PET), poly(phenylene oxide) (PPO) and poly(ether imide) (PEI). ... 

Uses Internal antislat, processing aidforthennoplaslics incl. PS, HIPS, ABS, PPO, PET, PVC, styrenic alloys, copolymers, acrylic esters, food-grade polymers emulsifier In m. of food-contact articles... 

The dependence of the overall crystallization rate on the composition of these two blends differs from those of the growth rates.(77) The half-time for syndiotactic poly(styrene) crystallization is plotted against the crystallization temperature for both type blends in Fig. 11.33. The half-times for the pure syndiotactic polymer are represented again by the sohd circles. For this type of measurement the halftimes increase with the addition of either poly(vinyl methyl ether) or PPO. The addition of poly(vinyl methyl ether) causes a larger increase in the half-time and thus a greater reduction in the crystallization rate. The overall crystallization rate is a reflection of both initiation and growth of crystalUzation. Both of these processes... 

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