CARLOS GAIA DA SILVEIRA

CARLOS GAIA DA SILVEIRA

Página do item completo

Resultados de Busca

Agora exibindo 1 - 10 de 38

Mechanical evaluation of PVC films modified by electron beam irradiation
2011 - CARDOSO, J.R.; MOURA, E.; SOMESSARI, E.S.R.; SILVEIRA, C.G.; PAES, H.A.; SOUZA, C.A.; MANZOLI, J.E.; GERALDO, A.B.C.
The polyvinyl chloride (PVC) is a technological and low cost polymer. Although this polymer is weather resistant, it presents high sensitivity to high energy irradiation because of the weakness of carbon-chloride bond face to carbon-carbon and carbon-hydrogen bonds [1]. Upon exposure to high energy irradiation, some carbon-chloride bonds are broken to give rise radicals like chlorine and organic chloride that are initiators of two concurrent processes: degradation and crosslinking. The degradation process on PVC is macroscopically observed by discoloration effects, where the material tends to darken or to turn yellow, mainly at a typical sterilization dose of 25 kGy [2]; this process yields hydrogen chloride as a byproduct, it is autocatalytic and it continues after irradiation exposure. By other way, the crosslinking leads to an improvement in thermal resistance and mechanical properties. The aim of this work is to evaluate the mechanical properties of PVC irradiated by electron beam to verify the degradation process. Also, mechanical properties are investigated on styrene grafted PVC by electron beam irradiation using mutual and pre-irradiation methods to verify the mechanical resistance changes of obtained product if grafting process is applied from non-irradiated and from pre-irradiated substrates. The PVC commercial film samples with 210 jam thickness were cut into a dumbbell-shape (gauge length: 25 mm, width: 4.10 mm, area: 0.86 mm2). The grafting media was styrene /butanol-1 mixture in several monomer concentrations (from 10% to 100%). The samples were irradiated on a Job 188 Dynamitron® Electron Beam Accelerator with 1.5 MeV energy. All irradiation procedures were performed in atmosphere air and the irradiation conditions comprised doses from 10 kGy to 100 kGy and dose rates of 2.2 kGy/s and 22.4 kGy/s. The styrene grafted samples were analyzed by gravimetry to determinate the grafting yield; the final values have been averaged from a series of three measurements. The Mid-ATR-FTIR was the spectrophotometer technique used for qualitative/semi-quantitative analysis of grafted samples. The Young's module and tensile strength of pre-irradiated and grafted PVC samples at both methods were measured at a Lloyd LXR tensile tester at a crosshead speed of 10.00 mm/min. We observed the decrease of Young's module and tensile strength with the increase of absorbed dose at pre-irradiated PVC samples, that it indicates degradation process. These mechanical parameters results are discussed to styrene grafted PVC samples.
Effect of ionizing irradiation on tilapia (Oreochromis niloticus) skin
2011 - FROSE, C.A.P.; MOURA, E.; YAMAGUISHI, R.B.; SOMESSARI, E.S.R.; SILVEIRA, C.G.; LEME, E.; GERALDO, A.B.C.; MANZOLI, J.E.
The culture of tropical tilapia (Oreochomis niloticus), as a non-native freshwater fish specie in Brazil, have had importance in the last decade due its fast growing, fast reproduction characteristics, high tolerance of climate variations in our country and high disease resistance. The high demand of whole fish or fillets is related to its good taste. Althought, its skin, that represents from 4.5 % to14 % of fish weight, is a byproduct that is generally discared or sold at low cost to feed mills. The general animal skin composition comprises protein, water, minerals and fatty matter where the relative portions of these materials depends of upon animal specie, age, breed, feeding and other animal habits. The putrecible raw animal skins can be chemically and physically treated to make it in non-putrecible stabilized material; it results in a soft and flexible polymeric material. The chemical process to obtain this material generally involves a crosslinking of