Search results for: extrusion blow molding

Authors: Bhrugesh Radadiya, Jaydeep Shah

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In Indian foundry industry, there is a need of defect free casting with minimum production cost in short lead time. Casting defect is a very large issue in foundry shop which increases the rejection rate of casting and wastage of materials. The various parameters influences on casting process such as mold machine related parameters, green sand related parameters, cast metal related parameters, mold related parameters and shake out related parameters. The mold related parameters are most influences on casting defects in sand casting process. This paper review the casting produced by foundry with shrinkage and blow holes as a major defects was analyzed and identified that mold related parameters such as mold temperature, pouring temperature and runner size were not properly set in sand casting process. These parameters were optimized using different optimization techniques such as Taguchi method, Response surface methodology, Genetic algorithm and Teaching-learning based optimization algorithm. Finally, concluded that a Teaching-learning based optimization algorithm give better result than other optimization techniques.

Keywords: casting defects, genetic algorithm, parametric optimization, Taguchi method, TLBO algorithm

Procedia PDF Downloads 702

Authors: Fauzi Jarushi, Paul Cosentino, Edward Kalajian, Hadeel Dekhn

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At certain depths during large diameter displacement pile driving, rebound well over 0.25 inches was experienced, followed by a small permanent set during each hammer blow. High pile rebound (HPR) soils may stop the pile driving and results in a limited pile capacity. In some cases, rebound leads to pile damage, delaying the construction project, and the requiring foundations redesign. HPR was evaluated at seven Florida sites, during driving of square precast, prestressed concrete piles driven into saturated, fine silty to clayey sands and sandy clays. Pile Driving Analyzer (PDA) deflection versus time data recorded during installation, was used to develop correlations between cone penetrometer (CPT) pore-water pressures, pile displacements and rebound. At five sites where piles experienced excessive HPR with minimal set, the pore pressure yielded very high positive values of greater than 20 tsf. However, at the site where the pile rebounded, followed by an acceptable permanent set, the measured pore pressure ranged between 5 and 20 tsf. The pore pressure exhibited values of less than 5 tsf at the site where no rebound was noticed. In summary, direct correlations between CPTu pore pressure and rebound were produced, allowing identification of soils that produce HPR.

Keywords: CPTU, pore water pressure, pile rebound

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Authors: S. Talebnezhad, S. Pourmahdian, D. Soudbar, M. Khosravani, J. Merasi

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Adding toughened polypropylene and plastomer in FFS 3 layered blown film formulation resulted in superior dart impact and MD tear resistance along with acceptable tensile properties in TD and MD. The optimum loading of toughened polypropylene and plastomer in each layer depends on miscibility of polypropylene in polyethylene medium, mechanical properties, welding characteristics in bags top and bottoms and friction coefficient of film surfaces. Film property tests and efficiency of FFS machinery during processing in industrial scale showed that about 4% loading of plastomer and 16% of toughened polypropylene (reactor grade) in middle layer and loading of 0-1% plastomer and 5-19% of toughened polypropylene in other layers results optimum characteristics in the formulation based on 1-butene LLDPE grade with MFR of 0.9 and LDPE grade with MFI of 0.3. Both the plastomer and toughened polypropylene had the MFI of blow 1 and the TiO2 and processing aid masterbatches loading was 2%. The friction coefficient test results also represented the anti-block masterbatch could be omitted from formulation with adding toughened polypropylene due to partial miscibility of PP in PE which makes the surface of films somewhat bristly.

