Journal of Composites The latest articles from Hindawi © 2017 , Hindawi Limited . All rights reserved. Residual Stresses Introduced to Composite Structures due to the Cure Regime: Effect of Environment Temperature and Moisture Mon, 21 Nov 2016 06:09:31 +0000 Material behaviour of structural components is very important to understand. In fibre reinforced polymer composite materials, this is more difficult in comparison to isotropic materials as they are made up of two constituents: the fibre and the matrix. For aerospace composite materials, the matrix is usually an epoxy resin that cures at a high temperature. This curing regime is known to introduce residual stresses to the composite material as it cools from the high cure temperature. However, how to consider these residual stresses in a structural analysis is still widely debated. In this paper, the authors investigated the offset of thermal residual strains introduced by the cure regime by the swelling of the composite when exposed to moisture. N. Chowdhury, J. Wang, W. K. Chiu, and W. Yan Copyright © 2016 N. Chowdhury et al. All rights reserved. Microwave Assisted Manufacturing and Repair of Carbon Reinforced Nanocomposites Thu, 13 Oct 2016 09:50:49 +0000 We report a composite capable of advanced manufacturing and damage repair. Microwave energy is used to induce thermal reversible polymerization of the matrix allowing for microwave assisted composite welding and repair. Composites can be bonded together in just a few minutes through microwave welding. Lap shear testing demonstrates that microwave welded composites exhibit 40% bond strength relative to composites bonded with epoxy resin. Double cantilever beam testing shows 60% recovery in delamination strength after microwave assisted composite repair. The interfacial adhesion and composite repair after microwave exposure are examined by X-ray computed tomography. The microwave processing is shown to be reproducible and consistent. The ability to perform scalable manufacturing is demonstrated by the construction of a large structure from smaller components. Edward D. Sosa, Erica S. Worthy, and Thomas K. Darlington Copyright © 2016 Edward D. Sosa et al. All rights reserved. Effect of Lycra Percentages and Loop Length on the Physical and Mechanical Properties of Single Jersey Knitted Fabrics Sun, 14 Aug 2016 11:54:33 +0000 Single jersey knitted fabrics are generally used to make underwear and outerwear such as T-shirts. Knit fabric can more easily deform or stretch by compressing or elongating the individual stitches that form the fabric. Cotton yarns, which are not elastomeric, do not have the ability of recovery to rearrange the stitches. As a consequence, single-knit fabrics may have permanent deformation. To improve the recovery performance of circular single-knit fabrics, it is now a common practice to knit a small amount of spandex fiber or yarn with companion cotton yarn. In this study the physical, dimensional, and mechanical properties of back plaited cotton/spandex single jersey knitted fabrics were investigated and the results are compared with knitted fabrics made from 100% cotton and the effect of spandex percentage was also studied. It was found that as the loop length increases, the wales density was not affected and specific fabric hand and extension increased, but bursting strength and fabric recovery decreased. The presence of Lycra in single jersey knitted fabric increases of course density, fabric thickness, and knitted fabric recovery, while fabric width, fabric porosity, and extension were decreased. Eman Eltahan Copyright © 2016 Eman Eltahan. All rights reserved. Radial Body Forces Influence on FGM and Non-FGM Cylindrical Pressure Vessels Tue, 26 Apr 2016 16:29:10 +0000 This study deals with the influence of radial body forces on FGM and non-FGM pressure vessels. It contains an extended overview of pressure vessels made from both kinds of material. Furthermore, full mathematical development of stress-strain field for both kinds of cylindrical vessels while being influenced by body forces has been performed. In addition, a new power law model for FGM materials was suggested and discussed. Finally, tables of composed plastic-elastic states are discussed. Jacob Nagler Copyright © 2016 Jacob Nagler. All rights reserved. Mechanical Properties Comparing Composite Fiber Length to Amalgam Sun, 13 Mar 2016 13:53:49 +0000 Photocure fiber-reinforced composites (FRCs) with varying chopped quartz-fiber lengths were incorporated into a dental photocure zirconia-silicate particulate-filled composite (PFC) for mechanical test comparisons with a popular commercial spherical-particle amalgam. FRC lengths included 0.5-mm, 1.0 mm, 2.0 mm, and 3.0 mm all at a constant 28.2 volume percent. Four-point fully articulated fixtures were used according to American Standards Test Methods with sample