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Typically, archers prepare two sets of bows for competitions in case of bow breakage, but if the limbs of the bow break during a match, archers can become psychologically disadvantaged, leading to potentially fatal consequences. Archers are very sensitive to the durability and vibration of their bows. While the vibration-damping properties of Bakelite® stabilizer are excellent, its low density and somewhat lower strength and durability are disadvantages. As a solution, we used carbon fiber-reinforced plastic (CFRP) and glass fiber-reinforced plastic (GFRP) for the archery limb with stabilizer, commonly used for the limbs of the bow, to manufacture the limb. The stabilizer was reverse-engineered from the Bakelite® product and manufactured using glass fiber-reinforced plastic in the same shape as the existing product. Analyzing the vibration-damping effect and researching ways to reduce the vibration that occurs during shooting through 3D modeling and simulation, it was possible to evaluate the characteristics and the effect of reducing the limb's vibration by manufacturing archery bows and limbs using carbon fiber- and glass fiber-reinforced composites. The objective of this study was to manufacture archery bows using CFRP and GFRP, and to assess their characteristics as well as their effectiveness at reducing limb vibration. Through testing, the limb and stabilizer that were produced were determined to not fall behind the abilities of the bows currently used by athletes, and they also exhibited a noticeable reduction in vibrations. [ABSTRACT FROM AUTHOR]

Highlights: [•] PULL/PVA/Ag hybrid nanofibers fabrication. [•] Good interactions between PULL and PVA possibly caused by hydrogen bonds. [•] Thermal stability of PULL/PVA/Ag nanofibers is influenced by Ag content. [•] Antibacterial activity of PULL/PVA/Ag nanofibers demonstrated. [ABSTRACT FROM AUTHOR]

Abstract: Poly(vinyl acetate–methyl methacrylate) (VAc–MMA) copolymer microspheres were prepared using suspension polymerization at low temperature initiated with 2,2′-azobis(2,4-dimethyl valeronitrile) (ADMVN). The poly(VAc–MMA) copolymer microspheres can be used over a large area where homopolymers, polyvinyl acetate (PVAc) and methyl methacrylate (PMMA) microspheres are capable of being put to use. The prepared microspheres were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). Obtained copolymer microspheres which have 200μm average diameter and higher thermal stability than those of homopolymer. [Copyright &y& Elsevier]

Abstract: Nanofibers of the composite of pullulan (PULL), poly(vinyl alcohol) (PVA), and montmorillonite clay (MMT) were prepared using electrospinning method in aqueous solutions. Pullulan is an interesting natural polymer for many of its merits and good properties. Because of biocompatibility and non-toxicity of PVA, it could be used in numerous fields. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FTIR), X-ray diffraction (XRD), and thermal gravimetric analysis (TGA) were done to characterize the PULL/PVA/MMT nanofibers morphology and properties. XRD patterns and FTIR data demonstrated that there were good interactions between PULL and PVA caused by possibly hydrogen bonds. Moreover, XRD data and TEM images indicated that intercalated and exfoliated MMT nanoplatelets can be obtained within the PULL/PVA/MMT nanofibers depending on the PULL/PVA blend ratios. Furthermore, the thermal stability and mechanical property (tensile strength) of PULL/PVA/MMT nanofibers could be enhanced more by exfoliated MMT nanoplatelets than intercalated structures of that nanoplatelets. [Copyright &y& Elsevier]

Poly(vinyl alcohol) (PVA)/montmorillonite (MMT) clay nanocomposite microspheres were synthesized through suspension polymerization followed by the heterogeneous saponification for the first time. The effects of MMT on the saponification rate of poly(vinyl acetate) (PVAc) microspheres were studied. It was found that the saponification rate of PVAc significantly increased in the presence of MMT particles. The molecular weight of extracted PVA from the PVA/MMT was lower than that of pure PVA synthesized under similar conditions. TGA, TEM and XRD measurements illustrated that the clay platelets were intercalated in the polymer matrix. [ABSTRACT FROM AUTHOR]

Abstract: A series of aqueous polyurethane–urea (PUU) dispersions having urushiol were synthesized by in situ step polymerization of isophorone diisocyanate (IPDI), poly(ethylene glycol) (PEG, M n =1000g/mol), urushiol, dimethylol propionic acid (DMPA), and ethylene diamine (EDA). Urushiol was extracted with acetone from the purified lacquer of Toxicodendron vernicifluum and the different concentrations (0, 11.8, 17.6, and 22.2wt.% based on the total solids) of urushiol were introduced during the PU prepolymer synthesis. Thermal stability, mechanical strength, antimicrobial, and anticorrosive properties of the urushiol/PUU films were investigated in terms of urushiol concentration. [Copyright &y& Elsevier]

