Philosophiae Doctor - PhD (Biotechnology) / Guayule (Parthenium argentatum) is grown for its high quality hypoallergenic natural rubber latex production. The plant is native to the Chihuahua desert of North America and successful trials have been done in Europe, the United States of America (USA) and the Republic of South Africa (RSA). It is already undergoing industrial scale development in the USA producing good quality rubber products with impressive stretchiness and strength. The performance of guayule lines AZ1, AZ2, AZ3, AZ4, AZ5, AZ6, OSU1, and 11591 was investigated in the Eastern and Western Cape regions in RSA with an ultimate goal of leading to commercial production. To ensure continuous supply of plants, and avoiding documented seed dormancy issues, a micropropagation protocol was established using the OSU1 guayule line. In addition, laboratory scale latex extraction was accomplished using the Waring blender method with KOH pH 11 buffer and the amount of latex was quantified using the 1 ml latex quantification method. The extracted latex homogenate from the different guayule lines was pooled and purified using Sodium Carboxymethyl Cellulose. The efficiency of different molecular weights (90 000, 250 000 and 700 000) of Sodium Carboxymethyl Cellulose was determined in creaming guayule latex at room temperature and 4 degrees celcius. The optimal creaming results were incorporated into creaming latex extracted from the different guayule lines during this study.

A modernidade exige materiais versáteis, resistentes e, durante um longo tempo os plásticos serviram a esse propósito. Entretanto, o acúmulo desses materiais ao serem descartados no meio ambiente tornou-se um problema Os polímeros biodegradáveis surgiram neste cenário como alternativa para evitar o acúmulo de resíduos plásticos no meio ambiente. O polihidroxibutirato (PHB) representa uma classe de polímeros biodegradáveis, mas que apresenta um alto custo e possui ainda propriedades térmicas limitadas. A borracha natural possui excelentes propriedades mecânicas, resistência ao envelhecimento, flexibilidade e apresenta melhor custo benefício se comparada com as borrachas sintéticas. Neste estudo, foram elaboradas misturas poliméricas de polihidroxibutirato (PHB) e látex de borracha natural em diferentes concentrações, por prensagem à quente. Os ensaios de calorimetria diferencial de varredura (DSC), análise termogravimétrica (TGA), espectrometria na região do infravermelho (FTIR), microscopia ótica (MO) e microscopia eletrônica de varredura (MEV) foram utilizados para caracterizar e avaliar as propriedades das misturas poliméricas. O PHB e as misturas com borracha natural foram submetidos ao ensaio de biodegradabilidade através do enterro em solo simulado, conforme a norma ASTM G 160-03, variando por um período de 2 a 17 semanas. Ao final de cada período foram determinadas a perda de massa, a morfologia dos corpos de prova e foram realizadas as análises de DSC, TGA e FTIR. As misturas poliméricas apresentaram menor resistência térmica do que o PHB. No ensaio de biodegradabilidade, as misturas foram consideradas biodegradáveis, segundo a norma ASTM G 160-03 e tiveram a porcentagem de cristalinidade reduzida, tendo o teor de borracha natural contribuído para aumentar a taxa de biodegradação. As análises por MEV comprovaram a existência de consórcios de microrganismos, responsáveis pela biodegradação do PHB e das misturas poliméricas / Modernity requires versatile , sturdy materials , and for a long time plastic served this purpose. However , the accumulation of these materials to be discarded in the environment has become a problem Biodegradable polymers have emerged in this scenario as an alternative to avoid the accumulation of plastic waste in the environment . The polyhydroxybutyrate ( PHB ) is a class of biodegradable polymers , but it is costly and still has limited thermal properties . Natural rubber has excellent mechanical properties , aging resistance , flexibility and presents best value compared to synthetic rubbers . In this study, polymer mixtures of polyhydroxybutyrate (PHB ) and natural rubber latex in different concentrations were prepared by hot pressing . Tests of differential scanning calorimetry ( DSC ) , thermal gravimetric analysis ( TGA ) , infrared spectroscopy (FTIR ) , optical microscopy (OM ) and scanning electron microscopy (SEM ) were used to characterize and evaluate the properties of polymer blends . The PHB and blends with natural rubber were subjected to biodegradation test by simulated soil burial , according to ASTM G 160-03 , for a period ranging 2-17 weeks. At the end of each period were determined mass loss , the morphology of the specimens and the analysis of DSC , TGA and FTIR were performed . The blends showed lower thermal resistance than the PHB . In the biodegradability test , the mixtures were considered biodegradable according to ASTM G 160-03 and had reduced the percentage of crystallinity , and the content of natural rubber contributed to increase the rate of biodegradation. The SEM analysis confirmed the existence of consortia of microorganisms responsible for the biodegradation of PHB and the polymer blends

