Resumo em Inglês:

This paper present the most relevant advances in the fields of: i) cellulose fibres surface modification; ii) cellulose fibres-based composite materials; and iii) nanocomposites based on cellulose whiskers or starch platelet-like nanoparticles. The real breakthroughs achieved in the first topic concern the use of solvent-free grafting process (plasma) and the grafting of the matrix at the surface of cellulose fibres through isocyanate-mediated grafting or thanks to "click chemistry". Concerning the second topic, it is worth to mention that for some cellulose/matrix combination and in the presence of adequate aids or specific surface treatment, high performance composite materials could be obtained. Finally, nanocomposites allow using the semi-crystalline nature and hierarchical structure of lignocellulosic fibres and starch granules to more deeply achieve this goal profitably exploited by Mother Nature

Resumo em Inglês:

Active packaging is one of the responses to the recent food-borne microbial outbreaks and to the consumer’s demand for high quality food and for packaging that is more advanced and creative than what is currently offered. Moreover, with the recent increase in ecological awareness associated with the dramatic decrease in fossil resources, research has turned towards the elaboration of more natural materials. This paper provides a short review of biomaterials exhibiting antimicrobial and antioxidant properties for applications in food preservation. The two main concepts of active biopackaging materials are briefly introduced. The different polysaccharides potentially used in packaging materials are then presented associated with a brief overview of research works related to biopackaging, exhibiting notably antimicrobial or antioxidant properties. Finally, future trends such as the release-on-demand of bioactive agents are discussed.

Resumo em Inglês:

The solid state polymerization (SSP) of PET/PC reactive extrusion blends - with and without cobalt catalyst - at different polymer ratios was studied. Thermal and rheological evaluations were performed. DSC results showed changes in the PET's Tg, Tch, Tm and Xc.. The melt flow rate (MFR) decreased for PET and the blends. The intrinsic viscosity increased. The variation in calorimetric and rheological properties might be attributed to the PET's chain extension reactions - esterification and transesterification. These reactions led to an increase in the PET's molar mass, consequently shifting the PET's Tg to lower temperature and PET's crystallization, besides reducing the blend miscibility and flowability.

Resumo em Inglês:

Gamma and ultraviolet radiation effects on hardness, elastic modulus and viscoelastic properties of polyurethane derived from castor oil (PU) were investigated by nanoindentation tests. Modifications on surface morphology, induced by radiation, were observed by atomic force microscopy. The polyurethane derivate from castor oil shows good resistance to gamma radiation, with only small changes in hardness, elastic modulus, viscoelastic properties and contact angle. The hardness of PU increases at the near surface region due to UVA radiation and decreases after UVC radiation. The contact angle for water drop decreases after UVC radiation, but not after gamma radiation, despite a significant increase in roughness. Such results are attributed to different responses from polyurethane to radiation energy. Increase in hardness due to UVA is attributed to a higher crosslinking at shallow depths, while a decrease in mechanical properties may be attributed to chain scission. These results are consistent with the modifications on viscoelastic properties. Shore D hardness did not show the same trend as observed by nanoindentation results. Hardness, viscoelastic properties and contact angle of castor oil polyurethane are more severely influenced by UVC radiation, while gamma radiation does not have a significant effect.

Resumo em Inglês:

Numerous studies have focused on polymer mixtures aimed at the potential applications of these materials. This work analyzed the effect of polymer reprocessing and the type and concentration of compatibilizer on the isothermal crystallization kinetics of polypropylene/wood flour composites. The composites, which were polypropylene grafted with acrylic acid (PP-g-AA) and maleic anhydride (PP-g-MA), were processed in a twin screw extruder with and without compatibilizer. Reprocessed polypropylene reached complete crystallization in less time than the composites with virgin polypropylene. The addition of wood flour to the composites did not change the kinetics significantly compared to that of the pure polymers, but the compatibilizers did, particularly PP-g-AA. The nucleation exponent (n) and crystallization rate (K) were calculated from Avrami plots. The values of n ranged from 2 to 3, indicating instantaneous to sporadic nucleation. The crystallization half-time of reprocessed polypropylene was shorter than that of virgin polypropylene and of the compositions containing PP-g-AA compatibilizer. The activation energy of crystallization and the equilibrium melting temperature were calculated, respectively, from Arrhenius and Hoffman-Weeks plots. Both of these parameters showed lower values in the composites, particularly in the ones containing compatibilizers.