dimensions of  mm3 across a 40 mm span to provide sufficient Euler flexural bending and prevent top-load compressive shear error. Mechanical properties for flexural strength, modulus, yield strength, resilience, work of fracture, critical strain energy release, critical stress intensity factor, and strain were obtained for comparison. Fiber length subsequently correlated with increasing all mechanical properties, . Although the modulus was significantly statistically higher for amalgam than all composites, all FRCs and even the PFC had higher values than amalgam for all other mechanical properties. Because amalgams provide increased longevity during clinical use compared to the standard PFCs, modulus would appear to be a mechanical property that might sufficiently reduce margin interlaminar shear stress and strain-related microcracking that could reduce failure rates. Also, since FRCs were tested with all mechanical properties that statistically significantly increased over the PFC, new avenues for future development could be provided toward surpassing amalgam in clinical longevity. Richard C. Petersen and Perng-Ru Liu Copyright © 2016 Richard C. Petersen and Perng-Ru Liu. All rights reserved. A Study on the Mechanical Properties of Oil Palm Mesocarp Fibre-Reinforced Thermoplastic Sun, 06 Mar 2016 11:57:33 +0000 Oil palm mesocarp fibre obtained from a palm oil processing mill was washed with detergent and water to remove the oil and sun-dried to enhance good adhesion to Linear Low Density Polyethylene (LLDPE). The fibre was pulverized and filtered through a sieve of pore size 300 microns. The Oil Palm Mesocarp Fibre Reinforced Thermoplastic (OPMFRT) was produced with a form of hand lay-up method and varying fibres weight ratio in the matrix from 5 wt% to 25 wt% in steps of 5 wt%. Tensile test was carried out to determine the tensile strength, tensile modulus, and elongation at break of the material. The hardness and impact strength of the composite were also determined. The results showed that tensile modulus and hardness of the OPMFRT increased by 50% and 24.56%, respectively, while tensile strength, impact strength, and percentage elongation of the OPMFRT decreased by 36.78%, 39.07%, and 95.98%, respectively, as fibre loading increased from 5 wt% to 25 wt%. The study concluded that the application of the OPMFRT developed should be restricted to areas demanding high rigidity and wear resistance. Olusola Femi Olusunmade, Dare Aderibigbe Adetan, and Charles Olawale Ogunnigbo Copyright © 2016 Olusola Femi Olusunmade et al. All rights reserved. Rayleigh-Ritz Vibrational Analysis of Multiwalled Carbon Nanotubes Based on the Nonlocal Flügge Shell Theory Sun, 27 Dec 2015 07:12:11 +0000 A nonlocal elastic shell model considering the small scale effects is developed to study the free vibrations of multiwalled carbon nanotubes subject to different types of boundary conditions. Based on the nonlocal elasticity and the Flügge shell theory, the governing equations are derived which include the interaction of van der Waals forces between adjacent and nonadjacent layers. To analytically solve the problem, the Rayleigh-Ritz method is employed. In the present analysis, different combinations of layerwise boundary conditions are taken into account. Some new intertube resonant frequencies and the associated noncoaxial vibrational modes are identified owing to incorporating circumferential modes into the shell model. H. Rouhi, M. Bazdid-Vahdati, and R. Ansari Copyright © 2015 H. Rouhi et al. All rights reserved. Effect of Sintering Mechanism on the Properties of ZrO2 Reinforced Fe Metal Matrix Nanocomposite Thu, 29 Oct 2015 11:27:05 +0000 The present paper reports phase, microstructure, and compressive strength of ZrO2 reinforced Fe Metal Matrix Nanocomposites (MMNCs) synthesized by powder metallurgy (P/M) technique. High purity grade iron metal powder was mixed with varying percentage of zirconium dioxide (5–30 wt%), compacted, and sintered in argon atmosphere in the temperature range of 900–1100°C for 1 to 3 hours. X-ray diffraction (XRD) analysis of specimens was done in order to study the phases present and scanning electron microscopy was carried out to determine the morphology and grain size of the various constituents. XRD result shows the presence of Fe, ZrO2, and Zr6Fe3O phase. Zr6Fe3O phase forms due to reactive sintering and is not reported earlier by researchers throughout the globe. SEM results showed the presence of dense microstructure with the presence of Fe, ZrO2, and some nanosize Zr6Fe3O phases. Pushkar Jha, Pallav Gupta, Devendra Kumar, and Om Parkash Copyright © 2015 Pushkar Jha et al. All rights reserved. Textile/Polypyrrole Composites for Sensory Applications Tue, 27 Oct 2015 08:12:26 +0000 Electrically conductive woven, knitted, and nonwoven composite fabrics are prepared by in situ chemical polymerization