Submitted by GUILHERME DOGNANI null (gdognani@bol.com.br) on 2016-02-18T16:52:20Z No. of bitstreams: 1 Dognani, G_Dissertação.pdf: 3231196 bytes, checksum: c5c016c95556862b76a9859f8b519f60 (MD5) / Approved for entry into archive by Juliano Benedito Ferreira (julianoferreira@reitoria.unesp.br) on 2016-02-19T17:27:35Z (GMT) No. of bitstreams: 1 dognani_g_me_bauru.pdf: 3231196 bytes, checksum: c5c016c95556862b76a9859f8b519f60 (MD5) / Made available in DSpace on 2016-02-19T17:27:35Z (GMT). No. of bitstreams: 1 dognani_g_me_bauru.pdf: 3231196 bytes, checksum: c5c016c95556862b76a9859f8b519f60 (MD5) Previous issue date: 2016-01-22 / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / A técnica de eletrofiação tem sido utilizada na obtenção de fibras com diversos materiais poliméricos. Neste trabalho, foram desenvolvidos, de maneira inédita, materiais eletrofiados a partir de borracha natural e polianilina. Por esta técnica, foram obtidas mantas eletrofiadas com fibras de diâmetro menor que 1 µm. Para o desenvolvimento destas mantas eletrofiadas tornou-se necessário primeiramente realizar um amplo estudo sobre os parâmetros de processo, o qual constou em variar o fluxo de vazão da solução polimérica de 0,1, 0,25, 0,5 mL/h, a tensão aplicada ao processo de 10, 12,5, 15 kV e a rotação do coletor rotativo onde as fibras foram depositadas em 30, 40, 50 rpm. Após o estudo dos parâmetros de eletrofiação, foi selecionada uma série com os melhores parâmetros, que proporcionou a obtenção de mantas de borracha natural denominadas BN. Estas mantas foram posteriormente recobertas com polianilina pelo método de polimerização in situ, obtendo mantas de BN/PAni dopada e BN/PAni desdopada. Para fins de comparação foram também produzidas membranas densas pelo método casting, que foram caracterizadas quanto suas propriedades elétricas, onde mostrou bons resultados, se comportando como material ôhmico alcançando a condutividade na ordem de 10-6 S/m para BN/PAni dopada, enquadrado assim entre os materiais semicondutores. Além das propriedades elétricas foram também investigadas as propriedades térmicas, espectroscópicas e morfológicas dos materiais estudados. Os resultados deste trabalho mostraram que é possível eletrofiar a borracha natural formando fibras de diâmetro que alcançaram valores mínimos de até 0,92 μm. / The electrospinning technique has been used to obtain fibers with various polymer materials. In this work were developed in an unprecedented fibers electrospun from natural rubber and polyaniline. For this technique, fibers mats were obtained with fiber diameter of less than 1 micrometers. For the development of these electrospun mats became necessary to first perform an extensive study on the process parameters, which consisted in varying the flow of polymer solution at 0.1, 0.25, 0.5 ml/h, the voltage applied to the process 10, 12.5, 15 kV and rotation of the collector where the fibers were deposited on 30, 40, 50 rpm. After studying the electrospinning parameters, it selected a series with the best parameters, which provided obtaining natural rubber mats called NR. These mats were covered with polyaniline by in situ polymerization method, getting NR/PAni doped and NR/PAni undoped mats. For purposes of comparison were also produced membranes by casting method, which were characterized as its electrical properties, which showed good results, behaving as ohmic materials reaching the conductivity on the order of 10-6 S/m for NR/PAni doped, entering among the semiconductor materials. In addition to the electrical properties were also investigated the thermal, spectroscopic and morphological materials properties. These results showed that it is possible produced natural rubber fibers electrospun forming diameter fibers that have reached minimum values of up to 0.92 micrometers. / FAPESP: 2013/18692-6