Resumo em Inglês:

Films of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) - PHBV with polyethylene glycol (PEG) were prepared by casting solvent evaporation. The thermal behavior, morphology, crystallinity and molecular weight of these films were studied by the following techniques: differential scanning calorimetry (DSC), scanning electron microscopy (SEM), X-ray diffraction (XRD), size exclusion chromatography (SEC). Mixtures of PHBV/PEG showed a high crystallinity degree, measured by XRD, with values ranging between 60 and 90% according to the concentration of PEG. The melting temperature of PHBV decreased with increasing addition of plasticizer (PEG) in the mixture. SEM results showed that the mixtures were uniform, except for the composition 50/50 which proved to be heterogeneous, as evidenced by the presence of two phases. PHBV had molar mass (Mw = 206000 g mol-1), while the introduced PEG molar mass (Mw = 1350 to 1650 g mol-1). The addition of PEG caused the crystallinity of the polymer films to increase owing to the high crystallinity of PEG. The melting point of the PHBV/PEG mixtures also diminished. In addition, SEC analysis of the blends indicated a reduced molar mass for the mixtures in comparison to pure PHBV (100/0).

Resumo em Inglês:

The toxicity of residues formed during water treatment is mainly a function of the chemicals used. The inorganic flocculants, when used, give rise to compounds harmful to humans and to the environment. An alternative solution is the use of tannins. However, despite the environmental benefits, when using tannin-based products in the treatment of industrial water, modifications may be imparted to the final product. In this work, tannin was evaluated as flocculating agent to treat the water used in the emulsion polymerization to produce SBR. The results show that good stability of the latex and acceptable color in the rubber can be achieved.

Resumo em Inglês:

In this study, epoxy nanocomposites containing different fractions of n-phenylaminopropyl (POSS) were prepared. The nanocomposites were studied by transmission electron microscopy (TEM), gel content, dynamic-mechanical analysis (DMA) and thermogravimetric analysis (TGA). The parameters for Avrami's equation were calculated from the degradation curves. The dispersions used to form the nanocomposites were effective above 5 wt % of POSS, and the gel content increased with the addition of POSS. The DMA analysis exhibited an increase in the storage modulus (E') and a shifting of Tg to higher temperatures upon POSS incorporation. The weight loss indicated that the POSS promoted an increase in thermal stability of the epoxy resin. The Avrami parameters demonstrated that the addition of POSS decreased the Avrami constant (k'), increased the half-life (t1/2) of degradation and promoted changes in the Avrami exponent (n). These results suggest that the increase in the glass transition temperature and thermal stability depend on the reactive groups in the POSS nanoparticles.

Resumo em Inglês:

Gelatin-based films containing soy lecithin or Yucca schidigera extract and glycerol as plasticizer were produced by casting and characterized for their mechanical properties, water vapor permeability (WVP), water solubility, opacity and morphology. The addition of glycerol reduced the tensile strength, with a difference of ~ 68% between the values for the minimum and maximum concentrations evaluated, both for the plasticizer and the surfactant. Elongation values reached 52% and 40%, for films containing yucca extract and lecithin, respectively, when higher amounts of plasticizer and surfactant were added. Lower values of WVP were obtained when the intermediate concentration of glycerol (20 g plasticizer/100 g protein) was used, reaching 0.14 and 0.15 g mm/m² h kPa, respectively, for films containing yucca extract and lecithin. The solubility was not affected by adding plasticizer and / or surfactants. The morphologies of the inner sections of the films, regardless of type of surfactant used, were compact, without pores or phase separation, indicating efficient incorporation of the compounds added to the protein matrix.

Resumo em Inglês:

The mechanical, viscoelastic and structural properties of starch/ poly (butylene adipate co-terephthalate) (PBAT) blown films produced by reactive extrusion were evaluated using citric acid (CA) and maleic anhydride (MA) as compatibilizers. Scanning electron microscopy images showed more homogeneous structure when CA and MA were included in the formulation. The tensile strength (MPa) was improved with the inclusion of the highest proportion of both compatibilizers (1.5 %wt). A larger elastic component with values between 0.42-0.45 for the degree of solidity (1-c1) was observed for the intermediate concentration of compatibilizers. A high level of glycerol (10 %wt) results in films with increased % elongation. Three partially miscible phases were observed in the blends. Biodegradable films of starch/PBAT with better properties could be produced by one-step reactive extrusion using CA and/or MA as compatibilizers.

