Form Of Mats Research Articles

Effect of fiber type on thermal and mechanical behavior of epoxy based composites

Natural fibers are lignocellulosic and hollow in nature and having good mechanical, thermal and structural properties. In the present research endeavor, three types of natural fibers (namely Sisal, Hemp and Nettle fibers) are used as reinforcement in woven mat form to fabricate 4-ply laminate composites with epoxy resin as matrix using hand layup process. Atomic force microscopy (AFM) and scanning electron microscope (SEM) have been used to get the surface roughness of fiber, to study the fracture behavior of the developed composites and effect of inter surface bonding between fibers and matrix. Thermogravimetric analysis (TGA/DTA) has been performed to study the thermal behavior and intersurface bonding among matrix and fibers for the developed composites. The results revealed that along with the applied pressure and viscosity of the matrix, surface roughness of the fiber also plays a significant role in deciding the mechanical properties and natural fiber with high surface roughness exhibits better mechanical properties.

Green tides on inter- and subtidal sandy shores: differential impacts on infauna and flatfish

Beach ecosystems extend from dune to offshore areas along most coasts, and provide essential services that are not provided by any other ecosystem. Indeed, sandy systems contain unique biodiversity and supply nursery and foraging areas for numerous commercially important marine species, such as flatfish. However, these systems are threatened by increasing anthropogenic pressure. Green tides (GT, i.e. accumulations of green opportunistic macroalgae) are a major human-induced threat to marine ecosystems, from inshore to nearshore. This eutrophication process greatly affects both benthic invertebrate communities and flatfish communities, within sheltered and non- or microtidal systems. However, the responses of dynamic open macrotidal sandy systems to eutrophication in the form of macroalgal mats are not yet fully understood. In particular, understanding the effects of GT on two connected biological compartments (infauna and flatfish) within two connected habitats (intertidal and subtidal) is crucial. Here, we set out to assess the influence of several environmental variables, including Ulva biomass, on the variability in infauna and flatfish communities in both the intertidal and the subtidal at four sites impacted or not by GT. In total, 110 biodiversity samples were analysed with classic and novel analytical approaches. Our results demonstrate that the presence of GT specifically impacts intertidal macroinvertebrate communities. However, small effects of GT on subtidal infauna communities, as well as on species-specific flatfish at both intertidal and subtidal, were still detectable. Our findings underline the vulnerability of highly dynamic ecosystems exposed to anthropogenic stress, in particular intertidal sandy shores.

PLA-Based Hybrid and Composite Electrospun Fibrous Scaffolds as Potential Materials for Tissue Engineering

The aim of the study was to manufacture poly(lactic acid)- (PLA-) based nanofibrous nonwovens that were modified using two types of modifiers, namely, gelatin- (GEL-) based nanofibres and carbon nanotubes (CNT). Hybrid nonwovens consisting of PLA and GEL nanofibres (PLA/GEL), as well as CNT-modified PLA nanofibres with GEL nanofibres (PLA + CNT/GEL), in the form of mats, were manufactured using concurrent-electrospinning technique (co-ES). The ability of such hybrid structures as potential scaffolds for tissue engineering was studied. Both types of hybrid samples and one-component PLA and CNTs-modified PLA mats were investigated using scanning electron microscopy (SEM), water contact angle measurements, and biological and mechanical tests. The morphology, microstructure, and selected properties of the materials were analyzed. Biocompatibility and bioactivity in contact with normal human osteoblasts (NHOst) were studied. The coelectrospun PLA and GEL nanofibres retained their structures in hybrid samples. Both types of hybrid nonwovens were not cytotoxic and showed better osteoinductivity in comparison to scaffolds made from pure PLA. These samples also showed significantly reduced hydrophobicity compared to one-component PLA nonwovens. The CNT-contained PLA nanofibres improved mechanical properties of hybrid samples and such a 3D system appears to be interesting for potential application as a tissue engineering scaffold.

Identification of a new-to-science cyanobacterium, Toxifilum mysidocida gen. nov. & sp. nov. (Cyanobacteria, Cyanophyceae).