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No. of bitstreams: 1 barros_nr_me_araiq.pdf: 2287500 bytes, checksum: 5687ecdf1e7aabf2b962b2fed752c410 (MD5) Previous issue date: 2016-02-25 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O látex extraído da seringueira Hevea brasiliensis têm mostrado promissores resultados em aplicações biomédicas, onde membranas produzidas deste material têm sido utilizadas como próteses e enxertos médicos devido às suas características de biocompatibilidade e estímulo natural à angiogênese. O objetivo desse trabalho consiste na incorporação de peptídeos em membranas de látex natural e no estudo de suas liberações. Esperamos com os resultados, viabilizar o uso do látex natural como sistema de liberação sustentada de peptídeos e/ou proteínas. A taxa de liberação dos peptídeos foi monitorada e quantificada por Cromatografia Líquida de Alta Eficiência (CLAE) em modo analítico. A incorporação do peptídeo às membranas de látex acompanhou diferentes caracterizações, dentre elas: Espectroscopia de Infravermelho por Transformada de Fourier (FTIR) que identificou a estabilidade dos peptídeos após incorporação ao látex natural pela preservação de bandas características para os peptídeos, dentre elas, as bandas 1643 – 1638 cm-1 deformação NH de aminas e C=O de amidas; 1524 - 1514 cm-1 deformação C=C de aromáticos; e 542 – 498 cm-1 deformação S-S, Capacidade de absorção de fluídos, Perda de massa em soluções aquosas, CLAE e Microscopia Eletrônica de Varredura (MEV). Durante os ensaios de liberação dos peptídeos pelas membranas de látex natural, observou-se a instabilidade dos peptídeos em solução, com degradação total em períodos que variaram de 48 a 120 horas nos valores de pH 7,4; 12,0; e água destilada (pH 5,6 – 6,4). Entretanto, para a solução de tampão acetato pH 4,0 não houve instabilidade dos peptídeos em solução. Desta forma, estes resultados sugerem a possível interferência causada por proteases alcalinas presentes no látex natural. Adicionalmente, com o propósito de eliminar das membranas o agente causador da degradação dos peptídeos, foram confeccionadas novas membranas submetidas ao tratamento de lavagem, e posteriormente os peptídeos foram adsorvidos às membranas. Durante os ensaios de liberação foi possível observar a liberação e a estabilidade dos peptídeos com liberação de 60% em 96 horas para o peptídeo desmopressina; 90% em 24 horas para somatostatina; 45% em 8 horas para ocitocina; e 80% em 24 horas para octreotida. A partir destes resultados podemos afirmar que o látex natural pode ser utilizado como matriz sólida na liberação tópica de peptídeos, no entanto, se faz necessária maior investigação sobre as enzimas proteolíticas presentes no látex natural extraído da seringueira Hevea brasiliensis. / The latex extracted from Hevea brasiliensis rubber tree have shown promising results in biomedical applications, where membranes produced from this material have been used as medical implants and grafts, due to its biocompatibility and natural stimulation of angiogenesis. The aim of this work was to incorporate peptides into natural latex membranes and the study of its release. We look forward to the results, enabling the use of natural latex as Controlled Release System of peptides and/or proteins. The rate of peptide release were monitored and quantified by High Performance Liquid Chromatography (HPLC) in an analytical way. The peptides incorporation into latex membranes followed different characterizations, such as: Fourier Transform Infrared Spectroscopy (FTIR) which identified the stability of peptides after incorporation into the natural latex by the preservation of characteristic bands for peptides, among them, 1643 - 1638 cm-1 NH strain of amines and amides C=O; 1524 - 1514 cm-1 strain C=C aromatic; and 542 - 498 cm-1 strain S-S, fluid absorption capacity, the loss in weight in aqueous solutions, HPLC and Scanning Electron Microscopy (SEM). During the release tests of peptides by the natural latex membranes, it was observed instability of the peptides in solution, with total extinction in periods that ranged between 48 and 120 hours in pH 7.4; 12.0; and distilled water (pH 5.6 - 6.4). However, for acetate buffer solution (pH 4.0) was not observed instability of peptides. Therefore, these results suggest that there are possible interferences caused by alkaline proteases present in the natural latex. Additionally, in order to remove the causative agent of degradation, were prepared new membranes subjected to washing treatment, and the peptides posteriorly adsorbed on the membranes. During the release tests, it was possible to observe the release and stability of peptides with 60% released at 96 hours for the peptide desmopressin; 90% in 24 hours for somatostatin; 45% in 8 hours for oxytocin; and 80% at 24 hours for octreotide. From these results we can say that the natural latex can be used as solid matrix in the topical & transdermal delivery of peptides, however, it is necessary further research into the proteolytic enzymes present in the natural latex extracted from the rubber tree Hevea brasiliensis.