Abstract: Transparent and conductive carbon nanotubes (CNTs)/polyurethane-urea (PUU) composite films were prepared by solvent evaporation-induced self-assembly (EISA). Pristine CNTs were treated with acids (H2SO4/HNO3 =3:1, v:v), acylated with thionyl chloride, and purified after filtration. These acylated CNTs (0.05wt.% in dimethylformamide, DMF) were deposited onto the 3-aminopropyl triethoxysilane (APTES)-modified glass substrate by DMF EISA at 100°C with the withdrawal rate of 3cm/h. The CNT layers of 200–400nm thicknesses were transferred to the PUU films by solution casting or resin transfer molding (RTM) at ambient temperature. Optical transmittances of the composite films were 60–75% at 550nm wavelength and their sheet resistances were 5.2×100–2.4×103 kΩ/square, and which varied significantly with type of CNTs and the transferring methods of CNT layers. [Copyright &y& Elsevier]

Abstract: Composites of conducting polythiophene (PTh) with the host filler multi-walled carbon nanotube (MWNT) have been synthesized by the in situ γ-radiation-induced chemical polymerization method at room temperature. The resultant cable-like morphology of the composite (PTh–MWNT) structures was characterized by field-emission–scanning electron microscopy with the energy dispersive spectroscopy, Fourier transform infrared, thermal gravimetric analysis, X-ray photoelectron spectroscopy, and transmission electron microscopy. The characterizations of the molecular structure of the PTh–MWNT composites indicated that interfacial entrapment occurred between the MWNT and PTh; and the MWNT functioned as a template for PTh polymerization. The standard four-point probe method was utilized for measuring the conductivity of the samples. The conductivity through the PTh–MWNT composites was much higher than the value obtained for the bulk PTh powders synthesized by the same method. The PTh–MWNT composites showed improved thermogravimetric stability compared to the PTh homopolymer in the temperature range 0–800°C. [Copyright &y& Elsevier]

Abstract: Conducting polyaniline (PAni)–titanium dioxide (TiO2) composite micron-sized rods have been synthesized using an in situ gamma radiation-induced chemical polymerization method. Aqueous mixtures of aniline, a free-radical oxidant and/or titania nanoparticles were irradiated with γ-rays. The formation of PAni–TiO2 composite submicron-rods is the result of free aniline cation-radicals and adsorbed aniline cation-radicals on the surface of TiO2 nanoparticles growing together with the aid of high-energy gamma irradiation. SEM and TEM images represent the PAni–TiO2 composite rods as having a diameter range of 0.2–0.5μm. Electrical conductivities were checked by the standard four-point probes method and found to be 0.28S/cm for bulk PAni and 0.15S/cm for PAni–TiO2 composite submicron-rods. UV–visible absorption spectroscopy showed two electronic bands at about 320 and 596nm for bulk PAni and blue-shifted bands due to the formation of PAni–TiO2 composites. Thermogravimetric analysis revealed that the composites have a higher degradation temperature than polyaniline alone. [Copyright &y& Elsevier]

Syndiotacticity-rich low molecular weight (LMW) poly(vinyl alcohol) (PVA) was synthesized by solution copolymerization of vinyl pivalate (VPi) and vinyl acetate (VAc) with various monomer ratios in tetrahydrofuran at low temperature using 2,2′-azobis(2,4-dimethylvaleronitrile) (ADMVN) as an initiator and successive saponification of copoly(VPi/VAc). Solution copolymerization of VPi and VAc by ADMVN and saponification produced water soluble syndiotacticity-rich LMW PVA with number-average degrees of polymerization (Pn)s of 220–520, syndiotactic diad (s-diad) contents of 55.5–61.3%, and with maximum conversions of VPi and VAc into copoly(VPi/VAc) of 70–80%. The effect of stereosequences of PVA was investigated in terms of morphology of water-soluble LMW PVA. Especially, to precisely identify the effect of syndiotacticity of LMW PVA on the change of morphology, we prepared various PVAs with similar Pn of 1200 and with different s-diad contents of 55.5–61.3%, respectively. The PVA with s-diad content of 61.1% revealed a well-defined fibrous morphology. Each fiber was composed of a number of microfibrils. As the s-diad content of PVA decreased, some morphological change was observed. The specimen with s-diad content of 59.9% formed a divided precipitate with microfibrillar structure. In contrast, in the case of PVA with s-diad content of 55.7%, irregular shaped particles were observed. [Copyright &y& Elsevier]

