Polybutadiene-1-Ethylene Copolymer

Figure 4 Plot of degree of crystallinity (XDSC) from DSC against crystallinity (Xp) determined by density measurements. (A), hydrogenated polybutadienes ( ), ethylene 1-butene copolymers ( ), ethylene 1-octene copolymers. Reprinted with permission from Ref. [72]. Copyright 1984 American Chemical Society. 

Polycarbonate is blended with a number of polymers including PET, PBT, acrylonitrile-butadiene-styrene terpolymer (ABS) rubber, and styrene-maleic anhydride (SMA) copolymer. The blends have lower costs compared to polycarbonate and, in addition, show some property improvement. PET and PBT impart better chemical resistance and processability, ABS imparts improved processability, and SMA imparts better retention of properties on aging at high temperature. Poly(phenylene oxide) blended with high-impact polystyrene (HIPS) (polybutadiene-gra/f-polystyrene) has improved toughness and processability. The impact strength of polyamides is improved by blending with an ethylene copolymer or ABS rubber. 

The formation of coagulum is observed in all types of emulsion polymers (i) synthetic rubber latexes such as butadiene-styrene, acrylonitrile-butadiene, and butadiene-styrene-vinyl pyridine copolymers as well as polybutadiene, polychloroprene, and polyisoprene (ii) coatings latexes such as styrene-butadiene, acrylate ester, vinyl acetate, vinyl chloride, and ethylene copolymers (iii) plastisol resins such as polyvinyl chloride (iv) specialty latexes such as polyethylene, polytetrafluoroethylene, and other fluorinated polymers (v) inverse latexes of polyacrylamide and other water-soluble polymers prepared by inverse emulsion polymerization. There are no major latex classes produced by emulsion polymerization that are completely free of coagulum formation during or after polymerization. 

Composition (type of polymeric components). The base polymer (which is to be modified) may be an amorphous polymer [e.g., polystyrene (PS), styrene-acrylonitrile copolymer, polycarbonate, or poly(vinyl chloride)], a semicrystalline polymer [e.g., polyamide (PA) or polypropylene (PP)], or a thermoset resin (e.g., epoxy resin). The modifier may be a rubber-like elastomer (e.g., polybutadiene, ethylene-vinyl acetate copolymer, ethylene-propylene copolymer, or ethylene-propylene-diene copolymer), a core-shell modifier, or another polymer. Even smaller amounts of a compatibilizer, such as a copolymer, are sometimes added as a third component to control the morphology. 

The impact resistance of polypropylene at low temperature has been improved by polyblending with EPDM or E-P rubber to make possible the application of this material in the automotive industry. The low-temperature properties of polyamides such as nylon 6 and nylon 66 have been improved by polyblending with ethylene copolymers or specially grafted polybutadiene (45). 

Commercially important elastomeric thermoplastic alloys are dynamically vulcanized blends of polypropylene with high volume fractions of EPDM, polybutadiene rubber, nitrile rubber, and butyl rubber (Santoprene , Vyram , Geolast and Trefsin ) all currently sold by Advanced Elastomer Systems, a joint venture of Monsanto and Exxon. Another recent member of the commercial dynamically cured elastomeric thermoplastic alloys is the blend of PVC and a crosslinked ethylene copolymer (Alcryn , DuPont). The current consumption of all the elastomeric thermoplastic alloys in the USA is over 23 kton/y, with the EPDM/PP blend (Santoprene ) assuming about 90% of the market share. 

High density polyethylene (HOPE) Linear low density polyethylene (LLDPE) Isotactic polypropylene (iPP) Syndiotactic polypropylene (sPP) tram-1,4-Polyisoprene Syndiotactic polystyrene (sPS) Cyclooleflns Ethylene-propylene copolymers Styrene-ethylene copolymers cw -1,4-polybutadiene rrarw -1,4-Poly isoprene Random ethylene-a-olefin copolymers Ethylene-propylene rubber (EPR) Ethylene-propylene-diene copolymers (EPDM)... 

Polybutadiene Vinyl acetate/butyl acrylate copolymer Vinyl chloride/ethylene copolymer binder, paper treatment Silica, colloidal binder, paper varnishes Dammar... 

Acetone oxime 1,4-Butylene qlycol diacrylate Chlorodiphenyl (54% Cl) Epoxidized polybutadiene Ethylene/methacrylic acid copolymer... 

To improve dyeability, flexibility, and toughness of isotactic polypropylene, PP, it was compounded in a Banbury-type mixer with ethylene-vinyl acetate, 7 wt% EVAc. Several other ethylene copolymers were also used. In Miliprint patent, EVAc or ethylene-ethyl acrylate copolymer, 18-32 wt% EVAc or EEA, was found to improve impact strength, elongation, and low brittleness temperature of PP. hi Firestone patent, linear polybutadiene, BR, was used. The Mitsubishi patent disclosed improvements of PP impact strength properties by blending it with 0.5-25 wt% ethylene-aliphatic esters, e.g., EVAc... 

