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Fiber Surface (fiber + surface)
Kinds of Fiber Surface Selected AbstractsSolid Contact Micropipette Ion Selective Electrode II: Potassium Electrode for SECM and In Vivo ApplicationsELECTROANALYSIS, Issue 17-18 2009Gergely Gyetvai Abstract Micropipette ion selective electrodes are very small, but fragile, short-life time sensors with very high resistance. Their high resistance is a draw back considering application in scanning electrochemical microscopy (SECM) and in life sciences. New, low resistance potassium micropipette electrodes were prepared, and applied. The electrode contains solid internal contact made of a carbon fiber lowered down all the way close to the orifice of the micropipette. The internal contact potential was kept constant by applying a doped, electrochemically prepared PEDOT coating on the fiber surface. The electrode performed well in in vivo experiments both in plant and animal tissue without capacitance neutralization and in SECM. [source] Time-of-flight secondary ion mass spectrometry analysis of the application of a cationic conditioner to ,clean' hairINTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 5 2004A. Harvey In this study the applicability of the surface-sensitive Time-of-flight secondary ion mass spectrometry (ToF-SIMS) technique to hair analysis and associated aqueous processing is evaluated. ToF-SIMS analysis of ,as received' human hair indicates the presence of silicones, anionic surfactants, and cationic conditioners, from previous treatments, on the fiber surface. Cleaning of the hair with SLS or SLES results in adsorption of the surfactants onto the fiber surface. In particular, the more non-polar surfactant components have greater substantivity for the fiber surface, as indicated by the relative increase in their ToF-SIMS intensity. Application of the Incroquat Behenyl 18-MEA conditioner to both ,virgin' and bleached hair results in the adsorption of the cationic C18, C20, C22, and C21 surfactant components onto the hair surface. The ToF-SIMS data indicate higher levels of conditioner on the bleached hair relative to the undamaged hair. [source] Manufacturing, mechanical characterization, and in vitro performance of bioactive glass 13,93 fibersJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 2 2006E. Pirhonen Abstract Fibers were manufactured from the bioactive glass 13,93 by melt spinning. The fibers were further characterized by measuring their tensile and flexural strength, and their in vitro performance was characterized by immersing them in simulated body fluid, which analyzed changes in their mass, their flexural strength, and surface reactions. The strength of glass fibers is highly dependent on fiber diameter, test method, and possible surface flaws, for example, cracks due to abrasion. In this study, the thinnest fibers (diameter between 24 and 33 ,m) possessed the highest average tensile strength of 861 MPa. The flexural strength was initially 1353.5 MPa and it remained at that level for 2 weeks. The Weibull modulus for both tensile and flexural strength values was initially about 2.1. The flexural strength started to decrease and was only ,20% of the initial strength after 5 weeks. During the weeks 5,40, only a slight decrease was detected. The flexural modulus decreased steadily from 68 to 40 GPa during this period. The weight of the samples initially decreased due to leaching of ions and further started to increase due to precipitation of calcium phosphate on the fiber surfaces. The mass change of the bioactive glass fibers was dependent on the surface area rather than initial weight of the sample. The compositional analysis of the fiber surface after 24 h and 5 weeks immersion did confirm the initial leaching of ions and later the precipitation of a calcium phosphate layer on the bioactive glass 13,93 fiber surface in vitro. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006 [source] Radiation model of a TiO2 -coated, quartz wool, packed-bed photocatalytic reactorAICHE JOURNAL, Issue 4 2010G. E. Imoberdorf Abstract The radiation field of a packed-bed photocatalytic reactor filled with quartz wool coated with titanium dioxide was modeled using the Monte Carlo technique and the following information: the radiation flux emitted by the lamps, the diameter size distribution of the quartz fiber cloth, the mass of quartz fibers and of TiO2 that was immobilized on the fiber surface as well as the refractive index, and the spectral absorption coefficient of the materials of the system. Modeling predictions were validated with radiometer measurements of the transmitted radiation through the reactor, the root mean square error being <9.7%. Finally, by means of a parametric study, the validated model was used to analyze the effect of the design variables, such