Hybrid nanobiocomposite films are prepared using a solution casting by incorporating TEMPO cellulose nanofibrils (TOCNs) and carbon nanotubes (CNTs) into an aqueous solution of pullulan (PULL). The presence of CNT is confirmed by XRD characterization, and the prepared film shows an increased degree of crystallinity after the addition of TOCNs and CNT. The maximum degree of crystallinity value is obtained for CNT 0.5 % (59.64%). According to the Fourier-transform infrared spectroscopy, the shifts of the characteristic -OH peak of PULL occurred after the addition of TOCNs and aqueous CNT (3306.39 to 3246.90 cm−1), confirming interaction between the TOCNs, CNTs, and PULL matrix. The prepared films show enhanced material properties including higher tensile strength (65.41 MPa at low CNT content (0.5%)), water barrier properties, and reduced moisture susceptibility (5 wt.% CNT shows the lowest value (11.28%)) compared with the neat PULL film. Additionally, the prepared films are almost biodegradable within 64 days and show excellent electrical conductivity (0.001 to 0.015 S/mm for 0.5–5% CNT), which suggests a new approach to transform natural polymers into novel advanced materials for use in the fields of biosensing and electronics. [ABSTRACT FROM AUTHOR]

PULL/TOCNs/MMT nanocomposite film could be successfully prepared by the solution casting method out of aqueous solutions. The incorporation of MMT and TOCNs improves the mechanical, thermal, water barrier properties, and decreases moisture susceptibility while maintained reasonable transparency and biodegradability of the ternary PULL nanocomposites film. • Ternary pullulan composite films were successfully prepared with TOCNs and various MMT contents. • The incorporation of MMT and TOCNs improves the mechanical and thermal properties. • Water barrier properties improved and moisture susceptibility reduced. • The prepared composite films are transparent and biodegradable. Nanocomposite film of pullulan (PULL), tempo cellulose nanofibrils (TOCNs) and, montmorillonite clay (MMT) were prepared using a solution casting method with aqueous solutions. X-ray diffraction data revealed that exfoliated MMT nanoplatelets are distributed within the PULL/TOCNs/MMT film structure. Fourier-transform infrared results revealed that there might be interactions among the TOCNs, MMT and PULL matrix led to improved tensile strength, thermal stability, water barrier properties, and decrease moisture susceptibility while maintained reasonable transparency and biodegradability of the ternary PULL nanocomposites. These excellent properties of the nanocomposites clearly indicate towards a new strategy for developing high-performance PULL-based nanocomposites by using two different types of fillers with various geometric shapes and aspect ratio. This kind of ternary nanocomposite film can be broadly used in food packaging and protection as a green and biodegradable film. [ABSTRACT FROM AUTHOR]

In this study, a novel film of poly(vinyl alcohol) (PVA)/pullulan (PULL) with improved surface characteristics was prepared from poly(vinyl acetate) (PVAc)/PULL blend films with various mass ratios after the saponification treatment in a heterogeneous medium. According to proton nuclear magnetic resonance (1H-NMR), Fourier transform infrared, and X-ray diffraction results, it was established that the successful fabrication of saponified PVA/PULL (100/0, 90/10, and 80/20) films could be obtained from PVAc/PULL (100/0, 90/10, and 80/20) films, respectively, after 72 h saponification at 50 °C. The degree of saponification calculated from 1H-NMR analysis results showed that fully saponified PVA was obtained from all studied films. Improved hydrophilic characteristics of the saponified films were revealed by a water contact angle test. Moreover, the saponified films showed improved mechanical behavior, and the micrographs of saponified films showed higher surface roughness than the unsaponified films. This kind of saponified film can be widely used for biomedical applications. Moreover, the reported saponified film dressing extended the lifespan of dressing as determined by its self-healing capacity and considerably advanced in vivo wound-healing development, which was attributed to its multifunctional characteristics, meaning that saponified film dressings are promising candidates for full-thickness skin wound healing. [ABSTRACT FROM AUTHOR]

