Preparation of magnetic and conductive graphite nanoflakes/SrFe<Subscript>12</Subscript>O<Subscript>19</Subscript>/polythiophene nanofiber-nanocomposites and its radar absorbing application

This study, we synthesized graphite-nanoflakes (GNFs) by acid treatment and thermal shock and then using the ultrasonic irradiation technique to exfoliate flake-carbon. The SrFe₁₂O₁₉ nanoparticles (NPs) were coated by co-precipitate method on GNFs after by alkaline treatment. Finally nanocomposite (GNF/SrFe₁₂O₁₉/PTh) was prepared by in-situ oxidative polymerization method in presence of thiophene (Th) as monomer. The magnetic and electrical conducting properties of the resulting nanocomposites were measured by using vibrating sample magnetometer and standard four-point-probe method, respectively. The synthesized nanocomposites were characterized by X-ray diffraction (XRD) and fourier transform infrared spectra (FTIR). In addition, morphological analyses were investigated by scanning electron microscopy (SEM). A minimum reflection loss (RL) of GNFs/SrFe₁₂O₁₉/PTh with 50 % wt GNFs/SrFe₁₂O₁₉ as core were observed ?28 and ?39 dB at 9.7 and 12 GHz for a 1.5 mm thickness. The results indicated that we can perform good microwave shielding in X-band (8–12 GHz) by these nanocomposites.     

The synergy effect of Graphene/SiO<Subscript>2</Subscript> hybrid materials on reinforcing and toughening epoxy resin

Based on the situ preparation of silica nanoparticles (SiO₂) on the surface of Graphene nanoplatelets (GNPs) in the previous work, these unique three dimensional (3D) materials were introduced into epoxy resin to study the reinforcing and toughening synergy effect on the composites. Firstly, the tensile tests showed that Graphene/SiO₂ hybrid materials attached with different size of SiO₂ particles exhibited different reinforcing and toughening effect on the composites. With the increasing of the diameter of SiO₂ particles, the toughness and strength properties of the composites firstly improved and then decreased, and when the average diameter was 0.14 μm, the elongation reached the max.. Meanwhile, the fractured surfaces presented on SEM images were consistent with the results of the tensile tests, which further explained the hybrid materials increased the interfacial adhesion between the fillers and matrix, leading to significant improvement in mechanical properties. Moreover, the DSC curves demonstrated that Graphene/SiO₂ hybrid materials accelerated the curing process of epoxy resin due to the cross-link structure between fillers and matrix. Lastly, the crack propagation modes were built to clarify the synergy effect mechanism of reinforcing and toughening on nanoparticles/epoxy resin composites.     

Effect of phase transformation on physical and biological properties of PVA/CaFe<Subscript>2</Subscript>O<Subscript>4</Subscript> nanocomposite

The thermal treatment method was employed to achieve higher homogeneity of calcium ferrite (CaFe2O4) and Poly (vinyl alcohol) (PVA) nanocomposites. The influences of phase transformation on physical and biological properties of calcined specimens were investigated by various experimental techniques including X-ray diffraction (XRD), Transmission Electron Microscopy (TEM), high resolution Field emission scanning electron microscope (FESEM) and Fourier transform infrared spectroscopy (FT-IR). Heat treatment was conducted at temperatures between 723 and 923 K, so that a phase transformation occurred from cubic to orthorhombic spinel structure at 923 K. The chemical analysis of the PVA/CaFe₂O₄ nanocomposite was performed by energy dispersion X-ray analysis (EDXA), demonstrated the PVA/CaFe₂O₄ nanocomposites contained the elements of C, Ca, Fe, and O. The formed nanocomposites exhibited ferromagnetic behaviors which were confirmed by using a vibrating sample magnetometer (VSM). The calcined specimens were carried out to an antimicrobial or antifungal test.     

