Bionanocomposites of poly-3-hydroxybutyrate (PHB), polyethylene glycol (PEG), and organophilic vermiculite (VMT) clay were prepared at 95/5/3% and 90/10/3%and blends at 95/5% and 90/10% PHB/PEG in the form of films obtained via solution intercalation. The films were submitted to hydrolytic degradation according to the ASTM F1635-11. X-ray diffraction (XRD) analysis, mass loss, visual inspection, and Fourier transform infrared (FTIR) spectroscopy evaluated the properties of films. XRD analysis showed that the polymer chains were intercalated into the organoclay layers, and some degree of exfoliation was observed from this analysis. FTIR was performed to calculate the carbonyl index and to quantify the causing group of the degradation process. The visual inspection results showed that the film surfaces were whitened and brittle. This characteristic was more evident for the 90/10% PHB/PEG blend and 90/10/3% PHB/PEG/VMT composite. The addition of the organophilic VMT clay at 95/5/3% (PHB/PEG/VMT) displayed a larger mass loss; FTIR showed that degradation of pure PHB occurred in the amorphous regions and that the presence of PEG and VMT increased the polymer degradation, decreasing crystallinity.
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.
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 (O 2) atmosphere (Condition 1); and Argon/Hydrogen (Ar/H 2) atmosphere followed by a plasma treatment under O 2 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 limited degradation of synthetic polymers used in food packaging when discarded in the environment is a major concern for society. Therefore, industry and academia have sought to develop biodegradable and eco-friendly materials for single-use in packaging. An interesting alternative for the food industry is biodegradable polymeric films, which is why different biopolymers have been used in the production of sustainable packaging. It is worth mentioning that the use of biodegradable polymers is one of the most successful innovations in the industry to address issues related to the environment. Among the available raw materials, starch extracted from different renewable sources is very promising for this purpose, due to its abundance, low-cost compared to other polymers and ability to produce non-toxic films. However, when used alone, pure starch has many limitations, which can be overcome by developing a mixture with other polymers (polymer blends), preferably from renewable and biodegradable sources, such as poly(lactic acid) (PLA). In this context, the absence of literature reviews evidencing the results of the application of films in foods led us to write this article, given the importance of polymer blends produced with different types of starch (cassava, corn, pea, potato, rice and wheat) and the PLA matrix. According to the results, it is clear that polymer blends based on PLA/Starch for food packaging are very promising, already being part of the industries solutions, aiming to minimize the large volume of plastic waste of petrochemical origin discarded in nature. Obviously, as with any technology, more research is needed to further improve the performance of the films, and while much research has made great strides, there are still limitations that prevent the commercialization of these materials.
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.
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.
A Têmpera é um tipo de Tratamento Térmico que consiste no resfriamento brusco de uma peça aquecida visando o aumento de Dureza, em que, a verificação do grau de dureza da peça submetida a esse tratamento é determinada através de Ensaios de Dureza, no qual, o Método Rockwell é o mais empregado. Dependendo do meio de resfriamento utilizado se tem diferentes taxas de transferência de calor com a peça a ser tratada, onde, são proporcionadas características distintas na dureza final da peça. Neste trabalho, foi analisado a influência da água e salmoura que atuaram como meio de resfriamento na têmpera do aço SAE 1045, por meio do Método Rockwell, e a modificação microestrutural foi verificada por Microscopia Óptica. Observou-se mediante a comparação da micrografia óptica da amostra de referência com a das amostras tratadas, que os grãos após a têmpera se tornaram menores e com a morfologia de agulhas devido à mudança de estrutura cristalina que aconteceu no tratamento. O resultado obtido para a dureza da amostra resfriada em salmoura foi menor do que a da amostra resfriada em água gelada.
In the babassu oil extraction industry, several types of by-products are generated, and one of them is the mesocarp, which when dried and ground, is transformed into a flour that is called “Babassu Mesocarp Flour” (BMF). Thus, the use of the BMF as a bio-reinforcement for Poly(Lactic Acid) (PLA) aiming at the production of composite films applied in food packaging is a promising alternative, which leads to the development of new products with added value. Therefore, in this work, before any attempt to produce films, the industrially extracted BMF was characterized for a better understanding of its chemical composition and inherent characteristics. The elemental analysis showed that this raw material is predominantly an organic material, however, it also presented contents of inorganic chemical elements according to the X-ray fluorescence analysis. Its particles exhibited an average diameter of 38.82 µm and a specific surface area of 3.02 m2/g. Through microscopic techniques, mainly by scanning electron microscopy, starch granules in different shapes and sizes were observed, since starch is the main component of the composition of this raw material. The results of X-ray diffraction and infrared spectroscopy showed a structure and functional groups, respectively, typical of starchy materials, evidencing the sustainable and biodegradable character of the BMF. The reported characteristics of the BMF are of great value in PLA-based film formulations, as this combination would reduce impacts on the environment, as both are ecologically correct.
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