of pyrrole using suitable oxidant and dopant. These composite fabrics show surface resistivity in the range ~1 to 2 kΩ. These composite fabric can alter their resistivity with various stimuli such as mechanical strain, pH, and humidity. So, in the present study, their response to pH, humidity, and mechanical strain is investigated. For all fabrics, similar behaviour has been observed regarding pH versus resistivity. The resistance of the composite fabric increases with the increase of alkalinity of pH. However, as bending strain increases, resistance steeply decreases for cotton fabrics, steeply increases for polyester fabrics, and initially decreases and then increases for wool fabrics. Regarding humidity sensitivity, sigmoid curves have been obtained for all kinds of fabrics. Subhankar Maity and Arobindo Chatterjee Copyright © 2015 Subhankar Maity and Arobindo Chatterjee. All rights reserved. A Preliminary Investigation on Processing, Mechanical and Thermal Properties of Polyethylene/Kenaf Biocomposites with Dolomite Added as Secondary Filler Tue, 13 Oct 2015 11:44:38 +0000 In this preliminary investigation, dolomite was added to the low-density polyethylene/kenaf core fiber (LDPE/KCF) biocomposites by using an internal mixer at 150°C, followed by compression molding at the same temperature. The dolomite contents were varied from 0 to 18 wt.%. The processing and stabilization torques, the stock and stabilization temperatures, the tensile and impact strengths, and the thermal decomposition properties of the prepared biocomposites have been characterized and analyzed. The processing recorder results of the LDPE/KCF biocomposites indicated that the stabilization torques and stabilization temperatures have increased with the addition of dolomite. Mechanical testing results showed that the presence of dolomite has increased the tensile stress, tensile modulus, and impact strength of the LDPE/KCF biocomposites. Thermogravimetric analysis results displayed that the thermal decomposition properties of the biocomposites have also increased with the increase of the dolomite content. This research led to the conclusion that the addition of dolomite in lower amounts (<20 wt.%) could act as a secondary filler for improving the processing, mechanical and thermal properties of LDPE/KCF biocomposites without surface treatments of the natural fiber. Ahmad Adlie Shamsuri, Mohammad Naqiuddin Mohd Zolkepli, Azmah Hanim Mohamed Ariff, Ahmad Khuzairi Sudari, and Mazni Abu Zarin Copyright © 2015 Ahmad Adlie Shamsuri et al. All rights reserved. Experimental Investigations into Abrasive Waterjet Machining of Carbon Fiber Reinforced Plastic Tue, 29 Sep 2015 06:37:23 +0000 Abrasive waterjet machining (AWJM) is an emerging machining process in which the material removal takes place due to abrasion. A stream of abrasive particles mixed with filtered water is subjected to the work surface with high velocity. The present study is focused on the experimental research and evaluation of the abrasive waterjet machining process in order to evaluate the technological factors affecting the machining quality of CFRP laminate using response surface methodology. The standoff distance, feed rate, and jet pressure were found to affect kerf taper, delamination, material removal rate, and surface roughness. The material related parameter, orientation of fiber, has been also found to affect the machining performance. The kerf taper was found to be 0.029 for 45° fiber orientation whereas it was 0.036 and 0.038 for 60° and 90°, respectively. The material removal rate is 18.95 mm3/sec for fiber orientation compared to 18.26 mm3/sec for 60° and 17.4 mm3/sec for 90° fiber orientation. The value for 45° fiber orientation is 4.911 µm and for 60° and 90° fiber orientation it is 4.927 µm and 4.974 µm, respectively. Delamination factor is found to be more for 45° fiber orientation, that is, 2.238, but for 60° and 90° it is 2.029 and 2.196, respectively. Prasad D. Unde, M. D. Gayakwad, N. G. Patil, R. S. Pawade, D. G. Thakur, and P. K. Brahmankar Copyright © 2015 Prasad D. Unde et al. All rights reserved. Unidirectional Cordenka Fibre-Reinforced Furan Resin Full Biocomposite: Properties and Influence of High Fibre Mass Fraction Wed, 09 Sep 2015 09:19:57 +0000 A full biocomposite was fabricated from Cordenka CR fibre and furan resin. High fibre mass fractions (FMF) were achieved by pressing the CR fibres into unidirectional sheets prior to incorporation into the resin. Results of testing indicated that the tensile properties of the biocomposite were improved by the initial increase of FMF from 51 to 64%, with a subsequent increase of FMF to 75% resulting in a deterioration of those properties. Examination of the tensile fracture surfaces with a scanning electron microscope (SEM) revealed moderate deterioration in fibre-matrix adhesion after the initial