as the radii of the quartz fibers, thickness of the TiO2 coatings, and amount of TiO2 -coated quartz wool, on the distribution and nonuniformity of the radiative energy distribution inside the reactor. © 2009 American Institute of Chemical Engineers AIChE J, 2010 [source] Draw ratio enhancement in nonisothermal melt spinningAICHE JOURNAL, Issue 3 2009Balram Suman Abstract Nonisothermal melt spinning of materials having a step-like viscosity variation with temperature is studied in this work. A set of nonlinear equations is used to describe the fiber behavior and to obtain the draw ratio, the square of the ratio of the fiber diameter at the entrance to that at the exit of the fiber-spinning device. The fluid-flow equation is based on a slender-jet approximation, and external heating and cooling have been accounted for with a one-dimensional model in order to obtain the fiber temperature and viscosity along the fiber length. The model is similar to that used by Wylie et al. (J Fluid Mech. 2007;570:1,16) but accounts for inertia, shear stress at the fiber surface, surface tension, gravity, cooling, and larger heating rates. Steady-state analysis reveals that the draw ratio increases with an increase in the pulling force, passes through a maximum, and then starts increasing again, resulting in three possible pulling forces for the same draw ratio. However, linear stability analysis reveals that depending on the strength of heating and/or cooling, at most two of the steady states are stable. The stability analysis also predicts complicated oscillatory and nonoscillatory dynamical behavior as the pulling force varies. Nonlinear simulations reveal that an unstable system always tends to limit-cycle behavior. Systems predicted as stable by the linear stability analysis are also stable for large-amplitude perturbations. External heating is found to dramatically enhance the draw ratio of the melt-spinning process. The addition of a cooling section suppresses the draw ratio, but this can be compensated for with a higher heating strength. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Chemical modification and surface reactions on carbon fibers studied by SERSJOURNAL OF RAMAN SPECTROSCOPY, Issue 12 2006Bing Xu Abstract Carbon fibers were modified by reacting with maleic anhydride (MA) and oxidation in nitric acid to alter their inert nature. Bismaleimide, acting as a model compound of polyimide, was chosen to react with the surface-active carbon fibers. Surface-enhanced Raman scattering was performed by chemically depositing Ag colloids on different carbon fiber samples, including raw, modified and post-reaction materials. The obtained enhanced Raman spectra explained the surface chemistry of the different carbon fiber samples and their further interaction with bismaleimide. The results could serve as a guide for the design of functional groups on carbon fibers and the manufacture of the carbon-fiber-reinforced polyimide matrix composites. Moreover, the effect of different laser powers and laser irradiation times on the carbon fiber surface was studied and is discussed. Copyright © 2006 John Wiley & Sons, Ltd. [source] Small molecule adsorption on to polyester capillary-channeled polymer fibers: Frontal analysis of naphthalene and naphthol (naphthalene and naphthol adsorption on capillary-channeled polymer fibers)JOURNAL OF SEPARATION SCIENCE, JSS, Issue 1 2010Christine M. Straut Abstract Frontal analysis was carried out employing poly(ethylene-terephthalate) capillary-channeled polymer fibers as the stationary phase for the immobilization of low-molecular-weight polycyclic aromatic hydrocarbon compounds (naphthol and naphthalene) from 2% methanol/water solutions. The effects of several experimental parameters on the frontal profile, the breakthrough volume, and the equilibrium parameters were determined for each solute. The amount adsorbed at exhaustion of naphthalene and naphthol was also compared. The kinetics and thermodynamics were maintained at relatively fast flow rates/linear velocities (,6,18,mm/s). Comparisons of dynamic capacity revealed that naphthalene was more retained than naphthol, in most situations more than five times that of the naphthol adsorption. This increase in capacity is most likely due to the multilayering of naphthalene on the surface of the fibers through ,,, interactions between the solute and the fiber surface and successive layering of solute molecules. The extent of layering is a function of the flow, with faster flow rates (and subsequent shear forces) reducing the extent of adsorbate,adsorbate interactions. Although the overall loading capacity of the capillary-channeled polymer fibers is far below porous phases, there are a number of attractive attributes that support further development. [source] Surface derivatization of poly(p -phenylene