Publicações - engenharias
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FERREIRA, PATRÍCIA LOUISE DA SILVA;
SEQUINEL, RODRIGO;
MENDES, MAYARA DE LIMA;
TAMAMOTO, JULIANA YUKARI;
FERREIRA, JOÃO VITOR DA SILVA;
GONGORA, BENHURT;
SILVA, FABIANO ROSA DA;
MONTEIRO, MARCOS ROBERTO;
BARICCATTI, REINALDO APARECIDO;
Carlos Itsuo Yamamoto
Palavra-chave:
biodiesel;
BIOCOMBUSTÍVEIS
Áreas do conhecimento:
Engenharias; Engenharia Química; Biocombustíveis
resumo ...
(pt)
The use of fuel emulsions has garnered increasing attention over the past decade as a potential route to replace fossil fuels with more sustainable and technologically feasible alternatives. This study explores the incorporation of oxygenated biocomponents, such as refined vegetable oil, waste cooking oil, ethanol, and octanol, into diesel B S500 (a blend of diesel containing 10% biodiesel and 500 ppm sulfur). A key challenge associated with the high viscosity of vegetable oils, when used directly without prior transesterification, was successfully addressed by the addition of an ethanol/octanol cosolvent. Acting as a surfactant, the cosolvent enabled the formation of homogeneous and stable emulsions, maintaining stability for up to 90 days. The resulting fuel emulsions exhibited properties, including calorific value, viscosity, cold filter plugging point, oxidation stability, and atmospheric distillation, that were comparable with standard diesel B, ensuring suitability for common fuel applications. Engine performance tests showed similar results to diesel B, with certain formulations significantly reducing hydrocarbon and carbon monoxide emissions. Additionally, formulations incorporating neutralized waste cooking oil delivered promising outcomes, reinforcing the feasibility of repurposing waste oils. Fuel emulsions offer a complementary solution to the existing biodiesel industry, providing an environmentally sustainable alternative, particularly in regions distant from centralized processing facilities for vegetable oils and animal fats.
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MARTINS, M.C.;
LANGARO, E.A.;
FARIAS, M.M.;
Marcelo Henrique Farias de Medeiros
Palavra-chave:
durability of concrete;
sulfate attack;
Reinforced Concrete
Áreas do conhecimento:
Engenharias; Engenharia Civil; Inovação
resumo ...
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PROENÇA, MELISSA;
OLIVEIRA, DAYANA RUTH BOLA;
RISSON, KATHLEEN DALL BELLO DE SOUZA;
POSSAN, EDNA;
Marcelo Henrique Farias de Medeiros
Palavra-chave:
pozolanas;
Resíduos de construção e demolição
Áreas do conhecimento:
Engenharias; Engenharia Civil; Inovação
resumo ...
Abstract The circularity in industrial processes is fundamental to different waste type...
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COSTACURTA DA SILVA, PEDRO GUILHERME;
ALVES, HELTON JOSÉ;
DA SILVA, ELIANE SOARES;
MACHADO, BRUNA;
BORBA, CARLOS EDUARDO;
Fabiano Bisinella Scheufele
Palavra-chave:
biogas;
Purificação de gases;
Modelagem Matemática;
Ácido sulfídrico
Áreas do conhecimento:
Engenharias; Engenharia Química; Engenharia Química
resumo ...
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SCHAFER, BENJAMIN C.;
Jong-hyoung Kim;
Felix Sharipov;
Gyeong-Seok Hwang;
Joost J. Vlassak;
KEITH, DAVID W.
Palavra-chave:
Radiometric force;
Accommodation coefficient;
Direct Simulation Monte Carlo;
Thermal Creep;
perforated structures
Áreas do conhecimento:
Engenharias; Engenharia Mecânica; Fenômenos de Transporte; Dinâmica dos Gases
resumo ...
Lightweight nanofabricated structures could photophoretically loft payloads in near-space. Proposed structures range from microscale engineered aerosols1, to centimetre-scale thin disks with variations in surface accommodation coefficients2,3, to sandwich structures with nanoscale thickness4,5 that might be extended to metre-scale width6,7. Quantitative understanding of how structural and surface properties determine photophoretic lofting forces is necessary to develop a practical flying device. Here we focus on thermal transpiration as the most promising photophoretic mechanism for lofting large devices8 and present a hybrid analytical–numerical model of the lofting force on a structure that consists of two perforated membranes spaced a small distance apart. We identify optimal structural parameters, including device size, membrane perforation density and distribution of the vertical ligaments that connect the two membranes, each as a function of atmospheric altitude. Targeting these optimal parameters, we fabricate structures with a heterogeneous ligament distribution, which efficiently compromises between structural rigidity and photophoretic performance. We measure how lofting forces generated by these structures depend on pressure using gases with three different molecular weights. We observed photophoretic levitation of a 1-cm-wide structure at an air pressure of 26.7 Pa when illuminated by 750 W m−2, about 55% the intensity of sunlight. Lastly, we describe the preliminary design of a 3-cm-radius device with 10-mg payload capacity at 75-km altitudes and discuss horizontal motion control, overnight settling, and applications in climate sensing, communications and Martian exploration. A photophoretic aircraft that can levitate via thermal transpiration is achieved under near-space conditions, providing a potential platform for climate sensing, communications and Martian exploration.
