Estudos pirolíticos dos óleos vegetais das partes (endocarpo mais mesocarpo e epicarpo) do fruto da Macauba (Acrocomia sclerocarpa M.) foram realizados sob atmosfera de hélio usando-se um pirolisador de filamento modelo Girdel 75 -Py -1, conectado diretamente a um CG/EM.Os experimentos foram realizados em diferentes temperaturas e tempos de pirólise, para avaliar como estes parâmetros afetam o processo pirolítico de obtenção dos produtos bem como a sua reprodutibilidade.A pirólise dos óleos gerou grande número de compostos tais como hidrocarbonetos, aldeídos e ácidos carboxílicos, este último refletindo a composição original dos óleos.A identificação de alguns compostos foi feita com o uso de um banco de dados , dos padrões de fragmentação das classes de compostos e dos cromatogramas de massas de alguns íons específicos tais como m/z 83, 85 e 60.O modo de ionização química positiva foi utilizado para confirmar as massas molares dos constituintes gerados a partir das pirólises, tendo como gás reagente, o metano, (CH4-CI).Pyrolytic studies of vegetable oils of Macauba (Acrocomia sclerocarpa M.) fruit's parts (endocarp plus mesocarp and epicarp) were undertaken under a helium atmosphere using a filament pyrolyser, Girdel Pyrolyzer 75-PY-1, coupled directly to a GC/MS.The investigation was performed using different temperatures and pyrolysis times to evaluate how these parameters affect the yield products and the reproducibility of the pyrolytic process.The pyrolysis of both oils yields a large number of compounds such as hydrocarbons, aldehydes and carboxylic acids, the latter reflecting the original composition of the oils.The identification of some compounds was carried out using a mass spectral library data base search (NIST) together with recognition of fragmentation pattern and mass chromatograms of some specific ions such as m/z 83, 85 and 60.The CH4-CI mode was used to confirm molecular weights of the constituents generated from pyrolysis, in some instances.
SynopsisThe ESR spectra of microcrystalline cellulose and purified cotton cellulose reacted with ceric ammonium nitrate in nitric acid were determined. The effects of the concentration of ceric ion, atmosphere, temperature, and graft copolymerization with acrylonitrile on the rates of formation and decay of radicals in the cellulose molecule were determined under both static and dynamic conditions. Under static conditions, after the desired conditions of reaction, the samples were frozen at -100 or -16OoC., and then the concentration of free radicals was determined. Under dynamic conditions ceric ion solution was continuously flowed through the celluloses while these determinations were being made a t 25OC. In the presence of oxygen the rate of decay of free radicals was decreased. On initiation of copolymerization reactions with acrylonitrile, there was an increase in radical concentration, then a decrease. Apparently, during graft copolymerization the radical site initially on the cellulose molecule was retained on the end of the growing polymer chain. Then additional ceric ion coordinated with the hydroxyl groups of the cellulose, leading to the formation of additional radical sites. An Arrhenius interpretation of the effect of temperature on the formation of these additional radical sites gave apparent activation energies for radical formation on cotton cellulose as 34 kcal./mole and on microcryst,alline cellulose as 29 kcal./mole.
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