Resumo em Espanhol:

Se presentan los resultados de la polimerización en emulsión de una resina acrílica estirenada usando surfactantes polimerizables, los cuales presentan ventajas técnicas como baja formación de espuma, alta resistencia de la película al contacto con agua y buena estabilidad en la polimerización. Se evaluó el efecto de estos surfactantes polimerizables en la distribución de tamaños de partícula de la resina; además se determinaron propiedades finales de la resina tales como porcentaje de sólidos, porcentaje de monómero libre, viscosidad y pH. Estos resultados se compararon con los obtenidos usando surfactantes convencionales no polimerizables del tipo alquil fenol etoxilado y alquilarilpoliglicol éter sulfato de sodio. Los resultados indican que que se pueden remplazar totalmente los surfactantes convencionales no polimerizables por los surfactantes poliméricos evaluados sin afectar significativamente las propiedades de la resina, mientras que la sustitución parcial de los surfactantes no polimerizables por los polimerizables induce, en algunos casos, a la formación de partículas con mayor tamaño a las presentes en la muestra estándar.

Resumo em Inglês:

Results on the emulsion polymerization of a styrenated acrylic resin using polymerizable surfactants are presented. These surfactants exhibit low foaming, high film strength upon contact with water and good stability in the polymerization. A comparison was made with results for conventional non-polymerizable alkyl aryl polyglycol ether sulphate, sodium salt and nonylphenolethoxylate surfactants. The effect of these polymerizable surfactants on the particle size distribution of the resin was evaluated; in addition to determining the final properties of the resin such as solids content, free monomer content, viscosity and pH. It is feasible to totally replace non-polymerizable surfactants by the polymerizable surfactants evaluated without affecting significantly the properties of the resin, while partial substitution of the non-polymerizable surfactants induces, in some cases, the formation of particles with larger sizes than those in the standard resin.

Resumo em Espanhol:

En este trabajo se estudiaron mezclas epoxy/poli-3-hidroxibutirato (PHB) en dos proporciones distintas 90/10 y 85/15. Para ello se prepararon muestras sometiéndolas a temperaturas de 80 ºC y 120 ºC, a efectos de producir el curado del epoxy. Se analizó la separación de fases y la cristalización del PHB mediante microscopía óptica y calorimetría diferencial de barrido. Asimismo la estructura lamelar del PHB se caracterizó mediante dispersión de rayos X de bajo ángulo. Se encontraron diferencias significativas entre las dos proporciones estudiadas; mientras que la muestra 90/10 presenta miscibilidad, la muestra 85/15 indica una separación de fases. Asimismo se encontró que, sobre todo para la muestra 90/10, el epoxy afecta considerablemente la estructura lamelar del PHB. Los resultados se analizaron en términos de la competencia entre los procesos de cristalización y separación de fases.

Resumo em Inglês:

In this work, epoxy/poly-3-hydroxybutyrate (PHB) blends in two different proportions, 90/10 and 85/15, were studied. For this purpose, the samples were submitted to 80ºC and 120ºC for the curing process of epoxy. The phase separation and the crystallization were analyzed using optical microscopy and differential scanning calorimetry. Likewise, the lamellar structure of PHB was characterized using small angle X-ray scattering. Significant differences between the two proportions studied were found; while the 90/10 sample presents miscibility, the 85/15 sample indicates a phase separation. Besides, the lamellar structure of PHB is affected due to the epoxy, mainly in the 90/10 sample. The results were analyzed on the basis of the competition between crystallization and phase separation processes.

Resumo em Inglês:

Melt blending of 1:1 poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and glycerol-plasticized starch (TPS) was performed in the presence of an organically-modified montmorillonite, incorporated at 2.5, 5, 7.5 and 10 wt% amounts. Scanning electron micrographs (SEM) revealed the role of the organoclay as a compatibilizing agent for the immiscible blend. The blends were also characterized by X-ray diffraction (XRD), tensile tests, humidity absorption and soil burial biodegradation tests. The results indicated improved properties of the hybrid materials in relation to TPS alone, with a faster biodegradation rate than PHBV.