Keywords: FFS 3 layered blown film, toughened polypropylene, plastomer, dart impact, tear resistance

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Authors: Dandi Bachtiar, Mohammed Ausama Abbas, Januar Parlaungan Siregar, Mohd Ruzaimi Bin Mat Rejab

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Short sugar palm fibre and thermoplastic polyurethane were combined to produce new composites by using the extrude method. Two techniques used to prepare a new composite material, firstly, extrusion of the base material with short fibre, secondly hot pressing them. The size of sugar palm fibre was fixed at 250µm. Different weight percent (10 wt%, 20 wt% and 30 wt%) were used in order to optimise preparation process. The optimization of process depended on the characterization mechanical properties such as impact, tensile, and flexural of the new (TPU/SPF) composite material. The results proved that best tensile and impact properties of weight additive fibre applied 10 wt%. There was an increasing trend recorded of flexural properties during increased the fibre loading. Meanwhile, the maximum tensile strength was 14.0 MPa at 10 wt% of the fibre. Moreover, there was no significant effect for additions more than 30 wt% of the fibre.

Keywords: composites, natural fibre, polyurethane, sugar palm

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Authors: Nisrin R. Abdelal, Steven L. Donaldson

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Composite materials are widely used in aviation industry due to their superior properties; however, they are susceptible to delamination. Through-thickness stitching is one of the techniques to alleviate delamination. Kevlar is one of the most common stitching materials; in contrast, it is expensive and presents stitching fabrication challenges. Therefore, this study compares the performance of Kevlar with an inexpensive and easy-to-use nylon fiber in stitching to alleviate delamination. Three laminates of unidirectional carbon fiber-epoxy composites were manufactured using vacuum assisted resin transfer molding process. One panel was stitched with Kevlar, one with nylon, and one unstitched. Mode I interlaminar fracture tests were carried out on specimens from the three composite laminates, and the results were compared. Fractographic analysis using optical and scanning electron microscope were conducted to reveal the differences between stitching with Kevlar and nylon on the internal microstructure of the composite with respect to the interlaminar fracture toughness values.

Keywords: carbon, delamination, Kevlar, mode I, nylon, stitching

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Authors: Ariangelo Hauer Dias Filho, Gustavo Antoniácomi de Carvalho, Benjamim de Melo Carvalho

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The work´s purpose was to evaluate the possibility of manufacturing casting tools utilizing Fused Filament Fabrication, a 3D printing technique, without any post-processing on the printed part. Taguchi Orthogonal array was used to evaluate the influence of extrusion temperature, bed temperature, layer height, and infill on the dimensional accuracy of a 3D-Printed Polymer Model. A Zeiss T-SCAN CS 3D Scanner was used for dimensional evaluation of the printed parts within the limit of ±0,2 mm. The mold capabilities were tested with the printed model to check how it would interact with the green sand. With little adjustments in the 3D model, it was possible to produce rapid tools without the need for post-processing for iron casting. The results are important for reducing time and cost in the development of such tools.

Keywords: additive manufacturing, Taguchi method, rapid tooling, fused filament fabrication, casting mold

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Authors: Habib Shaban

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Nanocomposites of isotactic polypropylene (iPP) and date wood fiber were prepared after modification of the host matrix by reactive extrusion grafting of maleic anhydride. Chemical and mechanical treatment of date wood flour (WF) was conducted to obtain nanocrystalline cellulose. Layered silicates (clay) were partially intercalated with date wood fiber, and the modified layered silicate was used as filler in the PP matrix via a melt-blending process. The tensile strength of composites prepared from wood fiber modified clay was greater than that of the iPP-clay and iPP-WF composites at a 6% filler concentration, whereas deterioration of mechanical properties was observed when clay and WF were used alone for reinforcement. The dispersion of the filler in the matrix significantly decreased after clay modification with cellulose at higher concentrations, as shown by X-ray diffraction (XRD) data.

Keywords: nanocomposites, isotactic polypropylene, date wood flour, intercalated, melt-blending

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Authors: Nouri, K., Ghassem Alaskari, M., K., Amiri Hazaveh, A., Nabi Bidhendi, M.

