Butadiene-piperylene copolymers

The synthesis of transtactic structures is based on catalysts in which the transition metal belongs to the 3d block (Ti, Cr, V, Ni). Particular emphasis is devoted to the synthesis of trans butadiene/piperylene copolymers and to their blends with synthetic cis-l,4-polyisoprene, with the aim of increasing the "green strength" of the latter. 

Figure 15. Behavior under strain of an unvulcanized tire ply (conventional recipe) based on NR (natural rubber 100%), 1R (synthetic cis-7,4-polyisoprene 100%), BP/1R (a 50/50 blend of IR and txans-butadiene-piperylene copolymer).

Figure 16. Processibility and green strength of trans-butadiene-piperylene copolymers as a function of melting point and Mooney viscosity.

G-5—G-9 Aromatic Modified Aliphatic Petroleum Resins. Compatibihty with base polymers is an essential aspect of hydrocarbon resins in whatever appHcation they are used. As an example, piperylene—2-methyl-2-butene based resins are substantially inadequate in enhancing the tack of 1,3-butadiene—styrene based random and block copolymers in pressure sensitive adhesive appHcations. The copolymerization of a-methylstyrene with piperylenes effectively enhances the tack properties of styrene—butadiene copolymers and styrene—isoprene copolymers in adhesive appHcations (40,41). Introduction of aromaticity into hydrocarbon resins serves to increase the solubiHty parameter of resins, resulting in improved compatibiHty with base polymers. However, the nature of the aromatic monomer also serves as a handle for molecular weight and softening point control. 

In a practical sense the hydrocarbon monomers that work best in anionic systems are styrene, a-methylstyrene, p-(tert-butyl)styrene, butadiene, isoprene, 2,3-dimethyIbutadiene, piperylene, stilbene, and 1,1-diphenylethylene. The latter two monomers give rise to alternating copolymers with other dienes but do not homopolymerize. Among the polar monomers (C) that can be polymerized are such monomers as 2-vinyIpyridine, pivalolactone, methacrylonitrile, methyl-methacrylate, ethylene oxide (not with Li-counterion), ethylene sulfide, and propylene sulfide. However, polymerization of many of these polar monomers suffers from side reactions and complicating termination or transfer reactions not present in the... 

Copolymers with acrylonitrile, butadiene, isoprene, acrylates, piperylene, styrene, and polyethylene have been studied. The high cost of sorbic acid as a monomer has prevented large-scale uses. The ability of sorbic acid to polymerize, particulady on metallic surfaces, has been used to explain its corrosion inhibition for steel, iron, and nickel (14). 

Tranv-1,4- and 1,2-polybutadiene can be hydrohalogenated under mild conditions with gaseous HCl. The same is true of copolymers of butadiene with piperylene and also of isotactic transAA-piperylene. The addition of HCl to the asymmetric double bond is trans for polypiperylene and occurs in a stereoselective way, judging from the NMR spectra. 

Marina et al. (1984) reported the effect of solvent nature on the copolymerization of butadiene with trans-piperylene. An aliphatic solvent (heptane) rather than an aromatic solvent (PhMe) ensured a high polymerization rate and favorable reactivity ratios, and gave a copolymer with a high content of ds-1,4 units. 

Acid, acid chloride and -OH functionalized telechelics have been described. Although this does not represent the most convenient way to synthesize such materials, the reaction of polybutadiene with controlled amounts of ozone has been used to synthesize hydroxy-terminated telechelic polybutadienes. The oxidative cleavage of copolymers of isobutylene with dienes such as piperylene, isoprene (butyl rubber) and butadiene is probably one of the most-studied cleavage reactions. " In particular, the preparation of carboxy-terminated telechelics has been extensively studied. ... 

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