Controlling the Properties of OPEFB/PLA Polymer Composite by Using Fe<Subscript>2</Subscript>O<Subscript>3</Subscript> for Microwave Applications

Microwave-absorptive polymer composite materials provide protection against interference to communication systems caused by microwave-inducing devices. Microwave-absorptive polymer composites were prepared from polylactic acid (PLA) biocomposite blended with oil palm empty fruit bunch (OPEFB) fiber and commercial Iron oxide (Fe₂O₃) as filler using the melt-blending method. The composites characterization was carried out using the scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses. The coefficient of reflection S₁₁ and coefficient of transmission S₂₁ of the composites for various Fe₂O₃ filler percentages were determined using a rectangular waveguide in connection with microwave vector network analyser (HP/Agilent model PNA N5227). These coefficients were then used to calculate microwave-absorption properties (in decibels). XRD analysis showed that increasing amounts of reinforced material (Fe₂O₃) reduces the crystallinity of the composites. SEM data indicated that Fe₂O₃ filler ratio increased in the composites, and adhesion to the cellulose fiber grew gradually until the highest percentage of filler was added. The complex relative permittivity and relative permeability were obtained within the broad frequency range of 8–12 GHz at room temperature for various percentages of filler and were measured by the transmission/reflection method using a vector network analyser. Fe₂O₃ embedment in OPEFB/PLA was observed to have resulted in enhancing the dielectric and magnetic properties. The values of permittivity and permeability increased with increasing Fe₂O₃ filler content. Theoretical simulation studied the relation between ε′ and ε″ of the relative complex permittivity in terms of Cole-Cole dispersion law. The result indicated that the processes of Debye relaxation in Fe₂O₃/OPEFB/PLA, the unique dielectric characteristics of Fe₂O₃ cannot be accounted for by both the Debye dipolar relaxation and natural resonance. Results further showed that the material transmission, reflection, and absorption properties could be controlled by changing the percentage of Fe₂O₃ filler in the composites.     

Evaluating the Mechanical Behavior of Basalt Fibers/Epoxy Composites Containing Surface-modified CaCO<Subscript>3</Subscript> Nanoparticles

Polymer matrix composites (PMCs) owing to their outstanding properties such as high strength, low weight, high thermal stability and chemical resistance are broadly utilized in various industries. In the present work, the influence of silanized CaCO₃ (S-CaCO₃) with 3-aminopropyltrimethoxysilane (3-APTMS) coupling agent at different values (0, 1, 3 and 5 wt.% with respect to the matrix) on the mechanical behavior of basalt fibers (BF)/epoxy composites was examined. BF-reinforced composites were fabricated via hand lay-up technique. Experimental results from three-point bending and tensile tests showed that with the dispersion of 3 wt.% S-CaCO₃, flexural strength, flexural modulus, tensile strength and tensile modulus enhanced by 28 %, 35 %, 20 % and 30 %, respectively. Microscopic examinations revealed that the development of the mechanical properties of fibrous composites with the incorporation of modified CaCO₃ was related to enhancement in the load transfer between the nanocomposite matrix and BF as well as enhanced mechanical properties of the matrix part.     

Fabrication and characterization of nano Al<Subscript>2</Subscript>O<Subscript>3</Subscript> filled PVA:NH<Subscript>4</Subscript>SCN electrolyte nanofibers by electrospinning

Present paper reports a method of preparing polymer composite electrolyte nanofiber mat using polyvinyl alcohol (PVA), ammonium thiocynate (NH₄SCN) salt, and aluminium oxide (Al₂O₃) nano particles based on electrospinning technique. Two-stage process of preparation of nanofibers, namely, preparation of nano particles filled PVA electrolyte gel solution followed by its electrospinning has been used. The so obtained nanofibers have been characterized by XRD, DSC, SEM, and Conductivity measurements. XRD patterns affirm the formation of nanocomposite while SEM pictures reveal formation of fibers on a nano scale format (300–800 nm). Fibers of the electrolytes are seen to be thermally stable. Ionic conductivity of electrolyte fiber is seen to improve in the presence of nano filler at room temperature with a maximum at 5.31×10⁻³ Scm⁻¹ for 4 wt% filler concentration, which is comparable to that for corresponding dried gel electrolyte films.     