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Pore pressure is one on the key Petrophysical parameter in exploration discussion and survey on hydrocarbon reservoir. Determination of pore pressure in various levels of drilling and integrity of drilling mud and high pressure zones in order to restrict blow-out and following damages are significant. The pore pressure is obtained by seismic and well logging data. In this study the pore pressure and over burden pressure through the matrix stress and Tarzaqi equation and other related formulas are calculated. By making a comparison on variation of density log in over normal pressure zones with change of sonic impedance under influence of compressional, shear, and Stonely waves, the correlation level of sonic impedance with density log is studied. The level of correlation and variation trend is recorded in sonic impedance under influence Stonely wave with density log that key factor in recording of over burden pressure and pore pressure in Tarzaqi equation is high. The transition time is in divert relation with porosity and fluid type in the formation and as a consequence to the pore pressure. The density log is a key factor in determination of pore pressure therefore sonic impedance under Stonley wave is denotes well the identification of high pressure besides other used factors.

Keywords: pore pressure, stonely wave, density log, sonic impedance, high pressure zone

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Authors: D. Sersab, M. Aberkane

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Residual stresses, in high-density polyethylene (HDPE) pipes, result from a nonhomogeneous cooling rate that occurs between the inner and outer surfaces during the extrusion process in manufacture. Most known methods of measurements to determine the magnitude and profile of the residual stresses in the pipe wall thickness are layer removal and ring slitting method. The combined layer removal and ring slitting methods described in this paper involves measurement of the circumferential residual stresses with minimal local disturbance. The existing methods used for pipe geometry (ring slitting method) gives a single residual stress value at the bore. The layer removal method which is used more in flat plate specimen is implemented with ring slitting method. The method permits stress measurements to be made directly at different depth in the pipe wall and a well-defined residual stress profile was consequently obtained.

Keywords: residual stress, layer removal, ring splitting, HDPE, wall thickness

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Authors: Luiz C. G. Pennafort Jr., Alexandre de S. Rios, Enio P. de Deus

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In the search for materials that replace conventional polymers in order to preserve natural resources, combined with the need to minimize the problems arising from environmental pollution generated by plastic waste, comes the recycled materials biodegradable, especially the composites reinforced with natural fibers. However, such materials exhibit properties little known, requiring studies of manufacturing methods and characterization of these composites. This article shows informations about preparation and characterization of a composite produced by extrusion, which consists of recycled PVC derived from the recycling of materials discarded, added of the micronized coconut fiber. The recycled PVC with 5% of micronized fiber were characterized by X-ray diffraction, thermogravimetric, differential scanning calorimetry, mechanical analysis and optical microscopy. The use of fiber in the composite caused a decrease in its specific weight, due to the lower specific weight of fibers and the appearance of porosity, in addition to the decrease of mechanical properties.

Keywords: recycled PVC, coconut fiber, characterization, composites

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Authors: Armin Najipour, A. M. Fattahi

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The aim of this research was to investigate the effect of the addition of multi walled carbon nanotubes on the mechanical properties of polyethylene/carbon nanotube nanocomposites. To do so, polyethylene and carbon nanotube were mixed in different weight percentages containing 0, 0.5, 1, and 1.5% carbon nanotube in two screw extruder apparatus by fusion. Then the nanocomposite samples were molded in injection apparatus according to ASTM: D6110 standard. The effects of carbon nanotube addition in 4 different levels and injection pressure in 2 levels on the hardness and impact strength of the nanocomposite samples were investigated. The results showed that the addition of carbon nanotube had a significant effect on improving hardness and impact strength of the nanocomposite samples such that by adding 1% w/w carbon nanotube, the impact strength and hardness of the samples improved to 74% and 46.7% respectively. Also, according to the results, the effect of injection pressure on the results was much less than that of carbon nanotube weight percentage.

