Abstract Green polyethylene and vermiculite clay composites were developed through the fusion intercalation technique with the aim of investigating their potential use as a building material. The composites were processed in a single screw extruder and molded in a hydraulic thermopress. For the purpose of this study, flame propagation resistance and the natural aging effects of green polyethylene and its composites were analyzed. The samples were exposed to the abiotic degradation test for 90 days with the aim of assessing the effects of climate conditions on the material’s morphology and mechanical properties. The flammability test demonstrated the catalytic effect of the clay, since for all composites evaluated, the flame propagation resistance was inferior to that of the pure green polymer. The effects of natural aging on the morphology of the materials were characterized by the transition of the polymeric matrix from a ductile aspect to a more fragile appearance and the emergence of voids and internal fractures Hence, the mechanical performance of the systems was directly affected, as a result of several types of abiotic degradation suffered by the samples.
Resumo Compósitos de polietileno verde e argila vermiculita foram desenvolvidos por meio da técnica de intercalação por fusão com o objetivo de investigar seu potencial uso como material de construção. Os compósitos foram processados em uma extrusora monorosca e moldados em uma termoprensa hidráulica. Para este trabalho, foram analisadas a resistência à propagação de chamas e os efeitos do envelhecimento natural do polietileno verde e seus compósitos. Amostras foram expostas a um ensaio de degradação abiótica durante 90 dias como forma de avaliar os efeitos das condições climáticas na morfologia e nas propriedades mecânicas do material. O teste de inflamabilidade evidenciou o efeito catalítico da argila, uma vez que para todos os compósitos avaliados, a resistência à propagação de chamas foi inferior em relação ao polímero verde puro. Os efeitos do envelhecimento natural na morfologia dos materiais foram caracterizados pela transição da matriz polimérica de um aspecto dúctil para uma aparência mais frágil e o aparecimento de vazios e de fraturas internas. Em virtude disso, o desempenho mecânico dos sistemas foi diretamente afetado, como resultado de diversos tipos de degradação abiótica sofrida pelas amostras.
Abstract Polymer processing parameters may considerably affect final product characteristic as, if properly chosen, these parameters may lead to products with optimal properties. The aim of this work is to evaluate the rheological characteristics of poly(ethylene terephthalate) (PET) by torque rheometry, as well as to estimate its incipient degradation rate during processing in an internal laboratory mixer. In order to estimate the temperature coefficient of the viscosity (β), and the pseudoplasticity index (n) of PET, two sets of experiments need to be performed. In the first one, the polymer is processed at three different temperatures at a single rotor speed for 10 min, getting temperature coefficient of the viscosity equal to β = 0.053 °C-1. In the second set of experiments, the resin (PET) is processed at a single temperature at six different rotor speeds for the same time interval and the pseudoplasticity index was determined, n = 0.78. From the results obtained, it is possible to indicate the internal mixer as an equipment not only for mixing polymers or composites, but as a tool for determining important rheological variables for predicting degradative processes.
Abstract The use of polymer blends and composites based on fossil-based and bio-based polymers has become an important environmentally protective alternative for common use and disposable plastics applications such as packaging, bottles and trays. The disposal of these more degradable products, however, may also harm the environment and, therefore, recycling these systems becomes relevant. Recycling involves reprocessing which can significantly change the morphology and properties of polymeric products. Therefore, this study deals with the effects of reprocessing cycles on the properties and morphology of blends and nanocomposites based on fossil and bio-based polymers. The systems investigated were: a) neat polypropylene (PP), b) a polypropylene/poly(3-hydroxybutyrate) (PP/PHB) blend and c) PP/PHB/organoclay nanocomposite compatibilized with polypropylene-g-maleic anhydride (PP-g-MA) and erucamide. These materials were submitted to up to seven extrusion cycles in a single screw extruder operating at 60 rpm. Samples were taken after the first, third, fifth and seventh extrusion cycles and their tensile properties and morphology were determined. Scanning electron microscopy indicated that two phases were observed in the blend which showed spherical PHB domains. The addition of clay, PP-g-MA and erucamide improved the adhesion between the nanocomposites components. X-ray diffraction analysis showed that crystallinity tended to increase with the number of reprocessing cycles for all systems investigated up to the fifth cycle and then tended to decrease. A 10% crystallinity increase was observed for neat PP in the fifth cycle. In general, the tensile properties of all systems decreased with reprocessing and the highest losses were observed for the PP/PHB blend after seven processing cycles with 50% and 37% decreases in stress at break and elastic modulus, respectively. Impact strength of the PP matrix and of the PP/PHB blend tended to decrease with reprocessing, except for the nanocomposite which showed a slight increase especially after the seventh processing cycle in which an 18% increase in impact strength was observed.
