Extrinsic electrically conducting polymer composites are versatile materials for applications in sensors, electrical components, antistatic coatings, among others. The use of carbon‐based conducting loads, such as graphene, in polymer nanocomposites allows the manufacturing of suitable electrically conducting films for a variety of applications. In our work, graphene sheets are covalently modified with histidine, phenylalanine, or beta‐alanine aminoacids, in order to improve dispersion and impart extrinsic conductivity to poly(vinyl alcohol) (PVA) films. The presence of organic groups in the surface of graphene sheets improved their dispersion in polymer matrices. In addition, such benign surface modifiers are suitable to produce environmentally friendly, electrically conducting loads for polymer nanocomposites. Our findings showed that aminoacid‐functionalized graphenes have good dispersability, resulting in semiconducting nanocomposite films with preserved thermal stability, suggesting that these carbon‐based nanoloads are suitable additives for PVA in applications including antistatic paints and coatings.
Form‐stable solid‐liquid phase change materials (FSSL‐PCM) are capable of latent heat storage by absorbing thermal energy at constant temperature while undergoing solid‐liquid state transitions. We suggest new nanocomposites based on biodegradable polyesters Poly(ϵ‐caprolactone) (PCL), Poly(3‐hidroxybutyrate) (P‐3‐HB) or their blends with Poly(ethylene oxide) (PEO) embedded in the nanopores of thermally expanded natural graphite (EG) as FSSL‐PCM. These nanocomposites are submitted heating‐cooling cycles, in the fusion‐crystallization temperature range, without appreciable changes in thermal stability or latent heat storage capabilities, as assessed by Fourier Transform Infrared (FTIR) Spectroscopy Analysis, Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC). Such materials are suitable as PCMs used as storage media in solar energy‐based low‐medium temperature latent storage systems, for example, water‐heating systems, air‐heating units, solar greenhouses, among others.
Polycarbonate is an engineering polymer due its outstanding properties and is widely used in several different applications. In some of these applications it can be exposed to certain liquids/solvents. In many cases, this liquid exposure may cause an effect known as Environmental Stress Cracking (ESC), which may lead to crack formation on the polymer surface and consequent reduction of its mechanical resistance, with loss of lifetime. On the other hand, polycarbonate medical supplies are often exposed to gamma rays in the radio-sterilization process, at doses up to 25 kGy. This exposure causes main chain scissions. In this present work, the viscosity average molecular weight decreased about 10% at 25 kGy. Elongation at break was drastically affected by ESC phenomenon. When simultaneously exposed to the ESC agents (methanol or isopropanol) and gamma radiation, combined effects of both takes place. Moreover, the stress relaxation rate of ~1000 Pa/s (air or methanol) and ~2200 Pa/s (isopropanol) at the dose of 100 kGy, suggests strong influence of isopropanol as surfactant on PC. Results of elongation at break and stress relaxation rate were reliable data to evaluate ESC and radiolytic effects on PC.
A Biorrefinaria Experimental de Resíduos Sólidos Orgânicos (BERSO) do Departamento de Energia Nuclear da Universidade Federal de Pernambuco (UFPE) produz biodiesel a partir de rejeitos de óleos e gorduras de cozinha produzidos na própria Universidade. Esse tipo de produção do biodiesel aparece como uma alternativa para a produção do biocombustível a partir de utilização de rejeitos. Entretanto, essa produção de biodiesel gera um subproduto, a glicerina bruta, em quantidade aproximada de 10% por litro do biocombustível obtido. Essa alta produção de resíduos traz problemas ambientais se a glicerina bruta for descartada no ambiente sem os devidos cuidados. Entretanto, o aproveitamento desse resíduo exige intensa purificação prévia, que acaba onerando o processo. Neste trabalho, é apresentado um processo simplificado de purificação da glicerina bruta que permitiu aumentar o teor de glicerol inicial, melhorando a viabilidade do processo de purificação. Desta maneira, o reaproveitamento tem o intuito de corroborar com a consolidação do processo sustentável para obtenção do biocombustível pela BERSO fazendo uso do subproduto obtido, o glicerol, que através de um processo de purificação e refinamento da fase bruta gera-se matéria-prima com teor de pureza acima de 80%.Palavras-chave: Biodiesel. Biocombustível. Glicerol. Purificação. Desenvolvimento sustentável. Simple Purification Process of Waste Glycerol from Berso-Ufpe Biorefinary Biodiesel Production: A Sustainable Practice A B S T R A C TExperimental Biorefinery of Solid Organic Waste (BERSO) of Nuclear Energy Department of Federal University of Pernambuco (UFPE) produces biodiesel from waste of oils and fats produced at University. This type of biodiesel production appears as an alternative for the production of biofuel from the use of waste. However, this biodiesel production generates a by-product, crude glycerin, in an approximate amount of 10% per liter of the biofuel obtained. This high production of waste brings environmental problems if crude glycerin is discarded into the environment without due care. However, the use of this residue requires intense prior purification, which ends up burdening the process. In this work,a simplified process of purification of crude glycerin is presented, which allowed to increase the initial glycerol content, improving the viability of the purification process. In this way, the reuse is intended to corroborate the consolidation of the sustainable process for obtaining biofuel by BERSO making use of the by-product obtained, glycerol, which through a process of purification and refinement of the crude phase generates raw material with purity content above 80%.Keywords: Biodiesel. Biofuel. Glycerol. Purification. Sustainable Development.
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