Polyesters
Mostrando 1-12 de 56 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. 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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3. Stabilization effect of kraft lignin into PBAT:Thermal analyses approach
ABSTRACT Sterically hindered phenols are an important class of synthetic antioxidants for polymers, commonly incorporated to inhibit polyolefins or polyesters oxidation. However, synthetic antioxidants use is under restricted regulation due to their potential health risk and environmental impacts. Thus, great interest has been attracted to the phenol-based n
Matéria (Rio J.). Publicado em: 16/09/2019
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4. 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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5. Evaluation of Techniques for Determination of Hydroxyl Value in Materials for Different Industrial Applications
ABSTRACT When some materials need to be characterized, the hydroxyl number (IOH) determination is especially useful, mainly for those applied in the aerospace field. Usually, this characterization is performed by wet chemistry, using methodologies involving several steps, such as derivatization. This is a time-consuming and costly step. On the other hand, wh
J. Aerosp. Technol. Manag.. Publicado em: 04/04/2019
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6. The influence of natural clay and organoclay vermiculite on the formation process of bionanocomposites with poly (3-hydroxybutyrate-co-3-hydroxyvalerate)
ABSTRACT During the last decades, a lot of research work focused on several biodegradable and biosourced polyesters for the purpose of reducing the non-degradable polymer wastes. These polyesters are particularly considered to be promising polymers for biomedical applications and short life-time products like packaging. As these packagings are rapidly discar
Matéria (Rio J.). Publicado em: 02/10/2017
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7. Preparation and properties of aromatic polyester/TiO2 nanocomposites from polyethylene terephthalate
The development of polyester based materials with enhanced properties as well as the use of post- consumer plastics as raw material has been an increasing market demand. This work aims the synthesis and characterization of aromatic polyesters/titanium dioxide nanocomposites from PET and using TiO2 (0, 1, 3 and 5% w/w) as filler by in situ polymerization. The
Mat. Res.. Publicado em: 05/02/2016
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8. MÉTODOS DE EXTRAÇÃO DE POLI-HIDROXIALCANOATOS A PARTIR DE BIOMASSA BACTERIANA
Polyhydroxyalkanoates (PHAs) are biodegradable and biocompatible polyesters intracellularly accumulated by many bacteria as an energy reserve material and carbon source. These biopolymers may be extracted from cells after their production phase, and the extraction process involves various individual operations to ensure adequate removal of the biopolymer fro
Quím. Nova. Publicado em: 2015-11
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9. Biodegradation of films of low density polyethylene (LDPE), poly(hydroxibutyrate-co-valerate) (PHBV), and LDPE/PHBV (70/30) blend with Paecilomyces variotii
The increased consumption of plastics in the world has been a subject of great concern and special attention by the scientific community. The aim is to promote development of materials that are biodegradable in a shorter time upon disposal in the environment. The most used synthetic plastics are difficult to biodegrade because they are made of long hydrocarb
Polímeros. Publicado em: 2015-02
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10. Aplicações de enzimas na síntese e na modificação de polímeros
Enzymes are biological catalysts that offer great potential for use in the synthesis and modification of polymers, being more specific and greener than chemical catalysts. In this work, enzymes from the classes of hydrolases (lipase, cutinase and protease) and of oxidoreductases (horseradish peroxidase, manganese peroxidase and laccase) were identified as th
Quím. Nova. Publicado em: 2014
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11. Effect of hyperbranched polyesters on HTPB polyurethane curing kinetic
Effects of hyperbranched polyesters on kinetics of the reaction between hydroxyl-terminated polybutadiene (HTPB) and isophorone diisocyanate (IPDI) were investigated. HTPB and IPDI were in-situ cured in the presence of two different hyperbranched polyesters, stearic acid ester-terminated hyperbranched polyester (SHPE) and acetate-terminated hyperbranched pol
Mat. Res.. Publicado em: 03/12/2013
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12. Synthesis and characterization of polyesters from glycerol by-product of biodiesel production
Glicerol, um sub-produto da produção de biodiesel, pode reagir com ácidos di-carboxílicos, resultando em poliésteres, e ser usado na composição de resinas do tipo uréia/formaldeído ou fenol/formaldeído para melhorar as qualidades de aderência e resistência à umidade dessas resinas. Neste trabalho, foram sintetizados seis tipos de resinas derivad
Journal of the Brazilian Chemical Society. Publicado em: 2012-07