Effect Of Matrix Type Research Articles

Seismic behaviors of steel-FRP composite bar-reinforced engineered cementitious composites columns under reversed cyclic loads

The combination of steel-FRP composite bar (SFCB) and engineered cementitious composites (ECC) in structures exposed to harsh conditions can offer benefits in mechanical performance and durability. In this study, the seismic behaviors of SFCB-reinforced ECC and concrete columns were investigated through reversed cyclic loading tests and the effects of matrix types, axial load ratios, and reinforcing bar types were discussed. The results showed that the SFCB-reinforced ECC columns experienced flexural failure characterized by SFCB fracture, whereas the SFCB-reinforced concrete columns failed owing to concrete crushing. The SFCB-reinforced ECC columns showed a 41.5 %− 116.3 % enhancement in deformation capacity and a 34.7 %− 65.2 % improvement in average energy dissipation coefficient compared with SFCB-reinforced concrete columns, which demonstrated that using ECC in SFCB-reinforced columns addressed issues of their low deformation and low energy dissipation capacity. In addition, the plastic hinge length of SFCB-reinforced columns increased substantially with the application of ECC, and the stiffness degeneration and residual deformation were reduced.

A novel modeling method to study compressive behaviors of 3D braided composites considering effects of fiber breakage and waviness defects

Fiber breakage and waviness defects are two significant and inevitable defects existing in three-dimensional braided composites (3DBCs). This work proposed a new method to create the numerical model containing fiber breakage and waviness defects at the micro-scale level according to experimental characterization results. The experimental tests of 3DBCs with various braiding angles and matrix types are then designed to verify the reliability and adaptability of the model. The results indicate that the fiber breakage and waviness defects both gave rise to an apparent decrease in the axial mechanical properties of the unidirectional and braided composites. The influences of two kinds of defects on 3DBCs are also related to the braiding angles. In addition, the effect of matrix type on the 3DBC is apparent that should not be neglected. The primary reasons of the change of compressive properties of 3DBCs with different matrix types are the variations of the matrix and interfacial properties. The proposed modeling method in this work can be extended for those composites that include a large quantity of fiber breakage and waviness defects.

Effect of Matrix Type on Properties of Moulding Sand with Barley Malt

The aim of the following work was to determine the possibility of using barley malt as a binder in moulding sands technology. The moulding sands prepared on the basis of three kinds of sands, i.e. quartz, olivine and chromite sands were analyzed. In order to determine the properties of moulding sands, typical determinations were made, i.e. moisture content, flowability, permeability, strength properties and abrasion wear. The obtained results indicate that it is possible to use barley malt as an independent binder for masses made of quartz, olivine and chromite sands.

Experimental analysis of the warm stamping of metal/thermoplastic polymer nanocomposite laminates

AbstractThe effects of matrix type, temperature, and weight percentage of nano‐reinforcement on maximum drawing force and drawing depth have been studied in warm stamping of reinforced metal/nanocomposite laminates. The laminates were composed of two thermoplastic polymers of glass fibers‐reinforced polypropylene and polyvinyl chloride, two reinforcements of nanoclay and multi‐walled carbon nanotubes as the core layer, and aluminum 1050‐O as the skin layer. Change of the matrix type from polyvinyl chloride to polypropylene increased the maximum drawing force and decreased the drawing depth. Besides, the drawing depth in most samples was decreased by increasing the weight percentage of the nano reinforcement. Increase of the temperature led to increasing the drawing depth and decreasing the maximum drawing force. Temperature had the greatest effect on the output parameters, especially the drawing depth.