increase of FMF. Further increase of the FMF to 75% was shown by SEM to result in worse fibre-matrix adhesion. On the other hand, the flexural, interlaminar-shear, and dynamic mechanical properties were adversely affected by the increase in fibre-mass fraction from 51 through 75%. These effects were mainly attributed to reduced fibre wetting that resulted in weakened fibre-matrix interfacial bonding and subsequent poor stress exchange at the fibre-matrix interface. Observations made with a digital microscope revealed normal crack behaviour in the laminated composite, and the shear fracture modes were I and II. This biocomposite has mechanical properties comparable to those of flax and glass fibre-reinforced furan resin biocomposites. Talent Malaba and Jiajun Wang Copyright © 2015 Talent Malaba and Jiajun Wang. All rights reserved. Effect of Curing on the Tensile and Flexural Performance of Fully Biodegradable Corn Starch/Areca Frond Composites Mon, 17 Aug 2015 12:04:08 +0000 Composites have monopolized the automotive, construction, and packaging industry. Their high strength to weight ratio has made them an integral part of numerous engineering applications. In this study biodegradable matrix is combined with areca frond fibres for developing composites for low strength structural applications. Areca frond fibres were extracted and treated with sodium bicarbonate to improve the surface characteristics. Hand lay-up and compression moulding techniques were used to fabricate composites having unidirectional fibre orientation. The specimens prepared were exposed to varied environments, namely, sunlight, OTG oven, steam oven, and hot air oven, for curing and the results were analyzed to best suit the implicated requirements. Scanning electron microscopy was used to observe the changes in surface characteristics of the frond fibres after treatment. Tensile and flexural strength of starch based/areca frond reinforced composites were evaluated according to ASTM standards. Test results revealed that composites cured in a steam oven resulted in improved tensile and flexural strength compared to other curing environments. Srinivas Shenoy Heckadka, Suhas Yeshwant Nayak, Manjeshwar Vijaya Kini, Revati Chowgule, and Pranay Jain Copyright © 2015 Srinivas Shenoy Heckadka et al. All rights reserved. Corrigendum to “Agro-Residues: Surface Treatment and Characterization of Date Palm Tree Fiber as Composite Reinforcement” Wed, 15 Apr 2015 13:09:59 +0000 Mohamed S. Aly-Hassan, Elsayed A. Elbadry, and Hiroyuki Hamada Copyright © 2015 Mohamed S. Aly-Hassan et al. All rights reserved. Visualizing the Microdistribution of Zinc Borate in Oriented Strand Board Using X-Ray Microcomputed Tomography and SEM-EDX Sat, 28 Feb 2015 08:03:44 +0000 Oriented strand board (OSB) is an important wood composite used in situations where fungal decay and termite attack can occur. To counter these threats, powdered zinc borate biocide is commonly added to OSB. The effectiveness of biocides depends on their even distribution within composites and resistance to leaching, but little is known about the distribution of zinc borate in OSB. Zinc is denser than wood and it should be possible to map its distribution in OSB using X-ray micro-CT. We test this hypothesis and chemically register zinc in OSB using SEM-EDX. Zinc borate particles aggregated at the wood-adhesive interface in OSB, creating interrupted lines of zinc oriented in the x-y plane. Zinc borate particles were also found in the lumens of wood cells. Zinc was distributed throughout OSB, although slightly less was present in the core of the composite than in surface layers. A network of zinc remained in OSB after leaching in water. The resistance of zinc to leaching may be due to its incorporation in glue-lines within OSB, in addition to its low water-solubility. We conclude that X-ray micro-CT is a powerful tool for studying the distribution of zinc in OSB and other wood composites containing zinc borate. Philip D. Evans, Vinicius Lube, Holger Averdunk, Ajay Limaye, Michael Turner, Andrew Kingston, and Timothy J. Senden Copyright © 2015 Philip D. Evans et al. All rights reserved. Fabrication of Friction Stir Processed Al-Ni Particulate Composite and Its Impression Creep Behaviour Tue, 03 Feb 2015 11:55:00 +0000 Nickel powders were troweled on roughened Al base plate using a friction tool made from tool steel. Friction stir processing (FSP) was carried out using a load of 8 kN and with a tool rotation speed of 800 rpm and thus a surface composite was processed. Processed samples were characterized for revealing the microstructural features. SEM and XRD analysis revealed the presence of fine Ni particles in the stir zone which lead to a significant increase in hardness. Using the “refined energy model,” the maximum temperature developed within the processed zone was estimated and found