L’objectif de ce travail a consisté à développer un revêtement polyuréthane (PU) ignifugeant à partir de caoutchouc naturel. Pour ce faire, deux types de diols ont été utilisés. Un oligoisoprène hydroxytéléchélique a été tout d’abord synthétisé et utilisé comme segment souple. Par ailleurs, un second oligomère phosphorylé, dont les groupements phosphonate ou phosphate sont connus pour offrir des propriétés retardatrices de flamme, et possédant une extrémité diol a été réalisé afin de servir d’extenseur de chaine au cours du procédé one shot d’obtention des revêtements. Ces oligophosphonates ou phosphates ont été obtenus quant à eux selon un procédé de polymérisation radicalaire contrôlé de type RAFT à partir de monomères diethyl (acryloyloxymethyl) phosphonate (DEAMP) et 2-acryloyloxyethyldiethylphosphate (ADEP) afin d'accéder à deux gammes de masses strictes (n~13 and n~21 ) et des dispersités étroites (Ð<1.2). Ces polymères ont été entièrementcaractérisés par RMN 1H, 31P, SEC et spectrométrie Maldi TOF et utilisés en synthèse de polyuréthanes selon deux procédés appelés additif et réactif. Les propriétés physicochimiques et mécaniques des matériaux PU synthétisés ont été comparés à ceux de matériaux PU incorporant selon les mêmes approches une petite molécule phosphorylée, afin de traduire les effets spécifiques de ces oligomères. Les revêtements polyuréthane synthétisés ont été caractérisés par FTIR et spectroscopie Raman afin de mesurer la dispersion des oligomères phosphorés au sein de la matrice polymère. En outre, les propriétés physicochimiques et notamment les propriétés ignifugeante ont été évaluées par TGA, DSC et LOI. En complément, les propriétés mécaniques ont été elles aussi évaluées (élongation à rupture, module, dureté et scratch test). Une étude de mapping par spectroscopie Raman a révélé une meilleure dispersion des additifs dans un matériau obtenu selon l’approche réactive, où l’oligomère phosphorylé est lié de manière covalente au squelette du Polyuréthane. De la même façon, cette dispersion apparaîtplus homogène pour l’utilisation d’un oligomère de chaine plus courte (n=13). Les propriétés ignifugeantes ont été démontrées grâce aux caractérisations TGA et DSC où la première étape de décomposition est retardée quels que soient les pourcentages d’oligomères incorporés à la matrice (1, 5 ou 8%). En outre, il s’avère que les mesures LOI démontrent un maximum proche de 30% pour un pourcentage d’oligomère de 8%, valeur très notablement supérieure à celle de l’additif de comparaison. Concernant les propriétés mécaniques, l’incorporation d’oligomères phosphorylés entraîne une augmentation du module et de la dureté et une diminution de la résistance à l’abrasion. Les valeurs d’élongation à rupture sont cependant très similaires, quelles que soient les formulations testées. Néanmoins, ces propriétés apparaissent très supérieures à celles de la matrice standard, démontrant une plus grande efficacité d’oligomères phosphorylés par comparaison avec une petite molécule de type phosphate ou phosphonate. Ces résultats encourageant laissent entrevoir une perspective d’application industrielle de cette méthodologie vers la production de caoutchoucs ignifugeants. / The aim of this research was to develop polyurethane (PU) coating from Natural Rubber (NR) presenting Flame Retardant (FR) properties. For this purpose, two kinds of diols were used. Hydroxytelechelic oligoisoprenes were firstly synthesized from Natural Rubber (NR) and used as softsegment. Secondly, diol chain end phosphorylated oligophosphonates or oligophosphates were synthesised that would cater as chain extender during the polyurethane synthesis one shot process. Such Phosphorylated oligomer was synthesized by RAFT polymerization of diethyl (acryloyloxymethyl) phosphonate (DEAMP) and 2-acryloyloxyethyl diethylphosphate (ADEP) monomer. A new trithiocarbonate based RAFT agent was synthesized (2-(dihydroxypropan-2-yloxy)carbonyl trithiocarbonate). This RAFT agent was used to polymerize each monomer with welldefinedmolecular weight and narrow dispersities (Đ<1.2). The polymer was well characterised by 1H, 31PNMR, SEC and Maldi TOF. The oligomers were synthesised with two different chain lengths, n≈13 andn≈21 to be used as additive and