Performance of FRP confined and unconfined engineered cementitious composite exposed to seawater

Conventional concrete suffers from brittle failures under mechanical behaviour, and lack of ductility results in the loss of human life and property in earthquake zones. Therefore, the degree of ductility becomes significant in seismic regions. This paper investigates the influence of poly-vinyl alcohol fibers, basalt fiber-reinforced polymer (BFRP) and carbon fiber-reinforced polymer (CFRP) fabrics on the ductility and mechanical performance of low (LCFA) and high (HCFA) calcium fly ash-based engineered cementitious composite concrete. The study also focuses on the mechanical behaviour of the CFRP and BFRP materials using different matrix types exposed to 3.5% seawater environment. Cyclic loading and scanning electron microscopy observations were also performed to see the effect of chloride attack on mechanical performance and ductility of the specimens. In addition, utilization of CFRP and BFRP fabrics as a retrofit material is also evaluated. Results indicated that the degree of ductility and mechanical performance were found to be superior for the CFRP-engineered cementitious composite hybrid specimens under ambient environment, while LCFA-CFRP hybrid specimens showed better performance under seawater environment. The effect of matrix type was also found significant when engineered cementitious composite is used together with fiber-reinforced polymer materials. In addition, both fiber-reinforced polymer materials can be used as a retrofit material under seawater environment.

Piezoresistive response of carbon nanotube composite film under laterally compressive strain

Carbon nanotubes (CNTs) have attracted great attention for strain sensor application due to their excellent electromechanical property. This paper focused on the piezoresistive response of high CNT loading composite film. The piezoresistive behavior of floating catalyst chemical vapor deposition (FCCVD)-grown CNT composite film under tension and lateral compression was investigated and compared with a graphite composite film. The effects of matrix type, functionalization and acid treatment on piezoresistive response of CNT composite film were discussed. The results showed that CNT composite film exhibited positive piezoresistive response under tension and negative piezoresistive effect under lateral compression. After eliminating the effect of geometrical deformation on gauge factor, the change in resistivity was more sensitive under lateral compression than under tension. Different from CNT composite film, graphite composite film showed less obvious piezoresistive behavior, and showed positive piezoresistive response regardless of tensile and laterally compressive loads. Furthermore, the piezoresistive response of CNT composite film was found to closely correlate with its modulus. Stronger interfacial bonding was proved to effectively enhance the piezoresistive response and increase the corresponding gauge factor. CNT/epoxy composite film with 1 h treatment in potassium permanganate solution reached a gauge factor of −5.9. These results revealed the key factors tailoring piezoresistive response of CNT composite film, and presented one potential approach to monitor biaxial strain. The present work should be useful in the in-plane strain monitoring by incorporating the CNT film into traditional composite.

The effect of matrix type on ageing of thick vinyl ester glass-fibre-reinforced laminates

In this research, glass fibre reinforced composite laminate samples were manufactured with filament winding technique using four different vinyl ester resin systems to study ageing. The manufactured laminate samples were conditioned in an environmental cabinet (70°C, 95 RH%), water immersion (95°C), and in sulphuric acid solution immersion under pressure (5% H2SO4, 95°C, 15bar). After 6 and 12months of conditioning, the samples were tensile tested and the results were compared with the initial values. Regardless of the matrix type, conditioning in the environmental cabinet resulted in the lowest weight gain and least decrease in tensile properties: the decrease in the tensile strength values was 10–25% after 12months’ conditioning depending on the vinyl ester used. The water immersion was more detrimental to the samples than the 5% H2SO4 immersion causing the highest weight gain and the greatest decrease in tensile strength (up to 65%). However, when comparing the tensile performance, it was noted that the highest weight gain did not inevitably correlate with the strongest ageing effect. In water immersion, the ultimate strength deteriorates faster than the proof stress level leading to a decreasing damage tolerance of the vinyl-ester composite laminates.