Abstract This study aims to evaluate the effects of natural weathering in the city of Teresina, State of Piauí, Brazil, on the morphology and mechanical properties of eco-composites based on high-density green polyethylene, powdered cork and compatibilizer processed in a twin-screw extruder and injection molded. The analyses revealed that although weathering induced surface bleaching of eco-composites and cracking, these effects were not intense in the compatibilized samples. The tensile properties of the investigated materials were affected by abiotic degradation, which led to a reduction of the tensile strength and elastic deformation of the eco-composites, however, the incorporation of PEgMA was fundamental for the maintenance of mechanical performance after natural aging. In general, the results obtained were satisfactory for external applications of the compatibilized eco-composite with 15% cork in the proposed weathering range, which indicates its possible use in temporary constructions.
ABSTRACT In this work, epoxy polymer composites laminated with cork and hollow glass microspheres were developed. The laminated composites were manually made and evaluated for the morphological characteristics of the scanning electron microscope and the influence of the incorporation of the fillers was evaluated by means of density and flexural strength. In general, good dispersion of both the cork powder and the hollow glass microspheres was observed in the central layers of the sheet, but the cork-based cores presented better adhesion to the matrix. It was also observed the reduction in the density of all the composites with respect to the pure matrix and that the flexural modulus of cork-based composites and those with hollow microspheres of glass, even with close values, were superior to modulus of bending of the pure epoxy system. Core laminates with cork incorporation may be applied as an alternative where weight reduction is required and also where there is the expectation of bending stresses higher than those supported by the pure resin.
RESUMO Neste trabalho foram desenvolvidos compósitos poliméricos epoxídicos laminados a base de cortiça e microesferas ocas de vidro. Os compósitos laminados foram confeccionados manualmente e avaliados quanto às características morfológicas em microscópio eletrônico de varredura e a influência da incorporação das cargas foi avaliada por meio da densidade e da resistência à flexão. De um modo geral, foi observada boa dispersão tanto do pó de cortiça como das microesferas ocas de vidro nas camadas centrais do laminado, porém os núcleos a base de cortiça apresentaram melhor adesão à matriz. Foi observada ainda a redução na densidade de todos os compósitos com relação à matriz pura e que os módulos de flexão dos compósitos a base de cortiça e os com microesferas ocas de vidro, mesmo com valores próximos, foram superiores ao módulo de flexão do sistema epóxi puro. Compósitos laminados com núcleo com incorporação de cortiça poderão ser aplicados como alternativa onde houver a necessidade de redução de peso e também onde houver a expectativa de solicitações de flexão superiores às suportadas pela resina pura.
Polyethylene (PE) is a polymer that has a low adhesion property, which is related to its low surface energy. However, the plasma treatment aims the modification of the surface properties without affecting the polymer structure. In this sense, the objective of this work was to prepare biocomposite films via flat extrusion with Green PE matrix and Expanded Vermiculite Clay (VMT), contents of 1, 3 and 6%. The films were treated by plasma in two different ways: Oxygen (O2) atmosphere (Condition 1); and Argon/Hydrogen (Ar/H2) atmosphere followed by a plasma treatment under O2 atmosphere (Condition 2). The results of the contact angle measurements indicated that the incorporation of VMT and the conditions used for plasma treatment increased the films wettability due to the hydrophilic character of VMT and also as a consequence of the plasma. In contrast, the XRD diffractograms indicated that there were no significant changes in the films structure.
The population increase, urbanization and climatic change adversely affect the agricultural production have prompted actions to improve the means of production without affecting the environment. One of the actions to make the production of food more efficient and sustainable is the use of plastics in protection of crops, soils and packaging, for example. Therefore, the aim of this work was to develop flat extruded mulch films of poly (butylene adipate-co-terephthalate)/2.5 and 5.0% sugar cane residue/2.0% carnauba wax for application in soil cover and characterize them as to their chemical structure, morphology and transmittance. The FTIR results suggest that there was no chemical interaction between the components of the mulch films. SEM images and optical microscopy showed that the polymer matrix was able to cover sugarcane residues and that the carnauba wax dispersed well in the PBAT matrix. In addition, carnauba wax addition increased the transmittance of these mulch films.
