Gel Permeation Chromatography
Mostrando 1-12 de 230 artigos, teses e dissertações.
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1. A Greener Enzymatic Oligoesterification of Biobased Renewable Synthons
Polyesters of xylitol and succinic acid were prepared yielding from 70 to 75% by enzyme-catalyzed esterification using a molar mass from 1:1 to 2:5 at 120 and 140 °C employing from 1 to 10% m/m of enzyme. Control over branching degree was achieved by tuning the reaction conditions (temperature, time, comonomer ratio, enzyme content). This one-step process f
J. Braz. Chem. Soc.. Publicado em: 2021-06
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2. Structural characterization and bioactivities of a polysaccharide from the stalk residue of Pleurotus eryngii
Abstract The structural characterization and bioactivities of a polysaccharide from the stalk residue of Pleurotus eryngii were investigated. Firstly the stalk residue of P. eryngii was collected from the top portion of spent mushroom substrate and processed to yield water-soluble polysaccharide. Subsequently this crude polysaccharide was purified by DEAE Se
Food Sci. Technol. Publicado em: 2020-06
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3. Lithium catalyst concentration influence on bio-polyols structure and polyurethane adhesives properties
ABSTRACT Polyol structure can be affected by the catalyst used for its synthesis and may affect the curing kinetics and mechanical strength of the final polyurethane (PU). This work aimed to study the influence of catalyst concentration on the structure of bio-based polyols and on the final properties of the polyurethane adhesive obtained from these polyols.
Matéria (Rio J.). Publicado em: 16/09/2019
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4. Obtenção e caracterização de copolímeros de Poliacrilonitrila (PAN) para uso em processos de fiação em extrusora
RESUMO A disponibilidade de novos materiais, processos e equipamentos sempre traz perspectivas favoráveis ao mercado. A busca por processos alternativos e pela redução do custo da obtenção de precursores de materiais de alto desempenho tem se tornado primordial para o desenvolvimento do setor industrial de produtos com valores mais acessíveis, visando
Matéria (Rio J.). Publicado em: 16/09/2019
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5. Model Molecules for Evaluating Asphaltene Precipitation Onset of Crude Oils
Predicting the compatibility of crude oils from different streams can be done by applying models that use the solubility parameter of the oils. The approximate solubility parameter value of a given crude oil can be calculated by observing the asphaltene precipitation onset caused by titration with n-heptane. For oils whose precipitation onset is not well def
J. Braz. Chem. Soc.. Publicado em: 23/05/2019
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6. Synthesis and characterization of the photoswitchable poly(methyl methacrylate- random-methacrylate spirooxazine)
Abstract The photoswitchable poly(methyl methacrylate-random-methacrylate spirooxazine) was synthesized via atom transfer radical polymerization with the feed mole ratio of MMA/MSp comonomer of about 5.5/1. Well-defined poly(methyl methacrylate- random-methacrylate spirooxazine) have been obtained with the average molecular weight (Mn) of 6500 g/mol and pol
Polímeros. Publicado em: 18/03/2019
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7. Influence of solvent used on oxidative polymerization of Poly(3-hexylthiophene) in their chemical properties
Abstract The aim of the study is to utilize the simplicity of oxidative polymerization with ferric chloride to originates poly(3-hexylthiophene) of lower molecular weight. So, the chloroform, in general used as solvent in this synthesis, was switched by dichloromethane. The obtained polymers were characterized by infrared spectroscopy (FTIR), ultra-violet v
Polímeros. Publicado em: 21/09/2018
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8. Exopolysaccharide production from Bacillus velezensis KY471306 using statistical experimental design
Abstract Exopolysaccharide (EPS) biopolymers produced by microorganisms play a crucial role in the environment such as health and bio-nanotechnology sectors, gelling agents in food and cosmetic industries in addition to bio-flocculants in the environmental sector as they are degradable, nontoxic. This study focuses on the improvement of EPS production throug
Braz. J. Microbiol.. Publicado em: 2018-09
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9. Ultrasound assisted miniemulsion polymerization to prepare poly(urea-urethane) nanoparticles
Abstract Recently, the physical and chemical effects of ultrasound in polymeric materials synthesis have attracted great attention. This work presents the synthesis of novel polymeric materials by polymerization of isophorone diisocyanate with different polyols. Polymers were synthesized by step miniemulsion polymerizations, using ultrasound bath and thermo
Polímeros. Publicado em: 21/05/2018
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10. Effect of solvents on the morphology of PMMA films fabricated by spin-coating
Abstract A method to produce thin layer of PMMA (poly (methyl methacrylate) films by spin coating is reported. PMMA is dissolved in xylene, a mixture of MIBK-xylene and chloroform. Varying the PMMA concentration and spin-coating speeds controls the thickness of the PMMA films. Using chloroform as solvent evidenced thickness around 10 μm. This thickness is s
Polímeros. Publicado em: 21/09/2017
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11. Novos surfactantes alquil poliglicosídicos à base de amilose extraída da batata inglesa (Solanum tuberosum L.)
Alkyl polyglycosides (APGs) are new biodegradable surfactants, non-toxic, synthesized from abundant renewable sources, potentially more appropriate than anionic surfactants. A range of glycosides denoted APG-Cy was synthesized by the Köenig-Knorr reaction using C10, C16 and C18 alcohols and derived from the degradation of amylose from English potato. The mo
Quím. Nova. Publicado em: 2017-04
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12. AN ALTERNATIVE ROUTE TO PRODUCE STANDARDS FOR GEL PERMEATION CHROMATOGRAPHY USING NITROXIDE MEDIATED POLYMERIZATION
Abstract All over the world standards for Gel Permeation Chromatography (GPC) are produced using ionic polymerization. Standards are commercialized in a broad range of molecular weight and their dispersity (Ð) must be lower than 1.1. This work proposes the synthesis of polystyrene standards using Nitroxide Mediated Polymerization (NMP), an alternative techn
Braz. J. Chem. Eng.. Publicado em: 2017-01