Enhanced physico-mechanical properties of polyester resin film using CaCO<Subscript>3</Subscript> filler

Bio-based CaCO₃ powder was synthesized via size reduction method from waste eggshells. The XRD analysis revealed that eggshell powder consists of CaCO₃ in calcite form. The inclusion level of CaCO₃ contents were varied of 5, 10, 15, 20 and 25 wt.% of prepared CaCO₃-polyester film. Effects of different proportions of prepared chicken eggshell and commercial CaCO₃ filler on the polyester resin composites films were compared by means of mechanical and physical test. It was found that the addition of CaCO₃ filler to the polyester films leads to improve the mechanical properties. The findings revealed that the best and optimum CaCO₃ filler content was 10 wt.% and among the prepared polyester films, eggshell CaCO₃-polyester films showed the best performance. The mechanical properties of CaCO₃-polyester films were measured in terms of tensile strength, elongation-at-break, tensile modulus, flexural strength and impact strength. For eggshell CaCO₃- polyester films, the maximum values of the aforementioned mechanical properties were 52.70 MPa, 4.63 %, 1868.70 MPa, 101.20 MPa and 8.40 kJ/m², respectively, whereas for commercial CaCO₃-polyester films those values were 48.12 MPa, 4.50 %, 1790.30 MPa, 97.50 MPa and 8.21 kJ/m², respectively. Further, water absorption of the composite films as a function of time had also been investigated at 10 wt.% filler content.     

A Novel Green Stabilization of TiO<Subscript>2</Subscript> Nanoparticles onto Cotton

Facile embedding of TiO₂ nanoparticles onto cotton fabric has been successfully attained by ultraviolet light irradiations. The adhesion of nanoparticles with fibre surface, tensile behaviour and physicochemical changes before and after ultraviolet treatment were investigated by scanning electron microscopy, energy dispersive X-ray and inductive couple plasma-atomic emission spectroscopy. Experimental variables i.e. dosage of TiO₂ nanoparticles, temperature of the system and time of ultraviolet irradiations were optimised by central composite design and response surface methodology. Moreover, two different mathematical models were developed for incorporated TiO₂ onto cotton and tensile strength of cotton after ultraviolet treatment and used further to testify the obtained results. Self-clean fabric through a synergistic combination of cotton with highly photo active TiO₂ nanoparticles was produced. Stability against ultraviolet irradiations and self-cleaning properties of the produced fabric were evaluated.     

Spherical Bacterial Cellulose/TiO<Subscript>2</Subscript> Nanocomposite with Potential Application in Contaminants Removal from Wastewater by Photocatalysis

Contaminants are often found in aquatic environments, for instance, heavy metals, dyes, parasites, pesticides, hormones and pharmaceuticals. Therefore, large amounts of these contaminants reaches wastewater via industrial and domestic effluents, causing major concern to human health. Heterogeneous photocatalysis is a technique for removing these contaminants in order to achieve better efficiency in water treatment. Then, bacterial cellulose (BC) produced in an agitated culture can form spherical bodies composed of nanofibers with high specific surface area. Moreover, Titanium dioxide (TiO₂) is a semiconductor containing high photocatalytic activity capacity. Thus, the main objective in this work was to produce spherical BC/TiO₂ nanocomposites for contaminants removal from wastewater by photocatalysis process. The incorporation of TiO₂ nanoparticles in the spherical BC matrix was performed by ex situ and in situ methods. In addition, Scanning Electron Microscope (SEM), Energy Dispersive Spectroscopy (EDS), Fourier Transform Infrared Spectroscopy (FTIR) and Thermogravimetric Analysis (TGA) were used as tools of morphological, chemical and thermal characterizations of the nanocomposites. Besides, photocatalysis tests were performed in order to evaluate the removal efficiency of methylene blue from aqueous solutions. The results of these tests exhibited a percentage of methylene blue removal of 70.83 and 89.58 % after 35 minutes for spherical BC/TiO₂ nanocomposites both, in situ and ex situ, respectively. Therefore, these results demonstrated that BC/TiO₂ to be a low cost material with high capacity of contaminants removing and a great potential for industrial applications.     

Polyacrylonitrile/electroconductive TiO<Subscript>2</Subscript> nanoparticles composite fibers <Emphasis Type="Italic">via</Emphasis> wet-spinning

For the first time, novel polyacrylonitrile (PAN)/electroconductive TiO₂ (EC-TiO₂) nanoparticles composite fibers have been successfully spun via wet-spinning. The composite fibers had uniform diameter and homogeneous surface. Moreover, at low content of EC-TiO₂ nanoparticles, the composite fibers realized a transition from an insulator to a conductor. This work has provided a simple and effective avenue for the production of PAN/EC-TiO₂ nanoparticles composite fibers that have great potential applications in the antistatic textiles.     