• A small amount of graphite improves the thermal conductivity of the composite. • The use of graphite affects the directional anisotropy of the thermal conductivity. • Epoxy composite with alumina and graphite is effective for heat dissipation. • The size of graphite particles causes a difference in the heat conduction effect. Heat-dissipative coating solutions with graphite and alumina as thermal conductive fillers were prepared, and the thermal conductivity and the thermal radiation characteristics were studied on the films cast from as-prepared solution. Thermal conductivity was separately measured in out-of-plane and in-plane directions of the film sample. Heat emissivity was measured from the surface of the film-coated Al plate. When a small amount of graphite was added, the thermal conductivity of the film was relatively improved as compared to that of the film with alumina alone. The in-plane thermal conductivity was relatively higher than that of the out-of-plane direction. [ABSTRACT FROM AUTHOR]

Breathable films were prepared based on linear low-density polyethylene (LLDPE), calcium carbonate (CaCO3), and aluminum (Al; 0, 2, 4, and 8 wt.%) using extrusion molding at a pilot scale. These films must generally be able to transmit moist vapor through pores (breathability) while maintaining a barrier to liquids; this was accomplished using properly formulated composites containing spherical CaCO3 fillers. The presence of LLDPE and CaCO3 was confirmed by X-ray diffraction characterization. Fourier-transform infrared spectroscopy results revealed the formation of Al/LLDPE/CaCO3 composite films. The melting and crystallization behaviors of the Al/LLDPE/CaCO3 composite films were investigated using differential scanning calorimetry. Thermogravimetric analysis results show that the prepared composites exhibited high thermal stability up to 350 °C. Moreover, the results demonstrate that surface morphology and breathability were both influenced by the presence of various Al contents, and their mechanical properties improved with increasing Al concentration. In addition, the results show that the thermal insulation capacity of the films increased after the addition of Al. The composite with 8 wt.% Al showed the highest thermal insulation capacity (34.6%), indicating a new approach to transform composite films into novel advanced materials for use in the fields of wooden house wrapping, electronics, and packaging. [ABSTRACT FROM AUTHOR]

Novel poly(vinyl alcohol) (PVA)/poly(vinyl butyral–vinyl alcohol) (P(VB-VA)) films with improved hydrophobicity were prepared from poly(vinyl acetate) (PVAc)/poly(vinyl butyral) (PVB) blend films with various mass ratios by saponification in a heterogeneous medium. The successful conversion of PVAc to PVA and PVAc/PVB to PVA/P(VB-VA) films was confirmed by Fourier transform infrared spectrometry, X-ray diffraction, and proton nuclear magnetic resonance analysis. This study also shows that the degree of saponification (DS) depends on the saponification time. The maximum DS of 99.99% was obtained at 96 h of saponification for all films, and the presence of PVB did not affect the DS at saponification times of 48–96 h. The effects of the PVAc/PVB blend ratio before and after saponification were determined by contact angle measurement, and the hydrophobicity was found to increase in both cases with increasing PVB content. Additionally, all the films exhibited improved mechanical properties after saponification, and the treated films possessed an unusual porous and uneven surface, in contrast with the untreated films. The prepared films with improved hydrophobicity can be used for various applications, such as biomaterials, filters, and medical devices. [ABSTRACT FROM AUTHOR]

Blown films based on low-density polyethylene (LDPE)/linear low-density polyethylene (LLDPE) and silica aerogel (SA; 0, 0.5, 1, and 1.5 wt.%) were obtained at the pilot scale. Good particle dispersion and distribution were achieved without thermo oxidative degradation. The effects of different SA contents (0.5–1.5 wt.%) were studied to prepare transparent-heat-retention LDPE/LLDPE films with improved material properties, while maintaining the optical performance. The optical characteristics of the composite films were analyzed using methods such as ultraviolet–visible spectroscopy and electron microscopy. Their mechanical characteristics were examined along the machine and transverse directions (MD and TD, respectively). The MD film performance was better, and the 0.5% composition exhibited the highest stress at break. The crystallization kinetics of the LDPE/LLDPE blends and their composites containing different SA loadings were investigated using differential scanning calorimetry, which revealed that the crystallinity of LDPE/LLDPE was increased by 0.5 wt.% of well-dispersed SA acting as a nucleating agent and decreased by agglomerated SA (1–1.5 wt.%). The LDPE/LLDPE/SA (0.5–1.5 wt.%) films exhibited improved infrared retention without compromising the visible light transmission, proving the potential of this method for producing next-generation heat retention films. Moreover, these films were biaxially drawn at 13.72 MPa, and the introduction of SA resulted in lower draw ratios in both the MD and TD. Most of the results were explained in terms of changes in the biaxial crystallization caused by the process or the influence of particles on the process after a systematic experimental investigation. The issues were strongly related to the development of blown nanocomposites films as materials for the packaging industry. [ABSTRACT FROM AUTHOR]