Keywords: carbon nanotube, injection molding, mechanical properties, nanocomposite, polyethylene

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Authors: Yagnik Patel

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This paper will analyze and explain two main objectives. First, it will examine the emergence of the insurgency in the state of Tripura. The State of Tripura was facing the full blow of insurgency problem since 1978 after the formation of Tripura National Volunteers (TNV). But, the roots of this insurgency were found even before 1978. This study will analyze the roots and trajectory of insurgency in the Tripura. Second, it will examine the role played by the police in counterinsurgency in the State of Tripura. Even though state police are mandated for the maintenance of the law and order and public order (like every police), the state police of Tripura have played a significant role in curbing the insurgency by enhancing their counterinsurgency (COIN) capabilities and re-structuring the new comprehensive COIN doctrine. And by the end of May 2015, the State Government has lifted The Armed Forces (Special Powers) Act (AFSPA) from the State of Tripura, as declaiming of the violence. The fight against the insurgency, usually done by the military or para-military, but nowadays the police organization is also becoming a vital state apparatus. After Punjab police and Andhra Pradesh police, Tripura police have also successfully curbed the insurgency from the state. This was the third time when successful counterinsurgency did by the state police in India. This has shown the importance of the police in the fight against the insurgency. In this regard, this paper will use both quantitative and qualitative research methods for an explanatory case study to analyze and explain the roots, causes and the trajectory of insurgency in the state of Tripura and the role played by the police in COIN in Tripura. Along with this, the paper will also examine the successful ‘Police Model of Tripura’.

Keywords: counterinsurgency, insurgency, police, Tripura state rifles

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Authors: Parsa Sheikhzadeh

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Polar bodies are cells that form by oogenesis in meiosis which differentiate and develop from oocytes. Although in many animals, these cells often die following meiotic maturation of the oocyte. Oocyte activation is during mammalian fertilization, sperm is fused with the oocyte's membrane, triggering the resumption of meiosis from the metaphase II arrest, the extrusion of the second polar body, and the exocytosis of cortical granules. The origin recognition complex proteins 4 (ORC4) forms a cage around the set of chromosomes that will be extruded during polar body formation before it binds to the chromatin shortly before zygotic DNA replication. One unique feature of the female gamete is that the polar bodies can provide beneficial information about the genetic background of the oocyte without potentially destroying it. Testing at the polar body (PB) stage was the least accurate, mainly due to the high incidence of post-zygotic events. On the other hand, the results from PB1-MII oocyte pair validated that PB1 contains nearly the same methylome (average Pearson correlation is 0.92) with sibling MII oocyte. In this article, we comprehensively examine the role of polar bodies in female human gametes.

Keywords: polar bodies, ORC4, oocyte, genetic, methylome, gamete, female

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Authors: S. M. A. Al-Qawabah, A. I. O. Zaid

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Aluminum and its alloys are versatile materials which are widely used in industrial and engineering applications due to their good and useful properties e.g. high strength to weight ratio, high thermal and electrical conductivities and good resistance to corrosion. However, against these favorable properties they have the disadvantage they solidifying large grain columnar structure which negatively affects their mechanical properties and surface quality. Aluminum alloys are normally grain refined by some alloying elements, such as Ti, Ti-B or Zr. In this paper, the effect of zirconium addition to Al grain refined by Ti after extrusion on its wear resistance is investigated under different loads and sliding speeds namely at 5,10 and 20 N loads and sliding speeds ranging from m/min. and m/min. the results are presented in three-dimensional wear mode. To the best the authors' knowledge, the wear of aluminum in 3-dimensions has never been tackled before. In this work, the wear resistance of by presenting the results of wear are presented and discussed on the time, load and speed plots.

Keywords: aluminum grain refined, addition of titanium, wear resistance, titanium

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Authors: Kuen-Ming Shu, Jyun-Wei Chen

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Encapsulated O-rings are specifically designed to address the problem of sealing the most hostile chemicals and extreme temperature applications. Ultrasonic vibration hot embossing and ultrasonic welding techniques provide a fast and reliable method to fabricate encapsulated O-ring. This paper performs the design and analysis method of the acoustic horns with double extrusion to process tube double side flange simultaneously. The paper deals with study through Finite Element Method (FEM) of ultrasonic stepped horn used to process a capsulated O-ring, the theoretical dimensions of horns, and their natural frequencies and amplitudes are obtained through the simulations of COMOSOL software. Furthermore, real horns were fabricated, tested and verified to proof the practical utility of these horns.

