Abstract: Epoxy matrix composites reinforced with recycled cellulose fibre (RCF) were fabricated and characterized with respect to their flexural and impact properties. Reinforcement of the epoxy by RCF resulted in a significant increase in the strain at failure, fracture toughness and impact toughness but only a moderate increase in flexural strength and flexural modulus. The effect of accelerated exposure to seawater on the flexural and impact properties was also investigated. The salient toughening mechanisms and crack-tip failure processes were identified and discussed in light of observed microstructures, in particular the orientation of RCF sheets to the applied load.

Abstract: Polylactide–flax fiber composites with 1, 10 and 20 wt% fiber were melt-compounded and subsequently molded via the conventional and microcellular injection-molding processes. Silane was used as a coupling agent. The effects of fiber and silane content on cell morphology, static and dynamic mechanical properties, and crystallization properties have been studied. The average cell size decreased while the cell density increased with the fiber content. The degree of crystallinity increased with the fiber content. Silane treatment of fibers affected neither the cell morphology nor the degree of crystallinity. The toughness and strain-at-break of solid samples decreased with the fiber content while silane treatment increased both properties; however, neither fiber content nor silane treatment had much influence on the toughness and strain-at-break of microcellular samples. The specific modulus of both solid and microcellular samples increased with the fiber content. The specific strength of the solid and microc...

Abstract: The paper presents the results of a complex study of the structure, phase composition and physical and mechanical properties of a new biocomposite material, bulk nanostructured titanium–calcium-phosphate coating, as well as its biological testing. The high-strength nanostructured titanium was obtained by multiple uniaxial pressing using an original press-mold within the temperature interval from 1023 to 623 K and the additional rolling deformation in combination with prior-recrystalline annealing. Such a treatment produces improvement in the mechanical properties of titanium up to the level of high-strength titanium alloys, for example, Ti-6Al-4V. It was found that the micro-arc technique of formation of calcium phosphate (Ca-P) coating in aqueous solutions of phosphoric acid, hydroxylapatite and calcium carbonate powders provides the generation of β-tricalcium phosphate that points to high biocompatibility. Adhesion strength of Ca-P coating to nanostructured titanium is no less than 25 MPa. Biological te...

Abstract: The article is an overview of our recent study on some particular aspects of polyelectrolyte complex (PEC) formation by oppositely charged polysaccharides when they are brought into contact in aqueous solutions. This type of complexation can lead to the thickening effect, jellification or PEC precipitation that find numerous applications in a variety of fields from the regulation of rheological characteristics of solutions to fabrication of functional materials by the layer-by-layer technique. Our focus was on the rheological aspects of water-soluble PEC formation and jellification, but to gain an insight into the mechanisms of the processes involved, atomic force microscopy, scanning electron microscopy and differential scanning calorimetry were also applied. As cationic polysaccharides, chitosan and cationic derivatives of hydroxypropylcellulose including hydrophobically modified samples were taken and, as their anionic counterparts, alginates, carrageenans, xanthans and fucoidans were used. Their combi...

Abstract: In order to throw light on the mechanism of organic compounds–clay interactions and to control the preparation of hydrophobic fillers, the effect of asphaltene adsorption from water-saturated toluene onto various clay minerals (kaolinite, illite) was studied. The modification of the clay surface charge and wettability were characterized, respectively, by microelectrophoresis and Washburn contact angle measurements. Further, the alteration of the surface area and chemical composition of the clay particles due to asphaltene adsorption were assessed using various methods such as N2-adsorption/desorption, X-ray diffraction (XRD) measurements, FT-IR and scanning electronic microscopy. The data indicate that upon asphaltene adsorption, the clay particles become hydrophobic, their contact angle with water increases, while their surface charge and surface energy are reduced. Furthermore, according to XRD data, no swelling of the clay by asphaltenes occurs in the water-saturated toluene, indicating that asphaltene...

Abstract: It was shown that the Plasma Electrolytic Oxidation (PEO) treatment followed by coating the superdispersed polytetrafluoroethylene (SPTFE) Forum® on the developed mesoporous PEO-layer resulted in a composite coating on the surface of metals and alloys (e.g., titanium, nitinol, steel). The electrochemical properties including contact corrosion currents of the galvanic couples steel/titanium with composite coating were studied by means of electrochemical impedance spectroscopy and potentiodynamic polarization. In addition, mechanical properties were examined. It was ascertained that the combination of PEO-produced coating with SPTFE provided increased corrosion stability of metals and alloys making them suitable for implantation surgery.

