Recebido em 3/5/12; aceito em 8/8/12; publicado na web em 7/12/12This work describes the synthesis of hydrogels of cellulose acetate (AC) crosslinked with 1,2,4,5-benzenotetracarboxylic dianhydride (PMDA). The crosslinking reaction was monitored by FTIR. Analysis of aromatic fragments from the alkaline hydrolysis of the gels by UV spectroscopy indicated that an increase in the stoichiometric ratio of dianhydride resulted in higher degrees of crosslinking. The non-porous nature of the gels was confirmed by analysis of nitrogen adsorption. Water absorption isotherms showed that as the temperature and degree of crosslinking increased, the percentage of water absorbed at equilibrium (%S eq ) also increased. The hydrogels presented second order swelling kinetics.

Três origens diferentes de biodiesel (algodão, mamona e palma) foram adulteradas com óleo de soja cru, em concentrações variando de 1 a 40% (m/m). Estas amostras foram analisadas por espectrometria de infravermelho médio (MIR) e os seus espectros foram estudados em três diferentes faixas espectrais: espectro inteiro (4000-665 cm-1), e nas faixas de 1800-1700 cm-1 e 1800-1000 cm-1. Para determinar a origem do biodiesel utilizado no sistema adulterado, os dados espectrais foram analisados pela ferramenta análise de componentes principais (PCA) e a melhor segregação das origens foi obtida para o espectro inteiro (4000-665 cm-1). A variância explicada foi de 99%, para os três primeiros componentes. Para quantificar o óleo de soja cru foi aplicada a ferramenta mínimos quadrados parciais (PLS). Os melhores resultados foram obtidos para a região espectral de 1800-1000 cm-1 , com valores de RMSEP (erro médio quadrático de previsão) variando de 1,10 a 1,47% (m/m). Three different biodiesel sources (cotton, castor and palm) were adulterated with raw soybean oil at concentrations ranging from 1-40% (m/m). These samples were analyzed by infrared spectrometry (MIR) and their spectra were studied at three different spectral ranges: full spectrum (4000-665 cm-1), and the spectral ranges of 1800-1700 cm-1 and 1800-1000 cm-1. To determine the source of biodiesel used in the adulterated system, the data were analyzed by PCA (principal components analysis) spectral analysis tool and the best segregation of the sources was obtained at the range of 4000-665 cm-1. The explained variance was of 99% for the first three components. To quantify the raw soybean oil partial least squares (PLS) tool was applied. The best results were obtained for the spectral range of 1800-1000 cm-1 , with values of RMSEP (root mean square error of prediction) varying from 1.10 to 1.47% (m/m).

We wish to report the first use of initiation by enolate ions in anionic dispersion polymerisation. The system that we have employed is of the type which has frequently been referred to in the literature in recent years as "group-transfer polymerisation" ' 3 'I. This unfortunate name arose from a misconception of the mechanism of certain anionic polymerisations initiated by enolate ions; in fact, reactions of this type had been known for many years3-8), and this fact is now recognised9). Enolate initiation has proved to be very useful for conducting anionic polymerisation at relatively high temperatures, and we are now able to report that its use can readily be extended to dispersion polymerisation.Dispersion polymerisation is a process in which reaction is performed in a solvent medium which is miscible with the monomer but not with the resulting polymer; the system contains a surface-active agent which stabilises the polymer particles against coalescence'0,''). In our experiments, the stabiliser was a block copolymer of the structure polystyrene-block-poly(ethene-co-propene) (PS-PEP); this has been used with success in other dispersion polymerisations ' ' 3 13). Experimental part a) MaterialsMethyl methacrylate was washed twice with aqueous KOH, twice with water, and then stored over Na2S0, for about 5 h. After filtratioa, the monomer was treated with CaH, , filtered again, and stored overnight in contact with a 4 A molecular sieve. It was subsequently passed through a column of basic alumina, and again stored over molecular sieves.Neptune was purified by distilling over CaH, , and storing over molecular sieves. (I-Methoxy-2-methyl-I-propenyloxy)trimethylsilane (MTS) (Aldrich) was used without further purification.Tetrabutylammonium fluoride (TBAF) (Aldrich) was used as a solution in dry tetrahydrofuran (0,1275 mol/L).The steric stabiliser, polystyrene-block-poly(ethene-co-propene) (PS-PEP), manufactured by the Shell Chemical Company under the trade-mark Kraton G1701 (34 wt.-To PS, mass-average molar mass Mi, = 1,05 . LO5 g . mol -I ) was purified by twice dissolving in toluene, precipitating into methanol, and drying overnight in a vacuum oven.

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Este trabalho descreve as sínteses de hidrogéis superabsorventes a base de acetato de celulose (AC), com grau de substituição 2.5, reticulado com dianidrido 3, 3', 4, 4' benzofenona tetracarboxílico (BTDA). As caracterizações das matérias primas foram realizadas por análises térmicas (TG/DTG) e espectroscopia na região do infravermelho (FTIR). O grau de substituição do acetato de celulose foi determinado por via úmida. A confirmação da reação de esterificação foi possível a partir da técnica de FTIR, espectroscopia UV-vis e análises térmicas (TG/DTG). A presença de poros no novo material foi analisada por microscopia eletrônica de varredura (MEV) e porosimetria (BET). A influência da concentração de dianidrido no meio reacional foi investigada, bem como a influência do aumento no grau de reticulação no comportamento térmico do material. Foram obtidas isotermas de absorção de água em diferentes temperaturas para os hidrogéis com diferentes graus de reticulação. Os coeficientes de difusão dos géis foram determinados, juntamente com a energia de ativação para o processo de inchamento usando a equação de Arrhenius. A entalpia de mistura do sistema gel-água foi determinada pela medida da quantidade máxima de água absorvida no equilíbrio a diferentes temperaturas, empregando a equação de Gibbs/Helmholtz.

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Polymer education relies on generally agreed terminology and nomenclature rules. The Polymer Division of the International Union of Pure and Applied Chemistry (IUPAC) generates and recommends such rules for naming processes and materials in polymer science. It is the goal of IUPAC that these recommendations be applied in polymer science curricula worldwide. For this purpose, a large amount of material has been provided by the Polymer Division of IUPAC, and in this paper these resources are described from the personal perspective of the authors. A discussion of terminology is then provided, including a detailed discussion of the term “dispersity” (M w/M n) and the rationale behind the recommended IUPAC names of different polymerization mechanisms. This is followed by a commentary on polymer nomenclature with examples. Finally, exemplary applications of resources provided by the Polymer Division of IUPAC for educational purposes around the world are presented.