Cyanobacteria occupy many niches within terrestrial, planktonic, and benthic habitats. The diversity of habitats colonized, similarity of morphology, and phenotypic plasticity all contribute to the difficulty of cyanobacterial identification. An unknown marine filamentous cyanobacterium was isolated from an aquatic animal rearing facility having mysid mortality events. The cyanobacterium originated from Corpus Christi Bay, TX. Filaments are rarely solitary, benthic mat forming, unbranched, and narrowing at the ends. Cells are 2.1×3.1μm (width×length). Thylakoids are peripherally arranged on the outer third of the cell; cyanophycin granules and polyphosphate bodies are present. Molecular phylogenetic analysis in addition to morphology (transmission electron microscopy and scanning electron microscopy) and chemical composition all confirm it as a new genus and species we name Toxifilum mysidocida. At least one identified Leptolyngbya appears (based on genetic evidence and TEM) to belong to this new genus.

Fabrication of chitosan/PEO nanofiber mats with mica by electrospinning

Abstract Chitosan (CS) is an excellent biocompatible natural antibacterial material that has attracted researchers to study its biological applications as artificial tissue scaffolds and wound-healing materials. In this research, CS has been mixed with polyethylene oxide (PEO) and mica at various weight ratios to prepare nanofibers; however, it is found to be a difficult task to prepare the nanofiber using pure CS. The composite in form of nanofibrous mat was prepared with CS/PEO solution and CS/PEO/mica solution using electrospinning. Processing conditions were adjusted to a flow rate of 6 ml/min, with an applied voltage of 27 kV. The distance of capillary tip to target was kept about 10 cm at 25°C with a collector having a speed of 200 rpm. The spinnability of solutions was also evaluated by using both plate and cylinder collectors. The composite mats were analyzed in detail using scanning electron microscopy (SEM), Fourier transform infrared (FTIR), thermogravimetric analysis, and X-ray diffractogram (XRD). SEM photomicrograms indicated that the morphology and diameter of the nanofibers were affected by weight ratio of CS/PEO, concentration of mica, and types of collector. Furthermore, mica was incorporated in the CS/PEO matrix to enhance the specific surface area. Molecular interactions between CS/PEO and mica were investigated using FTIR and XRD.

Designing superhydrophobic disordered arrays of fibers with hierarchical roughness and low-surface-energy

Hierarchical roughness and low surface energy are the main criteria for designing superhydrophobic surfaces with extreme water repellency. Herein, we present a step-wise approach to devise three-dimensional (3D) superhydrophobic disordered arrays of fibers in the form of nonwoven mats exhibiting hierarchical surface roughness and low surface energy. Key design parameters in the form of roughness factors at multiple length scales for 3D nonwoven mats have been quantified. The contact angles have been predicted for each of the wetting regimes that exists for nonwoven mats with predefined level of hierarchical surface roughness and surface energy. Experimental realization of superhydrophobic mats was attained by decorating the highly hydrophilic nonwoven viscose fibers with ZnO rods that effectively modulated the surface roughness at multiple length scales and subsequently, the surface energy was lowered using fluorocarbon treatment. Synergistic effects of hierarchical roughness and surface energy have systematically increased the static water contact angle of nonwoven mat (up to 164°) and simultaneously, lowered the roll-off angle (≈11°).

Thermal conductivity of refractory glass fibres

In the present study, the current international standards and corresponding apparatus for measuring the thermal conductivity of refractory glass fibre products have been reviewed. Refractory glass fibres are normally produced in the form of low-density needled mats. A major issue with thermal conductivity measurements of these materials is lack of reproducibility in the test results due to transformation of the test material during the test. Also needled mats are inherently inhomogeneous, and this poses additional problems. To be able to compare the various methods of thermal conductivity measurement, a refractory reference material was designed which is capable of withstanding maximum test temperatures (1673 K) with minimum transformation. The thermal conductivity of this reference material was then measured using various methods according to the different standards surveyed. In order to compare different materials, samples have been acquired from major refractory glass fibre manufacturers and the results have been compared against the newly introduced reference material. Materials manufactured by melt spinning, melt blowing and sol–gel have been studied, and results compared with literature values.