Resumo em Espanhol:

La estructura química del almidón de yuca se modificó mediante una reacción de acilación. El almidón de yuca modificado se mezcló con un prepolímero de uretano obtenido a partir de aceite de ricino modificado por transesterificación (MCO) y diisocianato de isoforona (IPDI) con el fin de preparar mezclas de almidón-poliuretano termoplástico. Los poliuretanos fueron expuestos a degradación in-vitro durante un período de 365 días y se evaluó la pérdida de masa y el cambio de las propiedades mecánicas y térmicas. El objetivo de este estudio fue examinar el efecto de la incorporación de almidón modificado por acilación en el poliuretano sobre las propiedades mecánicas, térmicas y la velocidad de degradación.

Resumo em Inglês:

The chemical structure of the cassava starch was modified by acylation. Cassava starch modified was mixed with urethane prepolymer based on castor oil modified by transesterification (MCO) and isophorone diisocyanate (IPDI) in order to prepare starch-blended thermoplastic polyurethanes. Polyurethanes were exposed to in-vitro degradation then monitored for changes in mass and mechanical and thermal properties over a period of 365 days. The effect of starch modified content on the thermal and physical properties of the resulting materials was detailed investigated by dynamic mechanical thermal analysis (DMTA) and measurements of mechanical properties. The aim of this study was to examine the effect of introducing starch modified into the polyurethane on the properties and in-vitro degradation.

Resumo em Português:

O objetivo deste trabalho foi estudar o efeito do tempo de envelhecimento natural do sistema catalítico versatato de neodímio/hidreto de di-isobutilalumínio/cloreto de t-butila sobre a polimerização de 2-metil, 1,3-butadieno (isopreno). Foram avaliadas a atividade catalítica e conversão, além da massa molar, distribuição de massa molar e microestrutura dos polímeros. Foi objetivo estudar também as características micro e macroestruturais do poli-1,4-cis-isopreno ao longo da polimerização. Os catalisadores envelhecidos apresentaram tempos mais curtos ao longo da polimerização e uma conversão mais alta em relação ao catalisador não envelhecido. Estes resultados em conjunto com a menor atividade catalítica nos catalisadores envelhecidos sugerem a provável desativação de alguns sítios ativos mais sensíveis. Não foi observada influência do envelhecimento do catalisador sobre a microestrutura do polímero. Houve também aumento da massa molar e estreitamento na polidispersão conforme o aumento da conversão.

Resumo em Inglês:

The goal of this work was to study the aging effects of the catalytic system neodymium versatate/diisobutylaluminium hydride/t-butyl chloride on 2-methyl, 1.3-butadiene (isoprene) polymerization. The catalytic activity, conversion and polymer characteristics (molar mass, molar mass distribution and microstructure) were evaluated. The macro and microstructural characteristics of poly-1.4-cis-isoprene along the polymerization were also studied. The aged catalysts have shorter times along the polymerization and a higher conversion than the non-aged catalyst. Together with the lower catalytic activity for aged catalysts, these results point to possible disabling of the most sensitive active sites. Aging of the catalyst did not affect the polymer microstructure. As the conversion progressed, the molar mass increased with a narrowing in the molecular weight distribution.

Resumo em Português:

Misturas de polipropileno, PP, e terpolímero de etileno-propileno-dieno, EPDM, são amplamente utilizadas na indústria automobilística, principalmente em parachoques, cuja destinação, após o seu uso, deverá atender a Política Nacional de Resíduos Sólidos. No presente trabalho, o efeito da incorporação de PP reciclado nas propriedades mecânicas e de escoamento das misturas PP virgem/EPDM foi avaliado através de um planejamento fatorial do tipo 2n, com n = 3 fatores: teor de PP reciclado, perfil de temperatura de processamento e velocidade de rotação da rosca. As variáveis de resposta analisadas foram: módulo de Young, resistência ao impacto e índice de fluidez (MFI). Os resultados mostraram que o aumento da temperatura de processamento tende a aumentar a rigidez, a resistência ao impacto e a fluidez do produto final. O aumento da velocidade de mistura mostrou uma influência mais significativa na resistência ao impacto do material; enquanto o aumento do teor de reciclado na mistura PP virgem/EPDM levou ao aumento das propriedades mecânicas, bem como do índice de fluidez do produto.