Phosphine-functionalized PVA/SiO 2 (pgf-PVA/SiO 2 ) composite nanofiber adsorbent (porous) was prepared using a facile electrospinning technique. The successful fabrication of the pgf-PVA/SiO 2 nanofibers was confirmed by field emission-scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and Fourier transform infrared (FTIR) analyses. The nanofiber adsorbent was evaluated for water sensitivity, N 2 adsorption–desorption isotherms, pore size distribution, and manganese (Mn +2 ) and nickel (Ni +2 ) ions removal from aqueous solution at various pH, contact times, and adsorbent dosages as well as at different regeneration/reuse cycles. The composite pgf-PVA/SiO 2 nanofibers (with 0.5 g/L fiber loading) can remove almost completely (96–98%) the aforementioned ions from aqueous solutions (initial concentration of 120 mg/L, pH 6) within 15 min of contact time. A reasonably simple acid treatment (with a 1 M HCl solution) was found to be extremely effective in regenerating the nanofiber adsorbent, and 92.5% of the metal ions were removed from the adsorbent even in the fifth regeneration/reuse cycle. Additionally, the adsorption equilibrium studies revealed the excellent adsorption capacities of the pgf-PVA/SiO 2 nanofiber for both Mn +2 and Ni +2 ions (234.7 and 229.9 mg/g, respectively). [ABSTRACT FROM AUTHOR]

A novel super-absorbent material was fabricated by electrospinning the natural polysaccharide pullulan (PULL) with polyvinyl alcohol (PVA) and montmorillonite (MMT) clay to form nonwoven webs, which were then heat treated. Transmission electron microscopy (TEM) micrographs, X-ray diffraction (XRD) patterns, and Fourier transform infrared (FTIR) analysis of the novel super-absorbent nanofibers suggest the coexistence of PULL, PVA, and MMT through the exfoliation of MMT layers in the super-absorbent nanofiber composite. The heat-treated PULL/PVA/MMT webs loaded with 5 wt% MMT electrospun nanofibers exhibited a water absorbency of 143.42 g g −1 in distilled water and a water absorbency of 39.75 g g −1 in a 0.9 wt% NaCl solution. Under extremely dry conditions, the PULL/PVA/MMT webs exhibited the ability to retain 43% distilled water and 38% saline water after being exposed to the atmosphere for one week. The heat treatment improved the crystallinity of the electrospun PULL/PVA/MMT super-absorbent webs and thus made the webs highly stable in aqueous environments. Overall, the addition of MMT resulted in improved thermal stability and mechanical properties and increased the water absorbency of the PULL/PVA/MMT composite. [ABSTRACT FROM AUTHOR]

For the first time, poly(vinyl alcohol) (PVA)/poly(methyl methacrylate–methallyl alcohol) (P(MMA-MAA)) (9:1, 7:3, 5:5) blend films were made simultaneously using the saponification method in a heterogeneous medium from poly(vinyl acetate) (PVAc)/poly(methyl methacrylate) (PMMA) (9:1, 7:3, 5:5) blend films, respectively. The surface morphology and characteristics of the films were investigated using optical microscopy (OM), atomic force microscopy (AFM), X-ray diffractometer (XRD), Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). Moreover, the effect of the PVAc content on the degree of saponification (DS) of the PVAc/PMMA films were evaluated and revealed that the obtained DS value increased with the increase in PVAc content in the PVAc/PMMA blend films. According to the OM results, the saponified films demonstrated increased surface roughness compared with the unsaponified films. The AFM images revealed morphological variation among the saponified PVAc/PMMA blend films with different mass ratios of 9:1, 7:3, and 5:5. According to the DSC and TGA results, all blend film types exhibited higher thermal property after the saponification treatment. The XRD and FTIR results confirmed the conversion of the PVAc/PMMA into PVA/P(MMA-MAA) films. Thus, our present work may give a new idea for making blend film as promising medical material with significant surface properties based on hydrophilic/hydrophobic strategy. [ABSTRACT FROM AUTHOR]