terephthalamide) fiber designed for novel separation and extraction mediaJOURNAL OF SEPARATION SCIENCE, JSS, Issue 17 2005Akira Abe Abstract The surface derivatization of poly(p -phenylene terephthalamide) fiber was studied. The obtained surface-derivatized filaments were packed into a fused-silica capillary to evaluate its surface characteristics by using GC. As the stationary phase for GC the surface-derivatized fibers showed higher retention for alkanes and alkylbenzenes than that with the untreated Kevlar fiber. The improvements on the retention power and the peak shape were observed on the benzyl-modified fibrous stationary phase. The derivatized fibrous materials were also evaluated as the extraction medium in fiber-in-tube SPE, and the effect of the surface modification on the extraction power was compared to the parent fiber. The results indicated that the modified fiber possessed a higher extraction power than the untreated fiber. Based on the facts, the successful modification of the fiber surface was estimated. [source] Electrospun Hybrid Nanofibers Based on Chitosan or N -Carboxyethylchitosan and Silver NanoparticlesMACROMOLECULAR BIOSCIENCE, Issue 9 2009Hristo Penchev Abstract Hybrid nanofibers from chitosan or N -carboxyethylchitosan (CECh) and silver nanoparticles (AgNPs) were prepared by electrospinning using HCOOH as a solvent. AgNPs were synthesized in situ in the spinning solution. HCOOH slowed down the cross-linking of the polysaccharides with GA enabling the reactive electrospinning in the presence of poly(ethylene oxide) (PEO). EDX analyses showed that AgNPs are uniformly dispersed in the nanofibers. Since AgNPs hampered the cross-linking of chitosan and CECh with GA in the hybrid fibers, the imparting of water insolubility to the fibers was achieved at a second stage using GA vapors. The surface of chitosan/PEO/AgNPs nanofibers was enriched in chitosan and 15 wt.-% of the incorporated AgNPs were on the fiber surface as evidenced by XPS. [source] Electrospun Composite Mats of Poly[(D,L -lactide) -co- glycolide] and Collagen with High Porosity as Potential Scaffolds for Skin Tissue EngineeringMACROMOLECULAR MATERIALS & ENGINEERING, Issue 9 2009Ye Yang Abstract Electrospun composite mats of poly[(D,L -lactide) -co- glycolide] and collagen with high porosities of 85,90% and extended pore sizes of 90,130,µm were prepared to mimic the ECM morphologically and chemically. The existence of collagen molecules on the fiber surface was confirmed, enabling the cells to find enhanced binding sites for their integrin receptors. The mechanical data for the blended fibrous mats indicated that they were sufficiently durable for dermal tissue engineering. Fibroblasts derived from GFP transgenic C57BL/6 mice were used to directly observe cell proliferation, and the inoculation of collagen enhanced cell attachment, proliferation and extracellular matrix secretion, which were found to be dependent on the amount of collagen in the composite scaffold. [source] Composite Polyamide 6/Polypyrrole Conductive NanofibersMACROMOLECULAR RAPID COMMUNICATIONS, Issue 6 2009Flavio Granato Abstract Conductive Polyamide 6 (PA-6) nanofibers were prepared by making a conductive polypyrrole coating obtained by a polymerization of pyrrole molecules directly on the fiber surface. A solution of PA-6 added with ferric chloride in formic acid has been electrospun and the fibers obtained showed an average diameter of 260 nm with a smooth surface. The fibers have been then exposed to pyrrole vapours and a compact coating of polypyrrole was formed on the fiber surface. The growth of the coating was monitored by measuring the increment of the fiber diameter and by FT-IR spectroscopy. The same technique was used to study the interaction between the ferric chloride and the polyamide chains. The polypyrrole coating on the fibers turned out to be conductive with a pure resistive characteristic and the stability of the conductivity was evaluated in air at room temperature. [source] Cover Picture: Plasma Process.PLASMA PROCESSES AND POLYMERS, Issue 1 2005Polym. Cover: The effect of pressure in the surface modification of poly(ethylene terephthalate) fibers induced by SF6 plasma treatment is shown by atomic force microscopy images of (a) the untreated surface and of the fiber surface after 60 s long SF6 plasma treatment at (b) 0.05 mbar, (b) 0.20 mbar and (c) 0.40 mbar. The RF power was 105W; PET fabrics were plasma-treated at 7.5 cm from the RF antenna. Further details can be found in the Full Paper by R. Barni, C. Riccardi, E. Selli,* M. R. Massafra, B. Marcandalli, F. Orsini, G. Poletti, and L. Meda on page 64. [source] The influence of fiber formation conditions on the structure and properties of nanocomposite alginate fibers containing tricalcium phosphate or montmorillonitePOLYMER COMPOSITES, Issue 