Abstract: The combined effects of alkali and ultrasound treatment of wood flour on the mechanical properties of polypropylene-based wood/plastic composites (WPCs) were examined FT-IR measurements confirmed that the alkali treatment removed both hemicellulose and lignin from the wood, and there was an increase in the number of hydroxyl groups on the cellulose surface This process was promoted by ultrasound treatment Mechanical testing of injection-molded WPC samples revealed that alkali treatment improved both composite strength and modulus when polypropylene grafted with maleic acid was used as a coupling agent The strength increase is due to improved adhesion between the fiber and matrix, while improved modulus is due to the removal of lignin and hemicellulose that are not as stiff as cellulose Polarized optical microscopy showed the presence of well-defined polymer crystals on the surface of the modified wood, and this is also responsible for the improved mechanical properties It is conclusively demonstrate

Abstract: Forced atmospheric (air) plasma treatment (FAPT) was applied to wood plastic composite (WPC) and continuous glass fiber reinforced plastic (FRP) surfaces to improve their adhesive bonding properties. The FRP was composed of oriented continuous E-glass fibers in a polypropylene matrix, while the WPC was fabricated using wood flour, polypropylene and additives. The FAPT was applied using two levels of discharge length projected from the discharge head (2.5″ and 1″) to ionize the air, oxidize the surfaces and improve wettability. The treatment was performed by passing the electrode over either surface, five or ten times. Surface characterization consisted of thermodynamic (surface energy determination), chemical (X-ray photoelectron spectroscopy), mechanical (shear strength) and microscopic (atomic force microscopy (AFM)) analysis. The results indicate that the acid–base component of the surface energy for both WPC and FRP after FAPT correlates with an increase in wettability. X-ray photoelectron spectroscop...

Abstract: Regenerated cellulose fiber (RN) and natural fiber (pine wood fiber (PW)) filled e-polycaprolactone (PCL) compound, PCL/RN (90/05 and 75/25 wt%) and PCL/PW (90/05, 75/25 and 50/50 wt%), are investigated with regard to interfacial adhesion, rheological properties, morphology, nucleation and mechanical properties. The interfacial adhesion of the RN filled PCL compounds shows better values than that of the PW filled ones. As the concentration of the RN and the PW particles is increased, the dynamic viscosity, the crystallization temperature and the elongation modulus are increased; however, the elongation strain is decreased. The viscosity of the RN filled compounds is higher than that of the PW ones at the same loadings. Striking differences are observed in elongation yield stress measurements. As the concentration of the particles is increased, while the elongation yield stress of the RN compounds is significantly increased, that of the PW compounds does not show significant improvement. More spherulites a...

Abstract: This paper investigates the feasibility of injection-molded wood–fiber/high-density polyethylene (HDPE) composite foams that can replace injection-molded HDPE solids in industrial applications. The study applies injection foam molding technology using a physical blowing agent to a wood–fiber/HDPE composite, and examines the effects of the processing parameters on the dimensional and mechanical properties and cell density of the composite foams. In addition, the physical properties and cost of wood–fiber/HDPE composite foams are compared with those of solid HDPE. The experimental results show that wood–fiber/HDPE composite foams that have a 20% weight reduction have superior physical properties, such as density, dimensional properties (68% decrease of shrinkage and 91% decrease of warpage) and mechanical properties (28% increase of Young's modulus). Furthermore, the cost analysis confirms that wood–fiber/HDPE composite foams are much less expensive (by 40%) than HDPE. Therefore, it is concluded that wood–f...

Abstract: Fil: Marcovich, Norma Esther. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnologia de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingenieria. Instituto de Investigaciones en Ciencia y Tecnologia de Materiales; Argentina

Abstract: The aim of this study was to investigate the effects of electron beam (EB) irradiation on the morphological properties, crystallinity and surface area of henequen fiber and on the mechanical and thermal properties of henequen fiber reinforced polypropylene (PP) composites. The structure of henequen fiber was characterized by X-ray diffraction, mercury porosimetry and BET surface area analysis. The EB irradiation of 10 kGy led to the increasing of crystalline and surface pore area of henequen fiber, which contributed to the number of interlocking places with PP. From the results of tensile and impact strength tests, the highest value was observed for the composite reinforced with the henequen fiber treated with EB dose of 10 kGy, decreasing overall as EB dose increased. This tendency was also shown by coefficient of thermal expansion (CTE) measurements, but the value of CTE decreased until 50 kGy, meaning that a large total surface area can provide many interlocking places and so improve adhesion between f...

Abstract: A developed nanomechanical analysis of atomic force microscopy (AFM) based on the JKR theory has been applied to butyl rubber; isoprene-co-isobutylene rubber (IIR, butyl rubber). The force–deformat...

Abstract: In the present work, the deformation and fracture behavior of PP/ash composites with different ash content was investigated. The effect of a silane coupling agent was also analyzed. From uniaxial t...