Mass transfer and kinetic studies on mercury adsorption by titania nanofibers

The stringent laws and tight regulation on heavy metal bearing wastewaters being discharged into the water stream lead to emergence of technically advanced and super effective treatment methods. Heavy metal contaminated aqueous streams have become a global concern due to their carcinogenicity and delirious effects on human health. In particular, the health hazards of mercury include adverse effect on central nervous system, pulmonary and kidney functions, etc. Having a maximum discharge limit of 0.001 mg/L, which is the lowest amongst other heavy metals, mercury contamination has become a matter of global concern. In the present study, TiO 2 having a proven track record for its affinity for heavy metals was lab synthesized in the form of fiber mats and tested for its adsorptive behaviour towards Hg(II) in aqueous system. The electrospinned nanofibers possessed smooth morphology and very high surface area ≈ 740 m 2 /g. The batch adsorption experiments showed titania nanofibers possessed great affinity towards Hg(II). At the most optimized conditions the removal percentage went remarkably high to 95.5% with initial Hg(II) concentration of 0.01 mg/L. Since the rate limiting steps in adsorption are of vital importance in order to define the rate parameters for design purposes, the present study takes into account External mass transfer, Weber and Morris and Boyd mass transfer diffusion models for Hg(II) adsorption on lab synthesized titania nanofibers. The equilibrium data were then analyzed using Langmuir, Freundlich and Temkin sorption models and the characteristic sorption parameters for each isotherm were determined. The Mass transfer mechanism appeared to be film diffusion controlled and data fitted best to Freundlich isotherm with regression value of 0.991. The discussion also focuses on few of the recently used adsorbents for Hg(II) uptake and their comparison with the present study on the basis of removal percentage and kinetics involved. Promising adsorbent characteristics and rapid Hg(II) uptake makes this process a convenient one.

Sheep Wool for Sustainable Architecture

Sheep wool is a natural material, already used for thermal insulation of pitched roofs, in the form of soft mats. The paper presents a research project called Cartonlana, concerning a new sheep wool-based product with two main innovative features: it is a stiff panel, unlike the existing soft wool mats; it has a low environmental impact, using local recycled sheep wool, otherwise disposed as special waste. Physical and chemical properties of Cartonlana panel were determined by measurements, in order to demonstrate its effectiveness as insulation for buildings: thermal conductivity, acoustic absorption coefficient, absorption of formaldehyde, thermal transmittance of a wall.

Evaluation of Mechanical Properties and Morphological Studies of Rice Husk (Treated/Untreated)–CaCO3 Reinforced Epoxy Hybrid Composites

Natural fiber reinforced composites are a very popular area of research because of the easy availability and biodegradability of these fibers. The manufacturing of natural fiber composite is done by reinforcing fibers in the particulate form, fiber form or in woven mat form. Natural fiber composites also utilize industrial wastes as a secondary reinforcements like fly ash, sludge etc. By keeping all these point of views in the present investigation the effect of rice husk flour (chemically treated/untreated) and micro sized calcium carbonate with epoxy resin have been evaluated. The diameter of rice husk flour was maintained at 600 µm through mechanical sieving machine. The husk flour was chemically treated with NaOH (5 % w/v). Mechanical properties like hardness, flexural impact and compression strength were evaluated and found to be superior in modified or chemically treated flour as compared to unmodified or untreated flour reinforced composites. Scanning electron microscopy (SEM) study was also undertaken for the developed composites. SEM study shows the distribution of the rice husk flour and calcium carbonate over the matrix.

Localized toughening of carbon/epoxy laminates using dissolvable thermoplastic interleaves and electrospun fibres

Mode-I interlaminar toughness improvement through epoxy-dissolvable thermoplastic phenoxy interleaves of different surface-to-volume ratios is reported. Shear yielding around the crack tip in the reaction-induced phase separated blend morphology was found to be the main toughening mechanism responsible. The dissolution behaviour of thermoplastic phenoxy fibre within epoxy resin was studied, and a simple relationship between dissolution time, temperature, and original fibre diameter is proposed. Thermoplastic interleaves in the form of continuous films and electrospun fibre mats of equivalent weights were employed in order to study the effect of surface-to-volume ratio on dissolution and toughening behaviour. The toughness improvements obtained for the dissolvable thermoplastic nanofibre interleaves were the highest ever reported for these types of toughening concepts, with a dramatic increment from 0.56kJ/m2 to 1.90kJ/m2 with only 1.6wt.% phenoxy interleaves. Differences in toughening behaviour between continuous films and nanofibre mats are explained in relation to differences in dissolution time.

Possibilities of Development of Thermal Insulating Materials Based on Waste Textile Fibers

The paper describes the possibility of using textile fibers (natural and synthetic) for the production of thermal insulation materials in the form of mats using in construction. The paper deals mainly with soft thermal insulation mats and the factors that affect the thermal insulation properties of the insulating material in its manufacture and subsequent incorporation into the structure.