Keywords: encapsulated O-rings, ultrasonic vibration hot embossing, flange making, acoustic horn, finite element analysis

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Authors: L. Nouri Taiba, Y. Bouhamidi, F. Kaouah, Z. Bendjama, M. Trari

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In the present study, an ecofriendly biocomposite namely calcium alginate immobilized Ammi Visnaga (Khella) extraction waste (SWAV/CA) was prepared by electrostatic extrusion method and used on the cadmium biosorption from aqueous phase with and without the assistance of ultrasound in batch conditions. The influence of low frequency ultrasound (37 and 80 KHz) on the cadmium biosorption kinetics was studied. The obtained results show that the ultrasonic irradiation significantly enhances and improves the efficiency of the cadmium removal. The Pseudo first order, Pseudo-second-order, Intraparticle diffusion, and Elovich models were evaluated using the non-linear curve fitting analysis method. Modeling of kinetic results shows that biosorption process is best described by the pseudo-second order and Elovich, in both the absence and presence of ultrasound.

Keywords: biocomposite, biosorption, cadmium, non-linear analysis, ultrasound

Procedia PDF Downloads 251

Authors: Armin Najipour, A. M. Fattahi

Abstract:

The aim of this research was to investigate the effect of the addition of multi walled carbon nanotubes on the mechanical properties of polyethylene/carbon nanotube nanocomposites. To do so, polyethylene and carbon nanotube were mixed in different weight percentages containing 0, 0.5, 1, and 1.5% carbon nanotube in two screw extruder apparatus by fusion. Then the nanocomposite samples were molded in injection apparatus according to ASTM:D638 standard. The effects of carbon nanotube addition in 4 different levels on the tensile strength, elastic modulus and elongation of the nanocomposite samples were investigated. The results showed that the addition of carbon nanotube had a significant effect on improving tensile strength of the nanocomposite samples such that by adding 1% w/w carbon nanotube, the tensile strength 23.4%,elastic modulus 60.4%and elongation 29.7% of the samples improved. Also, according to the results, Manera approximation model at percentages about 0.5% weight and modified Halpin-Tsai at percentages about 1% weight lead to favorite and reliable results.

Keywords: carbon nanotube, injection molding, Mechanical properties, Nanocomposite, polyethylene

Procedia PDF Downloads 237

Authors: Sehijpal Singh Khangura, Jai Inder Preet Singh, Vikas Dhawan

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Global warming, growing awareness of the environment, waste management issues, dwindling fossil resources, and rising oil prices resulted to increase the research in the materials that are friendly to our health and environment. Due to these reasons, green products are increasingly being promoted for sustainable development. In this work, fully biodegradable green composites have been developed using jute fibers as reinforcement and poly lactic acid as matrix material by film stacking technique. The effect of curing temperature during development of composites ranging from 160 °C, 170 °C, 180 °C and 190 °C was investigated for various mechanical properties. Results obtained from various tests indicate that impact strength decreases with an increase in curing temperature, but tensile and flexural strength increases till 180 °C, thereafter both the properties decrease. This study gives an optimum curing temperature for the development of jute/PLA composites.

Keywords: natural fibers, polymer matrix composites, jute, compression molding, biodegradation

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Authors: Kebin Li, Keith Morton, Matthew Shiu, Karine Turcotte, Luke Lukic, Teodor Veres

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We present a normally closed thermoplastic microfluidic valve design that uses microstructured valve seats to locally prevent the membrane from bonding to the valve seat during microfluidic channel sealing. The microstructured valve seat reduces the adhesion force between the contact surfaces of the valve seat and the membrane locally, allowing valve open and close operations while simultaneously providing a permanent and robust bond elsewhere to cover and seal the microfluidic channel network. Dynamic valve operation including opening and closing times can be tuned by changing the valve seat diameter as well as the density of the microstructures on the valve seats. The influence of the microstructured valve seat on the general flow behavior through the microfluidic devices was also studied. A design window for the fabrication of valve structure is identified and discussed to minimize the fabrication complexity.

