Doctor of Philosophy / The kinetics of electrosterically stabilized emulsion systems was studied. The aim of this was to understand the impact that steric and electrosteric stabilizers have on the kinetics of particle growth and particle formation in the area of emulsion polymerization. The well-established mechanisms that govern these processes for emulsions stabilized by conventional low molecular weight surfactants were used as a reference point for comparative purposes. Model latexes were synthesized that comprised of a poly(styrene) core stabilized by a corona of poly(acrylic acid). The advent of successful controlled radical polymerization techniques in heterogeneous media (via RAFT polymerization) allowed for latexes to be synthesized under molecular weight control. For the first time, the degree of polymerization of the stabilizing block on the particle surface was able to be controlled and verified experimentally using mass spectrometry techniques. Three latexes were made with different average degrees of polymerization of the stabilizing block; five, ten and twenty monomer units respectively. A methodology was developed to remove the RAFT functionality from the polymer chains present in the emulsion while retaining the desired particle morphology. Oxidation with tertbutylhydroperoxide (TBHP) was proven to be successful at eliminating the living character provided by the thiocarbonyl end-group. Extensive dialysis and cleaning of the latex was performed to ensure no residual TBHP or reaction by-products remained. Latexes with poly(styrene) cores were chosen for this work as poly(n-butyl acrylate) latexes were shown to be influenced by chain transfer to polymer, providing an additional kinetic complication. The three electrosterically stabilized emulsions were used as seed latexes in carefully designed kinetic experiments to measure the rate of polymerization as a function of time. Two independent techniques (chemically initiated dilatometry and γ-relaxation dilatometry) were used to measure the rate coefficients of radical entry (ρ) and exit (k) in these systems – the two parameters that essentially govern the rate of particle growth. The latexes were chosen such that they satisfied ‘zero-one’ conditions (i.e. that any given latex particle contains at most one growing radical at any given time) in order to simplify data analysis. Three different chemical initiators were used, each yielding a radical with a different electric charge. Results from γ-relaxation experiments demonstrated that the three electrosterically stabilized latexes gave very long relaxation times when removed from the radiation source, ultimately yielding very small k values. These values were up to a factor of 10 smaller than that predicted by the ‘transfer-diffusion’ model for exit for particles of that size. This reduction was attributed to a ‘restricted diffusion’ effect, where the exiting monomeric radical has to diffuse through a dense layer of polymer on the particle surface, where its mobility will be restricted. Modification of the Smoluchowski equation for diffusion-controlled adsorption/desorption to account for this postulate led to the development of a model that gave excellent semi-quantitative agreement with experiment. Chemically initiated dilatometric experiments (using three different types of initiator) gave the unusual result of very low reaction rates and low steady-state values of 'nbar', the average number of radicals per particle. Using the standard kinetic equations for styrene-based systems (where it is assumed that an exited monomeric radical undergoes re-entry), this led to the calculation of impossibly small values of the entry rate coefficient ρ (far below any background or ‘thermal’polymerization rate). However upon removing the assumption of re-entry and assuming that exited radicals undergo termination, the obtained values of ρ were in almost perfect agreement with the values predicted from the ‘control by aqueous phase growth’ entry mechanism. This unexpected result was attributed to chemical reaction with the poly(acrylic acid) stabilizers through chain transfer to polymer (via hydrogen-atom abstraction). This postulate was verified by separate experiments that demonstrated that poly(acrylic acid) could act as a reasonably efficient chain transfer agent for styrene polymerization. The addition of poly(acrylic acid) to the aqueous phase of a conventionally stabilized emulsion also led to the rate reduction seen previously. NMR experiments demonstrated the existence of poly(acrylic acid-graft-styrene), which could only be formed through termination of a poly(styrene) chain with a poly(acrylic acid) chain bearing a mid-chain radical (as the product of a chain transfer reaction). These additional terms of transfer and termination were included in the governing kinetic equations of emulsion systems (the Smith-Ewart equations) to develop a model to account for the behaviour of electrosterically stabilized latexes. The ultimate fate of an exiting radical was now shown to be a competition between fates; successful desorption into the aqueous phase, or chemical reaction (through transfer or termination) within the hairy layer. These additional terms were shown to significantly reduce the theoretical value of nbar, and were in excellent agreement with experiment. For small electrosterically stabilized particles with a densely packed ‘hairy layer,’ it was seen that transfer/termination is the dominant loss mechanism as opposed to desorption. The developed model showed that as the particle size was increased, the dominant loss mechanism once again became successful desorption into the aqueous phase. The model was shown to give excellent agreement with experimental data from ‘uncontrolled’ emulsion systems. To explain the highly unusual secondary nucleation behaviour seen in systems such as these, it was postulated that beta-scission of a poly(acrylic acid) chain bearing a mid-chain radical is an important mechanistic step in the nucleation mechanisms of these systems. Modelling (both steady-state and time-dependent) gave good agreement with experiment with a minimal number of adjustable parameters. Theory (and supporting experimental evidence) demonstrated that this nucleation mechanism is only significant at high particle numbers; under other conditions the well-known ‘homogeneous nucleation’ mechanism is once again dominant.

