PPO See: Polyphenylene oxides

Polymer blends can be subdivided into two kinds those of compatible and those of incompatible polymers. Real compatibility is an exception (see 9.1) an example is PS with PPE (polyphenylene ether, also called PPO, polyphenylene oxide). These two polymers can be blended with each other on such a small scale that it really looks like molecular miscibility. This blend shows, therefore, only one single glass transition. 

Polyphenylene oxide (PPO) ru A thermoplastic, linear, non-crystalline polyether obtained by the oxidative polycondensation on 2,6-dimethylphenol in the presence of a copper-amine complex catalyst. The resin has a wide useful temperature range, from below —170 to +190°C, with intermittent use to 205° C possible. It has excellent electrical properties, unusual resistance to acids and bases, and is pro-cessable on conventional extrusion and injection-molding equipment. Because of its high coat PPO is also marketed in the form of polystyrene blends (see Noryf ) that are lower-softening (Tg of PS is about 100°C vs 208°C for PPO), and have working properties intermediate between those of the two resins. 

These blends include epoxy-polyphenylene oxide (PPO) (see Fig. 7.7), epoxy-cyanate ester, and epoxy isocyanurate (see Fig. 7.8). While these materials have been developed to minimize impacts to common printed circuit manufacturing processes, they can affect productivity in multilayer lamination and drilling and can require special desmear and hole wall conditioning processes, depending on the design of the printed circuit and fabrication process used. On the other hand, they typically have less of an impact to these processes when compared to the even higher performance materials. 

Example 3. Estimate the configurational entropy changes that occur when a. 500 g of toluene (T) are mixed with 500 g of styrene monomer (S) A..500g of toluene are mixed with 500 g of polystyrene (PS), M = 100000 c. 500 g of PS, M — 100000 are mixed with 500 g of polyphenylene oxide (PPO) (see Chapter II, Example 4K), M = 100000. (This is one of the rare examples where two high molecular weight polymers are soluble in one another.)... 

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