8 2010Maciej Bogu The authors devised conditions for the formation of nanocomposite calcium alginate fibers containing tricalcium phosphate (TCP) or montmorillonite (MMT). The rheological, sorptive, and strength properties of these fibers, as well as their porous and supramolecular structures were subjected to analysis. It has been concluded that the presence of nanoadditives in the material of alginate fibers decreases their susceptibility to distortion in the drawing stage. The obtained fibers are characterized by an even distribution of the nanoadditive on the fiber surface. POLYM. COMPOS., 31:1321,1331, 2010. © 2009 Society of Plastics Engineers [source] Polyester composites reinforced with noncrimp stitched glass fabrics: Experimental characterization of composites and investigation on the interaction between glass fiber and polyester matrixPOLYMER COMPOSITES, Issue 3 2008Volkan Cecen The primary purpose of the study was to investigate the anisotropic behavior of different noncrimp stitched fabric reinforced polyester composites. The effects of geometric variables on composite structural integrity and strength are illustrated. Hence, tensile, three-point bending flexural and short beam shear tests were conducted up to failure on specimens strengthened with different layouts of fibrous plies in noncrimp stitched fabric. The remark, based on the observations while tensile testing, is that the stress,strain curves of polyester based composites were linear in the direction of fibers. However, in the matrix dominated orientations nonlinear relation between the stress and the strain was observed. Another aim of the present work was to investigate the interaction between glass fiber and polyester matrix. The experiments, in conjunction with scanning electron photomicrographs of fractured surfaces of composites, were interpreted in an attempt to explain the interaction between glass fiber and polyester and were interpreted in an attempt to explain the instability of polyester resin,glass fiber interfaces. It was concluded that the polymer was either deposited between adjacent fibers or as widely separated islands on the fiber surface. Infrared spectra of the cured polyester and its glass fiber composite were obtained by Fourier transform infrared spectroscopy. POLYM. COMPOS., 2008. © 2007 Society of Plastics Engineers [source] Kevlar and glass fiber treatment for thermoplastic composites by step polycondensationPOLYMER COMPOSITES, Issue 3 2007H. Salehi-Mobarakeh Nylon-6,6 was grafted at the surface of glass and plasma-treated Kevlar fibers for use in nylon,Kevlar thermoplastic composites. Hydroxyl and, in the case of Kevlar, amine end-groups occur at the fibre surface, either as defects or due to the plasma treatment. These were used as anchor points for nylon-6,6 step polycondensation. Fibers were subjected to successive dipping in adipoyl chloride/CH2Cl2 and aqueous hexamethylenediamine solutions in order to attach and grow high molecular weight polymer on the fiber surface. Grafted nylon was characterized by Fourier transform infrared spectroscopy, proton nuclear magnetic resonance, differential scanning calorimetry and thermogravimetry. It was shown that no backbiting occurred during the first stage of the grafting process and that the polymer quantity increased linearly with number of passes, up to ,50 passes for plasma-treated Kevlar and 100 for glass fibers, after which polymer quantity remained constant, within experimental error, which was attributed to the onset of termination reactions. POLYM. COMPOS., 28:278,286, 2007. © 2007 Society of Plastics Engineers [source] Polymerization compounding of HDPE/Kevlar composites.POLYMER COMPOSITES, Issue 2 2006The aim of this work is to perform the polymerization compounding to improve the properties of Kevlar/PE composites. The approach consists in involving the surface of a reinforcement in a polymerization process of a polymer to be used either as a matrix in the final composite or as a special surface treatment to enhance solid/polymer interface properties in the composite. The polymerization compounding process is illustrated here with the polyaramid fibers as reinforcements and polyethylene as a matrix. The number of active sites on the fiber surface, initially insufficient to anchor the catalyst, were increased by a hydrolysis reaction prior to the polymerization. The anchored catalyst was subsequently used to conduct the Ziegler,Natta polymerization reaction of ethylene. The modified fibers were incorporated into the polyethylene resin to produce composites at fiber concentrations as high as 15 wt%. The morphology of the fibers and the composites was tested using electron microscopy. Finally, the mechanical properties of the composites (in impact and tensile tests) were measured to characterize the properties of model composites. Polym. Compos. 