Nonwoven Matrix Research Articles

Photovoltaic Performance of Dye-sensitized Solar Cells assembled with Hybrid Composite Membrane based on Polypropylene Non-woven Matrix

Hybrid composite membranes were prepared by coating poly(ethylene oxide) and <TEX>$SiO_2$</TEX> particles onto the porous polypropylene nonwoven matrix. Gel polymer electrolytes prepared by soaking the hybrid composite membranes in an organic electrolyte solution exhibited ionic conductivities higher than <TEX>$1.1{\times}10^{-3}Scm^{-1}$</TEX> at room temperature. Dyesensitized solar cell (DSSC) employing the hybrid composite membrane with PEO and 10 wt % <TEX>$SiO_2$</TEX> exhibited an open circuit voltage of 0.77 V and a short circuit current of 10.78 <TEX>$mAcm^{-2}$</TEX> at an incident light intensity of 100 <TEX>$mWcm^{-2}$</TEX>, yielding a conversion efficiency of 5.2%. DSSC employing the hybrid composite membrane showed more stable photovoltaic performance than that of the DSSC assembled with liquid electrolyte.

A new type of bentonite-based non-woven composite

Sandwich-like composites based on clays and textiles are extensively applied in various fields, including civil engineering and environmental protection. In this paper, the synthesis of a new type of composite with embedded bentonite particles within a non-woven polyester matrix is presented. The synthesized composite has improved mechanical properties compared to the corresponding non-woven matrix. Although more than two-times thinner, the synthesized composite showed mechanical properties similar to those of a commercial composite chosen for comparison. Sorption test results confirmed that the contribution of the textile component to the sorption of aqueous Cu(II) ions by the composite was negligible. The sorption of aqueous Cu(II) ions on the synthesized composite was best-fitted using the Langmuir model. The presented study confirmed that the loss of bentonite particles from the composite can be eliminated using the suggested synthesis method.

Evaluation and Preparation of PET Aluminum Foil/PLA Nonwoven Compound Fabric as Electromagnetic Shielding Effectiveness Protective Clothing

This study designed a flexible electromagnetic resistant fabric it is not only apt to make protective clothing, but also simple process dependence on its application. Polylactide fiber (PLA) and the low melting polylactide fiber (LMPLA) were blended to fabricate nonwoven matrix. Then polyester (PET) aluminum foil inserted between two layers of PLA nonwoven matrix to fabricate a compound matrix by needle punching. Afterward, physical properties and electromagnetic shielding effectiveness of different layers compound matrix were be evaluated.The result indicated that Tensile strength of sample B was 189.16 N; tear strength of sample C was 579.43 N. Burst strength of sample B which was laminated five-layers compound matrix had best burst strength, 3326.18 N, and excellent electromagnetic shielding effectiveness, over 90 dB.

Process Technology and Performance Evaluation of Nylon 6/PU Stab Resistance Fabric Matrix

Stab resistance compound fabric is frequently used in daily life, industry, military and aerospace. In this study, Nylon 6 and Polyester short fibers were mixed in ratio of 70:30. The mixture was needle punched at speed 300 needle/min to form a stab resistant fabric. The non-woven fabric matrix, non-woven fabric/grid matrix, non-woven/water-bone polyurethane (PU), and matrix/grid/water-bone PU, were put to test their tensile stress, tear stress, and stab resistance. Latter, the most stab resistant compound matrix was constructed in lamination structures to examine the relationship between thickness and stab resistance. The result showed that stab resistance of the non-woven/grid/water-bone PU compound fabric was 115 N; the triple-layered sample D was 208 N.

Positive Effects of E-Beam Irradiation in Inorganic Particle Based Separators for Lithium-Ion Battery

An inorganic separator was prepared by coating inorganic submicrometer sized particles on a nonwoven matrix followed by an E-beam irradiation treatment. Its characteristics were investigated by scanning electron microscopy, tensile strength analysis, thermogravimetric analysis, ionic conductivity measurements, and charge–discharge analysis. The mechanical and thermal properties of the separator were greatly enhanced by the simple curing under E-beam irradiation. However, there was no significant change in the morphology or ionic conductivity of the E-beam treated separator.