Fabrication and Characterisation of Functionalised Superparamagnetic Bacterial Nanocellulose Using Ultrasonic-Assisted <Emphasis Type="Italic">In Situ</Emphasis> Synthesis

Ultrasonic-assisted in situ synthesis was performed using bacterial nanocellulose (BNC) and magnetite nanoparticles (Fe₃O₄ NPs) to synthesise superparamagnetic membranes as BNC/Fe₃O₄ nanocomposite films (BNC/Fe₃O₄ NCFs). Vibrating sample magnetometry of these BNC/Fe₃O₄ NCFs exhibited superparamagnetic properties with high saturation magnetisation at 40.57 emu g^-1. Morphology of BNC/Fe₃O₄ NCFs was studied by field-emission scanning electron microscopy. Results showed Fe₃O₄ NPs with diameter 30 to 50 nm trapped in a BNC structure. Fourier transform infrared spectroscopy analysis confirmed the incorporation of BNC and Fe₃O₄ NPs. Thermal properties of the nanocomposite films increased with Fe₃O₄ NPs in the BNC structure compared with native BNC. Surface wettability of BNC/Fe₃O₄ NCFs was determined by contact angle and revealed hydrophobic properties. Results showed that ultrasonic-assisted in situ synthesis of superparamagnetic BNC/Fe₃O₄ NCFs is an important property when utilising BNC/Fe₃O₄ NCFs with a hydrophobic nonpolar polymeric matrix in electronic device applications.     

Electrospun SiO<Subscript>2</Subscript>/PMIA nanofiber membranes with higher ionic conductivity for high temperature resistance lithium-ion batteries

The nanofiber membrane prepared by electrospinning has been widely applied in lithium-ion batteries. A powerful strategy for designing, fabricating and evaluating Poly-m-phenylene isophthalamide (PMIA) nanofiber membrane with SiO₂ nanoparticles was developed by electrospinning in this paper. The morphology, crystallinity, thermal shrinkage, porosity and electrolyte uptake, and electrochemical performance of the SiO₂/PMIA nanofiber membranes were investigated. It was demonstrated that the nanofiber membrane with 6 wt% SiO₂ possessed notable properties, such as better thermal stability, higher porosity and electrolyte uptake, resulting in higher ionic conductivity (3.23×10^-3 S·cm^-1) when compared with pure PMIA nanofiber membrane. Significantly, the SiO2/PMIA nanofiber membrane based Li/LiCoO₂ cell exhibited more excellent cycling stability with capacity retention of 95 % after 50 cycles. The results indicated that the SiO₂-doped PMIA nanofiber membranes had a potential application as separator in high temperature resistance lithium-ion batteries.     

Load of Ag<Subscript>3</Subscript>PO<Subscript>4</Subscript> Particles on Sulfonated Polyphenylene Sulfide Superfine Fibre with High Visible-light Photocatalytic Activity

Ag₃PO₄ was loaded on sulfonated polyphenylene sulfide (SPPS) superfine fibre by a facile precipitation method. Both the structure and properties of the as-synthesized Ag₃PO₄/SPPS composites were characterized via XRD, SEM, EDS, XPS, FTIR, and UV-vis. The photocatalytic performance of Ag₃PO₄/SPPS composites was investigated via degradation of Methylene blue(MB) solution under visible light irradiation. The degradation results revealed that the photocatalytic activity of Ag₃PO₄/SPPS composites was greatly enhanced by the incorporation of Ag₃PO₄ with SPPS superfine fibre. For concentrations of AgNO₃ and Na₂HPO₄ solutions of 0.3 M and 0.06 M in the preparation process, the Ag₃PO₄/SPPS composite showed higher photocatalytic activity under visible light irradiation.     