Effects of landscape composition and native oak forest configuration on cavity-nesting birds of North Africa

In the Kroumirie ecoregion of northwestern Tunisia, habitat fragmentation and degradation are the main drivers of contemporary landscape change. Continuous native oak forests have been converted into heterogeneous landscapes characterized by small forest fragments surrounded by a scrubby matrix. We examined the response of five species of cavity-nesting birds to these phenomena because they play a keystone role in these forest ecosystems. We quantified the relative effects of landscape composition and the configuration of mature oak forest on the occurrence of the focal species. We hypothesized that the occurrence of all focal species would increase with forest cover, whereas the effects of matrix type and mature forest configuration would be species-specific. For each focal species, we tested a set of 12 candidate models predicting their occurrence. Each model included landscape metrics describing oak forest configuration and landscape composition. We applied multimodel inference and model averaging on generalized linear models. Forest cover at the landscape level was the main driver of species occurrence. Secondary cavity-nesters responded positively to the proportion of oak forest at landscape and local scales, whereas the five focal species responded negatively to the proportion of low scrub. Great spotted woodpecker (Dendrocopos major) and Levaillant’s woodpecker (Picus vaillantii) responded positively to both forest amount and high scrub, suggesting a landscape complementation process. Lesser spotted woodpecker (D. minor) was the only species responding to forest configuration, possibly as a result of landscape supplementation. High scrub appeared to moderate the contrast between low scrub and forest fragments for primary cavity-nesters. However, it did not influence the occurrence of secondary cavity-nesters (e.g., Atlas flycatcher Ficedula speculgera and short-toed treecreeper Certhia brachydactyla). If an increase in the amount of mature oak forest cannot be achieved over the short term, the maintenance of high scrub around forest fragments and an improvement in the quality of low scrub through the addition of vertical structure should increase the frequency of occurrence of many of our focal species in oak forest of the Mediterranean Basin.

Tribological behavior and lubrication mechanism of self-lubricating ceramic/metal composites: The effect of matrix type on the friction and wear properties

This study aims at revealing the mechanisms of how matrix type and lubricant content affect the lubricating properties of graphite doped self-lubricating composites. Self-lubricating mechanism and tribological properties of three kinds of lubricating materials having different matrix-types (copper alloy, zirconia and alumina) are investigated. Results show that the effect of matrix type on the friction and wear properties of the composites is mainly related to its hardness and binding property with graphite. The variation of matrix-type causes significant changes in the degree of difficulty for extruding lubricants onto the friction surface from the material interior and plastic deformation resistance of composites, thus affecting the formation of lubricating and transferring films, and wear mechanisms of the materials. For copper alloy matrix that has low hardness and binding force with graphite, incorporating just a little graphite can greatly promote its lubricating performance. By contrast, alumina-graphite composite is difficult to achieve good lubrication when the graphite content (volume fraction) is less than 15% because of a relatively high hardness and brittleness of alumina matrix. Based on these analyses, we formulated some principles to design self-lubricating ceramic/metal composites.

Impact properties of low-alloy transformation-induced plasticity-steels with different matrix

The effects of matrix types on Charpy impact properties were investigated in Fe–0.2%C–1.5%Si–1.5%Mn (mass%) transformation-induced plasticity steels. The steels with annealed martensite and bainitic ferrite matrix possessed higher upper shelf Charpy impact absorbed energy than the steel with polygonal ferrite and martensitic matrix. In addition, the low ductile–brittle fracture appearance transition temperatures were achieved in annealed martensite and martensite types in comparison with those of other steels.

Spray congealing as a microencapsulation technique to develop modified-release ibuprofen solid lipid microparticles: the effect of matrix type, polymeric additives and drug–matrix miscibility

This study aimed to achieve modified-release of ibuprofen (IBU) by encapsulation within lipid-based matrix materials [cetyl alcohol (CA), stearic acid (SA) and glyceryl dibehenate (GB)] using spray congealing to produce solid lipid microparticles (SLMs). Polymeric additives, polyvinyl-2-pyrrolidone-vinyl-acetate and ethylcellulose, were employed as release-modifying agents. Spray-congealed SLMs yield, scanning electron microscopy (SEM)-based morphology, particle size, drug content and entrapment efficiency were investigated. The influence of matrix type, additive type and concentration and drug–matrix miscibility on release of IBU was elucidated. Yields (81.4–96.4%) and drug encapsulation efficiencies (88.4–100%) of SLMs were high for all formulations. SLMs were generally discrete, spherical and dense. Increasing additives concentration led to not only larger median size SLMs but also faster drug release due to increased hydrophilicity conferred by the additives. Solid solution systems (SA-IBU, GB-IBU) sustained the release of IBU better than solid dispersion system (CA-IBU). CA- and GB-based SLMs closely adhered to the Weibull model of drug release, while SA counterparts followed the Korsmeyer–Peppas model.