carboxyl groups or amino groups of skin proteins and the chemical reactive specie [1]. Also, physical process as UV irradiation have been successfully employed to crosslink collagenous biomaterials and thus, improved some mechanical characteristics [2]. The goal of this work was to study the tilapia skins exposed to ionizing irradiation from electron beams. The raw skins and the chemically degreased skins were the studied materials. The tensile strenght and elongation at break were the mechanical parameters evaluated. The optical microscopy was used to evaluate some histological characteristics in irradiated and non-irradiated samples. Also, the polymeric product obtained when skins are treated with oxidizing ions were used to compare some results. The tilapia raw skins were kindly available by APTA, a governmental agribusiness technological agency. These skins were scales free, slighted and frosted. The skins were irradiated in atmosphere air on a Job 188 Dynamitron® Electron Beam Accelerator with 1.5 MeV energy under comprised doses of 20 kGy and 40 kGy and dose rates of 2.2 kGy/s and 7.4 kGy/s. The mechanical parameters were measured at a Lloyd LXR tensile tester at a crosshead speed of 10.00 mm/min. Irradiated samples shows high integrity and high tensile strength in comparison to the polymeric product obtained by oxidizing ions reaction. These results are discussed.
A dosimetric survey of the DC1500/25/04 electron beam plant installed at IPEN-CNEN/SP
2016 - SOMESSARI, SAMIR L.; KUNTZ, FLORENT; SILVEIRA, CARLOS; BUENO, CARMEN C.; NAPOLITANO, CELIA M.; CALVO, WILSON A.P.; GONÇALVES, JOSEMARY A.C.
In this work we describe a dosimetric survey of the DC1500/25/04 electron beam accelerator installed in the Intense Sources of Radiation Laboratory at IPEN/CNEN-SP. As this accelerator has been used for innumerable applications in radiation processing, product surface and internal doses must be targeted and controlled via operational qualification such as beam energy, beam current, scan width and conveyor speed. The qualification was carried out in order to observe the current performances of the irradiation plant using Alanine (ESR) and CTA (UV Spectrophotometry) dosimeters. Energy (Electron penetration in material) calculations, scanning width/length, homogeneity and irradiation uniformity were evaluated according to ISO/ASTM 51649 and ISO11137-3, as well as process uncertainty establishment.
Analysis of the power system from an electron beam accelerator and the correlation with the theoretical dosimetry for radiation processing
2015 - SOMESSARI, SAMIR L.; SOMESSARI, ELIZABETH S.R.; SILVEIRA, CARLOS G. da; CALVO, WILSON A.P.
A dosimetric survey of the DC1500/25/04 electron beam plant installed at IPEN-CNEN/SP
2015 - KUNTZ, FLORENT; SOMESSARI, ELIZABETH S.R.; SILVEIRA, CARLOS G. da; BUENO, CARMEN C.; CALVO, WILSON A.P.; NAPOLITANO, CELIA M.; GONCALVES, JOSEMARY A.C.; SOMESSARI, SAMIR L.
Analysis of the power system from an electron beam accelerator and the correlation with the theoretical dosimetry for radiation processing
2014 - SOMESSARI, SAMIR L.; SOMESSARI, ELIZABETH S.R.; SILVEIRA, CARLOS G. da; CALVO, WILSON A.P.
Studies of electron beam curing application for coatings on different substrates
1994 - YAMASAKI, M.C.R.; LIMA, W.; SOMESSARI, E.S.R.; SILVEIRA, C.G.; ARAUJO, E.P.
Tratamento de efluentes industriais complexos pelo Processo de Oxidacao Avancada por feixe de eletrons
2001 - DUARTE, C.L.; SAMPA, M.H.O.; RELA, P.R.; OIKAWA, H.; BORRELY, S.I.; SILVEIRA, C.G.; CHERBAKIAN, E.H.; ABE, H.
Needs and emerging opportunities of electron beam accelerators on radiation processing technology for industrial and environmental application in South America
2009 - CALVO, W.A.P.; DUARTE, C.L.; MACHADO, L.D.B.; PINO, E.S.; POLI, D.C.R.; MANZOLI, J.E.; TOBIAS, C.C.B.; MATHOR, M.B.; SOMESSARI, E.S.R.; SILVEIRA, C.G.; SOMESSARI, S.L.; OMI, N.M.; RELA, P.R.
Electron beam accelerator facilities at IPEN-CNEN/SP
2007 - SOMESSARI, SAMIR L.; SILVEIRA, CARLOS G. da; PAES, HELIO; SOMESSARI, ELIZABETH S.R.