Keywords: hot-embossing, injection molding, microfabrication, microfluidics, microvalves, thermoplastic elastomer

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Authors: Pemika Ketsuwan, Pitt Supaphol, Manit Nithitanakul

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A typical used of ethylene methyl acrylate (EMA) gasket is in the manufacture of optical lens, and often, they are deteriorated rapidly due to high temperature during the process. The objective of this project is to improve the thermal stability of the EMA copolymer gasket by preparing EMA with cellulose and silica composites. Hydroxy propyl methyl cellulose (HPMC) and Carboxy methyl cellulose (CMC) were used in preparing of EMA/cellulose composites and fumed silica (SiO2) was used in preparing EMA/silica composites with different amounts of filler (3, 5, 7, 10, 15 wt.%), using a twin screw extruder at 160 °C and the test specimens were prepared by the injection molding machine. The morphology and dispersion of fillers in the EMA matrix were investigated by field emission scanning electron microscopy (FESEM). The thermal stability of the composite was determined by thermal gravimetric analysis (TGA), and differential scanning calorimeter (DSC). Mechanical properties were evaluated by tensile testing. The developed composites were found to enhance thermal and mechanical properties when compared to that of the EMA copolymer alone.

Keywords: ethylene methyl acrylate, HPMC, Silica, Thermal stability

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Authors: Parisa Amouzgar, Chan Eng Seng, Babak Salamatinia

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Pharmaceutical products are being increasingly detected in the environment. However, conventional treatment systems do not provide an adequate treatment for pharmaceutical drug elimination and still there is not a regulated standard for their limitation in water. Since decades before, pharmaceuticals have been in the water but only recently, their levels in the environment have been recognized and quantified as potentially hazardous to ecosystems. In this study chitosan with a bio-based NAC (Ct-NAC) were made as beads with extrusion dripping method and investigated for acetaminophen removal from water. The effects of beading parameters such as flow rate in dripping, the distance from dipping tip to the solution surface, concentration of chitosan and percentage of NAC were analyzed to find the optimum condition. Based on the results, the overall adsorption rate and removal efficiency increased during the time till the equilibrium rate which was 80% removal of acetaminophen. The maximum adsorption belonged to the beads with 1.75% chitosan, 60% NAC, flow-rate of 1.5 ml/min while the distance of dripping was 22.5 cm.

Keywords: pharmaceuticals, water treatment, chitosan nano activated carbon beads, Acetaminophen

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Authors: R. R. Ali, W. A. W. A. Rahman, R. M. Kasmani, H. Hasbullah, N. Ibrahim, A. N. Sadikin, U. A. Asli

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In this study, tapioca starch which acts as natural polymer was added in the blend in order to produce biodegradable product. Low density polyethylene (LDPE) and tapioca starch blends were prepared by extrusion and the test sample by injection moulding process. Ethylene vinyl acetate (EVA) acts as compatibilizer while glycerol as processing aid was added in the blend. The blends were characterized by using melt flow index (MFI), fourier transform infrared (FTIR) and the effects of water absorption to the sample. As the starch content increased, MFI of the blend was decreased. Tensile testing were conducted shows the tensile strength and elongation at break decreased while the modulus increased as the starch increased. For the biodegradation, soil burial test was conducted and the loss in weight was studied as the starch content increased. Morphology studies were conducted in order to show the distribution between LDPE and starch.

