Thermal and Oxidative Transformations of Polycyclohexadiene in the Solid Phase and Solution

Agabekov, V. E.; Chaplanova, Zh. D.; Gudimenko, Y.

doi:10.1080/00914039008039474

Cited by 3 publications

(4 citation statements)

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“…where u i,[POOH] and u ij are the rates of initiation by hydroperoxide and initiator, respectively, B is a complex constant. The rates u I attained upon the introduction of initiators are constant over a broad range of concentrations of the initiators (0.005 ± 0.1 mol kg 71 ) and amount to 5610 74 and 9610 74 mol kg 71 s 71 in the PCH + POOH + AIBN and PCH + POOH + LP samples, respectively. This is substantially higher than the u 3 values for the PCH samples containing only POOH.…”

Section: Initiated Discontinuous Increase In the Rate Of Oxygen Absor...mentioning

confidence: 93%

“…The curves shown in Fig. 15 were constructed using the values C = 0.08 mol kg 71 and [POOH] 1 = 0.02 mol kg 71 (the concentration of POOH at the end of the induction period) and the following kinetic parameters: The experimental dependence of the rate of oxygen absorption u 3 on the pressure of oxygen P O 2 at 95 8C found by Mikheev et al 19 is described by the theoretical equation for the heterophase process (see Section IV) 0X5 , where a = 0.79 mol kg 71 h 71 , b = 1.0610 74 Pa.…”

Section: Substitution Of This Relation To the Expression For Umentioning

confidence: 99%

“…Scheme 5 includes stages involving opening of six-membered carbon rings and elimination of ethyl radicals; this is confirmed by detection of ethylene upon the oxidation of PCH. 74 This scheme can be supplemented by the forward and backward inter-zone chemical induction steps considered above for polyolefins.…”

Section: Initiated Discontinuous Increase In the Rate Of Oxygen Absor...mentioning

confidence: 99%

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Heterophase mechanisms of thermal oxidation of polymers. New horizons

Mikheev¹,

Заиков²

2000

Russ. Chem. Rev.

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It is found that a long conventional c\v CO1 laser cannot be tuned selectively because of the multidirectional modes formed through reflections at grazing angles from the inner walls of the discharge tubes. This problem has been overcome by inserting a number of properly designed mode-selecting apertures right into the discharge tubes and selective tuning over more than l50 rotational lines in both P and R branches of three vlbrational bands (9.6.10.6 and 11.2 pm) has been achieved. The rotational lines of higher/-values that have a low gain tend to lase in the TE\l,o mode. In the R branch two consecutive lines are observed to lase simultaneously when the angular width of the active medium subtended at the grating allow the existence of two physically tilted beams of different wavelengths dispersed by the grating used. The output poser distribution over various lines almost follows that of the gain. The optimum design parameters of a long c\v CO, laser for tuning are obtained.

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Section: Initiated Discontinuous Increase In the Rate Of Oxygen Absor...mentioning

confidence: 93%

Section: Substitution Of This Relation To the Expression For Umentioning

confidence: 99%

Section: Initiated Discontinuous Increase In the Rate Of Oxygen Absor...mentioning

confidence: 99%

See 1 more Smart Citation

Heterophase mechanisms of thermal oxidation of polymers. New horizons

Mikheev¹,

Заиков²

2000

Russ. Chem. Rev.

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“…Earlier, it was shown that the PCHD powder [13] and its TVD film [14] are easily oxidized by air oxygen at room temperature with formation of intermolecular joints. It may quite be that similar processes occur in a wet film of Br-PCHD, as is indicated by the partial loss of its solubility in hot benzene.…”

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confidence: 99%

Spectral properties of thin films of modified polycyclohexadiene

2005

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Light-sensitive thin films with n-phenylene chains in their structure are formed by deposition from a solution and by thermal vacuum deposition of bromine-modified polycyclohexadiene (Br-PCHD). It is found that the Br-PCHD films possess photoluminescence properties. Using IR-, UV-, and x-ray photoelectron spectroscopy methods, it is shown that during storage and exposure to UV irradiation in air the Br-PCHD films undergo structuring because of having been photooxidized by the molecular oxygen adsorbed on the surface.Introduction. Thin films of organic polymers with a developed conjugation chain (polyparaphenylene, polyphenylenevinylene, and their derivatives) are of great interest when developing electroluminescent materials and devices [1][2][3]. Since the production of thin films of polyparaphenylenes (PPPh) by traditional wet methods (pouring, centrifuging, pulverizing, etc.) is difficult because of their extremely low solubility, the methods of thermal vacuum deposition (TVD) of these polymers [4,5] are gaining in importance. In [6], practically defect-free, transparent TVD films of PPPh possessing photo-and electroluminescent properties were obtained.Earlier [7,8], it was shown that, on heating, bromide-modified polycyclohexadiene (Br-PCHD) is subjected to dehydrobromination, and, during thermal vacuum deposition onto a specimen, on its substrate a thin, highly sensitive film is formed, the structure of which contains n-phenylene chains. Using EPR-, IR-, UV-, and NMR spectroscopy, it has been established that the material of TVD films obtained from Br-PCHD is a co-oligomer of paraphenylene with cyclohexadiene (COPhC). The length of the chain of continuous conjugation (p) in the TVD film of COPhC, calculated according to [9], is equal to 2.6, which is close to the corresponding value for the TVD film of n-terphenyl (p = 2.4) selected as a model compound [8].The PPPh films and the films of the oligomers of n-phenylene (C 6 H 5 -(C 6 H 4 ) n -C 6 H 5 , where n = 1-4) deposited in vacuum emitted in the blue region of the spectrum [6]. It might be expected that the thin Br-PCHD films of COPhC would also possess luminescent properties.The aim of the present work is to study the photoluminescent properties of thin films of COPhC formed as a result of both deposition from a solution and thermal deposition in vacuum and also their conversion on exposure to UV irradiation.Experimental. Br-PCHD was produced as a result of interaction of PCHD with molecular bromine in a solution of chloroform similarly to [7]. The carefully purified product of bromination is a light yellow powder that is very poorly dissolved in chloroform, benzene, and carbon tetrachloride.The elemental composition of Br-PCHD is as follows: Predicted, %: C -30.03; H -3.37; Br -66.60 (C 6 H 8 Br 2 ). Found, %: C -35.10; H -4.01; Br -62.17 (C 6 H 8.1 Br 1.6 ).To obtain a soluble product, Br-PCHD was heated for 14 h at a temperature of 190-200 o C and a pressure of about 10 −2 torr. After the thermal treatment, the content of bromine in the specimen was e...

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