Ultra-porous flexible PET/Aerogel blanket for sound absorption and thermal insulation

Ultra porous and flexible PET/Aerogel blankets were prepared at ambient pressure, and their acoustic and thermal insulation properties were characterized. Two methods were selected for the preparation of PET/Aerogel blanket. Method I was a direct gelation of silica on PET. PET non-woven fabric was dipped and swelled in TEOS/ethanol mixture, and pH of reaction media was controlled to 2.5 using HCl to promote hydrolysis. After acid hydrolysis, pH was controlled to 7,8,9, and 10 with NH4OH for the condensation. Method II was by the dipping of PET non-woven fabric in the dispersion of Silica hydrogel. The gelation process was same with Method I. However, PET fabric was not dipped in reaction media. After the hydrogel was dispersed and aged in EtOH for 24 hrs, then, PET non-woven fabric was dipped in the dispersion of hydrogel/EtOH for 24 hrs. The surface modification was carried out in TMCS/n-hexane solution, then the blanket was washed with nhexane and dried at room temperature to prevent the shrinkage. The silica areogels synthesized in optimum conditions exhibit porous network structure. Silica aerogel of highly homogeneous and smallest spherical particle clusters with pores was prepared by gelation process at pH 7. When direct gelation of silica was performed in PET nonwoven matrix (Method I), silica aerogel clusters were formed efficiently surrounding PET fibers forming network structure. The existence of a great amount of silica aerogel of more homogeneous and smaller size in the cell wall material has positive effect on the sound absorption and thermal insulation.

Increased FGF-2 secretion and ability to support neurite outgrowth by astrocytes cultured on polyamide nanofibrillar matrices

An electrospun nonwoven matrix of polyamide nanofibers was employed as a new model for the capillary basement membrane at the blood-brain barrier (BBB). The basement membrane separates astrocytes from endothelial cells and is associated with growth factors, such as fibroblast growth factor-2 (FGF-2). FGF-2 is produced by astrocytes and induces specialized functions in endothelial cells, but also has actions on astrocytes. To investigate potential autocrine actions of FGF-2 at the BBB, astrocytes were cultured on unmodified nanofibers or nanofibers covalently modified with FGF-2. The former assumed an in vivo-like stellate morphology that was enhanced in the presence of cross-linked FGF-2. Furthermore, astrocyte monolayers established on unmodified nanofibers were more permissive for neurite outgrowth when cultured with an overlay of neurons than similar monolayers established on standard tissue culture surfaces, while astrocytes cultured on FGF-2-modifed nanofibers were yet more permissive. The observed differences were due in part to progressively increasing amounts of FGF-2 secreted by the astrocytes into the medium; hence FGF-2 increases its own expression in astrocytes to modulate astrocyte–neuron interactions. Soluble FGF-2 was unable to replicate the effects of cross-linked FGF-2. Nanofibers alone up-regulated FGF-2, albeit to a lesser extent than nanofibers covalently modified with FGF-2. These results underscore the importance of both surface topography and growth factor presentation on cellular function. Moreover, these results indicate that FGF-2-modified nanofibrillar scaffolds may demonstrate utility in tissue engineering applications for replacement and regeneration of lost tissue following central nervous system (CNS) injury or disease.

Chemical aspects of uranium recovery from seawater by amidoximated electron-beam-grafted polypropylene membranes

The amidoximated macroporous membranes (AO membranes) were prepared by post irradiation grafting of acrylonitrile (AN) onto thermally bonded non-woven matrix of poly(propylene) sheet using electron beams. These precursor membranes were reacted with hydroxylamine to convert AN to AO groups, and conditioned by treating them with 2.5% KOH at 80°C for 1 h. The water uptake capacity in seawater, Na +-exchange capacity, and uranium loading capacity from seawater of AO membranes were found to be 200±10 wt.%, (3.1±0.2)×10 −4 mol/g, and (1.60±0.18)×10 −3 mol/g, respectively. The expected functional group density based on the degree of AN grafting (125 wt.%) and its subsequent conversion to AO groups (80%) was found to be 7.8×10 −3 mol/g. The comparison of the expected functional group density and uranium uptake capacity seems to suggest that UO 2 2+ forms a complex with AO groups in 1:4 proportion. The uranium could be quantitatively desorbed (>90%) from the AO membrane in Na 2CO 3 and mineral acids like HCl in the equilibration times of 60 min and 40 min, respectively. Alkaline conditioning was found to be necessary for reuse of the membrane equilibrated with acid. However, AO membranes equilibrated with Na 2CO 3 could be reused without any conditioning for uranium sorption.

