Grafted polymers, blends

Cyovin Self-extinguishing ABS graft polymer blends BorgWarner... 

Figure 6. Influence of milling temperature on P, D, EP and ED for COt on grafted polymer blends of PVC/EVA...

Because graft copolymers are much "easier" to obtain synthetically than heterogeneous diblock or triblock copolymers, they have also been used as compatibiUzers ia polymer blends. Theoretically, they are not as efficient as the diblocks (60), but they are successhilly and economically used ia a number of commercial systems (61). 

Two commercially significant graft copolymers are acrylonitrile—butadiene—styrene (ABS) resins and impact polystyrene (IPS) plastics. Both of these families of materials were once simple mechanical polymer blends, but today such compositions are generally graft copolymers or blends of graft copolymers and homopolymers. 

The relative U.S. production of styrene homopolymer and copolymer resins is also noteworthy (103) (Fig. 6). The impact polystyrene (graft and polymer blend) copolymers are produced in nearly the same quantities as styrene homopolymers. The ABS resins are synthesized in lesser, yet significant, quantities. 

Copolymer technology is progressing along two "fronts." First, new appHcations for copolymers are being found to increase the volume of materials that are already commercially available. One example of this is the rapid growth of styrenic block copolymers sold as asphalt (qv) and polymer modifiers over the past 10 years (Fig. 7). Another is the increased interest in graft and block copolymers as compatihilizers for polymer blends and alloys. Of particular interest are compatihilizers for recycled polymer scrap. 

R. D. Deanin, A. A. Deanin, and T. Sjoblom in L. H. Sperling, ed.. Recent Mdvances in Polymer Blends, Grafts, and Blocks, Plenum Press, New York, 1974, Chapt. 2. 

Today the common practice is first to dissolve the rubber in the styrene monomer and then to polymerise the styrene in the usual way. By this process the resultant blend will contain not only rubber and polystyrene but also a graft polymer where short styrene side chains have been attached to the rubber molecules. This gives a marked improvement in the impact strengths that can be obtained. 

Polychloroprene elastomer. Neoprene AC and AD are the most commonly used, mainly Neoprene AD because of its superior viscosity stability. For difficult-to-bond substrates, graft polymers Neoprene AD-G or AF) show better performance. For sprayable adhesives or high-viscosity mastics, the Neoprene AG offers excellent results. When specific properties (e.g. increase tack, improve wetting, increase peel strength) need to be met, blends of Neoprene AC or AD with Neoprene AG provide adequate performance. 

Copolymers (graft or block) made of immiscible sequences give rise to biphasic morphologies depending on the ratio of immiscible sequences (or of their lengths). Such possible microstructures are reported in Figure 33. A minor phase can be dispersed as nodules (spheres) or filaments (cylinders) while, when concentrations of both phases get similar, lamellar (interpenetrated) structures can appear. It should be noted that rather similar morphologies could also be found in (compatibilised) polymer blends. 

Sperling, L.H., ed. "Recent Advances in Polymer Blends, Grafts... 

Grading systems, for flax fiber, 77 617 Gradual failures, 26 981 Graduate students, role in facilitating research partnerships, 24 383 Graft copolymerization, 20 327. See also Graft polymerization Graft copolymers, 7 650-654 20 391 compatibilization efficiency of, 20 338 formation of, 23 395 in polymer blends, 20 324—325 in reactive compatibilization,... 

Frisch, K. C. et al., "Topologically Interpenetrating Polymer Networks", Recent Advances in Polymer Blends, Grafts and Blocks, ed. by L. H. Sperling, Plenum Press, N.Y. 19T8-... 

New Orleans, La., August 1999, p.752-3 POLYSTYRENE/POLYPROPYLENE POLYMER BLEND COMPATIBILISATION WITHOUT ADDITION OF PREMADE BLOCK OR GRAFT COPOLYMERS OR FUNCTIONALISATION Furgiuele N Khait K Torkelson J M (ACS,Div.of Polymer Chemistry)... 

In general, graft copolymers play often a role as compatibilizer in polymer blends (see Sect. 5.5). 

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