Resumo em Inglês:

Polypropylene, PP, and ethylene propylene diene copolymer (EPDM) blends are widely used in automotive industry, mainly in bumpers. Their disposal should comply with the rules of the Solid Residue National Policy. In the present study, the effect of recycled PP addition on the mechanical and flow properties of these blends was evaluated using a 2n factorial design, with n = 3 factors: recycled PP content, extrusion temperature profile and screw speed. The parameters analyzed were: Young modulus, impact strength and melt flow index (MFI). The results showed that the increase in temperature tends to increase rigidity, impact strength and the flow of the final product. The increase in blend speed showed a significant influence on the impact strength of the material; whereas the increase in recycled PP content led to an increase of the mechanical properties analyzed, as well as of the flow index of the product.

Resumo em Português:

O efeito de dois óleos vegetais, óleo de linhaça e óleo de amendoim, em composições de borracha natural (NR) foi avaliado. Um sistema de vulcanização convencional foi escolhido e, após a mistura os parâmetros reométricos (Mℓ, Mh, t s1 e t90) foram analisados. A cinética de vulcanização também foi estudada através de um modelo simplificado. A constante de taxa (k) foi determinada em 160° C, 170 °C e 180 °C e a energia de ativação (Ea) global do processo foi estimada. Os resultados experimentais permitem concluir que os óleos sozinhos ou combinados são capazes de atuar como ativadores e, juntamente com os demais ingredientes da composição, de vulcanizar a borracha. No entanto, uma densidade de ligações cruzadas satisfatória só é atingida quando o ácido esteárico está presente.

Resumo em Inglês:

The effect of two vegetable oils, linseed oil and peanut oil, in natural rubber (NR) compositions was available. A conventional system of vulcanization was chosen and, after the mixtures the rheometer parameters (Mℓ, Mh, t s1 e t90) were analyzed. The vulcanization kinetics was also studied through the simplified model. The constant rate (k) was determined at 160 °C, 170 °C and 180 °C, and the global activation energy (Ea) of the process was estimated. Experimental results show that oils alone or combined are capable of acting as activators and, together with the other components, vulcanize rubber. However, an adequate crosslinking density is only reached when stearic acid is present.

Resumo em Português:

O objetivo deste trabalho foi promover a adsorção da Strychnos pseudoquina ST. HILL (Quina do Cerrado) em microesferas de PEG e avaliar seu efeito imunomodulador sobre a atividade funcional de fagócitos de sangue humano. Foram coletadas 120 amostras de sangue humano para obtenção dos fagócitos. O extrato aquoso da planta foi obtido por maceração seguida de destilação. As microesferas de polietilenoglicol foram analisadas por microscopia de fluorescência, por citometria de fluxo e por espectroscopia no infravermelho e a atividade funcional dos fagócitos foi verificada através da liberação de superóxido, da fagocitose e da atividade microbicida. As análises de microscopia de fluorescência e de citometria de fluxo revelaram que as microesferas de PEG apresentaram um tamanho aproximado de 5,8 µm e que o extrato da "Quina do Cerrado" e suas frações foram capazes de adsorverem às microesferas de PEG. A adsorção da quina e de suas frações às microesferas de PEG aumentou a atividade funcional dos fagócitos. Estes dados permitem concluir que a adsorção do extrato de Strychnos pseudoquina ST. HILL. em microesferas de PEG pode ser um importante neomaterial funcional para futuras aplicações clínicas em doenças inflamatórias e crônicas degenerativas.

Resumo em Inglês:

The aim of this study was to evaluate the adsorption of Strychnos pseudoquina ST. HILL. ("Quina do Cerrado") onto PEG microspheres and to verify the immunomodulatory effect on blood phagocytes. 120 blood samples from humans were used to obtain the phagocytes. Preparation of plant extract of Strychnos pseudoquina ST. HILL. was carried out by maceration followed by distillation. The PEG microspheres were analyzed by fluorescence microscopy, flow cytometry and infrared spectrum, while the functional activity of phagocytes was measured by the release of superoxide, phagocytosis and microbicidal activity of blood phagocytes. The analysis of fluorescence microscopy and flow cytometry revealed that the PEG microsphere had approximately 5.8 µm in size and that "Quina do Cerrado" and its fractions were able to absorb onto PEG microspheres. The adsorption of the plant and its fractions to the PEG microspheres increased the functional activity of phagocytes. These data show that the adsorption of the extract of Strychnos pseudoquina ST. HILL. on PEG microspheres can be an important functional new material for future clinical applications in inflammatory and chronic degenerative diseases.