Abstract: In the present study, novel biocomposites with chopped jute fibers and thermosetting polycardanol were prepared using compression molding technique for the first time. Prior to biocomposite fabrication, jute fiber bundles were surface-treated at various concentrations using 3-glycidoxypropyltrimethoxy silane (GPS) and 3-aminopropyltriethoxy silane (APS), respectively. The interfacial shear strength, flexural properties and thermal properties of jute/polycardanol biocomposites reinforced with untreated and silane-treated jute fibers were investigated by means of single fiber microbonding test, three-point flexural test, dynamic mechanical analysis, thermogravimetric analysis and thermomechanical analysis. Both GPS and APS treatments played a role in improving the interfacial adhesion, reflecting that the organofunctional groups located at the end of silane coupling agents may contribute to linking between jute fibers and a polycardanol resin. As a result, it gave rise to increased interfacial shear strengt...

Abstract: It is important for the understanding of the complexity of a human hair structure to observe the ultra-structures and to measure their mechanical properties at the same point of the specimen We examined the extremely smooth surface of the hair cross-section by force modulation (FM) method and Young's modulus mapping method by analyzing force curves (FCs) in two-dimensional lattice being installed in an atomic force microscope (AFM) Consequently, the FM method was used to evaluate the changes in structural and mechanical properties in the internal structures of hair in air and in water performing any pre-treatment (chemical modification) on hair specimen It was also possible to determine the semi-quantitative changes caused by the chemical damages of hair and the repairing effect of conditioning agents at nano-size level with Young's modulus mapping method

Abstract: Nanotechnology-based organic coatings have attracted increasing interest in recent years due to their high performances. In this article, the development of nanotechnology-based coatings is reviewed with regard to their potential applications, such as UV-blocking coatings, anti-scratch coatings, anti-abrasion coatings, anti-corrosion coatings, super-hydrophobic coatings and barrier coatings. The market for nanocomposite coatings in China is also briefly described.

Abstract: Rheological and mechanical properties of the polycarbonate (PC)/carbon fiber (CF) composites with different initial fiber length, sizing effect of the fiber, fiber content and screw speed have been...

Abstract: The pore characteristics and morphological changes of henequen fiber after electron beam (EB) irradiation were studied, and their effects on interfacial adhesion between henequen fiber and polypropylene (PP) matrix of biocomposites were investigated. The surface morphologies of the fibers exposed to various EB irradiation doses were observed with an atomic force microscope (AFM). The porosity and pore distribution of fibers were characterized by mercury porosimetry and nonfreezing bound water (NFW) was measured by differential scanning calorimeter (DSC). Henequen fiber-reinforced polypropylene biocomposites were manufactured by the compression molding method and interlaminar shear strength (ILSS) was analyzed to examine the interfacial adhesion between henequen fiber and the PP matrix of the biocomposites. The AFM images indicated that pectin, waxy materials and impurities were removed from the surfaces of the henequen fibers during EB irradiation, resulting in changes of the surface morphology and charac...

Abstract: Nanocomposite solid polymer electrolytes (NSPEs) based on poly(vinylidene fluoride) (PVDF) were prepared by dispersing two kinds of organoclay (Cloisite® 30B, Cloisite® 15A) consisting of silicate layers in the polymer matrix. The effect of affinity between PVDF and organoclay as the filler on ionic conductivity was investigated in relation to its content, dispersed condition of organoclay, and structural changes of nanocomposites. The characterizations of PVDF-based nanocomposites with various organoclay contents were carried out by XRD, TEM, DSC, and DMA. In order to confirm the ion conduction properties of NSPEs with LiCF3SO3 at room temperature, ac impedance analyzer and FT-IR spectrometer were used. As a result, a higher ionic conductivity appeared in the case of NSPE with C15A than that with C30B and the maximum conductivity was 1.04 × 10–3 S/cm for the NSPE containing 5 wt% of C15A and 40 wt% of LiCF3SO3.

Abstract: Textural, mechanical and catalytic properties of porous composite materials Al2O3/Al, MeO x (Me)/Al2O3/Al with metal particles homogeneously distributed in the alumina matrix were studied. These ma...

Abstract: Pulp fibre-to-fibre bonds were studied using polarization microscopy and microtome cuts. The experiments showed considerable discrepancies between these two experimental methods. While microtome cuts clearly show if a bond between two fibres has formed, polarization microscopy cannot unambiguously discern between crossed unbonded fibres and bonded fibres; also certain bonds cannot be detected with this method. To examine these shortcomings, a physical model of polarization microscopy of bonded and unbonded pulp fibers was built. Experimental validation of the model gave good agreement between calculations and reflectance measurements. Calculations based on this model clearly demonstrate that only bonded fibres resembling a plane parallel plate show as bonds. However, crossings of unbonded fibers also appear as bonds if the two fibres are flat and plane parallel to each other. The model provides a consistent interpretation for polarization microscopy imaging of pulp fibre bonds, an important topic in resea...

