Chlorination polybutadiene

This investigation started as a continuation of research into aspects of grafting from1). Our original intention was to prepare thermoplastic elastomers by grafting polystyrene branches from lightly chlorinated polybutadiene backbones in conjunction with alkylaluminum coinitiators ... 

Grafting from, exploits the active sites, which exist or can easily be generated on a polymer. Halogenated polymers are most frequently used for this purpose poly(vinyl) chloride), polychloroprene, chlorinated EPDM, chlorobutyl rubber, bromobutyl rubber, chlorinated polybutadiene, chlorinated butadiene-styrene copolymers etc.145). 

MAJOR APPLICATION H-H PVC is mostly studied in academic field to understand its structure/property relationship, thermal degradation behavior, and mechanism. Its properties are compared to those of commercial head-to-tail PVC. Pure H-H PVC has no significant industrial applications. H-H PVCs containing 40-65 wt% of Cl, also called chlorinated polybutadiene rubber-resins, are used for coating, paint-based applications and the preparation of threads, tires, tubings, and films, etc. 

Chen, S.-H., Chuang, W.-H., Wang, A.A., Ruaan, R.-C. and Lai, J.-Y. 1997. Oxygen/nitrogen separation by plasma chlorinated polybutadiene/polycarbonate composite membrane. ... 

PMMA/PEO, polyethylene oxide PC/lithium salt of sulfonated polystyrene PS/polyphenylmethyl siloxane Chlorinated PE/chlorinated polybutadiene PS/carboxylated PPO PPO/poly(alpha-methylstyrene)... 

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). 

Carbon Cha.in Backbone Polymers. These polymers may be represented by (4) and considered derivatives of polyethylene, where n is the degree of polymeriza tion and R is (an alkyl group or) a functional group hydrogen (polyethylene), methyl (polypropylene), carboxyl (poly(acryhc acid)), chlorine (poly(vinyl chloride)), phenyl (polystyrene) hydroxyl (poly(vinyl alcohol)), ester (poly(vinyl acetate)), nitrile (polyacrylonitrile), vinyl (polybutadiene), etc. The functional groups and the molecular weight of the polymers, control thek properties which vary in hydrophobicity, solubiUty characteristics, glass-transition temperature, and crystallinity. 

Pyrotechnic mixtures may also contain additional components that are added to modify the bum rate, enhance the pyrotechnic effect, or serve as a binder to maintain the homogeneity of the blended mixture and provide mechanical strength when the composition is pressed or consoHdated into a tube or other container. These additional components may also function as oxidizers or fuels in the composition, and it can be anticipated that the heat output, bum rate, and ignition sensitivity may all be affected by the addition of another component to a pyrotechnic composition. An example of an additional component is the use of a catalyst, such as iron oxide, to enhance the decomposition rate of ammonium perchlorate. Diatomaceous earth or coarse sawdust may be used to slow up the bum rate of a composition, or magnesium carbonate (an acid neutralizer) may be added to help stabilize mixtures that contain an acid-sensitive component such as potassium chlorate. Binders include such materials as dextrin (partially hydrolyzed starch), various gums, and assorted polymers such as poly(vinyl alcohol), epoxies, and polyesters. Polybutadiene mbber binders are widely used as fuels and binders in the soHd propellant industry. The production of colored flames is enhanced by the presence of chlorine atoms in the pyrotechnic flame, so chlorine donors such as poly(vinyl chloride) or chlorinated mbber are often added to color-producing compositions, where they also serve as fuels. 

Polybuiyiene Chlorinated Rubber Polybutadiene PolyUoprene PolydimethylilloKanr... 

Head-to-head PVC prepared by adding chlorine to c/i-polybutadiene has been found to be less stable than ordinary head-to-tail polymer [70]. 