Resumo em Português:

Blendas imiscíveis de poliamida 6 e polietileno de baixa densidade foram preparadas com e sem a presença de polietileno enxertado com anidrido maleico como compatibilizante. Montmorilonita organofílica foi incorporada nas blendas por intercalação do fundido. Análises morfológicas e estruturais apresentaram boa dispersão da argila, com a obtenção de estruturas intercaladas e esfoliadas. A separação de fases foi observada nas amostras, e tanto o compatibilizante como a argila causaram redução no tamanho dos domínios. Esta estrutura proporcionou uma melhora significativa nas propriedades mecânicas das blendas, revelando o efeito de reforço causado pela argila. O módulo elástico e a tensão máxima aumentaram em até 300% e 100%, respectivamente. O efeito da compatibilização da argila foi positivo. Pelas análises de DSC pode-se observar o surgimento de um pico na região de fusão da PA6 atribuído à formação de uma nova fase cristalina devido à presença de argila.

Resumo em Inglês:

Immiscible blends of polyamide 6 and low density polyethylene were prepared with and without maleic anhydride grafted polyethylene used as a compatibilizer. Organophilic montmorillonite was incorporated in the blends by melt intercalation. Morphological and structural analysis showed good clay dispersion with partially exfoliated and intercalated structures. Phase separation was observed and domains size reduction was induced by the clay and the compatibilizer. Improvement on mechanical properties of compounds was observed, showing the reinforcing effect caused by the clay. Elastic modulus and tensile strength have increased up to 300% and 100%, respectively. The clay showed a positive effect on compatibilization. DSC analysis revealed a new melting peak for PA6 assigned to a new crystalline phase due the clay effect.

Resumo em Português:

O presente trabalho teve como objetivo determinar a adequabilidade de três amostras de biopolímero xantana (Xa 06, Xa 82 e Xa 106) e uma clairana como viscosificantes de fluidos de perfuração de poços de petróleo, comparando com uma amostra de xantana comercial, Xanvis®. Foram realizadas análises reológicas, determinados os conteúdos de acetil, piruvato e íons Na+ K+ e Ca2+, e avaliada a capacidade viscosificante segundo norma específica da Petrobras. Os conteúdos de grupos acetil e piruvato para as xantanas e clairana diferiram significativamente entre si, mas foram compatíveis com valores preconizados ou citados na literatura concernente. Com relação ao conteúdo de íons, a xantana comercial apresentou quantidade de cálcio superior, as amostras Xa 06, Xa 82 e Xa 106 tiveram maior teor de potássio e a clairana maior teor de sódio. A viscosidade e a viscoelasticidade da amostra de xantana comercial foram superiores às demais amostras analisadas. Na análise como viscosificante para fluidos de perfuração as amostras de xantana comercial e Xa 106 atingiram os requisitos estabelecidos para os parâmetros n, K e força gel da norma Petrobras N-2605. Com a interpretação conjunta dos resultados obtidos pode-se inferir que apenas as xantanas Xanvis® e Xa 106 apresentam características adequadas à utilização como viscosificante em fluido de perfuração de petróleo. As demais amostras possuem características reológicas adequadas à utilização como espessantes ou estabilizantes em outros segmentos industriais, como em alimentos, tintas e cosméticos.

Resumo em Inglês:

The aim of this study was to determine the suitability of three xanthans (Xa 06, Xa 82 and Xa 106) and a clairana biopolymer for use as drilling fluid thickeners and comparing them against a commercial sample, Xanvis®. Rheological analyses were performed to determine the acetyl, pyruvate and Na+ K+ and Ca2+ ion content and their thickening ability, according to Petrobras guidelines. The pyruvate and acetyl group content for the xanthans and the clairana biopolymer differed significantly, but they were consistent with the recommended values or those previously cited in the literature. With regard to the ion content, the commercial xanthan contained higher amounts of calcium, while Xa 06, Xa 82 and Xa 106 samples contained higher potassium levels and clairana had a higher sodium level. The viscosity and viscoelasticity of the commercial xanthan sample were higher than for the other samples. In the viscosity analysis of drilling fluids, Xanvis® and Xa 06 met the required parameters for n, K and gel strength (Petrobras regulation N-2605). In an analysis of the results obtained, only Xanvis® and Xa 106 presented the desired characteristics for use as drilling fluid thickeners. The other samples presented adequate rheological characteristics for use as thickeners and stabilizers in many industrial applications, such as food, paints and cosmetics.