to be around 275°C. Impression creep behaviour was assessed on both the base metal and processed zone at the temperature of 30, 100, and 200°C. Creep curves were generated and steady state creep rate (SSCR) values were found out to determine the activation energy. It is observed that friction stirred regions record higher creep rate values compared to the base metal. Estimated activation energy is in the range of 6 to 16 kJ/mol. Activation energy is marginally lower in the base metal compared to friction stir processed region. Prakrathi Sampath, Vineeth Krishna Parangodath, Kota Rajendra Udupa, and Udaya Bhat Kuruveri Copyright © 2015 Prakrathi Sampath et al. All rights reserved. Mechanical and Dielectric Behaviour of CaCu3Ti4O12 and Nb Doped CaCu3Ti4O12 Poly(vinylidene fluoride) Composites Sun, 14 Dec 2014 06:38:29 +0000 PVDF has been reinforced with different amount of CaCu3Ti4-5x/4NbxO12 with powder prepared by solid state ceramic method. Composites were prepared by melt extrusion method. Phase composition was studied using powder X-ray diffraction (XRD). Microstructural, dielectric, and mechanical properties have also been studied. These composites have Young’s modulus more than that of pure PVDF. Two dielectric relaxations, one at low frequency and the other at high frequency, have been observed in these composites. Dielectric relaxation at low frequencies is of Maxwell-Wagner type while the one observed at high frequency is due to hopping of electrons among different valent states of transition metal ions. Nature of dielectric relaxation has been analysed using H-N function. Anshuman Srivastava, Karun Kumar Jana, Pralay Maiti, Devendra Kumar, and Om Parkash Copyright © 2014 Anshuman Srivastava et al. All rights reserved. Agro-Residues: Surface Treatment and Characterization of Date Palm Tree Fiber as Composite Reinforcement Sun, 23 Nov 2014 07:58:21 +0000 The aims of this research are to investigate the effect of different surface treatment methods on the different properties of date palm fiber (DPF) compared to raw DPF fibers such as surface morphology, density, thermal stability, and tensile properties. The first surface treatment is called surface hand cleaning which can be carried out by cleaning the fibers by soft sand cloth; the second one is the same as the first one after DPF heat treatment in the furnace at 100°C for 1.5 h and the third one is by chemical treatment with 1% NaOH at 100°C for 1 h. The results showed that the mechanical performance of DPF was enhanced by the different treatments and the chemical treatment has pronounced effect on the behavior of DPF. Raw fibers showed the highest variability and presented the lowest value of Weibull modulus, whereas the fibers showed less variability by carrying out the different treatments. Moreover, using soda treatment cleans the fiber surface which causes fibrillation and therefore the tensile strength of the fibers increases. Elsayed A. Elbadry Copyright © 2014 Elsayed A. Elbadry. All rights reserved. Effect of Fiber Geometry and Representative Volume Element on Elastic and Thermal Properties of Unidirectional Fiber-Reinforced Composites Tue, 18 Nov 2014 10:20:07 +0000 The aim of present work is focused on the evaluation of elastic and thermal properties of unidirectional fiber-reinforced polymer composites with different volume fractions of fiber up to 0.7 using micromechanical approach. Two ways for calculating the material properties, that is, analytical and numerical approaches, were presented. In numerical approach, finite element analysis was used to evaluate the elastic modulus and thermal conductivity of composite from the constituent material properties. The finite element model based on three-dimensional micromechanical representative volume element (RVE) with a square and hexagonal packing geometry was implemented by using finite element code ANSYS. Circular cross section of fiber and square cross section of fiber were considered to develop RVE. The periodic boundary conditions are applied to the RVE to calculate elastic modulus of composite. The steady state heat transfer simulations were performed in thermal analysis to calculate thermal conductivity of composite. In analytical approach, the elastic modulus is calculated by rule of mixture, Halpin-Tsai model, and periodic microstructure. Thermal conductivity is calculated analytically by using rule of mixture, the Chawla model, and the Hashin model. The material properties obtained using finite element techniques were compared with different analytical methods and good agreement was achieved. The results are affected by a number of parameters such as volume fraction of the fibers, geometry of fiber, and RVE. Siva Bhaskara Rao Devireddy and Sandhyarani Biswas Copyright © 2014 Siva Bhaskara Rao Devireddy and Sandhyarani Biswas. All rights reserved. Generation of R-Curve from 