27:129,137, 2006. © 2006 Society of Plastics Engineers. [source] Study of interphase in glass fiber,reinforced poly(butylene terephthalate) compositesPOLYMER COMPOSITES, Issue 1 2004A. Bergeret It is well known that application of a coupling agent to a glass fiber surface will improve fiber/matrix adhesion in composites. However, on commercial glass fibers the coupling agent forms only a small fraction of the coating, the larger part being a mixture of processing aids whose contribution to composite properties is not well defined. The interfacial region of the composite will therefore be affected by the coating composition but also by the chemical reactions involved in the vicinity of the fiber and inside the surrounding matrix. The main feature of this study consists in dividing the interface region into two separate regions: the fiber/sizing interphase and the sizing/matrix interphase. A wide range of techniques was used, including mechanical and thermomechanical tests, infrared spectroscopy, gel permeation chromatography, carboxyl end group titrations, extraction rate measurements, and viscosity analysis. Experiments were performed on poly(butylene terephthalate) composites and results indicate that the adhesion improvement is due to the presence of a short chain coupling agent and of a polyfunctional additive, which may react both with the coupling agent and the matrix. According to the nature of this additive, it may be possible to soften the interphase and then to increase the composite impact strength. [source] Polymerization compounding composites of nylon-6,6/short glass fiberPOLYMER COMPOSITES, Issue 4 2003Wei Feng Nylon-6,6 was grafted onto the surface of short glass fibers through the sequential reaction of adipoyl chloride and hexamethylenediamine onto the fiber surface. Grafted and unsized short glass fibers (USGF) were used to prepare composites with nylon-6,6 via melt blending. The glass fibers were found to act as nucleating agents for the nylon-6,6 matrix. Grafted glass fiber composites have higher crystallization temperatures than USGF composites, indicating that grafted nylon-6,6 molecules further increase crystallization rate of composites. Grafted glass fiber composites were also found to have higher tensile strength, tensile modulus, dynamic storage modulus, and melt viscosity than USGF composites. Property enhancement is attributed to improved wetting and interactions between the nylon-6,6 matrix and the modified surface of glass fibers, which is supported by scanning electron microscopy (SEM) analysis. The glass transition (tan ,) temperatures extracted from dynamic mechanical analysis (DMA) are found to be unchanged for USGF, while in the case of grafted glass fiber, tan , increases with increasing glass fiber contents. Moreover, the peak values (i.e., intensity) of tan , are slightly lower for grafted glass fiber composites than for USGF composites, further indicating improved interactions between the grafted glass fibers and nylon-6,6 matrix. The Halpin-Tsai and modified Kelly-Tyson models were used to predict the tensile modulus and tensile strength, respectively. [source] Adhesion improvement in glass fiber reinforced polyethylene composite via admicellar polymerizationPOLYMER COMPOSITES, Issue 1 2003Usa Somnuk Admicellar polymerization (polymerization of monomer solubilized in adsorbed surfactant bilayers) has been used to form a thin film of polyethylene onto the surface of milled glass fibers using sodium dodecyl sulfate as the surfactant. The decrease in ethylene pressure was used to follow the solubilization and adsolubilization processes as well as the reaction processes. An increase in initiator (Na2S2O8) to surfactant ratio gave thicker and more uniform coatings of polymer onto the glass fiber surface according to SEM micrographs. Although a substantial amount of ethylene polymerized in solution according to the pressure drop, the decrease in pressure attributed to admicelle polymerization corresponded to the amount of polymer formed on the glass fiber, indicating little, if any, solution polymer deposited on the fibers. The admicellar-treated glass fiber was used to make composites with high-density polyethylene. The composites showed an increase in tensile and flexural strength over composites made from as-received glass fiber, indicating an improvement in the fiber-matrix adhesion of the admicellar-treated glass fiber. [source] Production of leather-like composites using short leather fibers.POLYMER COMPOSITES, Issue 6 2002Leather-like composites were prepared by addition of chemically modified short leather fibers (SLF) into a plasticized polyvinyl chloride (pPVC) matrix. The fibers were subjected to chemical modification by emulsion polymerization to achieve good interfacial adhesion between SLF and