Papers by Keyword: Nanocomposite Film

Abstract: A method using a combination of acid hydrolysis and ultrasonic homogenize were developed to obtain the CNF (cellulose nanofibers) from agave cantala fibers. Acid hydrolysis method able to produce the CNF with a diameter around of 45-50 nm, which can investigated by transmission electron microscopy (TEM). The homogenize mixing method between CNF 5 wt% colloidal and 3 wt% PVA (polyvinyl alcohol) with magnetic stirrer 350 RPM, at temperature of 50 °C, for 30 minutes followed by ultrasonic homogenizer has been causing CNF well distributed in the PVA matrix. PVA/CNF nanocomposites film was prepared by solution casting technique. Physical properties test by x-ray diffraction (XRD) and fourier transform infrared (FTIR) shows highly crystalline of CNF which indicates improvements the mechanical properties of PVA/CNF nanocomposite film. The tensile stress and elongation at break of PVA/CNF nanocomposite film were increased by 55 % and 137 %.

Abstract: Zinc oxide nanoparticles (ZnO-NPs) were successfully prepared by hydrothermal method at low temperatures (80°C) for 2 hours using zinc nitrate as starting materials. The average size of hydrothermally synthesized ZnO-NPs were comparable with commercial one as confirmed by Particle Size Analyzer (PSA). The incorporation of hydrothermally synthesized ZnO-NPs (0.5% and 1%, w/w) and glycerol as plasticizer (20%, w/w) into tapioca starch film significantly reduce water absorption capacity and water vapor transmission rate while increasing tensile strength and elongation at break of the composite film. These results suggest that hydrothermally synthesized ZnO-NPs have the potential as nanofiller to improve the physical and mechanical properties of biobased film.

Abstract: The incorporation of unmodified halloysite nanotube (HNT) in a thermoplastic sago starch (TPSS) film to form a nanocomposite material was investigated. The TPSS/HNT nanocomposite was fabricated through solvent casting method at varying HNT loading of 0, 0.25, 0.5, 1.0, 3.0, and 5.0 wt.%. Evaluation on mechanical and physical properties (tensile test, water absorption, thickness and density) was made to study the effect of HNT loading on the TPSS properties. Tensile strength achieved an optimum value at 0.25 wt.% of HNT loading and decreased with higher addition of HNT. Meanwhile higher amount of HNT in the nanocomposite film exhibited brittleness with the reduced tensile strain. Water absorption decreased with the addition of HNT due to the difficulty of water molecules to pass through the tortuous path of HNT structure. Thickness and density of the nanocomposite film, however, increased at higher HNT contents. FESEM (field emission scanning electron microscope) which examined the surface morphology of the TPSS/HNT nanocomposite displayed uniformly dispersed HNT in the plasticized starch matrix.

Abstract: A series of clay-based nanocomposite films were prepared by casting aqueous dispersions of exfoliated montmorillonite clay mixed with various loadings of water-soluble organic polymer. The clay films with a nacre-mimicking structure exhibited excellent flexibility and optical transparency even for high clay content (93 wt%).

Abstract: Plasmonic Ag decorated TiO₂ nano-wire film was firstly prepared by the combination of a hydrothermal method and a microwave-assisted chemical reduction process. The results show that Ag deposited TiO₂ film exhibits obvious visible light absorption due to surface plasmon resonance absorption of Ag nanoparticles. Besides, fluorescence quenching is observed in the composite film under the excitation of 250 nm. Photocatalytic tests show that Ag deposited TiO₂ exhibits enhanced photocatalytic activity for H₂ production by water splitting due to the synergistic effect between charge transfer and surface plasmon resonance absorption properties of Ag nanoparticles.

