LUIZ GUSTAVO HIROKI KOMATSU

LUIZ GUSTAVO HIROKI KOMATSU

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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.
Processing and antimicrobial efficacy of polypropylene/montmorillonite/silver nanocomposites as food packaging films
2016 - OLIANI, WASHINGTON L.; KOMATSU, LUIZ G.H.; LINCOPAN, NILTON; RANGARI, VIJAYA K.; LUGAO, ADEMAR B.; PARRA, DUCLERC F.
The aim this study was to use nanocomposites of polypropylene (PP), montmorillonite (MMT) and silver nanoparticles (AgNPs), prepared by melt intercalation in a twin-screw extruder, as a food packaging bactericide material. The use of nanoclay and nanosilver as additives for polymer matrices requires, in some cases (with non-polar matrices) the use of a compatibilizer agent which will act as a bridge or permanent buffer for nanoclay-nanosilver-matrix interaction. As compatibilizer agent it has been used a propylene graft maleic anhydride copolymer (PP-g-MA). The nanocomposites were evaluated by differential scanning calorimetry (DSC), X-Rays diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and determination of antibacterial activity. The results indicate the formation of microstructures predominantly exfoliated. Further, the antibacterial properties of the films were investigated against Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive) bacteria.
Thermal-oxidation behaviour of modified polypropylene nanocomposites obtained in molten state
2014 - KOMATSU, L.G.H.; OLIANI, W.L.; LUGAO, A.B.; PARRA, D.F.
Preparation and characterization of HMPP/MMT/silver nanocomposite films with antibacterial activity
2015 - OLIANI, WASHINGTON L.; KOMATSU, LUIZ G.H.; BERENGUER, ISABELLE; LINCOPAN, NILTON; RANGARI, VIJAYA K.; LUGAO, ADEMAR B.; PARRA, DUCLERC F.
Nanocompósitos de polipropileno (HMSPP)/argila montmorilonita: avaliação das propriedades térmicas e mecânicas
2014 - KOMATSU, L.G.H.; OLIANI, W.L.; LUGAO, A.B.; PARRA, D.F.
Microscopy, a vital technique for the study of microgels and nanogels polypropylene modified by gamma irradiation
2011 - OLIANI, W.; PARRA, D.F.; KOMATSU, L.G.; RIELLA, H.G.; LIMA, L.F.C.P.; LUGAO, A.B.
Thermooxidative degradation of HMSPP/CLAY nanocomposite
2013 - KOMATSU, LUIZ G.H.; OLIANI, WASHINGTON L.; LUGAO, ADEMAR B.; PARRA, DUCLERC F.