Hempcrete - Cement Composite with Natural Fibres

The paper describes use of hemp boon as a natural organic filler for building materials, especially concrete designed as heat - insulating filler material around the load-bearing structure of wooden buildings. In constructions, hemp has been used in the form of mats made of hemp fiber, with the addition of bonding bicomponent fibers and soda solution for protection against burning and rots. Mats are formed by pneumatic fleece, they are subsequently thermally treated and then cut to the desired dimensions. Calcium-hemp building material is a revolutionary construction and thermal insulating material which can be used for building the entire building, bricks or other insulation are not necessary. The trend is spreading across Europe from France, where the mixture of boon and lime was used in the 16th and 17th centuries for the construction of timber-framed houses. Although there are hundreds of buildings made from hempcrete in Europe, its use in our country develops very slowly. Concrete is a mixture of hemp boon, lime hydrate, cement and water. It is a recyclable material that offers high thermal and sound insulation. The biggest advantage is undoubtedly the speed of construction, namely hemp concrete hardens very quickly.

Effect of lignocellulosic fibers on mechanical, thermomechanical and hydrophilic studies of epoxy modified with novel bioresin epoxy methyl ester derived from soybean oil

Epoxy resin is modified with epoxy methyl soyate synthesized from soybean oil to toughen the matrix and reduce the viscosity of resin system. Unidirectional sisal fibers in mat form were incorporated at different orientations of [0/0] and [0/90] as reinforcement in epoxy blend having more toughened nature. Highly improved strength and modulus of the [0/0] laminated composite revealed strong interfacial region of matrix for binding the fibers. Further, notched impact strength of the composites was found to be more than 700% higher compared with modified epoxy blend. Dynamic mechanical analysis depicted an improvement in the storage modulus and higher damping factor of the [0/0] sisal fiber laminated composite, which confirms better damping properties under vibrating conditions. The fiber‐matrix interfacial adhesion in the composite was confirmed by scanning electron microscopic analysis of the fractured specimens. Contact angle and atomic force microscopic studies were carried out to reveal the hydrophilic nature. Copyright © 2015 John Wiley & Sons, Ltd.

Recycled Carbon Fiber as Flame Retardant in Palm-Based Polyurethane Composite

The effect of recovered carbon fiber (rCF) to the burning property of polyurethane composites was investigated. The carbon fiber reinforced polymer (CFRP) in mat form was first glycolysed at 190-200 oC and characterized by FTIR, TGA, DSC and SEM analyses. The rCF was added at 0, 0.5, 1.0 and 1.5% (w/w). The polyurethane filled with recovered carbon fiber composites (PU-rCF) have also undergone burning test. The TGA analysis of PU-rCF indicated the percentage of weight loss decreased from 95.6% to 91.4% as rCF content increased. The DSC showed the glass transition temperature, Tg of PU-rCF increased with increasing addition of rCF from 56.7 to 63.0oC. The burning rate of the PU-rCF decreased from 6.1 mm∙s-1 to 2.8 mm∙s-1 with increasing rCF. The FTIR analysis confirmed that there was no chemical interaction between the rCF and PU. The addition of rCF to PU has improved the burning property of the composite.

Characterization of Mechanical Properties of Hybrid Bamboo/GFRP and Jute/GFRP Composites

The superior properties of the natural fibers in comparison to their synthetic counterparts make them favorite for using as the reinforcement material in the polymer composites. But still the mechanical properties of these composites are lagging behind their synthetic counterparts like glass fiber reinforced polymer (GFRP). In this work an attempt is made to hybrid the bamboo and jute fiber polymer composites with the glass fiber. Two types of hybrid composites viz. bamboo/GFRP and jute/GFRP epoxy composites are prepared with the fiber alignment of 0o and 90o a plain weaved mat form. Different samples of hybrid composites with varying number of natural and glass fiber lamina are prepared. The no. of lamina of the composites is fixed to 4 layers. Composite samples with single type of reinforcement are also prepared. Different types of mechanical characterization are performed on these composite samples and a comparative analysis of these investigated properties is presented.

Electrospun polyurethane as an alternative ventricular catheter and invitro model of shunt obstruction.