Abstract: A polyvinyl alcohol (PVA) nanocomposite thin film embedded with zinc sulfide (ZnS) quantum dots was fabricated by a drop-casting method. The ZnS-embedded PVA films were characterized with polarized optical microscopy (POM), ultraviolet-visible (UV-vis) spectroscopy and photoluminescence (PL) spectroscopy. The POM study clearly exhibits the photo-elasticity effects of the ZnS/PVA film when stress is added. Optical absorption spectra showed strong red shift for the ZnS quantum dots in the PVA matrix. Room-temperature PL spectra demonstrated that the pure ZnS quantum dots show cyan emission at 517 nm while ZnS/PVA thin film gives off blue PL with a strong broad peak at 478 nm and a shoulder peak at 536 nm.

Abstract: Large-scale uniform Ag@TiO₂ films was prepared by RF magnetron sputtering in pure Ar plasma using polycrystalline TiO₂ semiconductor sintered target. The effect of annealing on the photochromic properties was studied to obtain a better understanding of the interaction of the structure. Ultraviolet-visible absorption and scanning electron microscopy were performed to investigate the possibility of tailoring the structure with consequent modification of the optical properties. Ag nanoparticles were formed between TiO₂ films after annealing the samples with Ag film structure. The annealed Ag@TiO₂ films present a photochromic property in comparison with the as-prepared samples. Such nanocomposite films can be used as smart windows, high density multiwavelength optical memory and rewritable electronic paper.

Abstract: Chitin nanofibers were prepared from prawn shell by a simple mechanical treatment after the removal of proteins and minerals. Since the exoskeleton of prawn is made up of a finer structure nano-fibrillation of prawn shell is easy, which allows chitin nanofibers to be prepared under neutral pH conditions. The obtained nanofibers were observed by FE-SEM and found to have a uniform width of approximately 20-40nm and high aspect ratio that more than 1000. Due to the size effect of the chitin nanofibers, the nanocomposite films had high transparency that the chitin nanofibers/epoxy resin nanocomposite transmitted 85.2% of light compared to the light transmittance of pure epoxy resin（91%）and the light transmittance of pure chitin nanofibers sheet (70.1%) at a visible wavelength of 600nm. In the study the coefficient of thermal expansion (CTE) from 20 to 160°C of the epoxy resin sheet was measured to be 170 ppm/K. By adding 40 wt% of chitin nanofibers, the CTE of the epoxy resin dropped to 22 ppm/K, approximately 1/8th of its original value. The novel material is a candidate for transparent substrates in the manufacturing optoelectronic devices such as flexible displays and solar cells.

Abstract: Homogenous cesium tungsten tri-oxide (CsxWO3) and molybdenum tri-oxide (Cs0.33MoO3) powder was prepared by solvothermal reaction using (NH4)10H2(W2O7)6, H8MoN2O4 and Cs2CO3 aqueous solution followed by annealing. The cesium doped tungsten tri-oxide (CsxWO3) and the cesium doped molybdenum tri-oxide (CsxMoO3) nanocomposite films was deposited by the sol-gel bar-coating method onto PET-film (polyethylene terephthalate film, thickness 186 ㎛) substrate. The structure and sizes of ceramic particles was observed XRD and PSA spectrometer, the optical properties of their films were investigated by UV-VIS, NIR spectrometer. Synthesized particles typically formed cubic structure for good absorption of NIR, size observed as being 30-100 nm and 3 nanoparticles showed a high transmittance in the visible wavelength region as well as excellent shielding capability of near-infrared (NIR) wavelength, indicating that CsxWO3, Cs0.33MoO₃ nanoparticles have a appropriate characteristic as solar filter applications.

Abstract: [FePt(2 nm)/Ag(d nm)]₁₀ mutilayers were deposited on single crystal MgO (100) substrates by magnetron sputtering. L1₀-FePt/Ag nanocomposite films with a high coercivity and a perpendicular orientation were achieved by annealing the as-deposited films at 600 °C for 15 min. The result of high resolution transmitting electron microscopy (HRTEM) shows apparent mutilayer structure of the [FePt(2 nm)/Ag(5 nm)]₁₀ film. We also found the good epitaxial growth of FePt on MgO [001] direction. Atomic force microscopy (AFM) observation on the surface morphology showed that the surface particle size and roughness degree decrease with increasing the Ag layer thickness.