Film trans-polybutadiene

Calculations. The spectrum of a typical high cis-1,4 polymer sample is shown before and after irradiation in Figure 1 and that of a trans-1,4 polymer film in Figure 2. The significant infrared bands are listed in Table II for all of the polybutadienes, with the assignments to the various modes of molecular oscillation as developed by Binder (2). The bands used to estimate quantitative changes in the olefin groups were those at 740 cm."1 for the cis isomer, 967 cm."1 for the trans isomer, and 910 cm."1... 

In later studies, Golub and Danon [329, 330] reported that, in addition to loss of unsaturation, polybutadiene and polyisoprene films and solutions undergo radiation-induced cis-trans isomerization. 

The chemiluminescence emission at 25-60° C was measured from films of cis-1,4-polybutadiene, 1,2-polybutadiene, and trans-polypentenamer. The polymers were autoxidized previously in air 100°C, or allowed to react with singlet molecular oxygen in solution, and then cast into films. Values of ft (or kaCOz -> 302)/K(102 + polymer -> products)) were determined in benzene for cis-1,4-polybutadiene and cis-1,4-poly-isoprene, and for model compounds cis-3-hexene and cis-3-meihyl-3-hexene by independent methods. The chemiluminescence emission from irradiated films of the polymers containing a dye sensitizer showed a complicated time dependence, and the results depended on the length of irradiation. 

After 10-min irradiation, the ir spectrum of the trans-polypentenamer film showed the expected weak 2.9 /x peak (O-H) without the 5.8 absorption (C=0), by analogy to 102-reacted 1,4-polybutadiene (20). Only minor changes in the spectrum were noted after decay of the chemiluminescence. In contrast to this result, the chemiluminescence from polymer films oxidized at 100 °C or singlet-oxygenated in solution and cast into films usually was invariant at 25 °C for several hours. 

Styrene-butadiene by NIR. Polybutadiene and styrene-butadiene copolymer are used extensively in the tire and rubber industries. As mentioned earlier in this chapter, there are various stereoisomers associated with the polymerization of butadiene cis-, trans-, and vinyl, and their relative amounts appreciably affect the polymer properties. NMR and infrared spectroscopy can accurately determine the microstructure and composition of these materials. These methods usually require extensive sample preparation and usually, dissolving the polymer in a solvent or pressing the polymer into a thin film. 

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