LUIZ GUSTAVO HIROKI KOMATSU

LUIZ GUSTAVO HIROKI KOMATSU

Página do item completo

Resultados de Busca

Agora exibindo 1 - 10 de 17

Nanocomposites foams of polypropilene modified by ionizing radiation containing CaCo3/ag° nanoparticles of bio-calcium carbonate-study of bactericidal effect
2019 - PARRA, DUCLERC F.; SILVA, ORELIO L. da; KOMATSU, LUIZ G.; CARDOSO, ELIZABETH C.L.; LUGAO, ADEMAR B.
This paper presents a study of high melting strengh polypropylene (HMSPP) foams by gamma irradiation with insertion of silver nanoparticles (AgNPs) adsorbed in carrier of CaCO3 (natural source) aiming bactericidal effect. The use of silver (Ag°) gives important antibacterial property since silver is highly toxic against bacterae. The HMSPP matrix was processed in a twin screw extruder under CO2 atmosphere and polypropylene nanocomposites (HMSPP-AgNC) were obtained in different concentrations of silver. The material was characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), field emission scanning electron microscopy (FESEM), X-ray diffraction spectroscopy (XRD), cytotoxicity assay and reduction colony-forming-unit (CFU). The analyzed foams showed spherical clusters and homogeneous regions with good distribution of the silver nanoparticles. Furthermore, the HMSPP@AgNCs foams exhibited a antibacterial efficiency against E. coli and S. aureus due to the presence of the biocidal silver nanoparticles.
AgNPs@ZnO hybride nanoparticles infused thermoplastic polyester elastomer and their biocide effect
2021 - PARRA, DUCLERC F.; MARCHINI, LEONARDO G.; KOMATSU, LUIZ G.H.; OLIVEIRA, CAMILA B. de; OLIANI, WASHINGTON L.; RANGARI, VIJAYA K.
This paper presents research results of biocidal effect of thermoplastic- polyester-elastomer (TPE-E) with incorporation of hybrid Ag/ZnO/SiO2 NPs (silver/Zinc oxide/SiO2 nanoparticles). These results were compared with various gamma-irradiated doses and processing techniques including extrusion, injection molding and compression molding. In all these processing techniques the TPE-E was mixed with mineral oil and Ag/ZnO/SiO2 nanoparticles. The TPE-E nanocomposites were characterized by differential scanning calorimetry (DSC), thermogravimetry analysis (TGA), Infrared FT spectroscopy (FTIR), surface enhanced Raman technique (SERS), FESEM (Field emission scanning electron microscopy), Energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), TEM (transmission electronic microscopy) and antimicrobial test. Antibacterial activity against E. coli and S. aureus, are reported and these results showed potential application in health care products.
Study of stability in gamma irradiation of luminescent film of PMMA with Eu(3+)/AG nanoparticles
2019 - LIMA, VINICIUS da S.; KOMATSU, LUIZ G.H.; LUGAO, ADEMAR B.; PARRA, DUCLERC F.
Lanthanides, which are part of rare earths, have attracted attention due to their optical properties not only in research field, but also, in industrial and technological areas. Eu3+ ions are among the most studied of the rare earth complexes because they present higher luminescence, due to the structures of their energy levels. The combination with ligands of high molar absorptivity can promote a higher emission of the rare earth ions. The luminescent polymer system used as markers was obtained from doping with rare earth complexes, incorporating a Europium complex containing tenoyltrifluoroacetonate (TTA) and triphenylphosphine oxide (TPPO) anion in the process of encapsulating silver nanoparticles in methyl polymethacrylate (PMMA). The luminescent and thermal properties of the material were analyzed in the luminescent films before and after exposure to ionizing radiation in a 60Co source at doses of 10, 30 and 50 kGy. The TTA ligand undergoes decay of the luminescence when the precursor complex is exposed to ionizing radiation. Once doped in the PMMA polymer matrix it will be possible to protect stabilizing the luminescence of the complex. The study of the luminescence properties was performed by the spectrofluorimetry technique. The thermal properties and the decomposition profile of the material were obtained by the Thermogravimetric Analysis (TGA / DTG) in N2 atmosphere. To investigate the enthalpic variations of the samples, the Differential Exploration Calorimetry (DSC) technique was used in N2 atmosphere.