Guided bone regeneration (GBR) is a technique where a barrier membrane is placed over the bone defect to prevent cell growth from the connective tissue and epithelium. Titanium (Ti) has excellent mechanical properties and is one of the most frequently used materials in implant dentistry. This study examined how graphene oxide (GO)-coated Ti (GO-Ti) membranes can enhance the osteogenesis of MC3T3-E1 preosteoblasts and promote new bone formation for potential applications to GBR. The physicochemical properties of GO-Ti membranes were characterized by atomic force microscopy, Raman spectroscopy, X-ray diffraction, and contact angle measurements. The cellular behaviors of MC3T3-E1 preosteoblasts on GO-Ti membranes were examined by cell counting kit-8 and alkaline phosphatase (ALP) activity assays. The effects of GO-Ti membranes on bone regeneration were evaluated by implanting them into rat calvarial defects. GO was coated uniformly on Ti substrates, which allowed a decrease in surface roughness and contact. GO-Ti membranes stimulated significantly ALP activity without interfering with their proliferation. Furthermore, GO-Ti membranes enhanced new bone formation significantly in full-thickness calvarial defects without inflammatory responses. Therefore, this suggests that GO-Ti membranes can be applied effectively to GBR because these graphene-coated Ti membranes have potent effects on stimulating osteogenic differentiation and exhibit superior bioactivity. [ABSTRACT FROM PUBLISHER]

Novel poly(vinyl alcohol) (PVA) nanofibers were prepared through the heterogeneous saponification of poly(vinyl acetate) (PVAc) nanofibers for the first time. To prepare the saponified PVA nanofibers, the effects of the alkali solution concentration and temperature were studied. It was found that the degree of saponification depended on the temperature and alkali solution concentration. Field emission scanning electron microscopy was utilized to characterize the morphology and properties of mats of the saponified PVA nanofibers, and unusual wrinkled and wound fibers were found. The conversion of PVAc nanofibers to PVA nanofibers was measured using proton nuclear magnetic resonance spectrometry, X-ray diffraction measurements, and Fourier transform infrared spectroscopy. [ABSTRACT FROM AUTHOR]

[Display omitted] • Al/thermoplastic composites have a higher tensile strength than 200 MPa, and an average EMI shielding properties of 94 dB. • Mechanical and EMI shielding performance of composites are affected by the interface adhesion. • The aramid nanofiber improves interlayer bonding and minimizes internal voids in the composites by mechanical interlocking. Structural composites for electric vehicles should have lightweight, mechanically strong, efficient electromagnetic shielding. Although thermoplastic composite material plays a structural role and aluminum thin film (Al foil) plays the role of electromagnetic wave shielding, poor interfacial adhesion and tear-resistance of Al foil need to be overcome. In this work, we demonstrated a novel, high-performance EMI-shielding multilayer structure based on an aluminum thin film (Al), glass fabric (GF), carbon fiber-reinforced thermoplastic (CFT), and thermoplastic adhesive. In particular, the interfacial adhesion at the mechanically weak interface has been significantly improved by a factor of 1.15 via the application of an aramid nanofiber-embedded (ANF) thermoplastic interlayer. We found that the distribution and entanglement of aramid nanofibers in the ANF adhesive layer precisely determine the mechanical properties of the entire structural composite. Efficient EMI shielding performance (an average of 94 dB at 0.2–1.0 GHz) of structural EMI shielding composites was possible using a uniform aramid nanofiber layer. [ABSTRACT FROM AUTHOR]

Poly(vinyl alcohol)/montmorillonite/silver hybrid nanoparticles are successfully fabricated by one-step electrospraying process in aqueous solution. The aim of this project is to design an optimum solution parameter for electrospraying system and evaluate inorganic material effects to antibacterial performance and thermal properties. Hybrid nanoparticles could be obtained at low molecular weight and concentration of the polymer. Transmission electron microscopy analysis showed montmorillonite and silver were well dispersed in poly(vinyl alcohol) nanoparticles and enhanced thermal properties of the composite material. In anti-bacterial test, the poly(vinyl alcohol)/montmorillonite/silver hybrid nanoparticles showed an excellent anti-bacterial performance. [ABSTRACT FROM AUTHOR]

Zein is a hydrophobic protein produced from maize and has great potential in a number of industrial applications such as food, food coating and food packaging. The objectives of this study are to determine the effects of montmorillonite on the wettability and microstructure properties of zein/montmorillonite nanocomposite nanofiber mats fabricated by the electrospinning technique in ethyl alcohol aqueous solution. The zein/montmorillonite nanofiber mats were characterized by field-emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, differential scanning calorimetry, thermogravimetric analysis and contact angle measurements. This study shows that the introduction of montmorillonite resulted in the improvement of the thermal stability and hydrophilicity for the zein matrix. X-ray diffraction patterns and transmission electron microscopy micrographs suggest the coexistence of intercalated montmorillonite layers over the examined montmorillonite contents. Since montmorillonite is a hydrophilic clay, its addition can be used not only to produce nanomaterials with the already known improved properties but also to enhance the hydrophilicity of material. [ABSTRACT FROM PUBLISHER]