the pPVC matrix. The SLF with chemical modification were obtained from three different reaction conditions where these SLF have different percentages of grafted and deposited PMMA polymer onto the fiber surface. The incorporation of the SLF into the thermoplastic matrix was carried out using a torque-rheometer and the composites obtained were molded by compression. Tensile and tear mechanical tests were performed on composite samples, and the morphology of the fractured surfaces was analyzed using scanning electron microscopy (SEM). The results show that the incorporation by grafting of polymethyl metacrylate (PMMA) onto the fibers produced a significant improvement of their interfacial adhesion to pPVC, promoting the compatibilization between the fiber surface and matrix. The findings are discussed and interpreted in terms of enhanced adhesion at phase boundaries. Overall, the results confirm that it is possible to produce modified leather composites based on a pPVC matrix, which exhibit relatively high tensile strength, tear resistance and flexibility. These composites are very suitable candidate materials for applications in the footwear industry. [source] Controlling the properties of single-polymer composites by surface melting of the reinforcing fibers,POLYMERS FOR ADVANCED TECHNOLOGIES, Issue 10-12 2002D. M. Rein Abstract All-thermoplastic single-polymer composites are materials in which both the reinforcing fibrous phase and the matrix between them are made of the same thermoplastic polymer. Excellent bonding is achieved by mutual entanglement macromolecules due to controlled surface melting of the fibers. This results in a uniform structure of a single chemical entity. The physical properties of the consolidated material, such as modulus and coefficient of thermal expansion (CTE), can be controlled by the extent of melting effected in the process, which determines the fiber/matrix ratio. The fabrication technology utilizes oriented polymer fibers in various forms: unidirectional lay-up, woven fabric or chopped fibers/non-woven felt. The key element in the processing scheme is the control of the fibers' melting temperature by hydrostatic pressure. The fibers are heated under high pressure to a temperature that is below their melting point at the high pressure but above the melting temperature at some lower pressure. Reduction of pressure for controlled time results in melting of the fibers, which starts at the fiber surface. This surface melting under controlled pressure followed by crystallization produces the consolidated structure. We illustrate and describe this process using fibers of ultra-high-molecular-weight polyethylene (UHMWPE), showing the effect of the processing conditions on the flexural modulus, fiber/matrix ratio, and CTE in plane and in the thickness direction. These properties are relevant to the use of such composites as substrates for microwave antennae. Copyright © 2003 John Wiley & Sons, Ltd. [source] Functionalization of cellulose acetate fibers with engineered cutinasesBIOTECHNOLOGY PROGRESS, Issue 3 2010Teresa Matamá Abstract In the present work, we describe for the first time the specific role of cutinase on surface modification of cellulose acetate fibers. Cutinase exhibits acetyl esterase activity on diacetate and triacetate of 0.010 U and 0.007 U, respectively. An increase on the hydroxyl groups at the fiber surface of 25% for diacetate and 317% for triacetate, after a 24 h treatment, is estimated by an indirect assay. Aiming at further improvement of cutinase affinity toward cellulose acetate, chimeric cutinases are genetically engineered by fusing the 3,-end coding sequence with a bacterial or a fungal carbohydrate-binding module and varying the linker DNA sequence. A comparative analysis of these genetic constructions is presented showing that, the superficial regeneration of cellulose hydrophilicity and reactivity on highly substituted cellulose acetates is achieved by chimeric cutinases. © 2010 American Institute of Chemical Engineers Biotechnol. Prog., 2010 [source] Glass Fibers with Carbon Nanotube Networks as Multifunctional SensorsADVANCED FUNCTIONAL MATERIALS, Issue 12 2010Shang-lin Gao Abstract A simple approach to deposit multiwalled carbon nanotube (MWNT) networks onto glass fiber surfaces achieving semiconductive MWNT,glass fibers is reported, along with application of fiber/polymer interphases as in-situ multifunctional sensors. This approach demonstrates for the first time that the techniques of conducting electrical resistance measurements could be applicable to glass fibers for in situ sensing of strain and damage; the techniques were previously limited to conductive and semiconductive materials. The electrical properties of the single MWNT,glass fiber and the "unidirectional" fiber/epoxy composite show linear or