Effect of Nanosilica Filled Polyurethane Composite Coating on Polypropylene Substrate

Acrylic based polyurethane (PU) coatings with various amounts of nanosilica contents were prepared using solution casting method. The nanosilica (SiO2) particles used are around 16 nm in diameter. The friction and wear test was conducted using the reciprocating wear testing machine. The tests were performed at rotary speed of 100 rpm and 200 rpm with load of 0.1 kg to 0.4 kg under 1 N interval. The effect of the PU/nano-SiO2 composite coating on friction and wear behavior of polypropylene substrate was investigated and compared. The worn surface of coating film layer after testing was investigated by using an optical microscope. The introduction of PU/nanosilica composite coating containing 3 wt% of nano-SiO2 content gives the lowest friction coefficient and wear rate to PP substrate. Both the friction and wear rate of PP substrate coated with >3 wt% of nano-SiO2 filled PU coating would increase with the increasing of applied load and sliding time

Influence of Annealing on Properties of Spray Deposited ZnO Thin Films

Zinc Oxide (ZnO) thin films were deposited on glass substrates via the spray pyrolysis technique. The films were subsequently annealed in ambient air from 300°C to 500°C. The morphology and structural properties of the thin films were studied by field emission scanning electron microscope (FESEM), atomic force microscopy (AFM), and X-ray diffractometry (XRD) techniques. Electrical resistivity of the thin films was measured using a data acquisition unit. The optical properties of the films were characterized by UV-vis spectroscopy and photoluminescence (PL) technique. X-ray diffraction data showed that the films were grown in the (002) direction with a hexagonal wurtzite structure. The average grain size ranged from 15 to 27 nm. Increasing annealing temperatures resulted in larger grain sizes and higher crystallinity, with the surface roughness of annealed films being more than twice if compared to unannealed film. The electrical resistivity of the films decreased with the increasing annealing temperature. The UV and visible band emissions were observed in the photoluminescence spectra, due to exciton and defect-related emissions, respectively. The transmission values of the films were as high as 90% within the visible range (400–700 nm)

Effect of Nanosilica and Titania on Thermal Stability of Polypropylene/Oil Palm Empty Fruit Fibre Composite

Degradation of polypropylene (PP) composites at elevated temperature for prolonged period has shortened the lifetime of PP composites. Thus, variety of fillers has been incorporated into PP matrix to improve thermal degradation stability. The effects of titania and nanosilica in PP reinforced with oil palm empty fruit bunch fibres (EFB) were investigated in this study. Mechanical properties of the samples were determined before and after thermal ageing. Morphology of the composite with varies fillers composition were analyzed using scanning electron microscope. The introduction of nanosilica into PP/EFB composite filled with titania has increased both the melting and glass transition temperature of PP. Chain splitting in molecular chains reduced with the incorporation of nanosilica and titania into PP and PP/FEB composites. The TGA study has showed that the addition of nanosilica has further enhanced the thermal stability effect of titania in PP/EFB composite. However, both the Izod impact strength and tensile strength of the composite reduced greatly after 20 days of thermal ageing

A review of natural fiber reinforced poly(Vinyl alcohol) based composites: application and opportunity

Natural fibers are fine examples of renewable resources that play an important role in the composites industry, which produces superior strength comparable to synthetic fibers. Poly(vinyl alcohol) (PVA) composites in particular have attracted enormous interest in view of their satisfactory performance, properties and biodegradability. Their performance in many applications such as consumer, biomedical, and agriculture is well defined and promising. This paper reviews the utilization of natural fibers from macro to nanoscale as reinforcement in PVA composites. An overview on the properties, processing methods, biodegradability, and applications of these composites is presented. The advantages arising from chemical and physical modifications of fibers or composites are discussed in terms of improved properties and performance. In addition, proper arrangement of nanocellulose in composites helps to prevent agglomeration and results in a better dispersion. The limitations and challenges of the composites and future works of these bio-composites are also discussed. This review concludes that PVA composites have potential for use in numerous applications. However, issues on technological feasibility, environmental effectiveness, and economic affordability should be considered

Effect of TEMPO-oxidization and rapid cooling on thermo-structural properties of nanocellulose

Recently, surface functionality and thermal property of the green nanomaterials have received wide attention in numerous applications. In this study, microcrystalline cellulose (MCC) was used to prepare the nanocrystalline celluloses (NCCs) using acid hydrolysis method. The NCCs was treated with TEMPO [(2,2,6,6-tetramethylpiperidin-1-yl)oxy radical]-oxidation to prepare TEMPO-oxidized NCCs. Cellulose nanofibrils (CNFs) also prepared from MCC using TEMPO-oxidation. The effects of rapid cooling and chemical treatments on the thermo-structural property studies of the prepared nanocelluloses were investigated through FTIR, thermogravimetric analysis-derivative thermogravimetric (TGA-DTG), and XRD. A posteriori knowledge of the FTIR and TGA-DTG analysis revealed that the rapid cooling treatment enhanced the hydrogen bond energy and thermal stability of the TEMPO-oxidized NCC compared to other nanocelluloses. XRD analysis exhibits the effect of rapid cooling on pseudo 2I helical conformation. This was the first investigation performed on the effect of rapid cooling on structural properties of the nanocellulose

Synergistic effect of (3-Aminopropyl)Trimethoxysilane treated ZnO and corundum nanoparticles under UV-irradiation on UV-cutoff and IR-absorption spectra of acrylic polyurethane based nanocomposite coating