Abstract: Excellent colloidal stability and antimicrobial activity are important parameters for silver nanoparticles (AgNPs) in a range of biomedical applications. In this study, polyethyleneimine (PEI)-capped silver nanoparticles (PEI-AgNPs) were synthesized in the presence of sodium borohydride (NaBH4) and PEI at room temperature. The PEI-AgNPs had a positive zeta potential of approximately +49mV, and formed a stable nanocolloid against agglomeration due to electrostatic repulsion. The particle size and hydrodynamic cluster size showed significant correlations with the amount of PEI and NaBH4. PEI-AgNPs and even PEI showed excellent antimicrobial activity against Staphylococus aureus and Klebsiella pneumoniae. The cytotoxic effects of PEI and PEI-AgNPs were confirmed by an evaluation of the cell viability. The results suggest that the amount of PEI should be minimized to the level that maintains the stability of PEI-AgNPs in a colloidal dispersion. [Copyright &y& Elsevier]

Abstract: A novel amperometric cholesterol biosensor was fabricated by the immobilization of ChOx (cholesterol oxidase) onto the chitosan nanofibers/gold nanoparticles (designated as CSNFs/AuNPs) composite network (NW). The fabrication involves preparation of chitosan nanofibers (CSNFs) and subsequent electrochemical loading of gold nanoparticles (AuNPs). Field emission scanning electron microscopy (FE-SEM) was used to investigate the morphology of CSNFs (sizes in the range of ∼50–100nm) and spherical AuNPs. Cyclic voltammetry, hydrodynamic voltammetry and amperometry were used to examine the performance of CSNF–AuNPs/ChOx biosensor. The CSNF–AuNPs/ChOx biosensor exhibited a wide linear response to cholesterol (concentration range of 1–45μM), good sensitivity (1.02μA/μM), low response time (∼5s) and excellent long term stability. The combined existence of AuNPs within CSNFs NW provides the excellent performance of the biosensor towards the electrochemical detection of cholesterol. [Copyright &y& Elsevier]

Abstract: Pullulan (PULL)/montmorillonite clay (MMT) nanofiber blend mats with various weight ratios have been fabricated by the electrospinning technique in aqueous solution. The PULL/MMT nanofiber mats are characterized by X-ray diffraction (XRD), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) and mechanical measurements. The study shows that the introduction of MMT results in improvement in tensile strength, and thermal stability of the PULL matrix. XRD patterns and TEM micrographs suggest the coexistence of intercalated MMT layers over the studied MMT contents. XRD analyses also reveal an increase of the crystallinity of the blend nanofiber mats with addition of MMT fillers. Moreover, FT-IR divulges that there might be possible interaction occurred between the MMT clay and PULL matrix. [Copyright &y& Elsevier]

Abstract: Nanocomposites of gold and multi-walled carbon nanotubes (MWNTs) were prepared with gold nanoparticles and MWNTs stabilized by 4-(dimethylamino)pyridine (DMAP) and dispersion agents, respectively, and studied in detail with UV/vis spectroscopy, transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). UV/vis spectra of Au-MWNT nanocomposites showed the characteristic surface plasmon bands at ∼525nm. There was only slight change on the band shape with change of dispersion agent for MWNTs. Through TEM images and XPS analysis, the distribution of gold nanoparticles on the sidewalls of MWNTs was deliberately investigated on three species of Au-MWNT nanocomposites treated with different dispersion agents and compared with one another. [Copyright &y& Elsevier]