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Orientadores: Telma Teixeira Franco, Gustavo Paim Valença / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-17T02:36:44Z (GMT). No. of bitstreams: 1 Aquino_DeniseSilvade_D.pdf: 1588390 bytes, checksum: 5d3661cf7830099209bf459925acca65 (MD5) Previous issue date: 2010 / Resumo: O presente trabalho determinou as constantes cinéticas e de equilíbrio para a produção de acrilato de sacarose a partir da esterificação direta do ácido acrílico com sacarose catalisada pela lípase comercial de Candida antarctica (Novozym 435). Para alcançar o objetivo proposto foram estudadas as melhores condições para a síntese do acrilato de sacarose, tais como: quantidade de biocatalisador, presença inicial de água no sistema reacional e razão molar dos substratos (sacarose/ácido acrílico).Na esterificação enzimática a formação do subproduto água deve ser controlada para evitar a hidrólise dos ésteres. A adição de peneira molecular 3 Å ao sistema foi investigada para remoção da água produzida e favorecimento do deslocamento do equilíbrio para síntese dos ésteres. O interesse na produção deste éster é devido a alta capacidade de absorção de água. Além disso, os carboidratos são a fonte renovável mais abundante na natureza e, conseqüentemente, uma das matérias primas mais promissora para o desenvolvimento de compostos de origem renovável. A maior conversão da sacarose (76 %) em acrilato de sacarose foi atingida nas seguintes condições: 78 g/L de lipase Novozym 435, razão molar de 1:6 (sacarose:ácido acrílico), ausência de água inicial no sistema reacional e 400g/L de peneira molecular. Com o conjunto de dados obtidos, foi proposto o mecanismo Pingue-Pongue Bi-Bi. Portanto, foi desenvolvida uma equação que representa o mecanismo proposto para a sequência de reações envolvida na esterificação da síntese do acrilato de sacarose. A estimativa dos parâmetros K1, K2, K3, K8, K9 e ? foi obtida utilizando a expansão em série de Taylor, ajuste pela equação de uma reta e pelo não linear por meio do programa computacional POLYMATH 6.0. O critério estabelecido para avaliação da qualidade do ajuste foi o 95% de confiança entre o valor experimental e o valor calculado pela equação ajustada. / Abstract: In this work the equilibrium and kinetics constants of the direct esterification of sucrose with acrylic acid catalyzed by lipase Candida antarctica (Novozym 435) were determined. The optimal conditions were studied such as: different amounts of enzyme and water, sucrose to acrylic acid molar ratio and molecular sieves content. Enzymatic esterifications are equilibrium reactions whose subproduct is water. The presence of this must be controlled to allow esterification of the lipase and to avoid hydrolysis of esters. The addition of molecular sieve 3 Å to the system was investigated to remove of produced water and to shift the equilibrium to the synthesis of ester. The interest in the sugar ester production is due the high capacity to absorb water. Renewable sugars are interesting alternative carbon sources for the production of chemicals by biotechnological routes. The highest sucrose conversion (76%) in sucrose acrylate was reached on the following conditions: 78 g/L of lipase, molar ratio 1:6 (sucrose:acrylic acid), without initial water and 400g/L of molecular sieve. The Ping-Pong Bi-Bi mechanism was proposed. Therefore, the equation represents the mechanism for the reaction sequence involved in the synthesis of sucrose acrylate was developed. The estimates of the parameters of the K1, K2, K3, K8, K9 and ? were obtained using the Taylos series expansion, set by a line equation and set non-linear by the computer program Polymath 6.0. The criterion used to value the quality of data fit was 95 % confidence level. / Doutorado / Desenvolvimento de Processos Químicos / Doutor em Engenharia Química