Enhanced Oxygen Availability Improves Liver‐specific Functions of the AMC Bioartificial Liver

Long-term culturing of primary porcine hepatocytes (PPH) inside the Academic Medical Center (AMC)-bioartificial liver is characterized by increased anaerobic glycolysis. Recommendations to increase oxygen availability were proposed in a previous numerical study and were experimentally evaluated in this study. Original bioreactors as well as new configuration bioreactors with 2.2-fold thinner nonwoven matrix and 2-fold more capillaries were loaded with PPHs and oxygenated with different gas oxygen pressures resulting in medium pO(2) (pO(2-med)) of either 135-150 mm Hg or 235-250 mm Hg. After 6 days culturing, new configuration bioreactors with pO(2-med )of 250 mm Hg showed significantly reduced anaerobic glycolysis, 60% higher liver-specific functions, and increased transcript levels of five liver-specific genes compared to the standard bioreactor cultures. Changed bioreactor configuration and increasing pO(2-med) contributed equally to these improvements. Histological examination demonstrated small differences in cell organization. In conclusion, higher metabolic stability and liver-specific functionality was achieved by enhanced oxygen availability based on a prior modeling concept.

New crosslinking agent as a Lewis acid for solid polymer electrolytes

Poly(ethylene glycol) borate acrylate (PEGBA) was synthesized as a new crosslinking agent for solid polymer electrolyte (SPE) based on non-woven matrix. It has not only three crosslinkable acrylate groups for higher crosslinking density, but also Lewis acid center acting as an anion receptor. The ionic conductivity of SPE containing 15 wt.% PEGBA reached 5.5 × 10 −4 S cm −1, because the content of non-volatile plasticizer, poly(ethylene glycol) dimethyl ether (PEGDME), could be increased to 85 wt.% without leakage. In addition, its transference number and electrochemical stability were also enhanced to 0.37 and 5.2 V, respectively, due to the presence of Lewis acid center in PEGBA.

Cellular Textile Composites with Non-woven Fabric Reinforcement

Grid-domed cellular textile composites with non-woven fabric reinforcement are designed for obtaining high-energy absorption capacities under impact conditions. This cellular composite is fabricated by compression molding commercially available bulk form non-woven polyester fabric and polypropylene matrix. The mechanical properties of the non-woven composites were studied. It was found that the composites exhibit high specific energy absorption capacity and retain the same level during three repeated impacts. By varying the fiber volume fraction, different modes of deformation were observed, which affect the energy absorption capacity. This can be attributed to the material properties of non-woven composite samples such as tensile and shear properties. The major deformation mode of this flat-topped cellular sample was identified as the internal convolution of the conical cell wall during plastic collapse. The theoretical predictions on the energy-absorption capacity for pure material or non-woven reinforced composite during the large deformation process are all in good agreement with the experimental results.

Highly ion-conductive solid polymer electrolytes based on polyethylene non-woven matrix

Highly ion-conductive solid polymer electrolyte (SPE) based on polyethylene (PE) non-woven matrix is prepared by filling poly(ethylene glycol) (PEG)-based crosslinked electrolyte inside the pores of the non-woven matrix. The PE non-woven matrix not only shows good mechanical strength for SPE to be a free-standing film, but also has very porous structure for high ion conductivity. The ion conductivity of SPE based on PE non-woven matrix can be enhanced by adding sufficient non-volatile plasticizer such as poly(ethylene glycol) dimethyl ether (PEGDME) into ion conduction phase without sacrificing mechanical strength. SPE with 20 wt.% crosslinking agent and 80 wt.% non-volatile plasticizer shows 3.1 × 10 −4 S cm −1 at room temperature (20 °C), to our knowledge, which is the highest level for SPEs. It is also electrochemically stable up to 5.2 V and has high transference number about 0.52 due to the introduction of anion receptor as an additive. The interfacial resistance between Li electrode and SPE is low enough to perform charge/discharge test of unit cell consisting of LiCoO 2/SPE/Li at room temperature. The discharge capacity of the unit cell shows 87% of theoretical value with 86% Coulombic efficiency.

Magnetic resonance imaging characterization of osteochondral defect repair in a goat model at 8 T