Fabrication of Polyether Sulfone Blend Imprinted Membranes for Selective Adsorption of <Emphasis Type="Italic">p</Emphasis>-hydroxybenzonic from Salicylic Acid

Highly selective polyether sulfone (PES) blend imprinted membranes for template p-hydroxybenzonic (p-HB) were synthesized by phase inversion imprinting technique using polybenzimidazoles (PBI) as a functional polymer and nanosized Al₂O₃ as the additives. The SEM analysis showed that cross-sectional morphology of membranes were strongly influenced by the content of nano-sized Al₂O₃. Compared with PES₁-MIM, PES₂-MIM and PES₄-MIM, the PES₃-MIM containing 2.0 wt.% nano-sized Al₂O₃ exhibited higher membrane flux, kinetic equilibrium adsorption value, binding capacity and better selectivity for p-HB. The experimental data of adsorption kinetic were well fitted to the pseudo-secondorder kinetic model using multiple regression analysis. Static adsorption isotherm experiments exhibited that the PES₃-MIM had the maximum adsorption capacity for p-HB. Moreover, selective experiment showed that the selectivity coefficients of PES₃-MIM for p-HB relative to salicylic acid (SA) was 3.670, showing that PES₃-MIM had excellent binding affinity and selectivity for separating p-HB form p-HB-contained aqueous solution.     

Hard Surface-adhesive Properties of TiO<Subscript>2</Subscript> Nanoparticles-encapsulated Microparticles Prepared by Spray Drying and Surface Coating Method

The aim of this study is to compare hard surface-adhesive properties of TiO₂ nanoparticles (TNPs)-encapsulated microparticles prepared by spray drying and surface coating method. Thus, TNPs were encapsulated with chitosan by spray drying and poly(L-lysine) by surface coating method, which were selected as positively charged materials. And then, the TNPs-encapsulated microparticles were investigated by particle surface properties and adhesion properties on hydroxyapatite (HAP) surface as model for hard surface-adhesion. The characteristics of TNPs-encapsulated Chitosan microcapsules (CM) and TiO₂ nanoparticles coated with cationic poly(L-lysine) polymer (TNPs-PLL) were determined with scanning electron microscope (SEM) image and zeta-potentials. The hard surface-adhesive properties on HAP surface were confirmed with SEM and whitening test. The zeta-potentials of TNPs and HAP were negative, -13 mV and -18 mV respectively, while TNPsencapsulated CM, and TNPs-PLL of positively charged polymers were positive, 13 mV and 57 mV respectively. Whitening test was carried out on model surface when shaking the samples. TNPs-PLL were adhered to HAP surface very much more than those of TNPs-encapsulated CM. Also, the change value of whiteness of the HAP surface treated with TNPs-PLL is large evidently, compared with TNPs-encapsulated CM.     

Poly(ethylene 2,6-naphthalate)/MWNT nanocomposites prepared by in situ polymerization: Rheological and mechanical properties

Poly(ethylene 2,6-naphthalate)/multi-walled carbon nanotube (PEN/MWNT) nanocomposites are prepared by in situ condensation polymerization in the presence of various acid-treated MWNT (a-MWNT) contents and their morphology, rheological and mechanical properties are investigated as a function of the a-MWNT content. SEM image of a plasma-etched nanocomposite exhibits that a-MWNTs are dispersed well in the PEN matrix by forming an interconnected network structure. Accordingly, rheological properties such as complex viscosities and shear moduli of PEN/a-MWNT nanocomposites at the terminal region of low frequency are much higher than those of pure PEN. Glass transition temperatures of nanocomposites also increase with the increment of the a-MWNT content, which stems from the reduced chain mobility due to the specific interaction between a-MWNTs and PEN matrix. Dynamic and tensile mechanical properties of nanocomposites are also higher than those of pure PEN and they increase with the increment of the a-MWNT content. The highly improved mechanical properties of PEN/a-MWNT nanocomposites are explained to originate from the interconnected network structure of a-MWNTs in PEN matrix as well as the strong interfacial adhesion between a-MWNTs and PEN matrix.     

Preparation and UV-protective property of PVAc/ZnO and PVAc/TiO<Subscript>2</Subscript> microcapsules/poly(lactic acid) nanocomposites