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Orientador: Telma Teixeira Franco / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-08-11T16:05:07Z (GMT). No. of bitstreams: 1 Fonseca_EricaVagetti_M.pdf: 992372 bytes, checksum: 21c68e3e6cf626421f55f2bf6ffd2a90 (MD5) Previous issue date: 2008 / Resumo: O presente trabalho visou o desenvolvimento de um processo de aplicação para o ácido acrílico através de um bioprocesso, o qual envolveu a esterificação enzimática do mesmo em meio orgânico, catalisada por lipases e proteases para obtenção de acrilatos de açúcar. O interesse na produção de ésteres contendo moléculas de açúcar se dá devido à sua promissora aplicação como materiais absorventes de água, aditivos para o tratamento de água e para fins biomédicos. Além disso, os carboidratos são a fonte renovável mais abundante na terra e, conseqüentemente, uma das mais promissoras substâncias da química sustentável para o desenvolvimento de compostos de alta biodegradabilidade. Como reagentes, os ésteres acrílicos de frutose foram obtidos por esterificação direta da frutose com ácido acrílico em terc-butanol na presença de lipases e proteases comerciais. Foram investigados alguns parâmetros que interferem nesse bioprocesso, tais como: razão molar dos reagentes e tipo de catalisador. Verificou-se que meios reacionais contendo excesso de ácido acrílico, favorecem as maiores conversões molares de frutose. Dentre as enzimas testadas, a única a catalisar a reação de esterificação do ácido acrílico com a frutose em terc-butanol foi a lipase Novozym 435. Sendo assim, um planejamento fatorial completo com dois níveis e com repetição foi proposto para verificar a influência simultânea das variáveis x1 (razão molar de frutose/ácido acrílico nos valores de 1:5 e 1:20) e x2 (umidade inicial do sistema nos valores de 0,16% e 0,40%) na conversão molar de frutose, na conversão molar de ácido acrílico e na produção de seus ésteres empregando a lipase Novozym 435. A análise estatística dos dados indicou que ambos os fatores tiveram efeitos significativos na síntese dos ésteres de frutose. Assim, uma aplicação de acido acrílico para a produção de ésteres degradáveis e com redução do impacto ambiental nos parece ser um caminho convergente dentro do âmbito da química sustentável (química verde) / Abstract: In the present work the reaction conditions for the direct enzymatic esterification of sugars with acrylic acid catalyzed by lipases and proteases in organic media was studied. There has been an increasing interest in the production of sugar esters because of their possible use as water absorbent materials, as additives in water treatment and as a biocompatible material. In addition, carbohydrates are the most abundant natural resources on earth and an ideal feedstock for the development of biodegradable materials. The esterification reaction of fructose with acrylic acid in tert-butyl alcohol was catalyzed by the commercial lipases Novozym 435, Lipozyme RM IM and Lipozyme TL IM and the proteases Novozym 539 HPF and Esperase HP F. The effects fructose/acrylic acid molar ratio and type of catalyst on the reaction were investigated. The esterification reaction was dependent on fructose/acrylic acid molar ratio, as follows: the higher the amount of acrylic acid to fructose ratio the higher the fructose conversion. Only lipase Novozym 435 catalyzed the esterification of acrylic acid with fructose. A full 22 factorial design was used to study the simultaneous influence of the effects of molar ratio (1:5 and 1:20) and initial moisture of the system (0,16 and 0,40%) on fructose conversion, acrylic acid conversion and amount of esters produced with the lipase Novozym 435 as catalyst. Statistical analysis of the data indicated that both factors had significant effects on the synthesis of sugar esters. Therefore, an application to acrylic acid in the production of biodegradable esters seems to be an interesting trend according with the white chemistry. The feasibility of the direct synthesis of sugar acrylates was shown in this work as well as the best reaction conditions for the production of sugar acrylates / Mestrado / Desenvolvimento de Processos Químicos / Mestre em Engenharia Química

Orientador: Maria Regina Wolf Maciel / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-23T17:27:22Z (GMT). No. of bitstreams: 1 BermudezJaimes_JohnHervin_M.pdf: 3572961 bytes, checksum: 92daf8d40cc8f811247948545b00f432 (MD5) Previous issue date: 2013 / Resumo: Na presente dissertação, descreve-se a síntese do ácido acrílico por método semi-sintético. Na primeira etapa, produz-se ácido láctico por fermentação de melaço de cana-de-açúcar, em biorreator BioFlo 415, usando as bactérias Lactobacillus delbrueckii, Lactobacillus plantarum e Leuconostoc mesenteroides, com estudo prévio, em Shaker, da temperatura, concentração de sacarose e concentração de extrato de levedura usadas com cada bactéria. Na fermentação com Lactobacillus delbrueckii, obteve-se o ácido láctico de concentração de 50,21 g/L e produtividade final de 1,26 g/L.h. Com Leuconostoc mesenteroides se produz uma concentração máxima de ácido láctico de 14,57 g/L com produtividade final de 0,41 g/L.h; e usando