A systematic study using design of experiments was applied in order to map out the thermal stabilization of electrospun polyacrylonitrile mats and to investigate how oxidation and cyclization reactions are affected by rate, temperature, and time in an oxidative environment. Cyclization indexes were estimated by a simple methodology based on differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy data. Values of enthalpy and relative intensities of bands assigned to CN and CN bonds were used on calculation. The statistical planning applied in this study was important to show that not always longest treatment is effective to stabilize polyacrylonitrile, but also samples obtained in less than 3 h presented low values of exothermic peak on DSC, values of cyclization indexes near to 90%, both from DSC and Fourier transform infrared spectroscopy techniques, reduced weight loss in thermogravimetric analysis and O/C ratio higher than 10% by X‐ray photoelectron spectroscopy, that are appreciated characteristics to a precursor of high‐performance carbon materials. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45458.

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The surface of vulcanized ethylene propylene diene terpolymers (EPDM) was modified by Ar and N2, microwave generated plasma in order to improve adhesion properties. Surface modification was characterized by universal attenuated total reflectance Fourier Transform Infrared (UATR/FT-IR), because it presented lower interference of ingredients of EPDM formulation when compared with other techniques used for the attenuated total reflectance (ATR) to different crystals (ATR/KRS-5 and ATR/Ge). Oxygenated groups were introduced on the surface after treatments which were formed when the activated surface was exposed to the plasma gas. In treatments with nitrogen, oxygen groups and probable nitrogen groups were formed on the surface and could be identified by FT-IR. Reduction in the measurement of the contact angle and an increase in the work of adhesion and in the peel strength (EPDM X Polyurethane (PU)) were observed after the treatment resulted in the improvement of the adhesion properties of the modified surface.

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Fourier transform infrared spectroscopy techniques, associated or not to others, are a well-studied subject used for characterizing polymers/energetic materials that have been employed mainly in aerospace industries. However, the infrared analyses are usually qualitative and performed using the mid-infrared. This paper discusses the Fourier transform infrared spectroscopy qualitative and quantitative methodologies, coupled or not with thin layer chromatography and thermogravimetric analysis, for characterization of aerospace polymer systems, in some cases, using mid-infrared, near-infrared and far-infrared regions, by traditional accessories and the latest generation spectra mode, universal attenuated total reflection. This short review was made based on methodologies developed during the last two decades and published by many scientific and industrial research groups, emphasizing studies usually carried out in the last five years. A critical assessment and future trends were included.

In the present work, a microwave excited plasma (2?45 GHz, 1 kW) was used to modify the surface characteristics of the ethylene propylene diene monomer rubber. The samples were treated with a mixture of nitrogen, hydrogen and argon plasmas. The operating gas pressure was in the 0?2-1 Torr range, the gas flowrate between 5 and 100 sccm and the treatment time varied from 10 to 600 s. The influence of the plasma treatment on the superficial characteristics of the samples was analysed by contact angle measurements and atomic force microscopy. The results show that the plasma treatment can promote an important decrease in the contact angle from 101u for untreated sample to 34u for samples treated in a mixture of H 2 /N 2 /Ar for 2 min, which corresponds an increase on the rubber surface adhesion work from 59 to 133 mJ m 22 .

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Resumo: Técnicas FT-IR (UATR, PAS e MIC, com objetiva ATR) foram escolhidas para a caracterização da superfície da borracha de EPDM vulcanizada, após tratamento em plasma de Ar/O 2 e N 2 /H 2 /Ar gerado em micro-ondas. Após tratamento, grupos oxigenados foram detectados por UATR e MIC/FT-IR, com objetiva ATR para as duas misturas gasosas, e possíveis grupos nitrogenados foram inseridos na superfície das amostras tratadas com plasma de N 2 /H 2 /Ar. A análise MIC/FT-IR sugeriu a formação de grupos em uma camada mais externa, para as amostras tratadas FT-IR Techniques (PAS, UATR and Objective ATR) Applied to the Characterization of Plasma-Modified Surface of EPDMAbstract: The FT-IR techniques UATR, PAS and MIC with ATR objective were chosen to characterize the surface of EPDM rubber vulcanized after treatment in Ar/O 2 or N 2 /H 2 /Ar plasma generated in a microwave oven. After treatment, oxygenated groups were detected by UATR and MIC-FT-IR, with ATR objective for the two gas mixtures, and possible nitrogenous groups were inserted on the surface after the plasma treatment with N 2 /H 2 /Ar. The MIC/FT-IR analysis suggested that groups were formed on an outermost layer, inferred from a reduced intensity of the CH 2 and CH 3 absorption bands for the treatment in N 2 /H 2 /Ar plasma, probably because nitrogen is less permeable than oxygen. Different speeds with PAS analyses (0.05 cm.s -1 and 0.2 cm.s -1) were used to evaluate the surface after treatment. Only for the speed 0.05 cm.s -1 in Ar/O 2 plasma were spectroscopic changes detected. The decrease in the contact angle and the increased resistance to peel indicated improvements in the bonding adhesive properties of the surface. Bonding failure was observed between the adhesive PU film and the EPDM rubber, which was confirmed by UATR/FT-IR. Keywords: EPDM, plasma, surface characterization, UATR/FT-IR, PAS, MIC. IntroduçãoO EPDM (etileno-propileno-dieno) é uma das borrachas sintéticas que tem apresentado rápido crescimento no mercado, podendo ser, amplamente, utilizada em vários setores [1] , como modificador termoplástico, isolante elétrico, isolante acústico, entre outros [2] , devido à sua cadeia hidrocarbônica saturada e à presença de duplas ligações na cadeia lateral [1] . A borracha de EPDM possui propriedade de volume superior em relação à propriedade de superfície, o que é comum entre os materiais poliméricos, que em geral, não conferem excelentes propriedades para ambos, em aplicações especifica. O processo de vulcanização, geralmente, piora as propriedades de superfície, pois durante a formação das ligações cruzadas, ingredientes como ácido esteárico, enxofre, entre outros, migram para a superfície e criam uma barreira entre o adsorvente e o adsorvido. Desta forma, é necessária a alteração da superfície para que se consiga uma boa adesão [3,4]