Polymer Degradation
Mostrando 13-24 de 233 artigos, teses e dissertações.
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13. Quantification by FT-IR (UATR/NIRA) of NBR/SBR blends
Abstract Rubber blends are important materials in automotive industry, as well as in other sectors. However, there are implications when suitable use of a polymer in an artifact is not made. In the automotive area, for example, the use of an elastomer without the fuel resistance requirement would result in component degradation, potential fuel leakage, and
Polímeros. Publicado em: 29/11/2018
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14. Non-isothermal decomposition kinetics of conductive polyaniline and its derivatives
Abstract The non-isothermal decomposition kinetics of conductive polyaniline (PANI) and its derivatives, poly(o-methoxyaniline) (POMA) and poly(o-ethoxyaniline) (POEA), was investigated by thermogravimetric analysis (TGA), under inert and oxidative atmospheres, using Flynn-Wall-Ozawa’s approach to assess the kinetic parameters of the decomposition process
Polímeros. Publicado em: 21/09/2018
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15. Rubber gloves biodegradation by a consortium, mixed culture and pure culture isolated from soil samples
Abstract An increasing production of natural rubber (NR) products has led to major challenges in waste management. In this study, the degradation of rubber latex gloves in a mineral salt medium (MSM) using a bacterial consortium, a mixed culture of the selected bacteria and a pure culture were studied. The highest 18% weight loss of the rubber gloves were de
Braz. J. Microbiol.. Publicado em: 2018-09
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16. Chain Elongation Influence in Copolymerization with Different Diesters of Norbornene 2,3-Dicarboxylic Acid Monomers via ROMP under Air Atmosphere
Diesters of norbornene 2,3-dicarboxylic acid (NBE-(COOR)2), in which R is an alkyl group, were synthesized from one-pot synthesis method with 5-norbornene-2,3-dicarboxylic acid and methanol and ethanol. The new monomers were, respectively, the dimethyl ester NBE-(COOCH3)2 and diethyl ester NBE-(COOCH2CH3)2. Norbornene was mixed with these monomers at differe
J. Braz. Chem. Soc.. Publicado em: 2018-06
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17. Preparation, Characterization and Photostability of Nanocomposite Films Based on Poly(acrylic acid) and Montmorillonite
Polyacrylic acid (PAA)/clay mineral (SWy-1) nanocomposites were prepared by intercalation in solution and their photostability was evaluated. For the nanocomposite films containing 5, 10 and 20 wt % in SWy-1 mass occurred intercalation along with some clay exfoliation, while for PAA/30%SWy-1, the intercalation of PAA chains into the clay interlayers was obse
Mat. Res.. Publicado em: 07/05/2018
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18. Replacement of Commercial Silica by Rice Husk Ash in Epoxy Composites: A Comparative Analysis
Since epoxy resins are used as composite matrix with excellent results, and silica is one of the fillers most often employed, this study compared the performance of rice husk ash (RHA) as filler in epoxy composites, in replacement for high-purity silica. Composites were molded containing 20%, 40%, and 60% (wt) silica or RHA. Viscosity analysis, infrared spec
Mat. Res.. Publicado em: 05/04/2018
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19. Degradation of Poly(Ethylene Oxide) Films Using Crystal Violet
The present study aimed to investigate the degradation of poly(ethylene oxide) (PEO) in the presence of cationic dye crystal violet irradiated under visible light. The preparation of the samples was done in the form of films obtained by casting. Degradation tests were carried out by 120 hours at room temperature. The degradation kinetics of the dye and polym
Mat. Res.. Publicado em: 01/02/2018
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20. Use of Amphiphilic Composites based on Clay/Carbon Nanofibers as Fillers in UHMWPE
In this work, it is proposed a new strategy to improve the dispersion of inorganic fillers in polymeric matrices by producing surface carbon nanostructures. Clay/carbon nanofibers particles were prepared and used as fillers to improve the mechanical and thermal properties of ultra-high molecular weight polyethylene (UHMWPE). Thermogravimetry (TG), differenti
J. Braz. Chem. Soc.. Publicado em: 2018-02
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21. In vitro analysis of a local polymeric device as an alternative for systemic antibiotics in Dentistry
Abstract The development of a biodegradable material with antimicrobial properties for local applications is required in the prevention and treatment of infectious diseases. The objective of this study was to produce blends of poly-L-lactide acid (PLLA) synthetic polymer associated with several antimicrobials, as an alternative in the prevention and treatmen
Braz. oral res.. Publicado em: 07/12/2017
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22. Thermal degradation of polymer systems having liquid crystalline oligoester segment
Abstract Block copolymers and blends comprised by liquid crystalline oligoester and polystyrene were prepared and their thermal stability were characterized by thermogravimetric analysis (TGA). The samples have shown three main decomposition temperatures due to (1) lost of flexible chain and decomposition of mesogenic segment, (2) decomposition of polystyren
Polímeros. Publicado em: 2017-12
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23. Evaluation of short-chain-length polyhydroxyalkanoate accumulation in Bacillus aryabhattai
Abstract This study was focused on the polyhydroxybutyrate (PHB) accumulation property of Bacillus aryabhattai isolated from environment. Twenty-four polyhydroxyalkanoate (PHA) producers were screened out from sixty-two environmental bacterial isolates based on Sudan Black B colony staining. Based on their PHA accumulation property, six promising isolates we
Braz. J. Microbiol.. Publicado em: 2017-07
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24. Gamma radiation effect on sisal / polyurethane composites without coupling agents
Abstract Natural fibers and polyurethane based composites may present chemical bonding between the components of the polymer and the lignin of the fiber. The incidence of radiation can cause degradation of the polymeric material and alter its mechanical properties. The objective of this study was to obtain and characterize cold pressed composites from polyur
Polímeros. Publicado em: 29/06/2017