Infrared (IR) spectroscopy, X-ray phase analysis, and scanning electron microscopy are used to study the spontaneous formation and increase in the amount of potassium hydrofluoride in the inner region of a sample of a partially chemically dehydrofluorinated polyvinylidene fluoride (PVDF) film during its long-term aging. The most probable mechanism behind the synthesis of potassium hydrofluoride is oxidative degradation of the sample with the formation of fluorocarbonyl groups and their subsequent hydrolysis under the action of atmospheric water. This results in the formation of hydrogen fluoride, which combines with potassium fluoride, a byproduct of primary dehydrofluorination. An increase in the content of potassium hydrofluoride continues as the sample ages until potassium fluoride remains in it. The appearance and subsequent development of spectral features characteristic of out-of-plane librational vibrations of water tetramers indicates the formation of a system of nanoscale pores in the sample after 100 000 min of its aging.

Changes in the molecular composition of the F-2ME poly(vinylidene fluoride) film during its chemical dehydrofluorination and subsequent aging are studied by infrared (IR) spectroscopy, scanning electron microscopy, and X-ray diffraction. The byproducts of chemical reactions are also identified. An increase in the reaction time from 10 to 40 min leads to an increase in the thickness of the samples, the concentration of double carbon–carbon bonds and ethoxy groups, as well as to an increase in the absorption peak centered at 3100 cm–1 presumably associated with stretching vibrations of =C–H bonds at the double carbon–carbon bond. Seven days after synthesis new peaks at 1840 and 2040 cm–1 appear in the sample spectra and begin to grow. Their intensities are proportional to each other and are greater the longer is the synthesis duration. Both features are characteristic of the IR spectrum of potassium hydrofluoride. Changes in the IR absorption spectra after a year of storing the samples in air and after additional washing of the sample with a synthesis duration of 40 min in a mixture of acetone and distilled water after 467 days of storage are analyzed.

Abstract —The stability of the atomic structure and physical and chemical properties of new materials is of crucial importance for their practical use. Long-term (more than 5 × 10 5 min) and regular monitoring of the molecular structure of a poly(vinylidene fluoride) film sample after its chemical dehydrofluorination and rinsing with ethanol is performed by the infrared (IR) spectroscopy technique. Changes in the absorption spectra of stretching oscillations of CH and OH bonds in the wave-number range 2500–3700 cm –1 are analyzed. The results of the study indicate the initial attachment of ethoxy groups to carbonized fragments of carbon chains and their subsequent detachment, accompanied by sample oxidation. A feature with a center near 3090–3100 cm –1 is found to be in all spectra, the origin of which cannot be unambiguously identified at present. A previously unknown effect of a steady, but different-rate decrease in the contribution to the infrared absorption of stretching vibrations of four molecular complexes of ethoxy groups is revealed. The oscillation frequencies of three of them steadily increase also at different rates.

FTIR spectra of a dehydrofluorinated poly(vinylidene fluoride) film were registered at different stages of its aging. A number of spectral features were noticed to grow with the sample aging. Three of them were assigned to the stretching vibrations of triple carbon-carbon bonds. Other bands were assigned to the libration, stretching, and combination vibrations of embedded water clusters consisting of 4, 5, or 6 molecules. The mechanism explaining synchronous formation of triple carbon-carbon bonds and small water clusters in the sample during its aging is proposed. SEM data on the surface morphology of the sample confirm the proposed mechanism.

A novel low-melting, low-viscosity, one-part bismaleimide resin based on m-xylylene bismaleimide has been developed and examined for application in vacuum-assisted resin infusion. The resin is a fully formulated system comprising a ternary eutectic BMI mixture blended with bis-( o-propenylphenoxy)benzophenone and 2,2'-bis(3-allyl-4-hydroxyphenyl)propane as co-monomers. The resin offers enhanced properties for melt processing techniques. The formulation strategy and chemistry is presented and discussed in detail. For resin infusion and/or resin transfer molding technologies, the melt processing temperature of the resin is in the range of 90–110℃. Processing data of the uncured and mechanical properties of cured neat resin are provided. The resin shows a T g of 285℃ when post-cured at 250℃ for 6 h. Finally, a 400 × 500 mm 2 carbon fabric laminate was successfully molded for demonstration by a VARI process. The microscopic study reveals no voids and no laminate surface imperfections. The VARI processing details are presented and discussed.