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RISSON, KATHLEEN DALL BELLO DE SOUZA;
PROENÇA, MELISSA PASTORINI;
Dayana Ruth Bola Oliveira;
ZARA, KÁTYA REGINA DE FREITAS;
POSSAN, EDNA
Palavra-chave:
Chemical additives;
Grindability index;
Milling;
Supplementary cementitious materials
resumo ...
Abstract This study aimed to evaluate the effect of mechanoactivation with and without grinding...
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SILVA, RICARDO JÚNIOR DE OLIVEIRA;
karin graf;
LEITE RIBEIRO OKIMOTO, MARIA LUCIA
Palavra-chave:
Polymer Recycling;
Plastic Waste Management;
Mechanical Recycling;
Chemical recycling;
Commodity Polymers
Áreas do conhecimento:
Engenharias; Engenharia de Materiais e Metalúrgica; Materiais Não-Metálicos; Polímeros, Aplicações
resumo ...
With the increasing production and consumption of plastics all over the world, polymer recycling techniques have been extensively studied in the literature. However, polymer recycling still faces some challenges that can hinder its optimal efficiency and sustainability, such as the decentralized origins of plastic waste and contamination. Therefore, understanding the intricacies of existing recycling methods plays a crucial role in advancing the management of plastic waste. This article provides a comprehensive overview of the polymer recycling techniques, examining mechanical, chemical, and thermal methods applied to commodity polymers (PET, HDPE, PVC, LDPE, PP, and PS) and selected thermosets (unsaturated polyester resin, phenolic, and epoxy resins). The review shows that although mechanical recycling is the most used method for thermoplastics because of its simplicity and cost-effectiveness, it still faces significant challenges regarding the degradation of mechanical properties and contamination. As for chemical recycling, it is regarded as a promising option to convert polymer waste into high-quality components; however, factors such as economic viability and technological and chemical reaction complexity still pose a significant challenge in the scalability of this technique. Thermal recycling, in turn, is responsible for generating thermal energy from urban solid waste. It enables the use of plastics that are difficult to reprocess through mechanical and chemical recycling routes. Nevertheless, some concerns remain regarding gas emissions and environmental impact.
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CALDONAZO, ALINE;
MALUCELLI, LUCCA CENTA;
FRANCO, TALITA SZLAPAK;
GRACIELA INES BOLZON DE MUÑIZ;
CADEMARTORI, PEDRO HENRIQUE GONZALEZ DE;
FLORES-SAHAGUN, THAIS HELENA SYDENSTRICKER
Palavra-chave:
nanocellulose;
renewable sources;
tensile strength, rheology;
mechanical reinforcement
resumo ...
(en)
Renewable natural sources have been recently used to produce nanocellulose for the mechanical reinforcement of polymers. Cortaderia selloana (a.k.a. pampas grass) is a worldwide spread grass species, being able to grow even at extreme climatic situations, like high temperatures, arid soil and sunny regions. Although it is capable of offering a relatively abundant quantity of lignocellulosic material, it was not considered before its utilization for technological ends. This study proposes a protocol of chemical and mechanical treatments that allowed the production of nanocellulose from this source and performed characterization techniques that evaluate the influence of these treatments on its morphological (width in the nanoscale), chemical, rheological and physical characteristics, allowing its further application. The obtained cellulose nanofiber (CNF) was used to improve characteristics of a well-known but underused polymer, the polyvinyl acetate (PVAc) commercial emulsion. The nanocomposites (PVAc-CNF) showed an improvement of the thermal and mechanical properties, and an addition of just 1.25% of CNF resulted in an increase of the tensile strength from ˜42 to ˜78 MPa and enhanced the thermal stability. The results obtained suggests an effect of defibrillation intensity on the rheological behavior and crystallinity index of the CNF, as well over the performance as a nanofiber for the PVAc matrix, where less defibrillated material showed a high viscosity and crystallinity index but was less effective on the mechanical reinforcement of the polymer. Suggesting that for each botanical species that could be considered for nanocellulose production it is important to evaluate the impact of the processing on the overall quality of the material and how it will implicate its application.
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Roger Borges;
Lilian F. M. do Amaral;
Camila Cristina Vieira Velloso;
Ludimila Araujo Lodi;
Joslaine Jacumazo;
WYPYCH, FERNANDO;
Caue Ribeiro de Oliveira
Sustainability Science and Technology,
v. 2,
p. 032002
2025
Palavra-chave:
Chrysotile;
asbestos;
detoxification
Áreas do conhecimento:
Ciências Exatas e da Terra; Química; Engenharia e Ciencia de Materiais; Materiais de Baixa Dimensionalidade Estrutural;
Engenharias; Engenharia Química; Meio ambiente
resumo ...
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MARTINS, MONALISA COELHO;
SILVA, ANELIZE SENISKI;
BRANDÃO CAPRARO, ANA PAULA;
REMENCHE, IGOR ROSSI;
Marcelo Henrique Farias de Medeiros;
DE SOUZA, DIEGO JESUS
Palavra-chave:
sulfate attack;
fertilizer factories;
Reinforcement corrosion;
migration coefficient;
microstructural changes;
durability of concrete
Áreas do conhecimento:
Engenharias; Engenharia Civil; Inovação
resumo ...
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