4ENF Specimens: An Experimental Study Wed, 12 Nov 2014 12:06:00 +0000 The experimental determination of the resistance to delamination is very important in aerospace applications as composite materials have superior properties only in the fiber direction. To measure the interlaminar fracture toughness of composite materials, different kinds of specimens and experimental methods are available. This article examines the fracture energy of four-point end-notched flexure (4ENF) composite specimens made of carbon/epoxy and glass/epoxy. Experiments were conducted on these laminates and the mode II fracture energy, , was evaluated using compliance method and was compared with beam theory solution. The crack growth resistance curve (R-curve) for these specimens was generated and the found glass/epoxy shows higher toughness values than carbon/epoxy composite. From this study, it was observed that R-curve effect in 4ENF specimens is quite mild, which means that the measured delamination toughness, , is more accurate. V. Alfred Franklin and T. Christopher Copyright © 2014 V. Alfred Franklin and T. Christopher. All rights reserved. Interfacial Adhesion Characteristics of Kenaf Fibres Subjected to Different Polymer Matrices and Fibre Treatments Thu, 06 Nov 2014 07:50:00 +0000 This study is aimed at determining the interfacial adhesion strength (IAS) of kenaf fibres using different chemical treatments in hydrochloric (HCl) and sodium hydroxide (NaOH) with different concentrations. Single fibre pullout tests (SFPT) were carried out for both untreated and treated fibres partially embedded into three different polymer matrices; polyester, epoxy, and polyurethane (PU) as reinforcement blocks and tested under dry loading conditions. The study revealed that kenaf fibres treated with 6% NaOH subjected to polyester, epoxy, and PU matrices exhibits excellent IAS while poor in acidic treatment. The effect of SFPT results was mainly attributed to chemical composition of the fibres, types of fibre treatments, and variation in resin viscosities. By scanning electron microscopy examination of the material failure morphology, the fibres experienced brittle and ductile fibre breakage mechanisms after treatment with acidic and alkaline solutions. Umar Nirmal, Saijod T. W. Lau, and Jamil Hashim Copyright © 2014 Umar Nirmal et al. All rights reserved. Multiscale Modeling of Elastic Properties of Sustainable Concretes by Microstructural-Based Micromechanics Sun, 02 Nov 2014 12:49:41 +0000 This paper addresses multiscale stiffness homogenization methodology to extract macroscale elastic mechanical properties of four types of sustainable concretes from their nanoscale mechanical properties. Nine different sustainable concrete mixtures were studied. A model based on micromechanics was used to homogenize the elastic properties. The hardened cement pastes were homogenized by three analytical methods based on Self-Consistent and Mori-Tanaka schemes. The proposed multiscale method combines advanced experimental and analytical methods in a systematic way so that the inputs are nanoscale phases properties extracted from statistical nanoindentation technique and mechanical properties of mixture ingredient. Predicted elastic properties were consistent with traditional experimental results. Linking homogenized mechanical properties of sustainable concrete to volume proportions through an analytical approach provides a critical first step towards rational optimization of these materials. V. Zanjani Zadeh and C. P. Bobko Copyright © 2014 V. Zanjani Zadeh and C. P. Bobko. All rights reserved. Effect of Chitosan Loading on the Morphological, Thermal, and Mechanical Properties of Diglycidyl Ether of Bisphenol A/Hexamethylenediamine Epoxy System Thu, 30 Oct 2014 07:43:01 +0000 The effect of chitosan filled diglycidyl ether of bisphenol A (DGEBA) epoxy system were investigated using the thermal, mechanical, and morphological properties. The mixing ratio of resin/hardener was kept constant while the chitosan of 1.0, 2.5, 5.0, 7.5, and 10 weight percentage (wt%) was incorporated into the system. The thermal stability and the transition behaviour of the chitosan filled epoxy system were analysed through a differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and Fourier transform infrared spectroscopy (FTIR) while atomic force microscope (AFM) and scanning electron microscopy (SEM) were used to investigate the morphology. It was observed that the additive tends to agglomerate, with the formation of clear phase separation, when the chitosan content increases above 5 wt%. At lower chitosan loading (2.5 wt% and below), relatively uniform dispersion of the additive can be achieved. The thermal stability of the system increases with chitosan loading while the mechanical tensile strength is compromised. B. Satheesh, K. Y. Tshai, and N. A. Warrior Copyright © 2014 B. Satheesh et al. All rights reserved. High Strain Rate Compressive Behavior of Polyurethane Resin and Polyurethane/Al2O3 Hollow Sphere Syntactic Foams Wed, 29 Oct 2014 00:00:00 +0000 Polyurethane resins and foams are finding extensive applications. Seat cushions and covers in automobiles are examples of these materials. In the present work, hollow alumina particles are used as fillers in polyurethane resin to develop closed-cell syntactic foams. The fabricated syntactic foams are tested for compressive properties at quasistatic and high strain rates. Strain rate sensitivity is an important concern for automotive applications due to the possibility of crash at high speeds. Both the polyurethane resin and the syntactic foam show strain rate sensitivity in compressive strength. It is observed that the compressive strength increases with strain rate. The energy absorbed up to 10% strain in the quasistatic regime is 400% higher for the syntactic foam in comparison to that of neat resin at the same strain rate. Dung D. Luong, Vasanth Chakravarthy Shunmugasamy, Oliver M. Strbik III, and Nikhil Gupta Copyright © 2014 Dung D. Luong et al. All rights reserved. Synthesis, Characterization, and Photoconductivity Studies on Poly(2-chloroaniline) and Poly(2-chloroaniline)/CuO Nanocomposites Tue, 14 Oct 2014 10:57:46 +0000 The poly(2-chloroaniline) and poly(2-chloroaniline)/CuO nanocomposites with various weight percentages (5%, 10%, 15%, 20%, and 25%) were synthesized by in situ chemical oxidative polymerization method using ammonium per sulphate (oxidant), HCl (dopant), and dodecyl benzene sulphonic acid as a surfactant at 0°C. The formation of polymer and its composites was confirmed by FTIR and UV-Visible spectroscopy. The SEM and X-ray diffraction studies clearly indicate the uniform dispersion of CuO nanoparticles into the polymer matrix. The thermal stability of the polymer and its composites increased with increase in the percentage of CuO nanoparticles. The polymer and composites exhibit fluorescence property and hence can be used in the light emitting diodes. The current voltage (I-V) curves clearly illustrate the enhanced conductivity on light exposure compared to the dark current. The conductivity of the polymer increased with increase in the percentage of CuO nanoparticles. Poly(2-chloroaniline)/CuO nanocomposites with 25% of CuO show a maximum conductivity of  S cm−1. The composites synthesized behave as organic metals due to their semiconducting nature. Porselvi Linganathan, Jency Sundararajan, and Jhancy Mary Samuel Copyright © 2014 Porselvi Linganathan et al. All rights reserved. Hybrid Fibre Polylactide Acid Composite with Empty Fruit Bunch: Chopped Glass Strands Tue, 14 Oct 2014 09:38:39 +0000 Hybrid polylactide acid (PLA) composites reinforced with palm empty fruit bunch (EFB) and chopped strand E-glass (GLS) fibres were investigated. The hybrid fibres PLA composite was prepared through solution casting followed by pelletisation and subsequent hot compression press into 1 mm thick specimen. Chloroform and dichloromethane were used as solvent and their effectiveness in dissolving PLA was reported. The overall fibre loading was kept constant at volume fraction, , of 20% while the ratio of EFB to GLS fibre was varied between of 0 : 20 to 20 : 0. The inclusion of GLS fibres improved the tensile and flexural performance of the hybrid composites, but increasing the glass fibre length from 3 to 6 mm has a negative effect on the mechanical properties of the hybrid composites. Moreover, the composites that were prepared using chloroform showed superior tensile and flexural properties compared to those prepared with dichloromethane. K. Y. Tshai, A. B. Chai, I. Kong, M. E. Hoque, and K. H. Tshai Copyright © 2014 K. Y. Tshai et al. All rights reserved. Sintering and Hardness Behavior of Fe-Al2O3 Metal Matrix Nanocomposites Prepared by Powder Metallurgy Wed, 10 Sep 2014 05:19:57 +0000 The present paper reports the investigations on sintering and hardness behavior of Fe-Al2O3 Metal Matrix Nanocomposites (MMNCs) prepared by Powder Metallurgy (P/M) route with varying concentration of Al2O3 (5–30 wt%). The MMNC specimens for the present investigations were synthesized by ball milling, followed by compaction and sintering in an inert atmosphere in the temperature range of 900–1100°C for 1–3 hours using Powder Metallurgy route. Phase and microstructures of the specimens were characterized by XRD and SEM. Reactive sintering takes place in these materials. During sintering nano iron aluminate (FeAl2O4) phase forms. Characterization was done by measuring density and hardness. Results have been discussed critically to illustrate the effect of various processing parameters on sintering and mechanical behavior. It is expected that the results of these investigations will be useful in developing Metal Matrix