Chemical carbonization of polyvinylidene fluoride is necessary for the synthesis on its basis of quasi-one-dimensional carbon structures having a prospect of use in microelectronics. To determine the details of the carbonization process, the concentrations of 19 F and 1 H nuclei were measured and the changes in the concentration of CF 2 , CH 2 , and OH groups in partially dehydrofluorinated polyvinylidene fluoride samples were studied using nuclear magnetic resonance and infrared spectroscopy. The efficiency of substitution of fluorine and hydrogen atoms by OH groups in the process of dehydrofluorination of polymer chains is estimated.

m ‐Xylylene bismaleimide, Compimide MXBI (hereafter MXBI), was developed as a building block for formulating bismaleimide resins with improved processability. MXBI on its own, or in combination with 4,4′‐bismaleimidodiphenylmethane (Compimide MDAB, hereafter MDAB) and with 2,2′‐diallylbisphenol‐A as a co‐monomer, provides very low‐melting resin blends, which can be processed at temperatures around 60–80°C via RTM (Resin Transfer Moulding), VARIM (Vacuum Assisted Resin Infusion Moulding), prepregging, and wet filament winding (FW). Uncured and cured resin properties were evaluated. The mechanical property spectrum of the MXBI/MDAB/diallylbisphenol‐A system with varying MXBI/MDAB ratio shows almost equivalent contributions of MXBI and MDAB to the mechanical properties of a system. Higher MXBI proportions are responsible for lower resin viscosities and hence superior processability. Copyright © 2015 John Wiley & Sons, Ltd.

XPS of partially crystalline PVDF film have been studied in the course of carbonization under Al Kα radiation. The long-term exposure of PVDF film and enhancement of the spectra resolution allowed further refinement of the previously proposed degradation model, which does not take into account practical impossibility of complete elimination of fluorine. Due to a random character of photon interactions with a polymer backbone, there is a possibility of the formation of isolated CF2 (CF) and CH2 (CH) groups that can never decay. The basic equation from the original model has been rewritten considering of formation of such groups. Kinetics of CF2 and CF groups elimination confirms that microscopic mechanism of their decay can be described by the second-order reaction.

Modification of poly(vinylidene fluoride) (PVDF) directly during radiation exposure was investigated using core level spectroscopy. The strongly non-equilibrium condition of PVDF was studied. The high-resolved C K-edge NEXAFS spectra of poly(vinylidene fluoride) have been measured. The spectra modification due to the polymer degradation caused by monochromatic synchrotron radiation has been revealed. Residual fluorine content was monitored using x-ray photoelectron spectroscopy. The study has shown a significant modification of PVDF chemical content and electronic structure in the course of carbonization under synchrotron radiation. Gradual defluorination of the PVDF sample takes place during irradiation with enrichment of carbon skeleton with hydrogen. In the initial stages of radiative modification, defluorinated system is inhomogeneous and changes under the influence of two simultaneous processes: photochemical defluorination and diffusion of unbounded fluorine atoms to the sample surface.

Under the action of ionizing radiation on a PVDF film, fluorine and hydrogen atoms bound to its linear carbon chain with single chemical bonds detach. Free atoms and HF molecules diffuse toward the film surface and escape from it. As a result of irradiation of the sample surface, a fluorine concentration depth profile arises. The fluorine distribution in the PVDF films subjected to long-term X-ray exposure was studied using X-ray photoelectron spectroscopy and Rutherford backscattering spectroscopy. Both methods yield close values of the fluorine concentration at a depth of ∼10 nm.

A dose effect of high-energy (20 key) electron irradiation on the chemical composition of PVDF films has been revealed using a scanning electron microscope Jeol JSM-7001F equipped with an X-ray fluorescence spectrometer Oxford INCA X-max 80. All the experimental series have demonstrated similar decreasing dependence of relative atomic fluorine content (F/C) upon the electron irradiation dose. The final non-zero F/C ratio can be explained in terms of primary defects in the original PVDF and secondary ones arising during irradiation. In general a defluorination process is consistent to a Le Moel model of PVDF degradation and can be satisfactorily described with a third-order kinetic equation, parameters of which depend on the type of a PVDF film. (C) 2012 Elsevier Ltd. All rights reserved.

