Polyblends and Alloys

Polyblends and alloys (compatible systems) introduced a new dimension to the world of polymers, leading to a significant saving by avoiding the manufacture of new polymers or copolymers. These are industrial mixtures that combine certain properties and thus often reduce the cost of the product. When compatibility is reached, division into separate phases is eliminated (which may reduce mechanical properties). Therefore the use of compatibiliz-ers as coupling agents has been increased. In the ideal case of compatibility 

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There are various polymers (including copolymers) in this family but the most common polycarbonate is that based on bisphenol-A, also known by the commercial names—Lexan (U.S.) or Macrolon (Germany). Several polyblends and alloys are already in use, combining PC with ABS, PET, PBT and others. 

Alloy a- 16i also 9- Il6i n [F aloiy fr. OF alei, fr. aleir to combine, fr. L alligare to bind] (1604) A blend of a polymer or copolymer with other polymers or elastomers. An important example is a blend of styrene-acrylonitrile copolymer with butadiene-acrylonitrile rubber. The term polyblend is sometimes used for such mixtures. Some writers restrict the term allow to mixtures of polymers that form a single phase, reserving the term blend for nonhomogeneous mixture. The sale of plastics blends and alloys worldwide was 1.3 billion pounds (0.95 Tg) in 1987 and was predicted to have increased by more than 50% by 1992. 

Certain polymers have come to be considered standard building blocks of the polyblends. For example, impact strength may be improved by using polycarbonate, ABS and polyurethanes. Heat resistance is improved by using polyphenylene oxide, polysulphone, PVC, polyester (PET and PBT) and acrylic. Barrier properties are improved by using plastics such as ethylene vinyl alchol (EVA). Some modem plastic alloys and their main characteristics are given in Table 1.2. 

Khandpur AK et al. (1995) Compatibilizers for A/B blends A-C-B triblock versus A-B diblock copolymers. Polyblends 95, SPE Regional Technical Conference on Polymer Alloys and Blends. Boucherville, Quebec, Oct 19-20, pp 88-96... 

Polyblends in which both phases are rigid are frequently called poly alloys. Poly (phenyl oxide) is blended with impact polystyrene to improve melt flow. Complete compatibility between the two phases is rare and was observed between poly (methyl methacrylate) and poly(vinylidene fluoride) by D. R. Paul and J. O. Altamirano. Thermoplastics are added to polyesters to reduce mold shrinkage. 

For useful polyblends, the term compatibilization refers to the absence of separation or stratification of the components of the polymeric alloy during the expected useful lifetime of the product. Optical clarity of a polyblend is related to the particle size of the dispersed phase and/or the difference in the... 

Bourry, D., Utracki, L. A., and Luciani, A., Polyblends- 95, NRCC/IMI Bi-annual symposium and SPE-RETEC on Polymer Alloys and Blends, Boucherville, QC, Canada, 1995.10.19-20. 

The physical mixing of two or more polymers to crate a material with properties different from each of the components has become an increasingly popular route to new materials development. The resulting blend or alloy greatly reduces the associated time and costs while permitting improved processibility and enhanced properties tailored to specific application areas. Many commercial examples of two-phase polyblends consist of a matrix polymer impact modified by the addition of rubber particles. Recently, however, TLCPs have received increasing attention in the scientific and technical literature as in situ reinforcements in polymer blends and microcomposites. The matrices examined in the literature include polyimides, PES, PEI, PEEK, polycarbonate, PET, PPS, and polyarylate. 

S.J. Monte, Polyblends - 97. NRCC/IMl Bi-annual Symposium and SPE-RETEC on Polymer Blends, Alloys and Filled Systems, Boucherville, 9-10 Oct 1997 Montell Impact Copolymer Polypropylene Commercial Information, https //polymers. lyondellbasell.eom/portal/site/basell/menuitem.81bdl022b7c8ec5bbaabbdl0e5548a0c/7VCM... 

Polyblend n. A colloquial term - shortened from polymer blend - used for physical mixtures of two or more polymers, for example, polystyrene and rubber or PVC and nitrile rubber. Such blends usually yield products with favorable properties of both components, sometimes opening markets not available to either of the neat resins. The term alloy is sometimes used for blends. 

Blends or Alloys Sometimes two or more plastics are mixed or alloyed to achieve special properties and are known as polyblends. ABS (acrylonitrile, butadiene and styrene) and PBT (polybutylene terephthalate) are often used in engineering applications with polycarbonate, polysulphone, etc. Several combinations and their improved features are given below (see Crawford (1992) for a more complete discussion of alloys). 

D. Vesely, Polymer Engineering and Science, Joint Meeting of POLYBLENDS 95 and RETEC on Polymer Alloys and Blends, 19-20 Oct. 1995 36 (1996) 1586. 

The complex rheology of polyblends, alloys, and filled plastics can be better understood when both capillary viscometer and stress controlled rotational rheometer are utilized. The capillary viscometer can provide more information about the effects of process history on the macrorheology of these kinds of plastics. This information is complimented with stress controlled rotational rheometry which is more suited for studying the microstructure. Very usefid is the yield stress data which relates to the interfacial bond strength between the clustered particles and the continuous matrix. 

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