Polypropylene block copolymer

POM Polyoxymethylene PPBC Polypropylene block copolymer PPHP Polypropylene homopolymer PPS Polyphenylene sulphide PPO Polyphenylene oxide PS Poly styrene... 

Thermoplastic polyolefin (TPO) is a generic name that refers to polyolefin blends usually consisting of some fraction of polypropylene (PP), polyethylene (PE) or polypropylene block copolymer (PP-b-EP or BCPP ), and a thermoplastic olefinic rubber, with or without a mineral reinforcing filler such as talc or wollastonite. Common rubbers include ethylene propylene rubber (EPR), EPDM rubber, ethylene-octene (EO) copolymer mbber, ethylene-butadiene (EB), and styrene-ethylene-butadiene-styrene (SEBS) block copolymer rubbers. Currently, there are a great variety of commercial polypropylene homopolymers, PP block copolymers, and olefinic rubbers available to make a wide range of TPO blends with densities ranging from 0.92 to 1.1. 

Table 6.8 The effect of bismaleimide structure on the mechanical properties of a 60% w/w magnesium hydroxide-filled polypropylene block copolymer [31].

J. Elastomers Plast. 9(7), 281 (1977). Thermoplastic IPNs. Block Copolymers blended with polypropylene. Block copolymers blended with polyethylene. 

Melt blending of polymers is a widely used technique for tailor-making polymeric materials to generate the desired properties. Blending polypropylene block copolymer (PPBC) with elastomeric ethylene-propylene-diene terpolymer (EPDM) produces a range of useful materials commercialized in early 1970 s that found significant uses in the automotive industry. Polyolefin-based bumpers dominate the automobile market in Europe and Japan and have made in-roads in the North American market. In India, the polyolefin blend for car bumpers was commercialized in 1992. 

Polypropylene block copolymer (produced by Indian Petrochemicals Corporation Ltd.) and EPDM (produced by Herdillia Unimers Ltd.) are the base polymers used in preparing the polyolefin blend. 

Fig. 2.19 TEM micrographs of (a) a sphemlite centre in a thin film of high density polyethylene stained with RUO4, (b) section of polyethylene-atactic polypropylene block copolymer stained with RUO4. Reproduced with permission (a) from Figure 15 in Trent, Scheinbeim and Couchman, Macromolecules, 1983, 16 589-598 (Copyright 1983) American Chemical Society, (b) fi om Figure 3 in Hong, Copyright (2001) with permission from Elsevier...

Hot-melt adhesives are 100% solids that, in the broadest sense, include all thermoplastic polymers. Polymers that are primarily used as hot-melt adhesives include ethylene-vinyl acetate copolymers (EVA), polyvinyl acetates (PVA), polyethylene (PE), amorphous polypropylene, block copolymers (thermoplastic elastomers), polyamides, and polyesters. The oldest hot-melt adhesive, which has been in use since early times, is sealing wax. In principle, glutins and glue jellies also may be regarded as hot-melt adhesives. However, modern hot-melt adhesives are primarily synthetic products. The simplest hot-melt adhesives are rosin-wax mixtures. But these products have limited strength and thermal stability. 

Ruan W H, Zhang M Q, Rong M Z and Friedrich K (2004) Mechanical properties of nanocomposites from ball milling grafted nano-silica/polypropylene block copolymer, Polym Polym Compos 12 257-267. 

Kai ger-Kocsis J and Kiss L (1987) Dynamic mechanical properties and morphology of polypropylene block copolymers and polypropylene/elastomer blends, Polym Eng Sci 27 254-262. 

Bar et al. [71] characterized the morphology of blends of poly(styrene)-WocA -poly(ethene-co-but-l-ene)-WocA -poly(styrene) with isotactic and atactic polypropylene block copolymers by ICAFM. Samples deposited from solution onto a glass substrate, dried, and annealed or quenched from the melt and by samples cut by an ultramicrotome were compared with earher TEM results. The polymer film on the side of the film-glass interface was studied rather than the free surfaces of the polymer. 

Other Uses. Large quantities of hydrocarbon resins are used in mastics, caulks, and sealants (qv). Polymers for these adhesive products include neoprene, butyl mbber, polyisoprene, NR, SBR, polyisobutylene, acryHcs, polyesters, polyamides, amorphous polypropylene, and block copolymers. These adhesives may be solvent or water-borne and usually contain inorganic fillers. 

Similarly, the random introduction by copolymerization of stericaHy incompatible repeating unit B into chains of crystalline A reduces the crystalline melting point and degree of crystallinity. If is reduced to T, crystals cannot form. Isotactic polypropylene and linear polyethylene homopolymers are each highly crystalline plastics. However, a random 65% ethylene—35% propylene copolymer of the two, poly(ethylene- (9-prop5lene) is a completely amorphous ethylene—propylene mbber (EPR). On the other hand, block copolymers of the two, poly(ethylene- -prop5iene) of the same overall composition, are highly crystalline. X-ray studies of these materials reveal both the polyethylene lattice and the isotactic polypropylene lattice, as the different blocks crystallize in thek own lattices. 

By block copolymerisation so that one component of the block copolymer has a Tg well below the expected service temperature range (e.g polypropylene with small blocks of polyethylene or preferably polypropylene with small amorphous blocks of ethylene-propylene copolymer). 

As shown in the previous section the mechanical and thermal properties of polypropylene are dependent on the isotacticity, the molecular weight and on other structure features. The properties of five commercial materials (all made by the same manufacturer and subjected to the same test methods) which are of approximately the same isotactic content but which differ in molecular weight and in being either homopolymers or block copolymers are compared in Table 11.1. 

Whilst it is inevitable that polypropylene will be compared more frequently with polyethylene than with any other polymer its use as an injection moulding material also necessitates comparison with polystyrene and related products, cellulose acetate and cellulose acetate-butyrate, each of which has a similar rigidity. When comparisons are made it is also necessary to distinguish between conventional homopolymers and the block copolymers. A somewhat crude comparison between these different polymers is attempted in Table 11.7 but further details should be sought out from the appropriate chapters dealing with the other materials. 

Polypropylene block and graft copolymers are efficient blend compatibilizers. These materials allow the formation of alloys, for example, isotactic polypropylene with styrene-acrylonitrile polymer or polyamides, by enhancing the dispersion of incompatible polymers and improving their interfacial adhesion. Polyolefinic materials of such types afford property synergisms such as improved stiffness combined with greater toughness. 

Antony P., Bandyopadhyay S., and De S.K., Thermoplastic elastomers based on ionomeric polyblends of zinc salts of maleated polypropylene and maleated EPDM rubber, Polym. Eng. Sci., 39, 963, 1999. Weiss R.A., Sen A., Pottick L.A., and Willis C.L. Block copolymer ionomers. Thermoplastic elastomers possessing two distinct physical networks, Polym. Commun., 31, 220, 1990. 

Blend with Isotactic Polypropylene and Styrene-Ethylene-Butylene-Styrene Block Copolymer... 

EPDM-g-glycidyl methacrylate SEBS block copolymer polypropylene... 

Figure 30 The hydroboration strategy of chain end olefinic unsaturation in polypropylene with 9-BBN for further conversion into block copolymers via polymer radicals. (Adapted from refs. 66 and 67.)...

Under these conditions, the polyethylene oxide blocks behave chromatographi-cally invisible and retention of the block copolymer is solely directed by the polypropylene oxide block, yielding fractions of different degrees of polymerization (m) with respect to PPO. The assignment of the peaks was based on comparison with the chromatogram of a polypropylene glycol. 

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