Lactobacillus plantarum se obteve uma concentração de ácido láctico de 50,59 g/L com produtividade final de 1.09 g/L.h. Na segunda etapa, sintetizou-se ácido acrílico por desidratação catalítica do ácido láctico comercial e do ácido láctico obtido da fermentação com Lactobacillus plantarum em reator tubular, a 300 °C e fluxo contínuo de CO2. Para isso, foram preparados, caraterizados e testados catalisadores suportados em zeólita básica do tipo NaY (KBr/NaY, KI/NaY e Ca3(Po4)2/NaY). Como resultado, quando o ácido láctico comercial foi usado, a maior seletividade obtida foi de 25,66 % com uso de KBr/NaY; já com o ácido láctico obtido por fermentação, a maior seletividade obtida foi de 16,65 % com uso de KI/NaY. Durante o presente projeto, os produtos tanto das fermentações como das desidratações foram caraterizados por cromatografia líquida de alta eficiência (HPLC) / Abstract: The present work deals whit the synthesis of acrylic acid by semi-synthetic method. In the first step, lactic acid was produced by fermentation of sugarcane molasses, in bioreactor BioFlo 415, using the bacteria Lactobacillus delbrueckii, Lactobacillus plantarum and Leuconostoc mesenteroides with a previous study, in Shaker, of the temperature, sucrose and yeast extract concentration used to each bacterium. In the fermentation with Lactobacillus delbrueckii, it was produced lactic acid with concentration of 50.21 g/L and final productivity of 1.26 g/L.h; with the Leuconostoc mesenteroides, it was produced lactic acid with concentration of 14.57 g/L and final productivity of 0.41 g/L.h; and using Lactobacillus plantarum, it was obtained a concentration of lactic acid of 50.59 g/L with final productivity of 1.09 g/L.h. In the second stage, acrylic acid was synthesized by catalytic dehydration of commercial and fermented lactic acid in a tubular reactor at 300 °C and continuous flow of CO2. For this, the catalyst support on NaY Zeolite basic (KBr/NaY, KI/NaY and Ca3(PO4)2/NaY) were prepared, characterized and tested. As results, when the commercial lactic acid was used, the largest selectivity was of 25.66% with use of KBr/NaY; whereas with lactic acid obtained by fermentation, the largest selectivity was of 16.65% using KI/NaY. In this design, all products were characterized by high performance liquid chromatography (HPLC) / Mestrado / Desenvolvimento de Processos Químicos / Mestre em Engenharia Química

Composites, in which the matrix and the reinforcing fillers are respectively, poly(acrylic acid) (PAA) with two different molecular weights, and chitin whiskers (CHW) were successfully prepared using an evaporation method. The weight fraction of CHW was varied from 0.03 to 0.73. Mechanical and thermal properties and crystallinity of the composites were characterised using tensile testing, differential scanning calorimetry, thermogravimetric analysis and X-ray diffraction. The tensile strength of the composite increased up to 11 wt % CHW after which it decreased. XRD characterisation showed a decrease in crystalline index, crystalline size, chitin crystalline peak and intensity as the content of PAA and its molecular weight increased. Raman spectroscopy was used for the first time to monitor the deformation of chitin film and CHW reinforced PAA composites. The Raman band located at 1622 cm^(-1) was monitored for deformation. On application of tensile deformation the Raman band initially located at 1622 cm^(-1) shifted toward a lower wavenumber. Raman band shift rates of -1.85 cm^(-1)/% for chitin film and -0.59 and -0.25 cm^(-1)/% for 73 and 23 wt % CHW content, respectively, were measured. The modulus of a single chitin whisker and composites were found to be 115, 37 and 16 GPa respectively, for a two dimensional (2D) in-plane distribution of CHW. CHW within a PAA matrix did not show any preferential alignment in a polarised Raman. The Raman intensity ratio〖 I〗_1698 /I_1622 showed that the strongest interaction of the carboxylic group in the composites occured at 3 wt % CHW content. The interaction gradually reduced as the CHW content increased. 