Polymeric syntactic foams are composites made from the mixture of Hollow Glass Microspheres (HGM) and polymer matrices. One of their main characteristics is their low density and the production of these composites using a matrix derived from renewable sources potentiates their development without neglecting sustainability. In this paper , the properties of High Density Polyethylene (HDPE)/HGM syntactic foams containing 1% and 5% w/w HGM and 5% w/w of a compatibilizer are assessed. The composites were prepared by two processing routes: single screw extruder and twin screw extruder. The morphology and mechanical properties (tensile and impact) of the syntactic foams thus manufactured were ascertained. Morphological analysis indicated that matrix/filler adhesion was poor for all samples and that the best HGM dispersions were obtained in twin screw extruded samples. Mechanical properties were affected by the processing route adopted and by the content of hollow glass microspheres added. Elastic modulus, tensile strength and strain were reduced by 20, 10 and 23%, respectively, in systems processed in a twin screw extruder. Impact strength was the exception, with an increase of more than 300%. Higher contents of hollow glass microspheres led to reductions in mechanical strength of the syntactic foams, varying from 5% for the elastic modulus to 50% for strain.
ABSTRACT Green Polyethylene (PE) is a synthetic polymer that has low surface energy, which results in poor adhesion properties. This factor causes some problems regarding the practical applications of polymers, such as poor adherence of printing inks, coatings, adhesives and metals to the surface of the polymer, among others. One way to alter this property is by applying a plasma treatment. In this sense, the objective of this work was to prepare, by flat extrusion, biocomposite films with Green PE matrix (PEPURO) and load of Expanded Vermiculite Clay (VMT) in the 1% content. The films were treated by plasma under two different conditions: under O2 atmosphere (C1); (Ar/H2) and a subsequent treatment by plasma under O2 (C2) atmosphere. The results indicated that the plasma treatments and the incorporation of VMT increased the hydrophilicity of the films, and the application of condition 2 (C2) was shown more efficiently. The untreated PEPURO presented a significant reduction of maximum tensile strength with the insertion of VMT, already with the application of treatments (C1 and C2) the resistance values were higher. In relation to the roughness it was possible to verify that the application of the plasma increased the surface roughness of the samples. These results indicated that increased hydrophilicity and roughness resulted in a significant increase in the interaction of fluids with the surface and also improvement of the adhesive characteristics of the polymer.
RESUMO O Polietileno (PE) Verde é um polímero sintético que apresenta baixa energia superficial, que resulta em fraca propriedade de adesão. Esta baixa adesão, provoca alguns problemas relativos às aplicações práticas dos polímeros, como fraca aderência de tintas de impressão, revestimentos, adesivos e metais à superfície do polímero, entre outros. Uma maneira de alterar essa propriedade é por meio da aplicação de um tratamento por plasma. Neste sentido, o objetivo deste trabalho foi preparar, via extrusão plana, filmes de biocompósitos com matriz de PE Verde (PEPURO) e carga de argila Vermiculita Expandida (VMT) no teor de 1%. Os filmes foram tratados por plasma em duas condições distintas: sob atmosfera de Oxigênio (O2) (C1); e sob atmosfera correspondendo a mistura de Argônio/Hidrogênio (Ar/H2) e um posterior tratamento por plasma sob atmosfera de O2 (C2). Os resultados indicaram que os tratamentos a plasma e a incorporação de VMT aumentaram a hidrofilicidade dos filmes, sendo que a aplicação da condição 2 (C2) mostrou-se de maneira mais eficiente. O PEPURO não tratado apresentou redução significativa de resistência máxima a tração com a inserção de VMT, já com a aplicação dos tratamentos (C1 e C2) os valores de resistência foram superiores. Em relação à rugosidade foi possível verificar que a aplicação do plasma aumentou a rugosidade na superfície das amostras. Estes resultados indicaram que o aumento da hidrofilicidade e da rugosidade resultaram em um aumento significativo na interação de fluidos com a superfície e também melhora das características adesivas do polímero.
