Investigation of polymerization of benzoxazines and thermal degradation characteristics of polybenzoxazines via direct prolysis mass spectrometry

Cataloged from PDF version of article.Polymerization of benzoxazines and thermal degradation mechanisms of polybenzoxazines were investigated using the direct pyrolysis mass spectrometry (DP-MS) technique. The benzoxazine structures were based on phenol and aniline and on bisphenol-A and methylamine or aniline. Polymerizations of the benzoxazines were carried out by curing them at elevated temperatures without addition of initiator or catalyst. DP-MS data showed the presence of chains generated by opposing polymerization reaction pathways indicating quite complex structures for the polybenzoxazines under investigation. Thermal decomposition of polybenzoxazines was started by the cleavage of methylamine or aniline linkages. It was determined that polybenzoxazines based on phenol were more stable than the corresponding bisphenol-A-based polybenzoxazines, while those based on methylamine were more stable than the corresponding polybenzoxazines incorporating aniline. Thus, it can be concluded that the presence of bulky groups decreased the extent of crosslinking which in return decreased the thermal stability. © 2012 Society of Chemical Industry

Pyrolysis Mass Spectrometric Analysis of styrene butadiene block and random copolymers

Cataloged from PDF version of article.Direct pyrolysis mass spectrometric analysis of a styrene-butadiene-styrene block copolymer indicated that thermal decomposition of each block shows a resemblance to the related homopolymer, giving a possibility of differentiation of blocks. However, the random analog, the styrene butadiene rubber, degraded in a manner that is somewhat in between in nature of the thermal characteristics of both homopolymers. This technique shows promise to differentiate thermal behaviors of each sequence in block polymers if any exist. Indirect pyrolysis mass spectrometric analysis gave no clear evidence for differentiation of the nature and the composition of the copolymers. © 1997 Elsevier Science Ltd. All rights reserved

Study on cloud computing perception of Turkish it sector

U radu je izvršena empirijska analiza o percepciji računarstva u oblacima (Cloud Computing – CC) u Turskoj. U tu svrhu analizom je potrebno odrediti stav rukovodećih ljudi informatičke tehnologije kao što su izvršni direktori i direktori za informatičke tehnologije ispitivanjem njihovih odgovora na upitnike u svrhu dobivanja mišljenja i stavova 98 javnih i privatnih direktora IT o CC. Svrha je ispitivanja odrediti kako CC shvaćaju društvene i privatne organizacije koje su već uključene u postupak e-transformacije. Dobiveni su sljedeći bitni rezultati: direktori obadva sektora, društvenog i privatnog, imaju pozitivan stav o uvođenju CC, smatraju da naročito web, e-mail, pohranjivanje podataka i aplikacije upravljanja procesom, odgovaraju za CC. Nedostatak dobro obrazovanog i iskusnog osoblja smatra se najvećom zaprekom za uvođenje CC po mišljenju kako učesnika iz javnog tako i privatnog sektora.In this paper an empirical study was carried out to study the Cloud Computing (CC) perception in Turkey. To this extent this study intends to determine the perception of Information Technology decision makers such as Chief Executive Officers and Chief Information Officers by means of a survey by questionnaire approach to explore 98 both public and private IT executives’ understandings and concerns about CC. The survey aims to determine how CC is perceived by public or private organizations that are already involved in the e-transformation process. Major results of the study are as follows: both public and private sector executives have positive perception over adoption of CC, participants think that especially web, e-mail, data storage and process management applications are adequate for CC. Lack of well-educated and experienced staff is found to be the common barrier on adopting CC by both public and private sector participants

Electrospun polyethylene oxide (PEO) nanofibers containing cyclodextrin inclusion complex

In this study, we obtained functional electrospun nanofibers containing stable fragrance/flavor molecule facilitated by cyclodextrin inclusion complexation. Menthol was used as a model fragrance/flavor molecule and we have electrospun poly(ethylene oxide) (PEO) nanofibers containing cyclodextrin-menthol inclusion complexes (CD-menthol-IC). We used two different solvent systems; water and water:ethanol and three types of CDs; α-CD, β-CD and γ-CD in order to find the optimal performance for the stabilization of menthol at high temperatures. We observed that the solvent system used for electrospinning process and the types of CDs (α-CD, β-CD and γ-CD) are very important to obtain CD-menthol-IC which ultimately determines the durability and temperature stability of menthol in the PEO nanofibrous web. We found out that it is better to use water rather than the water:ethanol solvent system for the inclusion complexation and additionally β-CD and γ-CD are most favorable choices since they are able to form complexation with menthol in the water solvent system. Despite the high volatility nature of menthol, our results demonstrated that the stability and temperature release of menthol was sustained to a very high and a broad temperature range (100 °C-250 °C) for PEO nanowebs containing CD-menthol-IC whereas the PEO nanofibers without CD and without CD-menthol complex could not preserve menthol even during storage. In brief, the results are very encouraging and open up for a variety of new exciting possibilities for the development of multi-functional electrospun nanofibers containing cyclodextrin inclusion complexes. Copyright © 2011 American Scientific Publishers All rights reserved

Characterization of degradation products of polyethylene oxide by pyrolysis mass spectrometry

The techniques of direct and indirect (evolved gas analysis) pyrolysis MS are used to characterize the thermal degradation products of polyethylene oxide. Using direct pyrolysis MS technique the main degradation process is determined to be due to CO and CC scissions yielding fragments characteristic of the polymer. Evolved gas analysis indicates formation of small molecular stable compounds such as C2H5OC2H5, CH3CHO, CO2, CO and C2H4. © 1994

A pyrolysis mass spectrometry study of polythiophene - Natural rubber and polythiophene - Synthetic rubber conducting polymer composites

The thermal behaviors and degradation products of conducting polymer composites prepared by electrooxidation of thiophene using natural rubber or synthetic rubber as the insulating matrix were studied by direct and indirect mass spectrometry techniques. The pyrolysis mass data revealed that a chemical interaction formed between the components of the composites during polymerization. Thermal characteristics of rubbers totally disappeared in the composites indicating presence of some chain scissions leading to degradation of rubbers during electrooxidative polymerization. The multiscan cyclic voltammetry runs showed that polythiophene is also electroactive on the rubber coated metal electrodes, with a small shift in the redox peaks compared to the one on the bare electrode

Conducting polymer composites of polythiophene with natural and synthetic rubbers

Electrochemical synthesis of conducting polymer composites of polythiophene was achieved. Synthetic and natural rubbers were used as the insulating polymer matrices. FT-IR, differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and mass spectrometry (MS) were utilized to characterize the composite blends. The conductivity measurements were done by using a standard four-probe technique. The above-mentioned methods show that the resultant composites have different properties compared to polythiophene due to interaction of the rubbers with electrochemical polymerization of thiophene, whereas the same argument is not valid for the polypyrrole synthesis via the same procedure