〖 CaCO〗_3 crystals were grown in CHW, PAA and CHW/PAA composites by a solution and evaporation casting method. In the absence of PAA and CHW, rhombohedral calcites were observed while rod-like aragonite polymorphs were seen when only PAA was used as a template. In the presence of only CHW, a morphological mixture of ellipsoidal and disc shape with traces of rhombohedral aggregate calcite were the features. In the presence of both PAA and CHW, the rhombohedral shape showed roughness with irregular faces while the vaterite polymorph continued to agglomerate with the observation of porosity at higher CHW content. The vaterite particles gradually decreased as the CHW content was decreased. At lower CHW content aragonite polymorph growth was favoured to the detriment of calcite. The results showed that the vaterite polymorph can be grown even at higher filler loading. The effect of 〖 CaCO〗_3 growth on the mechanical properties of CHW reinforced PAA indicated that better mechanical properties can be achieved at a CHW content of 3 wt % when compared with neat PAA and when 〖 CaCO〗_3 was not incorporated into the CHW/25PAA composites.

In industry the effective mixing and de-agglomeration of two solid particles is vital in applications that require the intimate contact of homogeneously mixed reagents. One such application is in the preparation of pyrotechnic delay elements with reproducible burn speeds. The concept of surfactant assisted particle micro-mixing is proposed. This theory is based in the use of two amphiphilic polymeric surfactants to form two separate stable dispersions of the two solid particles to be mixed, but with the subsequent requirement that the dispersants are able to interact with each other. The formation of the individual dispersions allows for the deagglomeration of the particles and thus their preparation for homogeneous mixing, which is facilitated by the interacting surfactants. Low molecular mass block copolymers of styrene and acrylic acid and poly( ethylene oxide)-poly(propylene oxide) (PEO-PPO) surfactants are the proposed dispersants which will allow for the surfactant interaction by means of hydrogen bonding between the poly(acrylic acid) block and the PEO. The poly(styrene-co-acrylic acid) block copolymer will be synthesised via Atom Transfer Radical Polymerisation (ATRP) and subsequently used in the dispersion experiments. The synthesis of the polystyrene macroinitiators to initiate the block copolymerisation of the t-butyl acrylate was carried out satisfactorily, with good molecular masses and molecular mass distributions. In addition, lH-NMR analysis carried out on the polystyrene macroinitiators confirmed their synthesis. The use of the polystyrene macroinitiators was successful in synthesising poly(styrene-co-t-butyl acrylate) block copolymers with slightly higher polydispersities in comparison to the macroinitiatiators themselves, but acceptable. Hydrolysis of the poly(styrene-co-t-butyl acrylate) block copolymer to poly(styrene-co-acrylic acid) was successful in the presence of trifluoroacetic acid as catalyst. Attempts to hydrolyse in basic conditions (NaOH) and alternatively in acidic conditions (HCI) were not successful. Use of the poly(styrene-co-acrylic acid) amphiphilic block copolymer to emulsion polymerise styrene requires the ionised form of the polymer and was therefore not favourable to observe surfactant-surfactant hydrogen bonding. In addition, attempts to synthesise a wax emulsion stabilised by a PEO containing surfactant proved to be unsuccessful. Subsequently, the micro-mixing experiments were carried out by using a poly(acrylic acid) stabilised melamine dispersion and a commercially available PEO containing surfactant stabilised wax emulsion. The interaction between the melamine and the poly(acrylic acid) allows for the formation of a stable melamine dispersion at above 7% poly(acrylic acid) : melamine ratio (mass basis). Analysis by SEM shows that without the poly( acrylic acid) dispersant no wax particles are found to occur on the melamine particle surface. However, in an attempt to determine whether the amount of wax interaction increases with poly(acrylic acid) content, it was found that in the absence of poly(acrylic acid) dispersant, the most amount of wax precipitated out with the melamine. This is possibly attributable to the preferential occlusion of the wax particles between the melamine particles rather than surface attachment. Introduction of the poly(acrylic acid), however, shows via SEM analysis that the hydrogen bond interaction between the acrylic acid group and the ethylene oxide group does occur, since the attachment of the wax particles on the melamine particle surface is observed. Although results show that the surfactant-surfactant interaction allows for the micro¬mixing of particles, some refinement is required with respect to the systems that this phenomenon can be applied to. In addition, factors such as particle type, particle size and surfactant type will influence the micro-mixing interaction. It is therefore recommended that these factors be investigated in order to completely identify the micro-mixing phenomenon. / Dissertation (M Eng (Chemical Engineering))--University of Pretoria, 2006. / Chemical Engineering / unrestricted