reactive FR in polyurethane films. As a reference molecule, a phosphatediol was synthesized to be used as a pendent group in polyurethane synthesis.Polyurethane films were fully characterised using FTIR, Raman spectroscopy, TGA, DSC and LOI.The mechanical properties were furthermore evaluated such as elongation at break, modulus, hardnessand scratch test. Polyurethanes with 1, 5, and 8% w/w of the phosphorylated oligomer were preparedaccording two different pathways so called additive or reactive. The main difference consists in thecovalent attachment of the phosphorylated oligomer to the PU backbone in the reactive pathway whilein the additive process, the oligomers are only physically incorporated in the PU. Raman mappingcharacterizations on the different films reveal a better homogeneous distribution of shortphosphorylated oligomer chains using a reactive pathways compared to the additive pathway as well asthe use of longer chains. Moreover TGA Analysis showed lower decomposition temperature on the firststep and an increased decomposition temperature on the second step of all phosphorylated treatedPUs. This indicates char formation from FR oligomer at lower temperature increases the decompositiontemperature on the second step. LOI measurements showed a maximum of 28.2% with shorterphosphate based oligomers added via reactive pathway at 8%w/w ratio.The mechanical properties of PU with phosphorylated oligomer gave similar elongation at breakbetween additive and reactive pathway. Compared to standard PU, the incorporation of the phosphorylated oligomer showed a decrease in scratch resistance and an increase in modulus and hardness. However, these oligomers (additive and reactive) performed better when compared withsmall molecule added as additive fillers. As a perspective, these phosphorylated oligomers on its own,with low Tg values (≈ -30oC), could be used in dry rubber FR application.

Ce travail de thèse porte, de manière globale, sur une meilleure compréhension du caoutchoucnaturel (NR). En effet, bien que ce matériau soit fortement utilisé dans l’industrie et ce depuisdes dizaines d’années, plusieurs de ses propriétés restent à ce jour mal comprises.Antérieurement à nos travaux, il a été fait un lien entre la biosynthèse du polymère et cespropriétés et il a été proposé que le caoutchouc naturel était constitué d’une chaînepolyisoprène (PI) 100% 1,4-cis de forte masse molaire (> 500 000 g/mol) fonctionnalisée en αet ω par une protéine et un motif phospholipidique respectivement. Ces bouts de chaîneseraient capables de s’auto-assembler pour créer un réseau physique qui confère au NR sespropriétés si intéressantes. L’objet de cette thèse a donc été de synthétiser un copolymère triblocProtéine/PI/Lipides afin de confirmer cette hypothèse en produisant en laboratoire unhomologue de NR. Pour ce faire, un PI hétéro-téléchélique cétone/aldéhyde a été obtenu pardégradation chimique de NR. Cette méthode a permis d’obtenir un PI 100 % 1,4-cis possédantdeux fonctions chimiques différentes en bout de chaine permettant ainsi le greffage sélectifd’une protéine où d’un motif lipidique. Ces deux couplages ont ensuite été étudiés séparément(PI/Protéine puis PI/Lipides) révélant des propriétés intéressantes dans le cas du copolymèredi-bloc PI/Lipide. Le couplage PI/Protéine s’est avéré plus compliqué et seul des copolymèresdi-blocs PI/Polypeptide ont pu être obtenus avec certitude, en utilisant des synthons PI commemacro-amorceurs. Une voie de synthèse a également été dégagée pour un tri-blockPolypeptide/PI/Lipide présentant une structure très proche du modèle de Tanaka. / This PhD work focuses on a better comprehension of natural rubber (NR). Indeed, despite thefact that this material has been used for a long time in industry, some properties remainunclear. Previous works of Tanaka allowed to make a link between the biosynthesis of thematerial and its properties. It was thus suggested that NR was composed of a high molar masschain of polyisoprene (PI, > 500 000 g/mol) functionalized at the α and ω chain-end by aprotein and a phospholipidic moiety respectively. These chain-ends would be able to selfassembleinto a pseudo-physical network which would explain some of the superior propertiesof NR. The goal of this PhD