Nanocomposites (MMNCs) for typical industrial applications. Pallav Gupta, Devendra Kumar, Om Parkash, and A. K. Jha Copyright © 2014 Pallav Gupta et al. All rights reserved. Baseline Moisture Resistance of PWP Cement Composite Boards Reinforced with Internal Glass Fiber Reinforcement under Accelerated Wet-Dry Aging Tue, 05 Aug 2014 12:30:41 +0000 The purpose of this study was to improve the mechanical characteristics and moisture resistance of parawood particle (PWP) cement composite board developed by the authors. PWP cement composites were prepared with a mixture containing 15.0% parawood particles, 43.0% cement, 41.2% water, and 0.86% CaCl2 (by weight) and the PWP cement composite boards were internally reinforced with bidirectional glass fiber woven roving [0°/90°]. The board properties were evaluated under accelerated aging with wet-dry cycles to establish the durability and moisture resistance and the effect on flexural strength of the composite boards. The mechanical characteristics determined were the equivalent modulus of rupture (eMOR), the equivalent modulus of elasticity (eMOE), and the deformability factor (DF). The experimental results suggest that the strength and stiffness of the PWP composite boards with internal reinforcement are four times higher than those of the original PWP composite boards under accelerated aging based on 100 wet-dry cycles, implying better durability of the boards in outdoor use. The results provide a baseline to which improved formulations and reinforcements or designs can be compared using the same measurement methodology. Woraphot Prachasaree, Sitthichai Piriyakootorn, Suchart Limkatanyu, and Abideng Hawa Copyright © 2014 Woraphot Prachasaree et al. All rights reserved. The Shifts of Band Gap and Binding Energies of Titania/Hydroxyapatite Material Thu, 10 Jul 2014 08:40:31 +0000 The titania/hydroxyapatite (TiO2/HAp) product was prepared by precipitating hydroxyapatite in the presence of TiO(OH)2 gel in the hydrothermal system. The characteristics of the material were determined by using the measurements such as X-ray photoemission spectroscopy (XPS), X-ray diffraction (XRD), diffuse reflectance spectra (DRS), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and energy dispersive X-ray (EDX). The XPS analysis showed that the binding energy values of Ca (2p1/2, 2p3/2), P (2p1/2, 2p3/2), and O 1s levels related to hydroxyapatite phase whereas those of Ti (2p3/2, 2p1/2) levels corresponded with the characterization of titanium (IV) in TiO2. The XRD result revealed that TiO2/HAp sample had hydroxyapatite phase, but anatase or rutile phases were not found out. TEM image of TiO2/HAp product showed that the surface of the plate-shaped HAp particles had a lot of smaller particles which were considered as the compound of Ti. The experimental band gap of TiO2/HAp material calculated by the DRS measurement was 3.6 eV, while that of HAp pure was 5.3 eV and that of TiO2 pure was around 3.2 eV. The shift of the band gap energy of TiO2 in the range of 3.2–3.6 eV may be related to the shifts of Ti signals of XPS spectrum. Nguyen Thi Truc Linh, Phan Dinh Tuan, and Nguyen Van Dzung Copyright © 2014 Nguyen Thi Truc Linh et al. All rights reserved. Multifunctional Thermally Remendable Nanocomposites Mon, 07 Jul 2014 12:26:57 +0000 Challenges associated with damage tolerance in polymer matrix composites must be successfully addressed in order to ensure highly reliable structures with significant weight savings. Self-healing materials provide a viable means to surmount damage tolerance concerns, thereby allowing for the realization of the mass reduction such structures have promised but not yet achieved. Introduction of multifunctional properties into self-healing composites can further extend their usefulness. This study examines the incorporation of carbon nanotubes into a self-healing composite in order to achieve this. Composite panels were fabricated with carbon fibers, a bismaleimide tetrafuran (2MEP4F) polymer resin, and various carbon nanotube materials. The composites exhibit enhancement in electrical, mechanical, and thermal properties. The healing mechanism is a thermally activated reversible polymerization of the 2MEP4F resin. The proposed method of heating exploits the enhanced microwave absorption inherent to carbon nanotubes to provide the thermal energy required for the reversible polymerization. Microwave testing demonstrated that the heating efficiency is increased, allowing uniform heating to the required temperature for polymer healing. Impacted composites show localized heating at the damage site, which implies that microwave heating can also be used as a means for damage detection and potential structural health monitoring. Edward D. Sosa, Thomas K. Darlington, Brian A. Hanos, and Mary Jane E. O’Rourke Copyright © 2014 Edward D. Sosa et al. All rights reserved.