The poly(vinyl acetate) (PVAc)/zinc oxide (ZnO) microcapsule and PVAc/titanium dioxide (TiO₂) microcapsule were synthesized via in-situ emulsion polymerization method. The PVAc/ZnO microcapsule and PVAc/TiO₂ microcapsule were characterized by fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis(TG), transmission electron microscopy (TEM), and UV-visible spectroscopy (UV-vis). Effect of PVAc/ZnO microcapsule and PVAc/TiO₂ microcapsule on properties of poly(lactic acid) (PLA) was evaluated by UV-vis, SEM and mechanical properties test. The results showed that the addition of PVAc/ZnO and PVAc/TiO₂ microcapsules as a UV-blocking additive could significantly enhance UV-blocking property of PLA/PVAc/ZnO microcapsule composites and PLA/PVAc/TiO₂ microcapsule composites compared with pure PLA, PLA/ZnO composites and PLA/TiO₂ composites. The mechanical properties of PLA/PVAc/ZnO microcapsule composites were better than those of PLA/ZnO composites due to good dispersability and compatibility of PVAc/ZnO microcapsule in PLA matrix. Also, the mechanical properties of PLA/PVAc/TiO₂ microcapsule composites were better than those of pure PLA and PLA/TiO₂ composites. This study demonstrates the great potentials of the intrinsically UV shield additive PVAc/ZnO and PVAc/TiO₂ microcapsules in the application of high performance matrix resin and composite material.     

Preparation of TiO<Subscript>2</Subscript>-coated ZnO Nanoparticles and Their Effect on the UV Absorption of a Poly(vinyl alcohol) Composite Film

Titanium oxide (TiO₂) and zinc oxide (ZnO) composite structured nanoparticles were prepared by combining a sol-gel process and a solvothermal method. Titanium (IV) isoproxide (TTIP), used as a TiO₂ precursor, was dissolved in a colloidal ZnO nanoparticle solution synthesized by the sol-gel method, and TiO₂ was synthesized via solvothermal synthesis onto the ZnO nanoparticles. The effects of reaction conditions such as pH, reaction temperature, and reaction time on the morphology of the composite nanoparticles and the ultraviolet (UV) absorbance of their polymer composite films were investigated. The UV absorption of the poly(vinyl alcohol) (PVA) composite film with TiO₂-coated ZnO nanoparticles was higher than that of the TiO₂, ZnO, and ZnO-coated TiO₂ composite films. The reaction pH was found to have the strongest influence on the UV absorbance of the PVA/(TiO₂/ZnO) composite film. A pH of 7.0, reaction temperature of 250 °C, and reaction time of 24 h were the optimum conditions for UV absorption.     

Effect of calcium carbonate nanoparticles on barrier properties and biodegradability of polylactic acid

In this study, the effect of calcium carbonate (CaCO₃) nanoparticles on the barrier properties and biodegradability of polylactic acid (PLA) was investigated. For this purpose, nanocomposite films with various CaCO₃ nanoparticle contents (0, 3, 5, 10, and 15 wt%) were prepared by solution casting method. The gas permeability of nitrogen (N₂), oxygen (O₂), and carbon dioxide (CO₂) was evaluated through a constant volume and variable pressure apparatus at different pressures and temperatures. According to results, barrier properties were improved by loading CaCO₃ nanoparticles up to 5 wt%, and the gas permeability of CO₂, O₂, and N₂ was decreased from 1.4, 0.31, and 0.07 Barrer to 0.48, 0.095, and 0.019 Barrer, respectively. In addition, it was also observed that the gas permeability of samples was decreased by increasing feeding pressure and increased by enhancing temperature. Furthermore, morphological results confirmed the formation of agglomerations and large clusters over 5 wt% CaCO₃ nanoparticles. Finally, the thermal properties and biodegradability of PLA were increased by employing CaCO₃ nanoparticles. These results suggested PLA nanocomposites as favorable candidates for food packaging applications.     

Biodegradable polylactide (PLA) fiber mats containing Al2O3-Ag nanopowder prepared by electrospinning technique — Antibacterial properties

This article presents a non-complex method of producing biodegradable polylactide (PLA) fiber mats containing Al₂O₃-Ag nanopowder which display strong antimicrobial activities against E.coli and S. lutea. The method of preparing fiber mats was electrospinning. This article also gathers the results of the analysis of morphology and mechanical properties of both the Al₂O₃ nanopowder and the PLA-Al₂O₃/Ag fiber mats. The examination of the Al₂O₃ nanopowder was conducted with the use of a scanning electron microscope (SEM) and surface area measurements (BET). The morphology of the PLAAl₂O₃/Ag fiber mats was examined using SEM and TEM. The results of the study confirm the great potential of the electrospun PLA-Al₂O₃/Ag fiber mats for antibacterial application.