Intracranial pressure and volume vary considerably between hydrocephalic patients, and with age, health and haemodynamic status; if left untreated, intracranial pressure rises and the ventricular system expands to accommodate the excess cerebrospinal fluid, with significant morbidity and mortality. Cerebrospinal fluid shunts in use today have a high incidence of failure with shunt obstruction being the most serious. Conventional proximal shunt catheters are made from poly(dimethyl)siloxane, the walls of which are perforated with holes for the cerebrospinal fluid to pass through. The limited range of catheters, in terms of material selection and flow distribution, is responsible in large part for their poor performance.In this study, we present an alternative design of proximal catheter made of electrospun polyether urethane, and evaluate its performance in the presence of glial cells, which are responsible for shunt blockage. The viability and growth of cells on catheter materials such as poly(dimethyl)siloxane and polyurethane in the form of cast films, microfibrous mats and porous sponges were studied in the presence of proteins present in cerebrospinal fluid after 48 h and 96 h in culture. The numbers of viable cells on each substrate were comparable to untreated poly(dimethyl)siloxane, both in the presence and absence of serum proteins found in cerebrospinal fluid. A cell culture model of shunt obstruction was developed in which cells on electrospun polyether urethane catheters were subjected to flow during culture in vitro, and the degree of obstruction quantified in terms of hydraulic permeability after static and perfusion culture. The results indicate that a catheter made of electrospun polyether urethane would be able to maintain cerebrospinal fluid flow even with the presence of cells for the time period chosen for this study. These findings have implications for the design and deployment of microporous shunt catheter systems for the treatment of hydrocephalus.

EPDM RECYCLED RUBBER POWDER CHARACTERIZATION: THERMAL AND THERMOGRAVIMETRIC ANALYSIS

ABSTRACT Investigations on ethylene–propylene–diene rubber (EPDM) with varying cross-link densities and carbon black contents, as well as commercial EPDM waste ground rubber (WGR), have been performed to improve characterization. The aim is to provide additional quality-control methods in the field of rubber recycling, as WGR is transformed and reused in the form of rubber mats mainly for playground, agricultural, sport, and automobile applications. Inductively coupled plasma optical emission spectrometry, atomic absorption spectrometry, and elemental (CHNS) analyses were used to determine the content of various chemical elements. Thermogravimetric analysis (TGA) was used to determine the amount of carbon black and inorganic material in the sample. Mass loss at 400 °C was related to cross-link density. TGA coupled with mass spectrometry showed that this mass loss corresponds to the loss of SO2 as cross-links are destroyed during heating. Melt point and glass transition temperatures determined by differential scanning calorimetry are mainly proportional to the ethylene/propylene weight ratio.

Habitat Preference in Pleurocarpus Mosses of Imphal District, Manipur, India

Mosses are remarkably successful plants that colonize a variety of habitats. They have specific requirements with regard to microenvironments factors such as temperature, light and water availability and substrate chemistry. The occurrence of a particular species may reflect the microclimate of the locality. Pleurocarpous mosses form extensive cover on the substrate and provide microenvironment for the activity of bacteria, fungi and invertebrates, thus constituting a kind of bryosystem. Present study has revealed 42 species of pleurocarpous mosses belonging to 30 genera and 16 families from Imphal district, Manipur, India. Hypnaceae are found to be most frequent. Majority of taxa are found as epiphytic growing on tree bark and branches. Erpodium mangiferae, Erythrodontium julaceum, Pterygynandrum decolor, Fabronia assamica are found most widely spread in the studied area. It seems that these species have high tolerance and adaptability to survive in the dry bark. Most of the pleurocarpous mosses in the present collection display mat form.

English

Otomycosis is a fungal infection of External auditory canal. Otomycosis has worldwide distribution with high prevalence in hot, humid and dusty climates of tropical and subtropical regions. Management of Otomycosis is dependent on thorough understanding of anatomy of external ear canal, knowledge of microbiology and pathophysiology of potential pathogens. OBJECTIVES: To determine importance of various aetio-pathological factors in causation of Otomycosis. To study pattern of fungal isolates encountered in cases of Otomycosis. To study management of the disease. MATERIALS AND METHODS: This study was undertaken in the Department of Otorhinolaryngology, Sri Siddhartha Medical College & Hospital, Tumkur from January 2012 to December 2012. It was a time bound study, wherein 51 cases were studied. OBSERVATION AND RESULTS: Highest incidence (25.5%) was noted in age group of 21-30 years. Common predisposing factor was use of unsterile material for cleaning ear in 55.3% cases. Fungal debris within canal in form of wet brownish black or grey mouldy mats/ spores with epithelial debris was found in 53.2% cases. Aspergillus was most common fungus isolated in 81%. Clotrimazole showed good response symptomatically and mycological clearance was seen within one week in 74.4% cases and persistence of disease up to 2 - 4 weeks was seen in 25.5% cases. On follow up failure or recurrence disease within 2 months was observed in 10.6% of cases. CONCLUSION: In conclusion Otomycosis/mycotic otitis externa is still a common problem and is often misdiagnosed for other chronic otitis conditions.