From the results obtained by thermal decomposition of both low-molecular weight vicinal dichlorides in the gas phase [74,75] and of the copolymers of vinyl chloride and /rthermal instability of PVC to the individual head-to-head structures. Crawley and McNeill [76] chlorinated m-1,4-polybutadiene in methylene chloride, leading to a head-to-head, and a tail-to-tail PVC. They found, for powder samples under programmed heating conditions, that head-to-head polymers had a lower threshold temperature of degradation than normal PVC, but reached its maximum rate of degradation at higher temperatures. 

Another exciting developing field is in material science. Chlorination and bromination of fullerenes (refs. 18,19) and solid state bromination of polyacetylenes (refs. 20,21) and of polybutadienes (ref. 22) are typical examples. 

Chlorination reactions. Chlorination of hydrocarbons has been carried out in Japan, chlorination of toluene in the United States, chlorination of tetrachloropentane in the former U.S.S.R. to give octachlorocy-clopentane, and chlorination of propanoic acid in France to give chloro-propanoic acid. Chlorination of methane by irradiation to give lower halomethanes was found to be cost-effective. Chlorination of various amorphous polymers such as polypropylene, polybutadiene, and PVC, has also been carried out. 

Acrylate rubber, EPDM and chlorinated polyethylene improve impact strength, replacing the polybutadiene of ABS ... 

Although not a telomerization, it is mentioned here, that syndiotactic 1,2-polybutadienes were prepared in aqueous emulsions with a 7t-allyl-cobalt catalyst [33]. Similarly, chloroprenes were polymerized using aqueous solutions of [PdCl2(TPPMS)2] and [RhCl(TPPMS)3] as catalysts at 40 °C in the presence of an emulsifier and a chain growth regulator (R-SH, R=Cio-Cis) [35]. Despite the usual low reactivity of chlorinated dienes, these reactions proceeded surprisingly fast, leading to quantitative conversion of 10 g chloroprene in 2 hours with only 50 mg of catalyst (approximate TOP = 3500 h- ). 

Like ldpe, polybutadienes are resistant to most nonoxidizing acids, alkalis, and salts. However, because they are unsaturated, the polyalkadienes are attacked by hydrochloric, hydrobromic, and hydrofluoric acids, as well as by hydrogen and chlorine. The reaction products, which are thermoplastic, have been used as commercial nonelastomcric plastics. NR and other diene elastomers are also attacked by peroxides and ozone. In the absence of an tioxidants and carbon black filler, these unsaturated elastomers are degraded in the sunlight. 

In a heterogeneous polyblend of two dissimilar elastomers, such as chlorinated butyl rubber and polybutadiene, a certain interfacial bonding... 

Although two dissimilar elastomers—e.g., chlorinated butyl rubber and polybutadiene—may crosslink when in contact with one another, does bonding exist between the two interfaces Based upon thermodynamic theory as well as microscopic observations, we know that two such elastomers are not molecularly dispersed in a blend, so the diagnostic problem is one of considering two dispersed phases. 

In view of the presence of similar labile chlorine atoms in PVC and the promoting effect of such halides in the preparation of cw-1,4-polybutadiene, the polymerization of butadiene was carried out in the presence of PVC using the Et2AlCl-Co compound catalyst system. The reaction proceeded readily, and the product was identified as a graft copolymer of cis-1,4-polybutadiene on PVC (7). 

Kastnlg and his co-workers(2) appear to have been the first to report that metal acetylacetonates activated by chlorinated hydrocarbons are capable of acting as initiators for the emulsion polymerisation of butadiene. Unfortunately the polymerisation recipes and rates of polymerisation were not published, but the data given for the structure of the polybutadienes obtained indicate that some degree of stereoregulation can be effected by this type of initiating system. This conclusion has not been confirmed by subsequent investigations. 

Polybutadiene with no substituent groups larger than hydrogen has greater resilience than natural rubber, in which a methyl group is contained in each iso-prcnc repeating unit. Polychloroprenes (neoprenes) have superior oil resistance but lose their elasticity more readily at low temperatures since the substituent is a bulky, polar chlorine atom. (The structures of these monomers are given in Fig. 1-4.)... 

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