work is to synthesize a Protein/PI/Lipid tri-block copolymer inorder to check this hypothesis and to synthesize hybrid material close to NR. First, a 1,4-cishetero-telechelic (ketone/aldehyde) PI of 10 000 g/mol was obtained by chemical degradationof NR, yielding a polymeric chain bearing two different functions at the chain-ends, allowingto perform a selective functionalization with both a lipidic moiety and a protein. Both di-blockcopolymers (PI/Lipid and PI/Protein) were synthesized and studied separately. The PI/Lipiddi-block copolymer revealed interesting properties. The synthesis of PI/Protein di-blockcopolymer revealed more difficult and only PI/Polypeptide di-block copolymer could havebeen obtainded. To this end, PI macro-initiator allowed the Ring-Opening Polymerization odN-carboxyanhydride. Finally, a chemical pathway was established, allowing to synthesize aPolypeptide/PI/Lipid tri-block close to Tanaka’s model.

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Orientador: Aldo Eloizo Job / Banca: Ana Maria Pires / Banca: Edgardo Alfonso Gomez Pineda / O Programa de Pós Graduação em Ciência e Tecnologia de Materiais, PosMat, tem caráter institucional e integra as atividades de pesquisa em materiais de diversos campi / Resumo: As membranas de BN foram obtidas do látex da seringueira Hevea Braziliensis, através da técnica de casting. Este trabalho apresenta as fases de obtenção e caracterização de membranas de borracha natural (BN) com incorporação coloidal de nanopartículas metálicas de prata (AgNPs) gerando compósitos de BN/Ag. A incorporação das partículas de prata na membrana de BN se deu através do método de reação in situ, no processo de redução química do sal de nitrato de prata (AgNO3), utilizando água como meio reacional, para diferentes tempos de redução. Os compósitos de Bn/Ag foram utilizados para aplicação no processo de separação dos parasitas infectantes de Leishmania braziliensis. Esta etapa é necessária na busca de uma vacina eficiente contra a leishmaniose causada pela espécie original do Brasil. A eficácia do processo foi verificada por meio dos estudos comparativos com o método de separação de protozoários utilizando a lã de vidro. Três testes biológicos foram realizados, sendo (i) a cinética de crescimento populacional in vitro das formas promastigotas e amastigotas: (ii) a síntese de óciso nítrico (NO) por macrófagos murinos e; (iii) infecção experimental de camundongos isogênicos BALB/c e C57BL6. A caracterização do compósito de BN/Ag foi realizada através das técnicas de Espectroscopia no Ultravioleta visível (UV-VIS), análises térmicas por calorimetria exploratório diferencial (DSC) termogravimetria (TG) e acoplamento de termogravimetria com infravermelho com infravermelho (TG/FT-IR). os resultados mostram a ocorrência da redução das nanopartículas de prata na membrana de Bn, em diferentes tempos, e que não interfere nas propriedades termomecânicas, nas temperaturas de transições de fase e na estabilidade térmica, quando comparado com a membrana de Bn pura. Os testes biológicos... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The natural rubber membranes (NR) were obtained from the latex Hevea braziliensis rubber tree, using the technique of casting. This work presents the stages of obtainment and characterization of NR membranes with colloidal incorporation silver metallic nanoparticles - AgNPs, producing composites of NR/Ag. The NR/Ag membranes were used for application into separation process of the Leishmania brasiliensis parasites. This stage is very important in the research for an effective vaccine against leishmaniasis, cuased by the original species in Brazil. The effectiveness of the process will be done through comparative studies across the methods of separation of protozoa, using the membranes NR/Ag and glass wool. There biological tests were accomplished: (i) the growth kinetics of population of promastigostas and amastigotes in vitro; (ii) the synthesis of nitric oxide NO by murine macrophages; and (iii) experimental infection of inbred mice BALB/c and C57BL6. The characterization of the composite NR/Ag was performed using the techniques of ultraviolet visible spectroscopy (UV-Vis), thermal analysis differential scanning calorimetry (DSC), thermogravimetry (TG) and thermogravimetry coupled with infrared (TG/FT-IR). The result show the occurrence of the reduction of silver nanoparticles in the membrane of NR in different reduction times and does not interfere in the thermomechanical property, at temperatures of phase transitions and thermal stability compared with the membrane of pure NR. The biological tests to maintain non-infectious phase without cell damage that the composite BN/Ag has the capacity to separate the two stage... (Complete abstract click electronic access below) / Mestre