Fabrication of polypropylene/silver nanocomposites for biocidal applications
2017 - OLIANI, WASHINGTON L.; PARRA, DUCLERC F.; KOMATSU, LUIZ G.H.; LINCOPAN, NILTON; RANGARI, VIJAYA K.; LUGAO, ADEMAR B.
This paper presents a study on biocidal effect of polymer nanocomposite films of gamma irradiated polypropylene (PP) and silver nanoparticles. The modified polypropylene was obtained from isotactic polypropylene (iPP) in pellets form by irradiation with gamma rays in the presence of acetylene. A new morphology with long chain branching of PP and distinct rheology is obtained by this process. The blend of 50/50 wt neat PP and PP modified by gamma radiation were further mixed using a twin screw extruder. The AgNPs were infused into this polymer blend at different concentrations of: 0.1%; 0.25%; 05%; 1.0%; 1.0% (PVP), 2.0% and 4.0% by wt%. These polymer nanocomposites were characterized by Raman spectroscopy, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), thermogravimetric analysis (TG), differential scanning calorimetry (DSC), X-ray diffraction (XRD), transmission electron microscopy (TEM), cytotoxicity test and Kirby-Bauer disk diffusion techniques. The bactericidal effect of Pseudomonas aeruginosa (P. aeruginosa) and Staphylococcus aureus (S. aureus) were assessed in detail.
Nanogels of the polypropylene modified by gamma irradiation and incorporation of AgNPs biocide
2016 - OLIANI, WASHINGTON L.; KOMATSU, LUIZ G.H.; LUGAO, ADEMAR B.; PARRA, DUCLERC F.
The objective of this work is to study the formation of nanogel and microgel in modified polypropylene (PP) and incorporation of silver nanoparticles. The PP in pellets was modified by gamma irradiation of pristine PP under a crosslinking atmosphere of acetylene in doses of 5, 12.5 and 20 kGy, followed by thermal treatment for radical recombination and annihilation of the remaining radicals. Thin film of polypropylene gel was obtained by extraction in boiling xylene for period of 12 hours at 138 °C, followed by decantation in beaker at room temperature of 25°C with the total volatilization of the xylene. Deposition of dried material on fine glass blades under agitation by settling process formed films containing nanosilver. The thin films of gel AgNPs formed of pristine PP, as well as, modified (i.e., irradiated) were characterized using Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDX), Atomic Force Microscopy (AFM), X-Ray diffraction (DRX), Differential Scanning Calorimetry (DSC) other than determination of antibacterial activity. The PP morphology indicated the nanogels and microgel formation with increase of spherulites concentration and crystallinity at dose 12.5 kGy. Further, the antibacterial properties of the gel-AgNPs polypropylene were investigated against Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive) bacteria.
Nanocomposites based on polypropylene with nanosilver particles and antibacterial behavior – a review
2016 - OLIANI, W.L.; PARRA, D.F.; KOMATSU, L.G.H.; LINCOPAN, N.; RANGARI, V.K.; LUGAO, A.B.
This paper presents a study of polypropylene (PP) films modified by gamma irradiation with insertion of silver nanoparticles (AgNPs) and montmorillonite (MMT) aiming bactericide effect. The use of silver (Ag) gives important antibacterial property since silver is highly toxic for bacteria. The PP matrix was processed in a twin screw extruder and polypropylene nanocomposites (PPNC) were obtained in different concentrations of 0.25%; 0.5%; 1.0%; 2.0% and 4.0% in wt% and 1% of MMT. The material was characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), field emission scanning electron microscopy (FESEM), X-ray diffraction spectroscopy (XRD), cytotoxicity assay and reduction colony-forming-unit (CFU). The analyzed films showed spherical clusters and homogeneous regions with good distribution of the silver nanoparticles. Furthermore, the PP@AgNPs films exhibited a strong antibacterial efficiency against S. aureus, E. coli and P. aeruginosa due to the presence of the biocidal silver nanoparticles.