nonlinear stress/strain, temperature, and relative humidity dependencies, which are capable of detecting piezoresistive effects as well as the local glass transition temperature. The unidirectional composites containing MWNT,glass fibers exhibit ultrahigh anisotropic electrical properties and an ultralow electrical percolation threshold. Based on this approach, the glass fiber,the most widely used reinforcement in composites globally,along with the surface electrical conductivity of MWNTs will stimulate and realize a broad range of multifunctional applications. [source] Fabrication and Drug Delivery of Ultrathin Mesoporous Bioactive Glass Hollow FibersADVANCED FUNCTIONAL MATERIALS, Issue 9 2010Youliang Hong Abstract Ultrathin mesoporous bioactive glass hollow fibers (MBGHFs) fabricated using an electrospinning technique and combined with a phase-separation-induced agent, poly(ethylene oxide) (PEO), are described. The rapid solvent evaporation during electrospinning and the PEO-induced phase separation process demonstrated play vital roles in the formation of ultrathin bioactive glass fibers with hollow cores and mesoporous walls. Immersing the MBGHFs in simulated body fluid rapidly results in the development of a layer of enamel-like apatite mesocrystals at the fiber surfaces and apatite nanocrystals inside the hollow cores. Drug loading and release experiments indicate that the drug loading capacity and drug release behavior of the MBGHFs strongly depends on the fiber length. MBGHFs with fiber length >50,µm can become excellent carriers for drug delivery. The shortening of the fiber length reduces drug loading amounts and accelerates drug release. The MBGHFs reported here with sophisticated structure, high bioactivity, and good drug delivery capability can be a promising scaffold for hard tissue repair and wound healing when organized into 3D macroporous membranes. [source] Laser scanning confocal microscope characterization of dye diffusion in nylon 6 fibers treated with atmospheric pressure plasmasJOURNAL OF APPLIED POLYMER SCIENCE, Issue 3 2008Chunxia Wang Abstract The effect of atmospheric pressure plasma treatment on wettability and dyeability of nylon 6 fibers is investigated. The plasma treatments resulted in an average of 10°,20° decrease in the advancing contact angle and 20°,30° decrease in the receding contact angle. An increased dye diffusion rate of nylon 6 fibers was observed using laser scanning confocal microscope (LSCM). Scanning electron microscope confirmed that the fiber surfaces were roughened, and X-ray photoelectron spectroscopy showed that the polar groups on the fiber surfaces increased after the plasma treatments. As the plasma treatment time increased, a greater degree of etching was achieved and more polar groups such as hydroxyl and carboxyl groups produced on the surfaces of the nylon 6 fibers, leading to a better wettability and thus a better dyeability of the fiber. This study proved that LSCM may be effectively used in detecting the change of dye diffusion rate in nylon fibers treated with plasmas and the mounting medium should have a close refractive index as the fiber to avoid distortion of the fiber cross section image. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Manufacturing, mechanical characterization, and in vitro performance of bioactive glass 13,93 fibersJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 2 2006E. Pirhonen Abstract Fibers were manufactured from the bioactive glass 13,93 by melt spinning. The fibers were further characterized by measuring their tensile and flexural strength, and their in vitro performance was characterized by immersing them in simulated body fluid, which analyzed changes in their mass, their flexural strength, and surface reactions. The strength of glass fibers is highly dependent on fiber diameter, test method, and possible surface flaws, for example, cracks due to abrasion. In this study, the thinnest fibers (diameter between 24 and 33 ,m) possessed the highest average tensile strength of 861 MPa. The flexural strength was initially 1353.5 MPa and it remained at that level for 2 weeks. The Weibull modulus for both tensile and flexural strength values was initially about 2.1. The flexural strength started to decrease and was only ,20% of the initial strength after 5 weeks. During the weeks 5,40, only a slight decrease was detected. The flexural modulus decreased steadily from 68 to 40 GPa during this period. The weight of the samples initially decreased due to leaching of ions and further started to increase due to precipitation of calcium phosphate on the fiber surfaces. The mass change of the bioactive glass fibers was dependent on the surface area rather than initial weight of the sample. The compositional analysis of the fiber surface after 24 h and 5 weeks immersion did confirm the initial leaching of ions and later the precipitation of a calcium phosphate layer on the bioactive glass 13,93 fiber surface in vitro. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006 [source] Superhydrophobic Mats of Polymer-Derived Ceramic FibersJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 8 2008Sourangsu Sarkar Solid preceramic polyaluminasilazane was synthesized through the reaction between liquid cyclosilazane and aluminum tri-sec-butoxide at 160°C. Electrospinning of polyaluminasilazane/polyethyleneoxide (1/0.0001 mass ratio) in chloroform solutions generated smooth fibers while the electrospun fibers from the chloroform/N,N -dimethylformamide solutions had submicrometer structures on the fiber surfaces. Smooth and rough SiCNO ceramic fibers were obtained by the pyrolysis of the green fibers with an 80% yield. Superhydrophobic mats of ceramic fibers were fabricated via a chemical vapor deposition of perfluorosilane onto the rough fibers. These superhydrophobic mats possess good chemical and thermal stability. [source] Electrospun, Biofunctionalized Fibers as Tailored in vitro Substrates for Keratinocyte Cell CultureMACROMOLECULAR BIOSCIENCE, Issue 9 2010Dirk Grafahrend Abstract Cell adhesion preventing fiber surfaces were tailored differently with bioactive peptides (a fibronectin fragment (GRGDS), a collagen IV fragment (GEFYFDLRLKGDK) and a combination of both) to provide an artificial extracellular matrix as a substrate for HaCaT keratinocyte cell culture. Therefore, a polymer blend containing a six-arm star-shaped statistical copolymer of ethylene oxide and propylene oxide in the ratio 80:20 (NCO- sP[EO- co -PO]) and poly-[D,L -(lactide- co -glycolide)] (PLGA) was electrospun. The resulting fibers were biofunctionalized and investigated as in vitro substrates using the HaCaT kerationcyte cell line. Appropriate surface chemistry on these electrospun fibers proved to prevent adhesion of keratinocytes, while additional immobilization of certain peptide sequences induced cell adhesion. These specific fibers enable investigation of immobilized active molecules and the subsequent cellular response to the scaffold. HaCaT keratinocytes were found to selectively adhere to those fibers modified with either collagen IV segment GEFYFDLRLKGDK or a mixture of the two peptide sequences GEFYFDLRLKGDK and GRGDS (1:1). However, the synergistic effects of both (the fibronectin fragment and the collagen IV fragment) seem to significantly increase the numbers of adherent keratinocytes. [source] Poly(ethylene oxide)- block -poly[2-(dimethylamino)ethyl methacrylate] as Strengthening Agent in Paper: Dynamic Mechanical CharacterizationMACROMOLECULAR MATERIALS & ENGINEERING, Issue 3 2010Arja-Helena Vesterinen Abstract To enhance adhesion properties of PEO on wood fibers, block polymers of PEO and 2-(dimethylamino)ethyl methacrylate were synthesized. The polymers were further modified to obtain strongly cationic species. The resulting polymers were used as additives in paper sheets. Papers were studied by DMA in a controlled-humidity chamber. Addition of the PEO block co-polymers enhanced paper strength. The strength of the paper sheets was highest when polymer with molecular weight of 400,kg,·,mol,1 was used as an additive. Highly cationic block co-polymers increased moduli of paper sheets more than their weakly cationic analogs, which indicated strong interaction with fiber surfaces. Strength of the paper sheets decreased both with increased temperature and humidity. [source] Interfacial strength in short glass fiber reinforced acrylonitrile-butadiene-styrene/polyamide 6 blendsPOLYMER COMPOSITES, Issue 3 2010Nihat Ali Isitman The purpose of this study is to derive the apparent interfacial shear strength of short glass fiber reinforced acrylonitrile-butadiene-styrene/polyamide 6 (PA6) blends with different PA6 contents. Tensile stress-strain curves and fiber length distributions are utilized within a continuum micromechanics approach which involves a unified parameter for fiber length distribution efficiency represented as a function of strain. The unique combination of predicted micromechanical parameters is capable of accurately reproducing the mechanical response of the composite to applied strain. In this way, the influence of PA6 on interfacial zone is revealed by outcomes of the predictive method and validated by scanning electron microscopy observations. Favored intermolecular interactions in presence of PA6 chains result in the formation of a PA6 sheathing layer on glass fiber surfaces which in turn causes a drop in the apparent interfacial shear strength. The reason behind is shown to be the shift of the fracture zone from fiber/matrix interface to sheathing layer/matrixinterphase. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers [source] | ||||||||||||||||