Butadiene and poly

Figure 13.6 Film cast from a 1 2 mixture of poly(styrene-co-butadiene) and poly(2-vinyl pyridine-co-butadiene) with about 15 mol% butadiene content (10 wt% solution of the copolymers in tetrahydrofuran). Dark areas, poly(styrene-co-butadiene) light areas, poly (2-vinyl pyridine-co-butadiene) [15]. Courtesy of Dr A. Schindler...

Shen et al. determined the BD/IP copolymerization parameters for the polymerization with the ternary catalyst system NdN/TIBA/EASC at 50 °C ted = 1.4 and np = 0.6 [92]. Over a wide range of BD/IP copolymer compositions the experimentally determined Tg values significantly deviate from the theoretical curve which was calculated by the Fox equation for random copolymers. Only for IP-contents < lOwt. % does the experimentally determined data coincide with the theoretical curve. Shen et al. also succeeded to synthesize block copolymers comprising poly(butadiene) and poly(isoprene) building blocks [92]. 

The catalyst system Nd(OCOCCl3)3/TIBA/DEAC was used for the copolymerization of BD and IP by Kobayashi et al. [176]. The copolymerization parameters were determined at 0 °C pbd = 1-22 and np = 1.14. This study also revealed that the microstructures of the poly(butadiene) and poly(isoprene) moieties were not influenced by polymerization temperature. 

In macromolecular chemistry helically wound carbon chains are well known. In isotactic polypropylene (Fig. 6) the methyl groups are arranged on a helix. Some other chiral polymers form helices, like polymethylmethacrylate, polytriphenylmethyl-methacrylate poly-l,2-butadiene and poly-tert-butylethylene oxide... 

Moreover, poly(trichlorobutadiene)s are known to undergo allylic rearrangements with migration of allylic chlorine (14%) and hydrogen (3-10%) atoms under the action of solvents [38]. This accounts for remarkable similarity of the IR spectra of dehydrochlorinated poly(l,l,2-trichloro-butadiene) and poly(l,2,3-trichlorobutadiene) (Figure 12.1). 

Moreover, If as has been suggested, similar emitting chromo-phores might appear in such diverse polymers as, for example, poly(propylene), poly(butadiene), and poly(amldes), where aS-un-saturated carbonyls have been identified by luminescence, the method loses some credibility. The presence of more than one type of emitting chromophore is a further complication, which may however provide further evidence of the type of polymer. Inspection of Table 11 reveals that, for example, In the polyamide Nylon 66 in chip form fluorescence is observed in the region of 417 nm, whereas phosphorescence Is seen at 400 nm. Clearly phosphorescence cannot be to the red of the fluorescence thus the phosphorescent species must be different from that which fluoresces. 

Scheme 1.30. Possible routes to give poly-c -1,4-butadiene and poly-trawi-l,4-bntadiene by insertion into the syn or anti -allyl complex.

Block copolymers can also be hydrogenated to produce unique products. Hydrogenated triblock copolymers of poly(styrene-co-butadiene-co-styrene) (SBS) are commercially available from the Shell Company under the trade name Kraton G. The middle block is usually a mixed microstructure of poly( 1,2-butadiene) and poly( 1,4-butadiene) units. The resulting product is a hydrogenated unsaturated polymer, which exhibits greater thermal and oxidative properties than the parent SBS triblock. 

Cationic cyclization of unsaturated elastomers such as poly(c -l,4-isoprene), poly(3,4-isoprene), poly(l,2-butadiene), and poly( 1,4-butadiene) usually leads to the formation of cyclized resinous products of no commercial value. An extensive review on the subject has been published by Schults et al. (1983). Cyclization of unsaturated elastomers, such as polyisoprene, can be carried... 

Using living polymerizations, the Shell Company was able to commercialize several poly(styrene-co-butadiene) and poly(styrene-co-isoprene) block copolymers known in the industry as Kraton 1101 and Kraton G. These block copolymers have found many uses in the shoe sole and adhesive industries. The physical properties were dependent on the macrostructure and microstructure of these block copolymers. 

Germany, in the guise of I. G. Farben, had the foresight to realize the importance of this area, and they dominated the early research and development work. Their commercial successes ranged from rubber-like materials—the co-polymers poly(styrene-butadiene) and poly(acrylonitrile-butadiene)— to thermoplastics like poly(vinyl chloride) and polystyrene. 

These polymers have more than one type of repeating unit in their structure. They are also known as heteropolymers. Examples are poly(ethylene-co-propylene), poly (styrene-co-butadiene) and poly (acrylonitrile-... 

Recently, two reports highlighted the use of MS/ MS to investigate fragmentation pathways of 4-alkyl-substituted PSs [90] and poly (alpha methylstyrene) [91]. The authors noted that the molar mass of the repeat unit is 118 g/mol for both polymers. This is an exceptional case. As a matter of fact, some common polymers obtained by poly addition are PS, PMMA, poly (butadiene), and poly(isoprene), and the LIr values do not superpose (they are 104,100,54, and 68 Da, respectively). 

ABS is actually a blend or graft of two random copolymers, poly(acrylonitrile- tet-butadiene) and poly(acrylonitrile-itof-styrene). 

The role of the initial domain structure in the melt and hence the crystallization pathway is illustrated by the properties of a series of diblock copolymers composed of hydrogenated poly(butadiene) and poly(3-methyl-1-butene) with varying molecular weights [53]. The change in molecular weights allows differing degrees of... 

Evaluation of IR spectra of acrylonitrile-butadiene-styrene (ABS) after UV irradiation shows that rubber double bands at 965 cm and 910 cm (Fig. 3.65), attributed to poly(trans-l,4-butadiene) and poly(l,2-butadiene), respectively, decrease with exposure time (Fig. 3.66) in a first order reaction, together with the carbon-carbon double stretching band at 3450 cm in addition, a saturated carbonyl band (centred at 1725 cm ) forms (Fig. 3.65) by a first order process (Fig. 3.67). During the initial stages of the photooxidation, bands at 1665, 1685 and 1699 cm due to a- and ) -unsaturated carbonyl groups, develop [1113,1936]. 

W01 Wohlfarth, Ch., Vapour-liquid equilibria of concentrated poly(styrene-co-butadiene) and poly(styrene-co-acrylonitrile) solutions, Macromol. Chem. Phys., 198, 2689, 1997. 

Figure 49 Concentration profiles of styrene, 1,3-butadiene, and poly(butadiene) calculated by SMCR (see text).

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