Abstract Studies about in vitro biodegradation of polymers have grown considerably due to the wide application of biodegradable polymers in biomedical areas. The objective of this study was to prepare bionanocomposites films of PHB, PEG, and organoclays by solution intercalation, and to evaluate the morphology, structure, hydrolytic degradation through FTIR and the calculation of carbonyl content. The results showed that bionanocomposites displayed intermediated dispersion of the filler, the polymer chains were intercalated into the organoclay layers and was observed some degree of exfoliation. There was an influence of PEG and of the clay on the degradation of the polymer, this fact was observed due to the decrease in the intensity of PHB carbonyl band in the region around 1275 cm-1, affecting the amorphous and crystalline regions of the polymer. This reduction can be associated with the increase in hydrophilicity of the polymer caused by the presence of the PEG and clay, suggesting the possibility of increasing the biodegradability of the pure polymer. In future research, there will be made characterizations to know if these materials can be used in medical devices.
In this work, biocomposites of poly (3-hydroxybutyrate) (PHB) / calcium carbonate from Rhea Americana eggshells were prepared and the effects of the addition of the inorganic filler in the polymeric matrix were assessed. The residue (powder) of the eggshell calcined at 400 ºC or in natura was inserted into a PHB solution for preparation of films via casting. Powder samples were characterized by X-Ray Fluorescence (XRF), X-Ray diffraction (XRD) and Thermogravimetry (TG/DTG) and films were characterized by X-Ray diffraction (XRD), Scanning Electron Microscopy (SEM) and biodegradation tests according to the ASTM G 160-03 norm: the results were reported as weight loss and visual inspection by optical microscopy (OM). From the results of the XDR, it was perceived that the peaks in the diffractograms of the powder obtained by milling the Rhea Americana eggshells corresponded to the diffraction patterns of the Calcite crystals, which is a calcium carbonate polyform, and that the calcination preserved the crystalline structure, maintaining the calcium carbonate in the samples. For the biocomposites, a peak characteristic to the calcium carbonate in 29.57º was detected, indicating the insertion of the filler to the polymer matrix. Through SEM the presence of small agglomerates, probably due to polymer particles that were not dissolved, was observed for the pure PHB film. With the addition of the filler in natura a greater porosity was formed in the surface of the biocomposite films, and with the calcined filler, homogeneous films with reduced porosity were obtained. From the weight loss and OM results, it was observed that the filler inserted into the polymeric matrix catalyzes the biodegradation process up to 60 days evaluation in different ways, depending on the type of sample used.
ABSTRACT During the last decades, a lot of research work focused on several biodegradable and biosourced polyesters for the purpose of reducing the non-degradable polymer wastes. These polyesters are particularly considered to be promising polymers for biomedical applications and short life-time products like packaging. As these packagings are rapidly discarded, especially the food ones, their accumulation becomes a serious environmental problem. In order to replace these materials with new ones that do not harm the environment, several studies are being carried out about these materials. However, it presents some limitations as its thermal instability in the molten state and high cost of production, being the incorporation of clay to the polymer matrix, forming bionanocomposites, a viable alternative since it improves the mechanical and thermal properties of the material when compared to the pure polymer, and may or may not reduce the total cost of production. Among commercially-available polyesters, polyhydroxyalkanoates (PHAs) are produced by various bacteria and known to be fully biodegradable. The aim of this study was to develop and to characterize bionanocomposites produced from the polymer matrix of poly (3-hydroxybutyrate-co-3-hydroxyvalerate) - PHBV and natural vermiculite and organoclay. The melt intercalation technique was used for obtaining systems in the form of films. The FTIR results unveiled changes in the bionanocomposites structure with the addition of the clay, verifying the incorporation and overlap of bands of both the natural clay and the quaternary ammonium salt. Through the XRD technique, it was observed a greater disorganization in the systems compared to the pure polymer, suggesting a structure of a microcomposite for the systems with natural clay and tending to a greater exfoliation for the systems with organoclay vermiculite. From the micrographs by MO and MEV, the films presented a small number of clusters for the natural systems and a more uniform structure for the organophilic systems, thus corroborating with the XRD. In this way, it was evidenced that the systems with organoclay were the ones that presented better against the characteristics desired for its possible industrial application. Thus, elaborated bionanocomposites may be an alternative to the substitution of synthetic polymers in the industry, for example, in food packaging.
Abstract This study aimed to prepare and to evaluate natural and modified PHB /vermiculite films in quantities of 1%, 3% and 6% by weight, through melt intercalation and solution intercalation methods. The bionanocomposites in the form of thin films, obtained by the melt intercalation method, were prepared in a single screw extruder and then molded via compression. In the preparation of the films by solution method, the systems were stirred and heated at 80 °C in the presence of the chloroform solvent. The systems were evaluated by X-ray diffraction and the degradation behavior was evaluated according to ASTM G 160-03, by visual inspection and through weight loss. It was observed that the percentage of clay and the method of obtaining of the films influenced in the structure and biodegradability of the systems.