Abstract: Reinforcing of polylactide (PLA) with fillers can be an interesting solution to reduce its global price and to improve specific properties. Starting from calcium sulfate (gypsum) as by-product of the lactic acid fermentation process, novel high performance composites have been produced by melt-blending PLA and this filler after a previous specific dehydration performed at 500°C for min. 1 h. Due to PLA sensitivity towards hydrolysis, it has first been demonstrated that formation of β-anhydrite II (AII) by adequate thermal treatment of calcium sulfate hemihydrate is a prerequisite. Then, the modification of filler interfacial properties with different coating agents such as stearic acid (SA) and stearate salts has been considered. The effect of surface treatment on molecular, thermal and mechanical properties has been examined together with the morphology of the resulting composites. To take advantage of the improved lubricity and better wetting characteristics, the filler was coated by up to 2% (by weight...

Abstract: Biocompatibility in research and development of advanced prosthetics is a current problem faced by medical researchers. A major challenge in tissue engineering is to find materials and processing techniques that allow them to produce extracellular matrices (ECM) mimicking scaffolds that promote cell growth and organization into a specific architecture, inducing cell differentiation and subsequent cell function. The ideal tissue repair material thus should consist of synthetic biomaterials, such as natural polymers mimicking the mechanical and biological functionality of the ECM. Cellulose acetate membranes were used as scaffolds for microvascular cell growth. Hydroxyapatite (HA) is a natural ceramic (responsible for strength and stability in the human skeletal system) operable as a biocomposite coating to improve the biocompatibility of implant substrates. In this work, HA was prepared from low cost natural calcium source — eggshells. Its structural properties were investigated by scanning (SEM), transmis...

Abstract: Mixed ionic–electronic conducting nanocomposite La0.8Sr0.2Ni0.4Fe0.6O3 (LSNF)–Ce0.8Gd0.2O2– δ (GDC) was prepared via ultrasonic dispersion of nanocrystalline powders of perovskite and fluorite oxides in water with addition of surfactant, followed by drying and sintering up to 1300°C. Analysis of the real structure of nanocomposite (studied by XRD and TEM with EDX) and its surface composition (studied by XPS) revealed moderate redistribution of elements between phases favoring their epitaxy. Results of impedance spectroscopy, oxygen isotope exchange, O2 TPD and H2 TPR experiments revealed a positive effect of composite interfaces on the oxygen mobility and reactivity agreeing with the ambipolar transport behavior of MIEC composite. Preliminary testing of button-size cell with functionally graded LSNF–GDC cathode layer supported on thin YSZ layer covering Ni/YSZ cermet demonstrated high and stable performance, which is promising for its practical application.

Abstract: Gold nanorods protected by hexadecyltrimethylammonium bromide were treated by an organosilane, aminopropyltriethoxysilane (APS) or vinyltrimethoxysilane (VS) in the presence of mercaptopropyltrimet...

Abstract: In this study, the effects of impregnation materials — di-ammonium phosphate, aluminium sulphate, potassium carbonate, calcium chloride, zinc chloride — on combustion properties of 3-ply laminated veneer lumbers (LVL) produced from oak (Quercus robur L.) bound by phenol-formaldehyde (PF), or poly(vinyl acetate) (PVAc) have been investigated. The pressure–vacuum method was used for the impregnation process. Combustion test was performed according to the procedure of ASTM-E 69 standards. According to the test results, zinc chloride was found to be the most successful fire retardant chemical in LVL with PF adhesive. Since zinc chloride diminishes combustion, it is possible to advise the use of LVL produced from oak with PF adhesive and impregnated with zinc chloride as a fire retardant building material where required.

Abstract: A number of new silica fillers have been obtained in the emulsion system and changes in their surface properties appearing as a result of modification with the following alkoxysilanes have been eva...

Abstract: The effects of surface treatment of nanometric titanium dioxide (TiO2) powder with octyltriethoxysilane on the hydrophobicity of the inorganic nanoparticles have been investigated. Thermogravimetric analysis (TGA), attenuated total reflection infrared spectroscopy (ATR-IR), laser scattering and specific BET-surface area and pore volume measurements were used as characterization techniques. The TiO2 nanoparticles were treated with solutions of supercritical carbon dioxide (scCO2) as solvent and silane molecules. A thermal resistant polysiloxane structure was formed on the TiO2 surface. The mesoporosity of the aggregates of TiO2 was preserved after the supercritical silanization process. The dispersibility of TiO2 in an organic hydrophobic phase (petroleum) was enhanced after the surface treatment. Optimization and modelling of the silanization process in scCO2 media was performed using experimental design. Reaction pressure (P), temperature (T) and processing time (t) were chosen as potential variables tha...