ZnO and corundum (α–Al2O3) nanoparticles were successfully synthesized by aqueous precipitation and sintering techniques respectively. ZnO nanoparticles were effectively coated with (3-aminopropyl)trimethoxysilane (APTMS) by polycondensation method to prevent the photocatalytic activity of ZnO during a UV-weathering study. X-ray diffractogram and FTIR were used to confirm the crystalline structure of as prepared nanoparticles, blue shift of the Alsingle bondO bond and the formation of a secondary amine via polycondensation of APTMS over ZnO surface. The prepared APTMS-ZnO, corundum and commercially available surface modified hydrophobic SiO2 (M − SiO2) nanoparticles were used to prepare the acrylic polyurethane (AP: Poly-Macrynal® SM 510 N coating resign) bases nanocomposite coating on a polyurethane substrate. Individual and mixed nanoparticles were dispersed into acrylic polyurethane to prepare the coating layer on polyurethane film substrate separately. IR-active and UV–visible regions of the FTIR and UV–Vis spectroscopies were used to investigate the synergistic effect of the nanoparticles on a selected range of the radiative spectrum, especially the UV-resistant and IR-absorption properties of the coated films with and without exposure of UV-irradiations. Polyurethane substrate coated with APTMS-ZnO (2 wt%) based acrylic polyurethane-based nanocomposite coating (APUC) layer containing 2 wt% corundum (D50) and 6 wt% M − SiO2 (F50) exhibited 98.77% and 97.60% of UV-resistant property respectively. These results indicate that the visible light transparency and transmittance ability reduced significantly after 500 h of UV-irradiation exposure. Both of the activity and deformation have great impact on the IR-absorption property of the APUC

Rheological properties of cellulose nanocrystal-embedded polymer composites: a review

Nanotechnology provides useful insights into the behavioural properties of materials from the nanoscale point of view, enabling researchers to develop new materials that were previously inconceivable. Cellulose is an ideal candidate for nanomaterial for nanotechnology because of its nanofibrillar structure, abundance, renewability, biodegradability and eco-friendly nature. Nanocrystalline cellulose materials have become the focus many studies related to these materials and their applications. This review summarises the current knowledge on the field of nanomaterials, focussing mainly on the rheological behaviour of polymer nanocomposites embedded with nanocrystalline cellulose. This review will enable better understanding of the use of nanocrystalline cellulose for the development and applications of cellulose nanocrystal-based nanocomposites

Effect of methyl methacrylate grafted kenaf on mechanical properties of polyvinyl chloride/ethylene vinyl acetate composites

In this work, the effect of grafted and ungrafted kenaf fiber on tensile, flexural, impact and hardness properties of polyvinyl chloride/ethylene vinyl acetate composites were studied. Grafted fibers were obtained from graft copolymerization reaction where methyl methacrylate was used as a monomer. The fiber loadings were varied from 0% to 30%. The addition of kenaf fiber had caused a decline in the impact and tensile strength of the PVC/EVA composite. Results revealed that the presence of PMMA on the surface of kenaf fiber has further enhanced the efficiency of stress transfer from the matrix to the fiber grafting thus improved the interfacial adhesion between the fiber and PVC/EVA matrix

Curcumin/Tween 20-incorporated cellulose nanoparticles with enhanced curcumin solubility for nano-drug delivery: characterization and in vitro evaluation

A poorly water-soluble anticancer drug, curcumin was loaded into cellulose nanocrystals by dissolving it in a commonly used nonionic surfactant medium. Results showed that the drug loading capacity of nanocellulose increased with increasing the surfactant concentration of the medium. The drug loading capacity of nanocellulose in surfactant medium was significantly higher (7.73 mg/g) when compared to the drug loading capacity (3.35 mg/g) in methanolic medium. The nanocellulose drug loaded in surfactant medium (TW/CNC) showed higher drug release compared to the nanocellulose drug loaded in methanolic medium (METH/CNC). It was 8.99 mg/L for TW/CNC and 2.65 mg/L for METH/CNC in simulated gastric fluid. Due to the increased stability of curcumin in acidic medium, all the nanoparticles showed higher drug release in simulated gastric fluid compared to phosphate buffered saline solution. The maximum dissolution of curcumin was 2.13 mg/mL in distilled water containing 4% (w/v) of surfactant. UV–visible spectra revealed that the curcumin retained its chemical activity after in vitro release. From these findings, it is believed that the incorporation of curcumin into nanocellulose in surfactant medium provides a promising approach for delivery of curcumin to stomach and upper intestinal tract

Thermal and dynamic mechanical properties of grafted kenaf filled poly (vinyl chloride)/ethylene vinyl acetate composites

The effects of kenaf and poly (methyl methacrylate grafted kenaf on the thermal and dynamic mechanical properties of poly (vinyl chloride), PVC and ethylene vinyl acetate, EVA blends were investigated. The PVC/EVA/kenaf composites were prepared by mixing the grafted and ungrafted kenaf fiber and PVC/EVA blend using HAAKE Rheomixer at a temperature of 150 °C and the rotor speed at 50 rpm for 20 min. The composites were subjected to Differential Scanning Calorimetric (DSC), Thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), Fourier transform infrared (FTIR) and Scanning Electron Microscopy (SEM) studies. The DSC data revealed that the crystallinity of the EVA decreased with the addition of 30% grafted and ungrafted kenaf fibers. TGA and derivative thermogravimetric (DTG) curves displayed an increase in the thermal stability of the composites upon grafting of the fiber. Studies on DMA indicate that the Tg of the PVC and EVA in the PVC/EVA/kenaf composites has been shifted to higher temperature with the addition of the kenaf fiber. The presence of PMMA on the surface of grafted kenaf fiber was further confirmed by the analytical results from FTIR. The morphology of fractured surfaces of the composites, which was examined by a scanning electron microscope, showed the adhesion between the kenaf fiber and the PVC/EVA matrix was improved upon grafting of the kenaf fiber