Engineered plastics content

Copolymers are typically manufactured using weU-mixed continuous-stirred tank reactor (cstr) processes, where the lack of composition drift does not cause loss of transparency. SAN copolymers prepared in batch or continuous plug-flow processes, on the other hand, are typically hazy on account of composition drift. SAN copolymers with as Httle as 4% by wt difference in acrylonitrile composition are immiscible (44). SAN is extremely incompatible with PS as Httle as 50 ppm of PS contamination in SAN causes haze. Copolymers with over 30 wt % acrylonitrile are available and have good barrier properties. If the acrylonitrile content of the copolymer is increased to >40 wt %, the copolymer becomes ductile. These copolymers also constitute the rigid matrix phase of the ABS engineering plastics. 

Phenolics are consumed at roughly half the volume of PVC, and all other plastics are consumed in low volume quantities, mosdy in single apphcation niches, unlike workhorse resins such as PVC, phenoHc, urea—melamine, and polyurethane. More expensive engineering resins have a very limited role in the building materials sector except where specific value-added properties for a premium are justified. Except for the potential role of recycled engineering plastics in certain appHcations, the competitive nature of this market and the emphasis placed on end use economics indicates that commodity plastics will continue to dominate in consumption. The apphcation content of each resin type is noted in Table 2. Comparative prices can be seen in Table 5. The most dynamic growth among important sector resins has been seen with phenoHc, acryUc, polyurethane, LLDPE/LDPE, PVC, and polystyrene. 

Rynite [Du Pont], TM for a glass-reinforced polyester engineering plastic it is extremely stiff, with glass content of 45%. A modified polyeth-... 

It is important to note that certain properties of these blends are better than those of the parent homopolymers. Adding PE to PP allows improvement of the low temperature impact behavior of PP [12]. In turn, the PP content contributes to the increase of toughness, high modulus and heat resistance to PE [13]. The PP/LDPE blends can be used as engineering plastics, consumer items for household use, goods with improved performance, etc. 

The general guideline for thermoplastics is that the greater the aromatic content, the greater the inherent fire resistance. Hence the fully aromatic thermoplastics (PPS, PES, PEEK, etc.) perform well on all the tests, without needing extraneous additives. Next in line are the semi-aromatic engineering plastics like PC, PBT, PET and the semi-aromatic nylons. Other nylons and polyolefins are less satisfactory. Nevertheless, nylon 6, 66 and 46... 

The mechanical properties of agro-polymers are generally a lot weaker than those of commodity engineering plastics. Their properties are also strongly dependent on moisture content as well as other plasticizers because of their characteristic hydrophilicity. Apart from these, the most prevalent factors alfecting the mechanical properties include processing conditions and composition. 

---