Waxd
Mostrando 1-12 de 25 artigos, teses e dissertações.
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1. Time domain NMR evaluation of poly(vinyl alcohol) xerogels
Abstract Poly(vinyl alcohol) (PVA)-based chemically cross-linked xerogels, both neat and loaded with nanoparticulate hydrophilic silica (SiO2), were obtained and characterized mainly through time domain NMR experiments (TD-NMR). Fourier-transform infrared (FT-IR) and wide angle X-ray diffraction (WAXD) analyses were employed as secondary methods. TD-NMR, thr
Polímeros. Publicado em: 08/08/2016
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2. Structural and Thermo-mechanical Evaluation of Two Engineering Thermoplastic Polymers in Contact with Ethanol Fuel from Sugarcane
Special polymers have been used in the manufacture of storage structures and pipelines avoiding corrosive processes during ethanol fuel transport/storage. Therefore, this work investigated comparatively the effects of the ethanol on the physical-mechanical properties of poly (ether ether ketone) (PEEK) and polyamide 11 (PA-11) based on ageing tests. The WAXD
Mat. Res.. Publicado em: 19/02/2016
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3. What Changes in Poly(3-Hydroxybutyrate) (PHB) When Processed as Electrospun Nanofibers or Thermo-Compression Molded Film?
In the present study, PHB film was prepared by thermo-compression molding and PHB nanofibers mat was produced through electrospinning process. The nanofibers morphology was confirmed by SEM. The film and nanofibers crystallinity degree was estimated by different methods. FTIR and WAXD indicated that PHB film is more crystalline than PHB nanofibers. However,
Mat. Res.. Publicado em: 12/02/2016
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4. Effect of Weathering and Accelerated Photoaging on PET/PC (80/20 wt/wt%) Melt Extruded Blend
In this study we investigated the natural weathering of a catalyzed blend of poly(ethylene terephthalate)/polycarbonate PET/PC (80/20wt/wt%). The results were compared to the accelerated photoaging tests. The specimens were characterized by wide angle X-ray diffraction (WAXD), optical microscopy (OM), thermogravimetry (TG/DTG), medium infrared spectroscopy (
Mat. Res.. Publicado em: 25/08/2015
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5. Influence of the beta crystalline phase fraction on the mechanical behavior of polypropylene/calcium carbonate/polypropylene - graft - maleic anhydride composites
The formation of the crystalline phase of polypropylene in the presence of four different types of CaCO3 was studied. All composites were prepared by melt mixing and extrusion and the concentration of CaCO3 was maintained at 5 wt %. Furthermore, in another series of composites, 5 wt % of polypropylene-graft-maleic anhydride (PP-g-MA) was added for comparison
Polímeros. Publicado em: 30/09/2014
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6. The effect of additives interaction on the miscibility and crystal structure of two immiscible biodegradable polymers
Poly lactic acid (PLLA) is a promising biopolymer, obtained from polymerization of lactic acid that is derived from renewable resources through fermentation. The characteristic brittleness of PLLA is attributed to slow crystallization rates, which results in the formation of the large spherulites. Its glass temperature is relative high, above room temperatur
Polímeros. Publicado em: 2014
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7. Characterization and shelf life of β-carotene loaded solid lipid microparticles produced with stearic acid and sunflower oil
Solid lipid microparticles were tested as microencapsulation systems for protecting β-carotene from degradation. Blends of long-chain (C18) solid lipids (70% stearic acid) and sunflower oil (30%) were used to produce lipid microparticles encapsulating the carotenoid. Polysorbate 80 (4%) was employed to stabilize the stearic acid microparticles. The concentr
Braz. arch. biol. technol.. Publicado em: 2013-08
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8. Nanocompósitos de blendas HDPE/LLDPE e OMMT - parte I: avaliação das propriedades termo-mecânicas e da resistência ao intemperismo
Nanocompósitos de blendas de polietileno de alta densidade (HDPE) com polietileno linear de baixa densidade (LLDPE) e OMMT (montmorilonita organofílica) foram preparados sob fusão em extrusora de dupla-rosca, utilizando HDPE-g-MA como agente compatibilizante. A caracterização estrutural foi realizada por análises de difração de raios X em alto ângul
Polímeros. Publicado em: 26/07/2013
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9. Caracterização estrutural de nanocompósitos de blendas HDPE/LLDPE e OMMT obtidos por diferentes sequências de mistura
Nanocompósitos de blendas de polietileno de alta densidade (HDPE) com polietileno linear de baixa densidade (LLDPE) e OMMT (montmorilonita organofílica) foram preparados em um reômetro de torque, utilizando-se como sistema compatibilizante uma mistura de HDPE-g-MA e LLDPE-g-MA, ambos com 1% de anidrido maleico. O efeito de cinco sequências de mistura na
Polímeros. Publicado em: 14/08/2012
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10. Nanocomposites of polyamide 6/residual monomer with organic-modified montmorillonite and their nanofibers produced by electrospinning
Nanocomposites of an organic-modified montmorillonite (MMT) and polyamide 6 (PA6) with a residual monomer were produced by melt mixing in a torque rheometer. By wide angle X-rays diffraction (WAXD), intercalated/exfoliated structures were observed in the PA6/MMT nanocomposites with 3 and 5 wt. (%) of MMT; on the other hand, when 7 wt. (%) of MMT was added, a
Materials Research. Publicado em: 07/08/2012
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11. Characterization of lyophilized liposomes produced with non-purified soy lecithin: a case study of casein hydrolysate microencapsulation
A commercial casein hydrolysate was microencapsulated in liposomes produced with non-purified soy lecithin, cryoprotected with two different disaccharides and lyophilized. The encapsulation efficiency of casein hydrolysate ranged from 30 to 40%. The powders were analyzed by differential scanning calorimetry (DSC), scanning electron micrography (SEM), infrare
Brazilian Journal of Chemical Engineering. Publicado em: 2012-06
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12. Structure and dynamics of poly(9,9-dioctylfluoren-2,7-co-benzothiadiazole) (F8BT) and correlations with its electrical properties / Estrutura e dinâmica molecular do poly (9,9-dioctylfluoren-2,7-diyl-co-benzothiadiazole) (F8BT) e correlações com suas propriedades elétricas.
The PHD project has two main goals. The first one is specifically related to investigations on molecular dynamics, structural conformations and packing of polyfluorene-based polymers. For this purpose, Wide Angle X-Ray Diffraction (WAXD), Solid-State Nuclear Magnetic Resonance (NMR) and Dynamical-Mechanical Thermal Analysis (DMTA) are being used as the main
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 16/09/2011