Orientador: Telma Teixeira Franco / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-08-07T15:01:29Z (GMT). No. of bitstreams: 1 Tsukamoto_Junko_D.pdf: 1866337 bytes, checksum: 5cac22304ad7fddc116a61d4e57a941f (MD5) Previous issue date: 2006 / Resumo: Reações enzimáticas em meio orgânico têm despertado grande interesse industrial devido às vantagens de obtenção de produtos puros pela maior especificidade das enzimas, pela redução de gastos energéticos e pela possibilidade de desenvolvimento de condições menos agressivas de processo. O uso de enzimas em síntese é uma alternativa viável à síntese orgânica e pode ser compreendida como processo relacionado ao novo conceito de ¿biotecnologia industrial¿ (white biotechnology), devido às preocupações ambientais e da sustentabilidade dos processos químicos. Processos biotecnológicos permitem a exploração racional de materiais renováveis (açúcares) para obtenção de produtos industriais, diminuindo a degradação ambiental. Uma rota enzimática é aqui proposta para obtenção de acrilatos de açúcares, monômero para confecção de polímeros biodegradáveis. O uso de enzimas em síntese orgânica oferece vantagens devido a especificidades na formação de produto, onde os custos de separação, purificação e tratamento de resíduos são minimizados. As lipases são responsáveis por 20% das biotransformações realizadas atualmente. Ésteres derivados de carboidratos e de ácidos graxos vêm sendo produzidos para a indústria alimentícia e farmacêutica, entretanto, mas não se encontram ainda ésteres tais como acrilatos de carboidratos no mercado. Esse projeto visou um estudo da produção de acrilatos de carboidratos pela reação direta via enzimática pela lipase comercial CalB. A esterificação de três monossacarídeos (D-glicose, D-frutose e D-xilose) e dois dissacarídeos (sacarose e maltose) com ácido acrílico pela CalB no solvente terc-butanol foi estudada. O efeito dos três seguintes parâmetros foi avaliado: temperatura, razão molar entre os reagentes (açúcar: ácido acrílico) e quantidade de enzima sobre a conversão a ésteres foi avaliada. A conversão da reação foi acompanhada por cromatografia líquida (CLAE-IR) e por MALDI TOF MS / Abstract: Industrial interest in enzymatic reactions in organic media is due to the possibility of obtain pure compounds with the use of highly specific enzyme, the decrease in energy costs and the possibility of using mild process conditions. The development of new enzymatic processes for chemical synthesis as a viable alternative to the organic synthesis is related to the new concept of "industrial biotechnology" (white biotechnology), with higher concerns with the environment and the sustainability of chemical processes. Biotechnological processes that make a more rational use of renewed resources such as sugars to produce chemicals decrease, in most cases, the environmental impact. In this work an enzymatic route is proposed for the production of sugar acrylates, a biodegradable monomer. The use of enzymes in organic media has the advantage of high specificity to the desired product, lower separation and purification costs, and minimization of residue formation. Currently, lipases are responsible for 20% of all biotransformations. Esters derived from fatty acid and carbohydrates are produced for the food and pharmaceutical industries. However, acrylate esters of carbohydrate are still not found in the market. This aim of this work was to study the production of acrylates of carbohydrates by the direct enzymatic reaction of sugars with acrylic acid on the commercial lipase CalB. The esterification of three monosaccharide (D-glucose, D-fructose and xylose) and two disaccharides (sucrose and maltose) with acrylic acid on CalB in tert-butanol was studied. The effects of temperature, molar ratio of the reactants (sugar to acrylic acid) and amount of enzyme on the conversion to esters were studied. The esterification reaction was monitored by HPLC and MALDI TOF MS / Doutorado / Desenvolvimento de Processos Químicos / Doutor em Engenharia Química

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Nutrition and Food Science, 1980. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Bibliography: leaves 201-212. / Rajen Kantilal Dalal. / M.S.