This study was performed to non-invasively visualize and characterize osteochondral (OC) repair in ex vivo goat stifles using an 8 T magnetic resonance imaging (MRI) scanner and to compare the MR morphology with images obtained from 1.5 T, gross morphology and histology. Mature, neutered male goats were assigned to an 8-week (n = 4) or 16-week (n = 4) study period. Two cylindrical OC defects (7 mm diameter, full cartilage thickness and 1mm into subchondral bone) were surgically created in the right stifle: one in the medial femoral condyle (MFC) and the other in the trochlear groove (TG). The implant matrices (non-woven or foam) were secured in the defect using a bottom anchored fixation device (FD). The contralateral left stifles served as time zero controls. At the day of necropsy, implants were placed at both defect sites (MFC and TG) on the normal left stifles. Following necropsy, the ex vivo goat stifles (intact and encapsulated) were disarticulated. Within 24 h postnecropsy, MR scans of the stifles along the mid-sagittal plane of the OC defect were acquired at 8 T and 1.5 T. MR relaxation times, T1 and T2, were measured at the region of repair tissue (RT) and adjacent native cartilage. Immediately after MR imaging, the stifles were dissected, grossly examined, and a sagittal OC block corresponding to the MR region of interest was prepared for formalin fixation. The high-resolution MR images enabled visualization of cartilage and bone integrity surrounding the implant as well as delineating the margins of RT/implant matrix and the FD. On spin echo sequence, the RT variably appeared as high, intermediate or low MR signal intensity; whereas, the FD always appeared as low signal intensity. In general, the MR signal intensity of 8-week RT was slightly higher compared to 16-week RT; however, there was no difference in RT morphology of stifles implanted with the non-woven matrix or foam matrix. Subchondral sclerosis appeared as low signal intensity. The 8 T MR images showed better delineation of the stifle tissues compared to the images acquired at 1.5 T. The T2 relaxation time of the RT appears to indicate (inconclusive due to small number of samples) a slight variation in the RT type between 8 weeks and 16 weeks. At both study times, the defects grossly appeared whitish to reddish but did not have the characteristic hyaline appearance typical of articular cartilage (AC). The gross appearance of the MFC and TG RT differed, which was predominantly mottled and recessed with fissuring of adjacent native AC in the MFC. Histologically, the RT of both 8-week and 16-week postsurgical defects predominantly comprised fibrovascular connective tissue with only few samples showing the presence of fibrocartilaginous and/or hypertrophic chondrocytes within the defect RT at 8 weeks. Also, compared to 8-week, the 16-week RT appeared to be more fibrotic. Using 8 T scanner, high-resolution MR images of ex vivo encapsulated goat stifles confirmed the capability of high-field MR imaging to distinguish the defect RT from the FD and adjacent joint tissues. The extent of OC repair and adjacent bone lesions (at 8 weeks and 16 weeks) observed in the MR images compared well with those observed on the corresponding histological sections.

Electrochemical effect of coating layer on the separator based on PVdF and PE non-woven matrix

The coated separator was prepared by coating poly(vinyl acetate) (PVAc) on the surface of the novel separator based on poly(vinylidene fluoride) (PVdF) and polyethylene (PE) non-woven matrix. The ionic conductivity of the coated separator was 1.1 × 10 −3 S cm −1 at 25 °C, a little higher than that of bare separator. The coated separator showed smoother surface morphology and better adhesion property toward electrodes, and thereby it resulted in lower total resistance than the bare separator. The discharge capacity of the unit cell with coated separator at C/2 rate was maintained at about 84% of the theoretical capacity, which is quite higher than that of the unit cell with the bare separator.

Electrospun fine-textured scaffolds for heart tissue constructs

The structural and functional effects of fine-textured matrices with sub-micron features on the growth of cardiac myocytes were examined. Electrospinning was used to fabricate biodegradable non-woven poly(lactide)- and poly(glycolide)-based (PLGA) scaffolds for cardiac tissue engineering applications. Post-processing was applied to achieve macro-scale fiber orientation (anisotropy). In vitro studies confirmed a dose–response effect of the poly(glycolide) concentration on the degradation rate and the pH value changes. Different formulations were examined to assess scaffold effects on cell attachment, structure and function. Primary cardiomyocytes (CMs) were cultured on the electrospun scaffolds to form tissue-like constructs. Scanning electron microscopy (SEM) revealed that the fine fiber architecture of the non-woven matrix allowed the cardiomyocytes to make extensive use of provided external cues for isotropic or anisotropic growth, and to some extent to crawl inside and pull on fibers. Structural analysis by confocal microscopy indicated that cardiomyocytes had a preference for relatively hydrophobic surfaces. CMs on electrospun poly( l-lactide) (PLLA) scaffolds developed mature contractile machinery (sarcomeres). Functionality (excitability) of the engineered constructs was confirmed by optical imaging of electrical activity using voltage-sensitive dyes. We conclude that engineered cardiac tissue structure and function can be modulated by the chemistry and geometry of the provided nano- and micro-textured surfaces. Electrospinning is a versatile manufacturing technique for design of biomaterials with potentially reorganizable architecture for cell and tissue growth.