Resumo Este trabalho teve como objetivo preparar e avaliar filmes PHB/vermiculita natural e modificada nas quantidades em peso de 1%, 3% e 6% através dos métodos intercalação por fusão e intercalação por solução. Os bionanocompósitos obtidos pelo método intercalação por fusão foram preparados em uma extrusora monorosca e posteriormente os filmes foram moldados via compressão. Na preparação dos filmes por solução, os sistemas foram submetidos à agitação e aquecimento a 80 °C. Os sistemas foram avaliados por difração de raios-X e o comportamento de biodegradação foi avaliado de acordo com a norma ASTM G 160-03. O acompanhamento da biodegradação foi realizado por meio de inspeção visual e perda de massa. Observou-se que o percentual de argila e o método de obtenção dos filmes influenciaram na estrutura formada e na biodegradação dos sistemas.
The flammabilities of nanocomposites made with three polypropylene grades (homo and copolymers) with 5 wt % of organoclay (Cloisite 20A), 5 or 15 wt % of maleated polypropylene as compatibilizer, and 0, 0.5 or 1 wt % of cis-13-docosenamide (Erucamide) as co-intercalant, were studied using the horizontal burning test UL94HB. Masterbatches prepared in an internal mixer were diluted in the polypropylene matrix using a corotating twin-screw extruder, with different screw configurations and operating at 240 or 480 rpm. Results indicate that the high burning rate of the composites was not affected by the processing conditions. For all formulations was observed a significant reduction in smoke release, lack of dripping and the formation of a char surface layer, that protected the core of the samples.
A inflamabilidade de nanocompósitos com três tipos de polipropileno (homo e copolímeros) contendo 5% de argila montmorilonita organofílica (Cloisite 20A), 5 e 15% de polipropileno enxertado com anidrido maleico como agente compatibilizante e 0, 0,5 e 1% de cis-13-docosenamida (Erucamida) como agente co-intercalante foi estudada através do teste de queima horizontal UL94HB. Concentrados foram preparados em misturador interno e diluídos com a matriz de polipropileno em extrusora de dupla rosca corrotacional com diferentes configurações de rosca e velocidades rotação de 240 e 480 rpm. Os resultados indicaram aumento da velocidade de queima dos compósitos quando comparados às das matrizes e que a velocidade de queima não foi afetada pelas condições de processamento. Em todos os casos, foi observado durante o ensaio uma redução da emissão de fumaça, ausência de gotejamento de material e a formação de uma camada carbonácea, levando à preservação da estrutura interna da amostra.
PP/organoclay/PP-g-MA/erucamide composites with 5% commercial organo-montmorillonite (Cloisite 20A), 5 and 15% maleated polypropylene as compatibilizer, and 0, 0.5 and 1% erucamide as a co-intercalating agent were prepared by melt intercalation. A masterbatch of compatibilizer and organoclay was compounded in an internal mixer and then diluted in the polypropylene matrix in a corotating twin-screw extruder. The compounds were characterized by x-ray diffraction, optical microscopy and mechanical properties. Results indicate that the organoclay acted as a reinforcer. Addition of the co-intercalating agent significantly increased the interlayer spacing of the clay, without notably affecting the mechanical behavior of the composites. Optical microscopy showed the dispersive effect of the screw profile used, which promoted the breaking of clay agglomerates.
Compósitos de PP/argila/PP-g-MA/erucamida contendo 5% (em peso) de argila montmorilonita organofílica (Cloisite 20A), 5 e 15% de PP-g-MA como agente compatibilizante e 0, 0,5% e 1% de cis-13-docosenamida (erucamida) como agente co-intercalante, foram preparados por intercalação no estado fundido. Concentrados de argila e compatibilizantes foram processados em misturador interno e em seguida diluídos com a matriz de polipropileno em extrusora de dupla rosca corrotacional. Os compósitos foram caracterizados através das propriedades mecânicas, difração de raios X e microscopia óptica. Os resultados indicaram o efeito reforçante da argila organofilizada. A presença de co-intercalante aumentou significativamente a distância interlamelar da argila em todos os compósitos, em geral, não afetando notavelmente o comportamento mecânico dos compósitos. Por microscopia óptica foi possível observar o efeito dispersivo do perfil de rosca utilizado, que promoveu a quebra dos aglomerados de argila.