LUIZ GUSTAVO HIROKI KOMATSU

LUIZ GUSTAVO HIROKI KOMATSU

Página do item completo

Resultados de Busca

Agora exibindo 1 - 7 de 7

Effects of silver addition in zinc oxide nanoparticles on films of HMSPP/SEBS against Staphylococcus aureus and Escherichia coli contamination
2022 - KOMATSU, LUIZ G.H.; CAJADO, GIUSEPPE M.; PARRA, DUCLERC F.
In this research we decided to analyze the addition of silver (Ag°) on zinc oxide (ZnO) utilizing two nanoparticles: the synthesized zinc oxide-doped-silver nanoparticles (ZnO/Ag_Lab) utilizing the zinc nitrate as metal precursor for ZnO and silver nitrate as metal precursor for Ag°; and the commercial nanoparticle ZnO/Ag. For the study of application of the nanoparticles, they were processed in the form of films and the polymer utilized was the blend of HMSPP (high melt strength polypropylene) and styrene-ethylene/butadiene-styrene. For the study of nanoparticles, they were submitted to biocide tests against Staphylococcus aureus (ATCC 6538) and Escherichia coli (ATCC8739) and XRD (X-Ray Diffraction). The XRD analysis results indicated, in both of nanoparticles, with the presence of wurtzite phase of ZnO, being that on the commercial nanoparticles the intensity of peak was higher than that of synthesized one, on other hand, the peaks attributed to Ag°, were more intense in the synthesized nanoparticle.
The effect of ZnO nanoparticles as Ag‑carrier in PBAT for antimicrobial films
2022 - SOUZA, ALANA G. de; KOMATSU, LUIZ G.H.; BARBOSA, RENNAN F.S.; PARRA, DUCLERC F.; ROSA, DERVAL S.
Zinc oxide (ZnO) and ZnO-silver (ZnO-Ag) nanoparticles (NPs) are widely used in different fields, such as biomedicine and food packaging, due to their recognized antibacterial activity and safety for human health. In this paper, ZnO and ZnO-Ag NPs were incorporated into poly(butylene adipate-co-terephthalate) (PBAT), in two contents (0.5 and 1 wt%), to prepare antibacterial films. The NPs were characterized by TEM and FT-Raman, and the films were analyzed by FT-Raman and FTIR, mechanical properties, SEM–EDS, TGA, DSC, XRD, and antibacterial properties against Escherichia coli. The results indicate that both NPs were physically retained in the polymer structure, with a strong electrostatic interaction between the mixture components, reflecting excellent mechanical behavior. The films showed good thermal stability, without significant changes, and the nanocomposites enhanced PBAT crystallinity from 18 to 23% and 27% for PBAT-ZnO and PBAT-ZnO-Ag films, respectively. The mechanical, thermal, and crystallinity results indicated the excellent potential of NPs in biodegradable films to improve properties and expand applicability. The antimicrobial activity is higher for PBAT-ZnO-Ag films than the pristine PBAT due to the synergic effect between the NPs and the oxidation–reduction potential of each nanoparticle, where the ZnO protect and stabilized the Ag-NPs, acting as an Ag-carrier, enhancing its antimicrobial effects after the film’s preparation and allowing its applicability in biomedical products or food packaging.
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.
Effect of ionizing radiation applied to PLA used as compatibilizing agent in reinforced eGG shell PBAT/PLA bio-based composites
2021 - CARDOSO, ELIZABETH C.L.; PARRA, DUCLERC F.; SCAGLIUSI, SANDRA R.; KOMATSU, L.G.H.; LUGAO, ADEMAR B.
Bio-filler from eggshells as reinforcement of bio-based polymers are based on their benefits as adequate strength and stiffness, besides friendly, degradable and renewable environment. Eggshell is an agricultural waste considered as garbage, contributing to pollution; nevertheless, it can be transformed into bio-calcium carbonate, acquiring new values. As biodegradable polymers, there were chosen PLA (poly-lactic-acid) and PBAT (butylene adipate co-terephthalate), thermoplastics capable to be processed via conventional methods. PLA is a linear, aliphatic thermoplastic polyester, high in strength and modulus, but brittle. PBAT is a synthetic polymer, very flexible, based on fossil resources with high elongation at break, but low strength. It will be required the use of compatibilizers, for reducing interfacial tension exhibited by PLA/PBAT immiscible blend, considering their extreme glass transition temperatures: 62 ° C for PLA and – 30 ° C for PBAT. Herein it was used ionizing radiation for inducing compatibilization by free radicals, improving dispersion and adhesion of blend phases, without using chemical additives, at room temperature. PLA, acting as compatibilizer, was previously e-beam and gamma radiated, at 150 kGy. PBAT/PLA 50/50 blend with 15 phr of biofiller from avian eggs 125 μm particle size and both compatibilizers were homogeneized in a co-rotating twin-screw extruder, within a temperature profile 120 to 145 ° C, from hopper to die. Characterization involved: Differential Scanning Calorimeter, Thermogravimetric Analyses, Fourier Transform Infrared Spectroscopy, Wide Angle X-Ray Diffraction, Tensile Strength and Elongation at Break.
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.
Thermal ageing and accelerated weathering of HMSPP: structural and morphological studies
2016 - OLIANI, WASHINGTON L.; KOMATSU, LUIZ G.H.; LUGAO, ADEMAR B.; PARRA, DUCLERC F.
This work focuses of the influence of weathering factors UV radiation, humidity, and temperature on the structure and morphology poly(propylene) (PP) with high melt strength (HMSPP), also called poly(propylene) modified by irradiation. The HMSPP was prepared from isotactic poly(propylene) (iPP) in presence of acetylene at 110 kPa pressure and irradiated with g of 60Co at doses of 5, 12.5 and 20 kGy. It has been observed that HMSPP deteriorates in the weathering and thermal resistance, and the long-term stability of HMSPP, beyond substantial color changes. The aged samples were characterized by infrared spectroscopy (FTIR), optical microscopy (OM) and differential scanning calorimetry (DSC). The optical microscopy shows different mechanisms on thermal and artificial weathering ageing. The ageing result under elevated temperature in HMSPPs exposed surfaces follows the order: HMSPP 20>12.5>5 kGy>iPP. The intense crack formation in surface exposed justifies thermooxidative degradation.
Nanocomposites of irradiated polypropylene with clay are degradable ?
2016 - KOMATSU, L.G.H.; OLIANI, W.L.; LUGAO, A.B.; PARRA, D.F.