Resumo em Português:

Neste trabalho foi desenvolvida uma nova metodologia de reciclagem química do poli(tereftalato de etileno) grau garrafa pós-consumo, PETpc, através da reação de despolimerização em meio alcalino (solução de hidróxido de sódio, NaOH, de 7,5 mol L-1 a 100 ºC) e como catalisador o tensoativo catiônico brometo de hexadeciltrimetrilamônio, CTAB (1 × 10-2 mol L-1). A presença de CTAB aumentou o rendimento da reação em cerca de 85% e reduziu o tempo reacional de 6 para 2 h, quando utilizado em mistura NaOH/CTAB na proporção de 4:1 (% v/v) com 2 g de PETpc. O produto final, o monômero ácido tereftálico, TPA, foi caracterizado por análise termogravimétrica, calorimetria diferencial varredura, espectroscopia na região do infravermelho com transformada de Fourier e espectrometria de massas. Os resultados foram comparados com os da matéria-prima, PETpc. Além disso, o catalisador CTAB permaneceu no meio reacional (fase aquosa), sem interferir no processo de purificação do TPA.

Resumo em Inglês:

In this work, a new analytical methodology has been developed for the chemical recycling of post-consumption bottle-grade poly(ethylene terephthalate), PETpc through depolymerization reaction in alkaline solution (NaOH solution of 7.5 mol L-1 at 100 ºC), using the surfactant cetyl trimethyl ammonium bromide (CTAB, 1 × 10-2 mol L-1) as catalyst. The presence of CTAB increased the reaction performance by ca. 85%, while the reaction time was decreased from 6 to 2 h when the mixture NaOH/CTAB was used in a proportion of 4:1 (% v/v) with 2 g of PETpc. The final product, the monomer terephthalic acid (TPA), was characterized by thermogravimetry analysis, differential scanning calorimetry, Fourier transform infrared spectroscopy and mass spectrometry. The results were compared with those for the raw material, PETpc. Furthermore, the catalyst CTAB remained in the alkaline environment (aqueous phase), without interfering with the TPA purification process.

Resumo em Português:

O interesse por polímeros biodegradáveis tem aumentado devido ao baixo impacto ambiental dos mesmos. No entanto, muitos desses produtos disponíveis no mercado são frágeis, difíceis de processar e têm alto custo. Uma das técnicas para superar essas deficiências é através de blenda com outros polímeros. Este trabalho avaliou várias composições de blenda PHB/PP, utilizando-se um aditivo pró-degradante deste último, de forma a tornar a formulação oxibiodegradável em solo simulado (ASTM D6003). O comportamento mecânico, térmico e químico de corpos de prova de tração das amostras enterradas foi acompanhado através de medidas de resistência à tração, DSC, FTIR, GPC e SEM. Parte das amostras foi envelhecida em estufa a 90 ºC por 10 dias, de forma a acelerar a oxidação do PP pelo aditivo. A blenda composta por 56 wt% de PP / 40 wt% de PHB / 3 wt% de GMA / 1 wt% de MnSt foi a mais susceptível à oxibiodegradação, tendo reduzido depois de 180 dias de enterramento em solo, a tensão de tração em 40%, alongamento na ruptura em 46% e a massa em 24%. Estes valores foram superiores ao próprio PHB puro e o efeito sinérgico ocorrido nestas blendas foi atribuído à aceleração da degradação do PHB pelo PP oxidado.

Resumo em Inglês:

The interest in biodegradable polymers has increased because of their environmental advantages. Blending them with other polymers is one of the techniques currently employed to overcome their brittleness, poor processing and cost. This work evaluated different blend compositions of PHB/PP, using a pro-degrading additive for this latter, to make the formulation prone to oxo-biodegradability in simulated soil (ASTM D6003). The mechanical, thermal and chemical behavior of buried injection molded tensile bars was monitored through measurements of tensile strength, DSC, FTIR, GPC and SEM. Part of the samples was oven aged at 90 ºC for 10 days in order to accelerate the PP oxidation by the additive. The blend made of 56 wt% of PP / 40 wt% of PHB / 3 wt% of GMA / 1 wt% of MnSt was the most susceptible to oxo-biodegradation, having reduced after 180 days of burring in soil, its tensile stress by 40%, tensile elongation by 46% and mass by 24%. These values were even higher than the ones for the pure PHB. This synergic effect was attributed to the acceleration of PHB degradation by the oxidized PP.