Песин Леонид Абрамович – доктор физико-математических наук, профессор, кафедра общей и теоретической физики, Челябинский государственный педагогический университет. e-mail: pesin@cspu.ru. Грибов Игорь Васильевич – кандидат физико-математических наук, старший научный сотрудник, лаборатория электрических явлений, Институт физики металлов УрО РАН. e-mail: gri@imp.uran.ru Москвина Наталья Анатольевна – кандидат физико-математических наук, научный сотрудник, лаборатория электрических явлений, Институт физики металлов УрО РАН. Кузнецов Вадим Львович – доктор технических наук, лаборатория электрических явлений, институт физики металлов УрО РАН. Евсюков Сергей Евгеньевич – кандидат химических наук, лаборатория синтеза, Evonik Technochemie GmbH, Dossenheim, Germany. Богатырёва Мария Евгеньевна – студентка, Челябинский государственный педагогический университет. Хананова Александра Викторовна – студентка, Южно-Уральский государственный университет. Pesin Leonid Abramovich is Dr. Sc. (Physics and Mathematics), Professor, General and Theoretical Physics department, Chelyabinsk State Pedagogical University. e-mail: pesin@cspu.ru. Gribov Igor Vasilievich is Cand. Sc. (Physics and Mathematics), Senior Staff Scientist, Electric Phenomena Laboratory, Physics of Metals Institute of the Ural Branch of Russian Academy of Sciences. e-mail: gri@imp.uran.ru. Moskvina Natalia Anatolievna is Cand. Sc. (Physics and Mathematics), scientific associate, Electric Phenomena Laboratory, Physics of Metals. Institute of the Ural Branch of Russian Academy of Sciences. Kuznetsov Vadim Lvovich is Dr. Sc. (Engineering), Electric Phenomena Laboratory, Physics of Metals Institute of the Ural Branch of Russian Academy of Sciences. Evsyukov Sergey Evgenievich is Cand. Sc. (Chemistry), Synthesis Laboratory, Evonik Technochemie GmbH, Dossenheim, Germany. Bogatyryova Mariya Evgenievna is student of Chelybinsk State Pedagogical University. Khananova Aleksadra Viktorovna is student of South Ural State University

Morilova Viktoria Mikhailovna is Post-Graduate Student, General and Theoretical Physics Department, Chelyabinsk State Pedagogical University. Морилова Виктория Михайловна - аспирант, кафедра общей и теоретической физики, Челябинский государственный педагогический университет. Evsyukov Sergey Evgenievich is Cand. Sc. (Chemistry), Synthesis Laboratory, Evonik Technochemie GmbH, Dossenheim, Germany. Евсюков Сергей Евгеньевич - кандидат химических наук, лаборатория синтеза, Evonik Technochemie GmbH, Dossenheim, Germany. Koryakova Olga Vasilievna is Cand. Sc. (Chemistry), Organic Material Laboratory, Institute of Organic Synthesis of the Ural Department of the Russian Academy of Sciences, Ekaterinburg. Корякова Ольга Васильевна - кандидат химических наук, лаборатория органических материалов, Институт органического синтеза УрО РАН, г. Екатеринбург. Andreychuk Vladimir Petrovich is Cand. Sc. (Physics and Mathematics), Associate Professor, General and Theoretical Physics Department, Chelyabinsk State Pedagogical University. Андрейчук Владимир Петрович - кандидат физико-математических наук, доцент, кафедраобщей и теоретической физики, Челябинский государственный педагогический университет. Pesin Leonid Abramovich is Dr. Sc. (Physics and Mathematics), Professor, General and TheoreticalPhysics Department, Chelyabinsk State Pedagogical University. Лесин Леонид Абрамович - доктор физико-математических наук, профессор, кафедра общей и теоретической физики, Челябинский государственный педагогический университет. e-mail: pesin@cspu.ru

The samples of poly(vinylidene fluoride) (PVDF) filmwas exposed to long termAlKa radiation, electrons and ion bombardment with the aimof surface carbonization. An influence of secondary electrons on the electron emission spectra of PVDF film and its carbonized derivatives has been studied. Original routines of the CKVV and C1s spectra shape parameterization for PVDF and its dehydrofluorinated derivatives have been developed and carefully described. Analysis of C1s and C KVV lineshape has revealed obviously different electronic structure of carbonized layers derived fromPVDF via two kinds of radiative treatment. In case of Ar+ bombardment the sp2- bonds predominate. The Al Ka irradiation leads to some other form(s) of carbon, but additional ion bombardment transforms them into species with predominating sp2-bonding. The most puzzling result of this study is that both photons and ions produce the same depth gradient of fluorine in the layers of carbonized surface accessible for XPS analysis.