An elastomer which upon heating turns into regularly behaving linear polymer. Polystyrene-polybutadiene block copolymers, polypropylene blends with ethylene-propylene-diene terpolymer provide examples. 

Figure 7. Scanning electron micrographs of polyethylene copolymers, (a) Hydrogenated polybutadiene (ethylene-butene)...

PolymGrizabiG Block Copolymars. Unsaturated hydrocarbon polymers with a large number of polymerizable double bonds can be used to prepare fully cross-linked vesicle membranes. This has been demonstrated for polybutadiene block copolymers (23,168) and methacroyl-fimctionalized block copolymers (87) using free-radical polymerization, and for polycinnamoylethylmethacrylate block copolymers using a [2-1-2] photoaddition (68). Poly(ethylene oxide-6-3-(trimethoxysilyl)propyl methacrylate) vesicles could be efficiently cross-linked with triethylamine (79,80). PLA-PNIPAM block copolymer vesicles were cross-linked by chain extension of the PNIPAM block using hexamethylene diacrylate (77). 

Our laboratory developed ID and 2D spectra-spatial ESRI for the study of het-erophasic systems, such as poly(acrylonitrile-butadiene-styrene) (ABS) and heterophasic propylene-ethylene copolymers (HPEC) containing bis(2,2,6,6-tetram-ethyl-4-piperidinyl) sebacate (Tmuvin 770) as the HAS, and exposed to thermal treatment and UV irradiation.The major objectives were to examine polymer degradation under different conditions to assess the effect of rubber phase (polybutadiene in ABS and ethylene-propylene rubber in HPEC) on the extent of degradation and to evaluate the extent of stabilization by HAS. The repeat units in ABS and the formula of Tinuvin 770 are shown in Fig. 2. 

Synthetic polymers that are commercially manufactured in the quantity of billions of pounds may be classified in three categories (1) plastics, which include thermosetting resins (e.g., urea resins, polyesters, epoxides) and thermoplastic resins (e.g., low-density as well as high-density polyethylene, polystyrene, polypropylene) (2) synthetic fibers, which include cellulosics (such as rayon and acetate) and noncellulose (such as polyester and nylon) and (3) synthetic rubber (e.g., styrene-butadiene copolymer, polybutadiene, ethylene-propylene copolymer). 

Reproduced with permission from Handbook of Polyolefins Synthesis and Properties, 1st Edition, Eds., C. Vasile and R.B. Seymour, Marcel Dekker, New York, NY, USA, 1993. Copyright Marcel Dekker, 1993. (c) Dilatometric-determined melting temperature of ethylene copolymers versus mole percent of branches. The dashed line represents equilibrium temperature for random copolymers. Experimental results diazoalkane copolymers with methyl branch (O) ethyl branch ( ) propyl branch (A) hydrogenated polybutadiene (A) EVA ( ) [30]... 

Another widely used approach is the in situ polymerization of an intractable polymer such as polypyrrole onto a polymer matrix with some degree of processibil-ity. Bjorklund [30] reported the formation of polypyrrole on methylcellulose and studied the kinetics of the in situ polymerization. Likewise, Gregory et al. [31] reported that conductive fabrics can be prepared by the in situ polymerization of either pyrrole or aniline onto textile substrates. The fabrics obtained by this process maintain the mechanical properties of the substrate and have reasonable surface conductivities. In situ polymerization of acetylene within swollen matrices such as polyethylene, polybutadiene, block copolymers of styrene and diene, and ethylene-propylene-diene terpolymers have also been investigated [32,33]. For example, when a stretched polyacetylene-polybutadiene composite prepared by this approach was iodine-doped, it had a conductivity of around 575 S/cm and excellent environmental stability due to the encapsulation of the ICP [34]. Likewise, composites of polypyrrole and polythiophene prepared by in situ polymerization in matrices such as poly(vinyl chloride), poly(vinyl alcohol), poly(vinylidine chloride-( o-trifluoroethylene), and brominated poly(vi-nyl carbazole) have also been reported. The conductivity of these composites can reach up to 60 S/cm when they are doped with appropriate species [10]. 

FEP fluorinated ethylene propylene PBS polybutadiene-styrene copolymer... 

The preparation of ethylene copolymers (or terpolymers) such as linear low-density polyethylenes (LLDPE), ethylene/propylene elastomers (EP), ethylene/ propylene/diene terpolymers (EPDM) is also based on these catalytic systems. Stereoregular polyisoprene and polybutadiene elastomers are also obtained by this method of polymerization the formation of 1,4-m-polydienes requires the prior double coordination of the monomer onto the growing active center ... 