Novel porous separator based on PVdF and PE non-woven matrix for rechargeable lithium batteries

The novel porous separator based on PVdF (poly(vinylidene fluoride)) and a PE (polyethylene) non-woven matrix is prepared by coating PVdF/NMP solution on the matrix (NMP: N-methyl-2-pyrrolidone). The pore structure is generated in the PVdF region by phase inversion of the polymer solution. The PE non-woven matrix imparts mechanical strength and a thermal shut-down property to the separator, while the PVdF component provides a hydrophilic ionic conducting phase. The physical properties of the separator, such as morphology, pore size and its distribution, porosity and mechanical strength, are measured. The ionic conductivity of the separator is 8.9 × 10 −4 S cm −1 at 25 °C. The capacity at the C/2 rate is maintained at about 86% of the initial value on the 100th cycle at the room temperature. The electrolyte is stable up to 4.5 V in the presence of the novel separator.

A fibrous-bed bioreactor for continuous production of monoclonal antibody by hybridoma.

A fibrous-bed bioreactor (FBB) has been developed to culture hybridoma cells for long-term continuous production of monoclonal antibody (MAb). A non-woven polyester fibrous matrix was used to immobilize the cells to reach a high viable cell density of 3 x 10(8) cells cm(-3) packed bed, which gave a high volumetric MAb productivity of 1 g L(-1) day(-1) under continuous feed conditions with the medium containing 10% serum. Reducing the medium serum content to 1% increased MAb production to 6.5 g L(-1) day(-1) in a repeated batch FBB culture. MAb production was higher at higher dissolved oxygen (DO) levels in the range between 10% and 70% of air saturation, although DO did not significantly affect glucose metabolism and lactate production. The medium LDH (lactate dehydrogenase) level increased dramatically when the DO level was decreased from 30% to 10%, suggesting that a critical DO level of approximately 30% is necessary for maintaining the FBB culture for long-term operation. Compared with suspension cultures in T-flasks and spinner flasks, the FBB culture had a lower lactate yield from glucose (0.80 vs. 0.91 g g(-1), produced MAb at a higher concentration (up to 442 mg L(-1) vs. 83.5 mg L(-1), and was stable for continuous long-term operation (more than 1 month). The superior FBB performance was attributed to the highly porous fibrous matrix that enabled the efficient mass transfer, cell immobilization, and continued growth and regeneration that are critical to maintaining a high density of viable and productive cell populations. The cells immobilized in the fibrous matrix had high viability (>85%) even though many of them were in growth arrest (G1/G0 phase) as indicated by their smaller cell size (<10 microm). Scanning electron microscopic studies of the cell-matrix showed that the high density of cells formed large clumps within the interstitial spaces of the fibrous matrix. Their close contact and interaction with each other might have contributed to their ability to survive well under adverse conditions such as low DO and low serum content in the medium. It was also found that the cells present inside the fibrous matrix had a higher viability and lower apoptosis than those present in the liquid suspension, indicating that the fibrous matrix had selectively retained healthy, nonapoptotic cells and dislodged apoptotic and dead cells; this also might have contributed to the stability of the long-term culture. This work demonstrated that the FBB originally developed for microbial fermentation also gave excellent results in achieving high cell density, productivity, and product concentrations, and should have a good potential for industrial animal cell culture applications.

Mass Cultivation of Anaerobic Ammonium-Oxidizing Sludge Using a Novel Nonwoven Biomass Carrier

Biological conversions of nitrogenous compounds closely resembling the chemistry of the anammox reaction were developed and maintained for approximately two years in fixed-bed, continuous-flow unit processes. Using a novel nonwoven matrix for biomass attachment, the anaerobic, autotrophic biofilm cultures were robust enough to survive occasional operational anomalies and to rebound quickly from temporary setbacks. Using a 2.7-l reactor with a hydraulic retention time of 7.5 hours, influent ammonium (NH 4 +) and nitrite (NO 2 -) concentrations of approximately 250 mg N/l, each, were successfully treated with a total nitrogen (T-N) removal efficiency of 60%. T-N and NH 4 + volumetric removal rates of 40 and 20 mg N/l.h, respectively, were maintained for a one-year period of operation, which are in a suitable range for industrial applications. Using the nonwoven material of the 2.7-l reactor as a seed for a larger 14-l reactor, a fast transition to a stable, relatively high T-N mass removal rate of approximately 300 mg/h (NH 4 -N removal, 150 mg/h) was possible. These results suggest that attached-growth processes such as employed here, with a nonwoven matrix, could serve well not only as a means of nitrogen abatement but also for mass cultivation of the slowly growing anaerobic ammonium-oxidizing cultures for use in development of new reactors.