Modification of the photoelectron and C KVV spectra during the long-term surface degradation of partially crystalline PVDF under simultaneous soft X-ray and electron irradiation are reported. Deep radiative carbonization brings about the formation of carbynoid structures (chain-like carbon) in the surface; as a result the shape of the electron emission spectra of carbon in the carbonized sample essentially differs from that of graphite and PVDF. Analysis of carbon core-level electron spectra via decomposition onto spectral components shows presence of partially (CH, CF) and fully (=C=, -C≡) carbonized units of polymeric chain thus pointing on two-step mechanism of polyme ric chain transformation from the initial to a carbynoid. Results of the mathematical modeling of the first step of the chain transformation show it to be a second order process.

Chebotarev Sergey Sergeevich - Candidate of Science (Physics and Mathematics), senior teacher, General and Theoretical Physics department, Chelyabinsk State Pedagogical University. Чеботарев Сергей Сергеевич - кандидат физико-математических наук, старший преподаватель, кафедра общей и теоретической физики, Челябинский государственный педагогический университет. e-mail: sergius2ch@yandex.ru Andreychuk Vladimir Petrovich - Cand. Sc. (Physics and Mathematics), Associate Professor, General and Theoretical Physics Department, Chelyabinsk State Pedagogical University. Андрейчук Владимир Петрович - кандидат физико-математических наук, доцент, кафедра общей и теоретической физики, Челябинский государственный педагогический университет. Pesin Leonid Abramovich - Doctor of Physics and Mathematics, Professor, Instrument Production Technique department, South Ural State University. Песин Леонид Абрамович - доктор физико-математических наук, профессор, кафедра технологии приборостроения, Южно-Уральский государственный университет. e-mail: pesin@cspu.ru Semochkin Pavel Sergeevich - Post-Graduate Student, General and Theoretical Physics Department, Chelyabinsk State Pedagogical University. Семочкин Павел Сергеевич - аспирант, кафедра общей и теоретической физики, Челябинский государственный педагогический университет. Sokolova Maria Nikolaevna - researcher, Ekaterinburg. Соколова Мария Николаевна - исследователь, г. Екатеринбург. Evsyukov Sergey Evgenievieh - Candidate of Science (Chemistry), Synthesis Laboratory, Evonik Technochemie GmbH, Dossenheim, Germany. Евсюков Сергей Евгеньевич - кандидат химических наук, лаборатория синтеза, Evonik Technochemie GmbH, Dossenheim, Germany.Gribov Igor Vasilievieh - Candidate of Science (Physics and Mathematics), senior staff scientist, Electric Phenomena Laboratory, Physics of Metals Institute of the Ural Branch of Russian Academy of Sciences. Грибов Игорь Васильевич - кандидат физико-математических наук, старший научный сотрудник, лаборатория электрических явлений, Институт физики металлов УрО РАН. e-mail: gri@imp.uran.ru Moskvina Natalia Anatolievna - Candidate of Science (Physics and Mathematics), scientific associate, Electric Phenomena Laboratory, Physics of Metals Institute of the Ural Branch of Russian Academy of Sciences. Москвина Наталья Анатольевна - кандидат физико-математических наук, научный сотрудник, лаборатория электрических явлений, Институт физики металлов УрО РАН. Kuznetsov Vadim Lvovieh - Doctor of Engineering Science, Electric Phenomena Laboratory, Physics of Metals Institute of the Ural Branch of Russian Academy of Sciences. Кузнецов Вадим Львович - доктор технических наук, лаборатория электрических явлений, Институт физики металлов УрО РАН.

It has been studied how photoelectron and CKVV spectra of partially crystalline poly(vinylidene fluoride) (PVDF) are modified during a long-term degradation of its surface under soft X-rays (AlK α), which is accompanied by a flow of secondary electrons having different energies, and upon exposure to a unfocused beam of 600 eV Ar+ ions. In both cases, the surface layer of the sample is enriched with carbon owing to defluorination. The shape of the electron emission spectra of the carbonized layer depends on an external effect; that is, whether soft X-ray photons or ions are used for defluorination. In the case of bombardment with Ar+, there is clear evidence for the dominance of the sp2 bonds between carbon atoms, as can be seen from the specific shape of the C KVV band and the C1s spectrum. The most surprising result of this study is that both photons and ions produce the same depth gradient of residual fluorine at an equal fluorine concentration in the carbonized surface layer. The reason for this is not clear and needs further investigation.