Polymer Degradation
Mostrando 1-12 de 233 artigos, teses e dissertações.
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1. Method for Cleaning Back-Produced Water from Polymer Flooding Operations to Determine Polymer Molar Mass Using Size-Exclusion Chromatography
One of the methods used by the oil industry to increase production is to inject water, containing polymer, into the reservoir. The viscosity of the aqueous solution is primarily responsible for the efficiency of this method, and is achieved using polymers with high molar mass. However, polymer degradation can occur during pumping and fluid displacement in th
J. Braz. Chem. Soc.. Publicado em: 2020-12
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2. Characterization of Nanocellulose Obtained from Cereus Forbesii (a South American cactus)
Crystalline cellulose nanofibers are obtained from the bark of Cereus Forbesii, a cactus native to the arid areas of South America. The obtaining of cellulose nanofibers was carried out in several steps: pretreatment of the raw material, elimination of hemicellulose and lignin to obtain cellulose, and an acid hydrolysis of cellulose to obtain crystalline cel
Mat. Res.. Publicado em: 20/01/2020
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3. Weathering Resistance of Waterborne Polyurethane Coatings Reinforced with Silica from Rice Husk Ash
Abstract: Waterborne polyurethanes (WPUs) are interesting materials for coatings when compared to solvent-based polyurethanes, once that reducing the concentration of volatile organic compounds that are harmful for human health and the environment. However, the WPU has low weathering resistance. In order to improve this behavior among others properties, ino
An. Acad. Bras. Ciênc.. Publicado em: 25/11/2019
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4. Microbial Synthesis and Characterization of Biodegradable Polyester Copolymers from Burkholderia Cepacia and Cupriavidus Necator Strains Using Crude Glycerol as Substrate
Abstract Polymers are materials of pronounced importance in the modern world, since they are massively present in everyday life, especially in the form of packaging. However, most of these materials are derived from non-renewable sources and their disposal generates large volumes of waste, which is extremely damaging to natural environments. In this context,
Braz. arch. biol. technol.. Publicado em: 24/10/2019
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5. Fotodegradação de hidrogel de poliacrilamida na presença de substâncias químicas para o uso na agricultura
RESUMO Utilizado na agricultura como condicionante do solo, a poliacrilamida, constituinte básico do hidrogel, tem a característica de absorver, por processo físico, água e a estocar para as plantas conforme sua necessidade hídrica. Entretanto, a poliacrilamida sofre degradação de sua cadeia, devido à ação da radiação ultravioleta e de sais prese
Matéria (Rio J.). Publicado em: 16/09/2019
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6. Avaliação da utilização da pós cura nas propriedades térmicas e mecânicas de um sistema epóxi de cura à temperatura ambiente
RESUMO Neste trabalho, uma resina epóxi de cura a temperatura ambiente foi submetida a ciclos térmicos de pós cura para verificar as alterações nas propriedades térmicas e mecânicas finais do material. As amostras foram obtidas por vazamento em molde metálico e os ciclos de pós cura foram realizados a 75°C, 90°C, 110°C por uma hora e um ciclo de
Matéria (Rio J.). Publicado em: 16/09/2019
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7. SENSITIVITY ANALYSIS FOR MODEL COMPARISON AND SELECTION IN TISSUE ENGINEERING
ABSTRACT Computational modeling has been proven to be very useful in tissue engineering over the past years. Because the model is a simplification of the experimental system, the processes accounted for in the model should be analyzed carefully. However, new and complex models are usually proposed without a clear comparison with the basic ones. In this study
Braz. J. Chem. Eng.. Publicado em: 15/07/2019
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8. ASSESSMENT OF POLYHYDROXYALKANOATE SYNTHESIS IN SUBMERGED CULTIVATION OF Cupriavidus necator AND Burkholderia cepacia STRAINS USING SOYBEAN AS SUBSTRATE
ABSTRACT Polyhydroxyalkanoates (PHA) are biocompatible and biodegradable polyesters produced by prokaryotic microbes for energy storage and carbon reserve. These polymers are an option to diminish the massive impact caused by inadequate disposal of synthetic plastics. In this study, evaluation and characterization of PHA produced by Cupriavidus necator (IPT
Braz. J. Chem. Eng.. Publicado em: 15/07/2019
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9. Mechanical and bioactivity assessment of wollastonite/PVA composite synthesized from bentonite clay
Resumo Os compósitos de vidro/polímero podem imitar a estrutura natural do osso possuindo uma configuração fibra-matriz que proporciona propriedades físicas e biológicas apropriadas. As cerâmicas de wollastonita são conhecidas por suas bioatividade e biocompatibilidade promissoras quando aplicadas na regeneração óssea. O álcool polivinílico (PVA
Cerâmica. Publicado em: 06/06/2019
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10. Avaliação do efeito do tratamento corona na performance de estabilizadores de UV em filmes de PEBD
RESUMO A indústria de polímeros tem passado por muitos avanços na última década, dentre eles, podem-se citar as inovações em processamento e no uso de aditivos, o que permite que eles sejam utilizados em diversas aplicações, especialmente quando expostos ao ambiente externo. Porém, para algumas aplicações específicas, o polímero precisa ser sub
Matéria (Rio J.). Publicado em: 20/05/2019
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11. The Effect of Red Pigment and Photo Stabilizers on the Photo Degradation of Polypropylene Films
The aim of this work was to evaluate the photo degradation of PP films containing photo stabilizers, a ultraviolet absorber and a hindered amine light stabilizer (HALS), and a red pigment. The films were produced by extrusion and exposed to the UV radiation in the laboratory for up to 15 weeks. The results obtained from FTIR, UV-vis and colorimetry showed th
Mat. Res.. Publicado em: 11/04/2019
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12. Morphological, thermal and bioactivity evaluation of electrospun PCL/β-TCP fibers for tissue regeneration
Abstract Electrospinning is a simple and low-cost way to fabricate fibers. Among the various polymers used in electrospinning, polycaprolactone (PCL) stands out due to its excellent biodegradability and biocompatibility. However, PCL has some limitations such as low bioactivity, hydrophobic surface, and long in vivo degradation. Calcium phosphate ceramics h
Polímeros. Publicado em: 18/03/2019