Abstract: Sulfonated polyaniline–titanium dioxide (SPAni–TiO2) hybrid composites have been synthesized by using a new strategy in one-pot system of UV-cured polymerization method. Aqueous solution of aniline and orthoanilinic acid comonomers, a free-radical oxidant and titania precursor were irradiated by UV rays. Hydrolysis and reprecipitation of the titania precursor in aqueous aniline and orthoanilic acid lead to the formation of titanium dioxide particles which in turn catalyze oxidation of comonomers to sulfonated polyaniline. The resultant SPAni–TiO2 composites were characterized by using different spectroscopy analyses like X-ray diffraction, UV–visible (UV–vis) and infrared spectroscopy. The UV–vis absorption bands revealed that SPAni–TiO2 nanocomposites are optically active and the blue-shifted peaks due to the presence of titania within the SPAni matrix. Scanning electron microscopy and transmission electron microscopy of the nanocomposite showed a uniform size distribution with spherical and granular morphology. Thermogravimetric analysis revealed that the SPAni–TiO2 composites have a good thermal stability than the pristine SPAni. [Copyright &y& Elsevier]

Thermoplastic composites are rapidly emerging as alternative materials for auto parts owing to recyclability as well as excellent stiffness- and strength-to weight ratios. In this study, an optimal stacking sequence using twill-weave carbon fiber-reinforced polypropylene (CF/PP) prepregs and random fiber-reinforced polypropylene (RFP) sheets were investigated for the fabrication of an automobile fender. The lamination consisting of CF/PP only incurred imperfect resin impregnation. RFP insertion between CF/PP layers improved the resin impregnation. The hybrid stacking sequence not only reduced internal void contents but also increased the flexural and impact strength of the composite laminate. Using the optimal stacking sequence, a real-scale composite fender was fabricated and impact tests were performed. The test results were compared with the ones from an existing steel fender. In case of the steel fender, permanent deformation was observed even in one attempt, while no visible damage was found from the composite fender even after five consecutive impact tests. [ABSTRACT FROM AUTHOR]

Abstract: One of the most important issues in the research related to Zn–air batteries is the hydrolysis of the aqueous solution. We have investigated the effectiveness of Zn ions and the anions of various acids as gas suppressants in the battery. Zn ions can function as a gas suppressant on a Pt surface, but they can stimulate additional gas production when they are deposited as Zn metal. On the other hand, the counter anions of weak acids behave as adsorbates to cover Zn metal effectively. [Copyright &y& Elsevier]

Disposable PP-straws are cylindrical tubes composed of a thermoplastic film and are readily used as thermoplastic composites intermediate if carbon fiber (CF) is reinforced. Herein, we used PP-straw as a matrix material and developed a carbon fiber PP-straw prepreg (CSP) using CF reinforced materials. Disposable straws can be recycled to produce composites by using PP-straws, and the manufacturing process of the thermoplastic composite material is simplified. The CF content suitable for PP-straws was determined at 40 wt% by tensile strength and electrical resistance changes in pressurizing CSP. In manufacturing CSP, field emission scanning electron microscopy (FE-SEM) showed that the PP matrix was impregnated when the gap between the fibers was >5 μm, thus air texturing was used to widen the gap between the CF tows. Suitable fiber configurations for the CSP were formed at 4 kPa of air texturing pressure, and the CSP properties were degraded because of damaged fibers under higher-pressure conditions. The tensile impact and inter-laminar shear strengths (ILSS) were evaluated, and the improved properties of the CF PP-straw composites were confirmed with increasing fiber length. [ABSTRACT FROM AUTHOR]

Abstract: Controlling the nanocrystalline structure of TiO2 powders is very important for the application to dye-sensitized solar cells (DSSC) because the efficiency of DSSC is considerably influenced on the change of the TiO2 nanostructures. Nanocrystalline TiO2 powders were synthesized by the conventional sol–gel method, in which titanium iso-propoxide was reacted under various acid conditions. As-prepared TiO2 powders were calcined at 600°C for 5h. The structural informations of the calcined TiO2 powders were in detail characterized by X-ray diffraction, nitrogen adsorption isotherm, and electron microscopy. The structural analysis of as-prepared TiO2 powders supported that their crystal structures were changed by the variation of acid solutions. In order to study the structural variations of the TiO2 powders, some acid solutions were prepared with the selected mixtures of H2SO4, HCl, and HNO3. The nanocrystalline properties such as crystal type and porosity were mainly affected by the use and the amount of H2SO4. [ABSTRACT FROM AUTHOR]

Abstract: Gold-decorated multi-walled carbon nanotubes were prepared by electrostatic interaction in solution states and they have been studied in detail with UV/Vis spectroscopy, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and cyclic voltammetry (CV). Gold nanoparticles and their composites showed the similar surface plasmon absorptions. XPS results were in good agreement with the composite morphologies of TEM images. HOMO/LUMO energies and the energy band gaps of MWNTs in their composites were analyzed by CV measurements. [Copyright &y& Elsevier]