Development and evaluation of glibenclamide floating tablet with optimum release

Glibenclamide is a poorly soluble drug with narrow absorption window. The strategy of this work was to enhance the dissolution rate of Glibenclamide by solid dispersion (SD) technique with optimum formulation being developed as floating tablets. Binary SDs of drug and poloxamer 407 were prepared at different ratios. Ternary dispersion was prepared by the addition of sodium bicarbonate as third component. For floating tablets, a series of floating formulations was prepared using HPMC k4 (F1), HPMC k15 (F2) and combination of both with Carbopol (F3), using ternary solid dispersion as the drug matrix. Effect of matrix type was studied, F4 and F5 were prepared using the same floating matrix as F3 but drug was either binary poloxamer SD or physically mixed with bicarbonate. Unprocessed drug in floating matrix was used as control. All SDs increased drug dissolution rate, with ternary mixture showing the highest dissolution efficiency reflecting synergism between poloxamer and sodium bicarbonate. Solid state characterization showed evidences of decreased drug crystalline structure. F3 showed the best floating behavior. Considering floating behavior together with the release pattern, F3 was the optimum formulation. Overall, employing drug as ternary SD with optimum dissolution can provide flexibility in developing controlled release floating system.

Mechanical Properties of Woven Fabric Reinforced All-Polypropylene Composites

Random copolymer polypropylene (co-PP) and beta-nucleated PP (β-PP) produced with nucleant, which was not completely selective, were used as matrix materials. The effect of matrix type and consolidation temperature on the static and dynamic mechanical properties of woven tape-reinforced all-PP composites were investigated. The mechanical properties of all-PP composites strictly depended on the matrix type and the consolidation temperature. Co-PP-based composites had higher tensile strength and lower impact strength than β-PP-based composites. The maximum tensile strength and storage modulus was achieved at a consolidation temperature of 10°C above the melting point of both matrix materials.

Movement behaviour within and beyond perceptual ranges in three small mammals: effects of matrix type and body mass

1. For animal species inhabiting heterogeneous landscapes, the tortuosity of the dispersal path is a key determinant of the success in locating habitat patches. Path tortuosity within and beyond perceptual range must differ, and may be differently affected by intrinsic attributes of individuals and extrinsic environmental factors. Understanding how these factors interact to determine path tortuosity allows more accurate inference of successful movements between habitat patches. 2. We experimentally determined the effects of intrinsic (body mass and species identity) and extrinsic factors (distance to nearest forest fragment and matrix type) on the tortuosity of movements of three forest-dwelling didelphid marsupials, in a fragmented landscape of the Atlantic Forest, Brazil. 3. A total of 202 individuals were captured in forest fragments and released in three unsuitable matrix types (mowed pasture, abandoned pasture and manioc plantation), carrying spool-and-line devices. 4. Twenty-four models were formulated representing a priori hypotheses of major determinants of path tortuosity, grouped in three scenarios (only intrinsic factors, only extrinsic factors and models with combinations of both), and compared using a model selection approach. Models were tested separately for individuals released within the perceptual range of the species, and for individuals released beyond the perceptual range. 5. Matrix type strongly affected path tortuosity, with more obstructed matrix types hampering displacement of animals. Body mass was more important than species identity to determine path tortuosity, with larger animals moving more linearly. Increased distance to the fragment resulted in more tortuous paths, but actually reflects a threshold in perceptual range: linear paths within perceptual range, tortuous paths beyond. 6. The variables tested explained successfully path tortuosity, but only for animals released within the perceptual range. Other factors, such as wind intensity and direction of plantation rows, may be more important for individuals beyond their perceptual range. 7. Simplistic scenarios considering only intrinsic or extrinsic factors are inadequate to predict path tortuosity, and to infer dispersal success in heterogeneous landscapes. Perceptual range represents a fundamental threshold where the effects of matrix type, body mass and individual behaviour change drastically.