A modernidade exige materiais versáteis, resistentes e, durante um longo tempo os plásticos serviram a esse propósito. Entretanto, o acúmulo desses materiais ao serem descartados no meio ambiente tornou-se um problema Os polímeros biodegradáveis surgiram neste cenário como alternativa para evitar o acúmulo de resíduos plásticos no meio ambiente. O polihidroxibutirato (PHB) representa uma classe de polímeros biodegradáveis, mas que apresenta um alto custo e possui ainda propriedades térmicas limitadas. A borracha natural possui excelentes propriedades mecânicas, resistência ao envelhecimento, flexibilidade e apresenta melhor custo benefício se comparada com as borrachas sintéticas. Neste estudo, foram elaboradas misturas poliméricas de polihidroxibutirato (PHB) e látex de borracha natural em diferentes concentrações, por prensagem à quente. Os ensaios de calorimetria diferencial de varredura (DSC), análise termogravimétrica (TGA), espectrometria na região do infravermelho (FTIR), microscopia ótica (MO) e microscopia eletrônica de varredura (MEV) foram utilizados para caracterizar e avaliar as propriedades das misturas poliméricas. O PHB e as misturas com borracha natural foram submetidos ao ensaio de biodegradabilidade através do enterro em solo simulado, conforme a norma ASTM G 160-03, variando por um período de 2 a 17 semanas. Ao final de cada período foram determinadas a perda de massa, a morfologia dos corpos de prova e foram realizadas as análises de DSC, TGA e FTIR. As misturas poliméricas apresentaram menor resistência térmica do que o PHB. No ensaio de biodegradabilidade, as misturas foram consideradas biodegradáveis, segundo a norma ASTM G 160-03 e tiveram a porcentagem de cristalinidade reduzida, tendo o teor de borracha natural contribuído para aumentar a taxa de biodegradação. As análises por MEV comprovaram a existência de consórcios de microrganismos, responsáveis pela biodegradação do PHB e das misturas poliméricas / Modernity requires versatile , sturdy materials , and for a long time plastic served this purpose. However , the accumulation of these materials to be discarded in the environment has become a problem Biodegradable polymers have emerged in this scenario as an alternative to avoid the accumulation of plastic waste in the environment . The polyhydroxybutyrate ( PHB ) is a class of biodegradable polymers , but it is costly and still has limited thermal properties . Natural rubber has excellent mechanical properties , aging resistance , flexibility and presents best value compared to synthetic rubbers . In this study, polymer mixtures of polyhydroxybutyrate (PHB ) and natural rubber latex in different concentrations were prepared by hot pressing . Tests of differential scanning calorimetry ( DSC ) , thermal gravimetric analysis ( TGA ) , infrared spectroscopy (FTIR ) , optical microscopy (OM ) and scanning electron microscopy (SEM ) were used to characterize and evaluate the properties of polymer blends . The PHB and blends with natural rubber were subjected to biodegradation test by simulated soil burial , according to ASTM G 160-03 , for a period ranging 2-17 weeks. At the end of each period were determined mass loss , the morphology of the specimens and the analysis of DSC , TGA and FTIR were performed . The blends showed lower thermal resistance than the PHB . In the biodegradability test , the mixtures were considered biodegradable according to ASTM G 160-03 and had reduced the percentage of crystallinity , and the content of natural rubber contributed to increase the rate of biodegradation. The SEM analysis confirmed the existence of consortia of microorganisms responsible for the biodegradation of PHB and the polymer blends