Styrenic PPOs

Like polystyrene these blends have the following useful characteristics  

The range of blends now available comprises a broad spectrum of materials superior in many respects, particularly heat deformation resistance, to the general purpose thermoplastics but at a lower price than the more heat-resistant materials such as the polycarbonates, polyphenylene sulphides and polysulphones. At the present time the materials that come closest to them in properties are the ABS/ polycarbonate blends. Some typical properties are given in Table 21.1. 

In common with other engineering thermoplastics there are four main groups of modified PPOs available. They are  

Amongst the special grades that should be mentioned are those containing blowing agents for use in the manufacture of structural foams (see Chapter 16). 

Modified polyphenylene oxides may be extruded, injection moulded and blow moulded without undue difficulty. Predrying of granules is normally only necessary where they have been stored under damp conditions or where an 

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In addition to polystyrene and high-impact polystyrene there are other important styrene-based plastics. Most important of these is ABS, with a global capacity of about 5 X 10 t.p.a. and production of about 3 X 10 t.p.a. The styrenic PPO materials reviewed in Chapter 21 have capaeity and production figures about one-tenth those for ABS. Data for the more specialised styrene-acrylonitrile copolymers are difficult to obtain but consumption estimates for Western Europe in the early 1990s were a little over 60000 t.p.a. 

Blends of PPO with a styrenic material, usually, but not always, high-impact polystyrene. (Referred to below as Styrenic PPOs.)... 

The blending of PPO and polyamides requires special grafting techniques to give a good bond between the two polymers, as otherwise the two polymers are incompatible. Whilst these polymers show the good dimensional stability and toughness of styrenic PPOs, they also have... 

The higher water absorption (typically 3.5% compared with about 0.3% at saturation for a styrenic PPO). 

Figure 32.1. Polar diagrams for three thermoplastic materials, CYCOLOY (a PC/ABS blend), ULTEM (polyetherimide) and NORYL (a styrenic PPO). The shaded area indicates the range...

The most common polymers used for instrument panel stmctnres are acrylonitrile-butadiene-styrene (ABS), acrylonitrile-butadiene-styrene blended with polycarbonate (ABS/PC), polycarbonate (PC), poly(phenylene oxide) blended with nylon (PPO/nylon), poly(phenylene oxide) blended with styrene (PPO/styrene), polypropylene (PP), and styrene-maleic anhydride copolymer (SMA) [3]. The percentage of each of these polymers typically used in year 2000 models is shown below in Table 17.3 [3], All of these materials by themselves... 

Fig. 11.32 Spherulite growth rate, G, for syndiotactic poly(styrene) in blends with poly(vinyl methyl ether) and with PPO, as a function of the crystallization temperature Tc. Composition pure syndiotactic poly(styrene) poly(styrene)-PPO 90/10, 80/20, poly(styrene>i)oly(vinyl methyl ether) 80/20, O 70/30, 60/40. (From Cimmino et al. (77))...

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