Keywords: biopolymers, degradable polymers, starch based polyethylene, injection moulding

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Authors: Mohammed H. Rady, Mohd Sukri Mustapa, S Shamsudin, M. A. Lajis, A. Wagiman

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The present study is aimed at investigating microhardness and density of aluminium alloy chips when subjected to various settings of preheating temperature and preheating time. Three values of preheating temperature were taken as 450 °C, 500 °C, and 550 °C. On the other hand, three values of preheating time were chosen (1, 2, 3) hours. The influences of the process parameters (preheating temperature and time) were analyzed using Design of Experiments (DOE) approach whereby full factorial design with center point analysis was adopted. The total runs were 11 and they comprise of two factors of full factorial design with 3 center points. The responses were microhardness and density. The results showed that the density and microhardness increased with decreasing the preheating temperature. The results also found that the preheating temperature is more important to be controlled rather than the preheating time in microhardness analysis while both the preheating temperature and preheating time are important in density analysis. It can be concluded that setting temperature at 450 °C for 1 hour resulted in the optimum responses.

Keywords: AA6061, density, DOE, hot extrusion, microhardness

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Authors: A. Hamma, A. Pegoretti

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The paper focuses on the evaluation of mechanical performances and viscoelastic behaviour of starch-grafted-PP reinforced with kenaf fibres. Investigations were carried out on composites prepared by melt compounding and compression molding. Two aspects have been taken into account, the effects of various fibres loading rates (10, 20 and 30 wt.%) and the fibres aspect ratios (L/D=30 and 160). Good fibres/matrix interaction has been evidenced by SEM observations. However, processing induced variation of fibre length quantified by optical microscopy observations. Tensile modulus and ultimate properties, hardness and tensile impact stress, were found to remarkably increase with fibre loading. Moreover, short term tensile creep tests have proven that kenaf fibres improved considerably the creep stability. Modelling of creep behaviour by a four parameter Burger model was successfully used. An empirical equation involving Halpin-Tsai semi empirical model was also used to predict the elastic modulus of composites.

Keywords: mechanical properties, creep, fibres, thermoplastic composites, starch-grafted-PP

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Authors: Fatemeh Sadat Miri, Morteza Ehsani, Seyed Farshid Hosseini

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The present research is concerned with the optimization of extrusion parameters of ABS sheets by the Taguchi experimental design method. In this design method, three parameters of % recycling ABS, processing temperature and degassing time on mechanical properties, hardness, HDT, and color matching of ABS sheets were investigated. The variations of this research are the dosage of recycling ABS, processing temperature, and degassing time. According to experimental test data, the highest level of tensile strength and HDT belongs to the sample with 5% recycling ABS, processing temperature of 230°C, and degassing time of 3 hours. Additionally, the minimum level of MFI and color matching belongs to this sample, too. The present results are in good agreement with the Taguchi method. Based on the outcomes of the Taguchi design method, degassing time has the most effect on the mechanical properties of ABS sheets.

Keywords: ABS, process optimization, Taguchi, mechanical properties

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Authors: Anil Kawan, Soon Jae Yu, Jong Min Park

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GaN-based 365 nm wavelength ultraviolet (UV) light emitting diodes (LED) have various applications: curing, molding, purification, deodorization, and disinfection etc. However, their usage is limited by very low output power, because of the light absorption in the GaN layers. In this study, we demonstrate a method utilizing removal of 365 nm absorption layer buffer GaN and thinning the n-type GaN so as to improve the light extraction efficiency of the GaN-based 365 nm UV LED. The UV flip chip LEDs of chip size 1.3 mm x 1.3 mm were fabricated using GaN epilayers on a sapphire substrate. Via-hole n-type contacts and highly reflective Ag metal were used for efficient light extraction. LED wafer was aligned and bonded to AlN carrier wafer. To improve the extraction efficiency of the flip chip LED, sapphire substrate and absorption layer buffer GaN were removed by using laser lift-off and dry etching, respectively. To further increase the extraction efficiency of the LED, exposed n-type GaN thickness was reduced by using inductively coupled plasma etching.