Análise da degradação dos nanocompósitos de polipropileno modificado sob condições de envelhecimento acelerado em estufa e natural
2016 - KOMATSU, L.G.H.; OLIANI, W.L.; LUGAO, A.B.; PARRA, D.F.
O entendimento dos mecanismos de degradação que agem sob os nanocompósitos polimericos frente ao intemperismo (luz UV, calor, chuva ácida e entre outros), é o ponto chave para o desenvolvimento de novos aditivos. Para esta análise, as amostras de nanocompósitos de polipropileno modificado por radiação gamma foram obtidos por meio de processamento em extrusora de dupla rosca. Posteriormente estas amostras foram submetidas a ensaios de envelhecimento acelerado em estufa e envelhecimento natural. Os efeitos dos ensaios de envelhecimento foram avaliados por meio das técnicas de, Calorimetria Exploratória Diferencial (DSC), Espectroscopia de Infravermelho pela Transformada de Fourier (FT-IR), Índice Carbonila (IC), Índice de Fluidez (IF), Espectroscopia de Energia Dispersiva (EDS) e Microscopia Eletrônica de Varredura (MEV). Com o decorrer do ensaio de envelhecimento foi possível realizar uma correlação entre o índice de carbonila e índice de fluidez durante o processo degradativo.
Estudo comparativo de nanocompósitos de polipropileno modificado sob condições de envelhecimento ambiental e acelerado
2016 - KOMATSU, LUIZ G.H.
O entendimento dos mecanismos de degradação que agem sob os nanocompósitos poliméricos frente ao intemperismo (luz UV, calor, oxigênio, chuva ácida, entre outros), é o ponto chave para o desenvolvimento de novos aditivos e novas aplicações. Para este trabalho a síntese do nanocompósito foi realizada no estado fundido, utilizando-se uma extrusora de dupla rosca. A matriz polimérica utilizada foi o HMS-PP (polipropileno com alta resistência do fundido) sintetizado por irradiação gama e a argila Montmorilonita. Para melhor compatibilização entre a matriz e a nanocarga, foi utilizada o agente compatibilizante andrido maléico. Para os ensaios de envelhecimento ambiental e acelerado em estufa, os corpos de prova foram confeccionados por meio de termoprensagem. A caracterização dos efeitos da adição de argila e do envelhecimento nos nanocompósitos, presupôs o emprego das técnicas de ensaios mecânicos, Calorimetria Diferencial Exploratória (DSC), Termogravimetria (TGA), Espectroscopia no Infravermelho por Transformada de Fourier (FT-IR), Espectrometria de Fluorescêcia de Raios X por Dispersão de Comprimento de Onda (WDXRF), Microscopia Eletrônica de Varredura (MEV), Índice de Fluidez (IF), Difração de Raios-X (DRX) e Espectroscopia de Energia Dispersiva (EDS). Foram ensaiadas amostras com 0,1; 1; 3; 5 e 10% de argila. A amostra com porcentagem de 5% de argila demonstrou uma melhor estabilidade frente ao ensaio de envelhecimento ambiental e no envelhecimento acelerado em estufa. Por outro lado na amostra com maior porcentagem de argila (10%) ocorreu o inverso, sob ensaio ambiental houve maior degradação e sob envelhecimento acelerado em estufa, manteve-se resistente até 56 dias de envelhecimento. Nas porcentagens estudas (menor que ≤ 3%) de argila, pode-se constatar um equilíbrio entre o efeito barreira da argila e a ação dos íons metálicos que aceleram o processo degradativo.
Estudo da foto-oxidação de nanocompósitos de polipropileno com cloisite 20 A
2013 - KOMATSU, LUIZ G.H.; OLIANI, WASHINGTON L.; PARRA, DUCLERC F.
Estudo da degradação ambiental de nanocompósitos de polipropileno com cloisite 20 A
2011 - KOMATSU, LUIZ G.H.; OLIANI, WASHINGTON L.; PARRA, DUCLERC F.