Figure 11.1 Final melting temperatures of ethylene copolymers as a function of branch content ethylene copolymers containing methyl (open circles), ethyl (open square), and n-propyl (solid triangles) branches hydrogenated polybutadiene (open triangles) ethylene-vinyl acetate (solid circles). Dashed line represents Flory s equilibrium theory for random copolymers (p = Xa), as given in Equation (11.2). Reprinted with permission from Reference [12]. Copyright 1984, American Chemical Society.

Figure 11.3 Morphology map for nonisothermally crystallized ethylene copolymers, drawn schematically based on experimental data for fractions of linear low density polyethylene and hydrogenated polybutadienes. Spherulitic superstructure is observed within the domeshaped region defined by the three axes eopolymer molecular weight (M), branch content, and nominal crystallization temperature. Reprinted with permission from Reference [23]. Copyright 1981 American Chemical Society.

Acrylonitrile—Butadiene—Styrene. ABS is an important commercial polymer, with numerous apphcations. In the late 1950s, ABS was produced by emulsion grafting of styrene-acrylonitrile copolymers onto polybutadiene latex particles. This method continues to be the basis for a considerable volume of ABS manufacture. More recently, ABS has also been produced by continuous mass and mass-suspension processes (237). The various products may be mechanically blended for optimizing properties and cost. Brittle SAN, toughened by SAN-grafted ethylene—propylene and acrylate mbbets, is used in outdoor apphcations. Flame retardancy of ABS is improved by chlorinated PE and other flame-retarding additives (237). 

Pubhcations on curing polymers with TAIC include TEE—propylene copolymer (135), TEE—propylene—perfluoroaHyl ether (136), ethylene—chlorotrifluoroethylene copolymers (137), polyethylene (138), ethylene—vinyl acetate copolymers (139), polybutadienes (140), PVC (141), polyamide (142), polyester (143), poly(ethylene terephthalate) (144), sdoxane elastomers (145), maleimide polymers (146), and polyimide esters (147). 

Fig. 15. Oxygen permeability versus 1/specific free volume at 25 °C (30). 1. Polybutadiene 2. polyethylene (density 0.922) 3. polycarbonate 4. polystyrene 5. styrene-acrylonitrile 6. poly(ethylene terephthalate) 7. acrylonitrile barrier polymer 8. poly(methyl methacrylate) 9. poly(vinyl chloride) 10. acrylonitrile barrier polymer 11. vinyUdene chloride copolymer 12. polymethacrylonitrile and 13. polyacrylonitrile. See Table 1 for unit conversions.

The economic importance of copolymers can be cleady illustrated by a comparison of U.S. production of various homopolymer and copolymer elastomers and resins (102). Figure 5 shows the relative contribution of elastomeric copolymers (SBR, ethylene—propylene, nitrile mbber) and elastomeric homopolymers (polybutadiene, polyisoprene) to the total production of synthetic elastomers. Clearly, SBR, a random copolymer, constitutes the bulk of the entire U.S. production. Copolymers of ethylene and propylene, and nitrile mbber (a random copolymer of butadiene and acrylonitrile) are manufactured in smaller quantities. Nevertheless, the latter copolymers approach the volume of elastomeric butadiene homopolymers. 

Commercially, anionic polymerization is limited to three monomers styrene, butadiene, and isoprene [78-79-5], therefore only two useful A—B—A block copolymers, S—B—S and S—I—S, can be produced direcdy. In both cases, the elastomer segments contain double bonds which are reactive and limit the stabhity of the product. To improve stabhity, the polybutadiene mid-segment can be polymerized as a random mixture of two stmctural forms, the 1,4 and 1,2 isomers, by addition of an inert polar material to the polymerization solvent ethers and amines have been suggested for this purpose (46). Upon hydrogenation, these isomers give a copolymer of ethylene and butylene. 

The polyols used are of three types polyether, polyester, and polybutadiene. The polyether diols range from 400 to about 10,000 g/mol. The most common polyethers are based on ethylene oxide, propylene oxide, and tetrahydrofuran or their copolymers. The ether link provides low temperature flexibility and low viscosity. Ethylene oxide is the most hydrophilic and thus can increase the rate of ingress of water and consequently the cure rate. However, it will crystallize slowly above about 600 g/mol. Propylene oxide is hydrophobic due to hindered access to the ether link, but still provides high permeability to small molecules like water. Tetrahydrofuran is between these two in hydrophobicity, but somewhat more expensive. Propylene oxide based diols are the most common. 

FIGURE 1.12 Master curve of tear energy Gc versus rate R of tear propagation at Tg for three cross-linked elastomers polybutadiene (BR, Tg — —96°C) ethylene-propylene copolymer (EPR, Tg — —60°C) a high-styrene-styrene-butadiene rubber copolymer (HS-SBR, Tg — —30°C). (From Gent, A.N. and Lai, S.-M., J. Polymer Sci., Part B Polymer Phys., 32, 1543, 1994. With permission.)... 

---