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

Simulation of nanodielectrics: nanoparticle and interphase effects on electric field distributions

Nanodielectrics have been regarded as a class of material system that can provide significantly improved chemical, mechanical and dielectric properties over conventional microcomposites. This is due to the presence of a high volume fraction of the interphase between nanoparticles and polymers. However, precise effects of nanodielectrics are not well understood, leading to difficulties in interpreting the dielectric behaviours of nanodielectrics. In the current work, effects of nanoparticle distributions, interparticle distances, nanoparticle sizes, interphase permittivities and interphase thicknesses on the possible electric field variations within a nanodielectric model have been simulated using Finite Element Method Magnetics (FEMM) 4.2. The results demonstrate that different nanoparticle and interphase configurations lead to different effects on the electric field intensity within the nanodielectric model. Mechanisms leading to changes in dielectric properties based on the observed electric field variations are discussed

Genipin crosslinked chitosan/PEO nanofibrous scaffolds exhibiting an improved microenvironment for the regeneration of articular cartilage

Towards optimizing the growth of extracellular matrix to produce repair cartilage for healing articular cartilage (AC) defects in joints, scaffold-based tissue engineering approaches have recently become a focus of clinical research. Scaffold-based approaches by electrospinning aim to support the differentiation of chondrocytes by providing an ultrastructure similar to the fibrillar meshwork in native cartilage. In a first step, we demonstrate how the blending of chitosan with poly(ethylene oxide) (PEO) allows concentrated chitosan solution to become electrospinnable. The chitosan-based scaffolds share the chemical structure and characteristics of glycosaminoglycans, which are important structural components of the cartilage extracellular matrix. Electrospinning produced nanofibrils of ∼100 nm thickness that are closely mimicking the size of collagen fibrils in human AC. The polymer scaffolds were stabilized in physiological conditions and their stiffness was tuned by introducing the biocompatible natural crosslinker genipin. We produced scaffolds that were crosslinked with 1.0% genipin to obtain values of stiffness that were in between the stiffness of the superficial zone human AC of 600 ± 150 kPa and deep zone AC of 1854 ± 483 kPa, whereas the stiffness of 1.5% genipin crosslinked scaffold was similar to the stiffness of deep zone AC. The scaffolds were degradable, which was indicated by changes in the fibril structure and a decrease in the scaffold stiffness after seven months. Histological and immunohistochemical analysis after three weeks of culture with human articular chondrocytes (HACs) showed a cell viability of over 90% on the scaffolds and new extracellular matrix deposited on the scaffolds

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

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

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

Effects of PTFE micro-particles on the fiber-matrix interface of polyoxymethylene/glass fiber/polytetrafluoroethylene composites

Reinforcing polyoxymethylene (POM) with glass fibers (GF) enhances its mechanical properties, but at the expense of tribological performance. Formation of a transfer film to facilitate tribo-contact is compromised due to the abrasiveness of GF. As a solid lubricant, for example, polytetrafluoroethylene (PTFE) significantly improves friction and wear resistance. The effects of chemically etched PTFE micro-particles on the fiber-matrix interface of POM/GF/PTFE composites have not been systematically characterized. The aim of this study is to investigate their tribological performance as a function of micro-PTFE blended by weight percentage. Samples were prepared by different compositions of PTFE (0, 1.7, 4.0, 9.5, 15.0 and 17.3 wt.%). The surface energy of PTFE micro-particles was increased by etching for 10 min using sodium naphthalene salt in tetrahydrofuran. Tribological performance was characterized through simultaneous acquisition of the coefficient of friction and wear loss on a reciprocating test rig in accordance to Procedure A of ASTM G133-95. Friction and wear resistance improved as the micro-PTFE weight ratio was increased. Morphology analysis of worn surfaces showed transfer film formation, encapsulating the abrasive GF. Energy dispersive X-ray spectroscopy (EDS) revealed increasing PTFE concentration from the GF surface interface region (0.5, 1.0, 1.5, 2.0, 2.5 µm)

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

Dielectric properties of thermally aged polypropylene Nanocomposites

This paper reports on an investigation into the effects of thermal aging on the structure and dielectric properties of polypropylene (PP) nanocomposites. Magnesium aluminate (MgAl2O4), calcium carbonate (CaCO3), and surface-modified calcium carbonate (CaCO3T) nanofillers have been added to PP and the resulting nanocomposites have been subjected to aging at 110 °C and 140 °C. The results show that unfilled PP experiences a 13% reduction in its DC breakdown strength after aging at 110 °C and that its DC breakdown strength reduces by 27% after aging at 140 °C. In contrast, the reduction in the DC breakdown strength of all investigated PP nanocomposites is much less pronounced than that of the unfilled PP after aging. Specifically, the DC breakdown strength of PP/MgAl2O4 nanocomposites, PP/CaCO3 nanocomposites, and PP/CaCO3T nanocomposites reduces by 8%, 14%, and 14%, respectively, after aging at 140 °C. Possible mechanisms affecting the DC breakdown strength of the unfilled PP and PP nanocomposites before and after aging are consequently discussed

Quality Of Life Of Patients With Chronic Obstructive Pulmonary Disease Based On Clinical Phenotypes

Background and Aims: Spanish chronic obstructive pulmonary disease (COPD) guideline classifies COPD into 4 clinical phenotypes: nonexacerbator (A), asthma-COPD overlap (B), exacerbator with emphysema(C) and exacerbator with bronchitis (D). Methods: A cross-sectional study of quality of life (QOL) based on COPD phenotypes utilizing St George’s Respiratory Questionnaire (SGRQ-c) conducted in University Malaya Medical Center from 1 June 2017 – 31 May 2018. Results: Of 220 patients, 189 patients with post bronchodilator force expiratory volume in 1 second (FEV1)/force vital capacity (FVC) of <0.70 were recruited. Their demographic, clinical characteristics and SGRQ-c score are as shown in Table 1. Patients with phenotype C and D had poorer modified medical research center (MMRC) performance status and global initiative for COPD (GOLD) class based on FEV1. Nevertheless, only patients with phenotype D had significant higher total SGRQ-c score than others. They also scored significant higher in sub-components of COPD symptoms, activities and impacts. Patients with phenotypes B had numerically higher SGRQ-c total and symptoms score than those with phenotype A and C. The total and sub-components SGRQ-c score of patients with phenotype A and C were almost similar. Conclusion: Patients with phenotype D had poorest QOL, followed by phenotype B. These groups of patients need additional medical attention, in terms of pharmacology treatment, physiotherapy and rehabilitation