Preparation of unsaturated polyester–styrene beads using gamma irradiation and chemical polymerization routes for use in the recovery of some alkali metal ions

AbstractSuspension polymerization of unsaturated polyester–styrene was carried out in different media using different routes of polymerization. The effects of matrix type and concentration hold up, viscosity, irradiation dose, and the agitation speed on the resultant polymer characteristics were examined. The formed beads were physically identified using scanning electron microscopy, hardness, and particle size analysis techniques. They were smooth having typical spherical surfaces; the beads diameters were in the range of about 5–200 μm. The size of the resin beads was found to decrease with increase in the concentration and viscosity of the dispersant and impeller speed. The resultant beads were applied in the recovery of Li+, Na+, K+, and Cs+ ions from acidic media. The distribution coefficients of the alkali metal ions were calculated; the order of selectivity was Li+ > Na+ > K+ > Cs+ in case of the chemically processed resin beads, while the selectivity lies in the order of Li+ < Na+ < K+ < Cs+ in case irradiation processed ones. Finally, the economics of production of the unsaturated polyester–styrene resins using different methodologies was studied. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1149–1160, 2007

Direct determination of toxic trace metals in honey and sugars using inductively coupled plasma atomic emission spectrometry

A rapid method for the determination of Pb, Cd, Cu, Cr, Co, Ni, Mn and Zn in honey and sugars without prior digestion or ashing of the sample was developed, using inductively coupled plasma atomic emission spectrometry (ICP-AES). The critical instrumental parameters such as sample flow rate and radio frequency incident power were thoroughly optimized. The effect of matrix type and its concentration was also examined for glucose/fructose, sucrose and honey matrices. The sensitivity was investigated using calibration curves obtained in presence of the above matrices. The obtained recoveries for Cd, Cu, Cr, Co, Ni and Mn at the μg l −1 level were satisfactory and practically independent of the matrix used for the calibration standards. The recoveries of Pb and Zn were less sufficient. Various commercial samples of honey, sugar, glucose and fructose were analyzed with respect to their toxic metal content. The method can be applied for routine analysis, quality and environmental pollution control purposes at the μg l −1 level of concentration, after suitable dilution of the samples.

Effect of fibre length on fatigue of short carbon fibre/epoxy composite

The effect of fibre length on the fatigue of a random short carbon fibre/epoxy composite containing 1, 5 or 15 mm length fibres has been studied. All laminates gave a sloping S-N curve with longer fatigue lives obtained at decreasing peak stresses. The fatigue life was independent of fibre length at any peak strain, within experimental variation. Damage accumulation during fatigue cycling is studied in terms of residual strength and modulus reduction. Both techniques suggest that fatigue failure is the result of a ‘sudden death’ mode of failure. Finally, the effect of matrix type on the fatigue life of laminates containing 5 mm length fibres was investigated by adding a greater quantity of flexibilizer to the epoxy matrix. Shorter fatigue lives were obtained for laminates having the more flexible matrix.

Effect of impact perforation load on GFRP composites

The results of an experimental study on the impact behaviour of woven glass cloth reinforced plastic laminates are presented. Impact tests were carried out with a split Hopkinson pressure bar apparatus on two types of glass fibres laid in a thermosetting resin. The relative impact curves allow the identification of both the beginning of fibre failure and the material perforation resistance. The effects of matrix type and number of plies on the perforation impact energy are also discussed.

Effect of matrix type and form of stress state on mechanical properties of high-strength cast iron

Effect of matrix type and form of stress state on mechanical properties of high-strength cast iron