Keywords: extraction efficiency, light emitting diodes, n-GaN thinning, ultraviolet

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Authors: Pattamaphorn Phuangngamphan, Rewadee Anuwattana, Narumon Soparatana, Nestchanok Yongpraderm, Atiporn Jinpayoon, Supinya Sutthima, Saroj Klangkongsub, Worapong Pattayawan

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This research aims to utilize the agricultural waste and plastic waste in Thailand in a study of the optimum conditions for preparing composite materials from water hyacinth and oil palm fiber and plastic waste in landfills. The water hyacinth and oil palm fiber were prepared by alkaline treatment with NaOH (5, 15 wt%) at 25-60 °C for 1 h. The treated fiber (5 and 10 phr) was applied to plastic waste composite. The composite was prepared by using a screw extrusion process from 185 °C to 200 °C with a screw speed of 60 rpm. The result confirmed that alkaline treatment can remove lignin, hemicellulose and other impurities on the fiber surface and also increase the cellulose content. The optimum condition of composite material is 10 phr of fiber coupling with 3 wt% PE-g-MA as compatibilizer. The composite of plastic waste and oil palm fiber has good adhesion between fiber and plastic matrix. The PE-g-MA has improved fiber-plastic interaction. The results suggested that the composite material from plastic waste and agricultural waste has the potential to be used as value-added products.

Keywords: agricultural waste, waste utilization, biomaterials, cellulose fiber, composite material

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Authors: Ashgar Ali Ali Mohamed, Farheen Baig Sardar Baig

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In Malaysia, the Whistle-blower Protection Act 2010 provides protection to a person in an organization who exposes misconduct, alleged dishonest or illegal activity that violates the existing laws, among others. For example, alleged fraud, health and safety violations, and corruption, to name but a few. Undeniable, most whistle-blowers are internal to an organisation who report misconduct of a fellow employee or superior within their company and they frequently face reprisal at the hands of the organisation which they have accused. In fact, many people do not consider blowing the whistle because of fear of retaliation and losing their relationships at workplace. Although whistle-blowers are protected under law from employer retaliation, there have been many cases where punishment for whistleblowing has occurred, such as suspension, demotion, termination, or harsh mistreatment by other employees. Hence, this paper will analyse the adequacy of the legal protection available to employees who whistle-blow on their employers with reference to the Whistle-blower Protection Act 2010. Reference will also be made to the approach taken in other selected jurisdiction with a view of highlighting the adequacy of the Malaysian legislation on this subject besides strengthen employee whistle-blower protection. Further, reference is also made to the Islamic approach on this subject with particular reference to the concept of amr-bil-Ma’roof (ordering for acknowledged virtues) and nahi anil munkar (forbidding from sin). Allah (SWT) says: “And there should be a group amongst you who invite towards good, order for acknowledged virtues, forbid from sin and these it is that are the successful ones” (Al Imran(Chp 3), verse 104).

Keywords: whistleblower protection, employee whistleblower, detrimental and reprisal, Malaysian law

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Authors: J. Shiri, A. Mansourizadeh, F. Faghih, H. Vaez

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In this study, porous polyvinylidene fluoride (PVDF) hollow fiber membranes are fabricated via a wet phase-inversion Process and used in the gas–liquid membrane contactor for physical CO2 absorption. Effect of different air gap on the structure and CO2 flux of the membrane was investigated. The hollow fibers were prepared using the wet spinning process using a dope solution containing PVDF/NMP/Licl (18%, 78%, 4%) at the extrusion rate of 4.5ml/min and air gaps of 0, 7, 15cm. Water was used as internal and external coagulants. Membranes were characterized using various techniques such as Field Emission Scanning Electron Microscopy (FESEM), Gas permeation test, Critical Water Entry Pressure (CEPw) to select the best membrane structure for Co2 absorption. The characterization results showed that the prepared membrane at which air gap possess small pore size with high surface porosity and wetting resistance, which are favorable for gas absorption application air gap increased, CEPw had a decrease, but the N2 permeation was decreased. Surface porosity and also Co2 absorption was increased.

Keywords: porous PVDF hollow fiber membrane, CO2 absorption, phase inversion, air gap

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Authors: Mahmoudi Noureddine

Abstract:

The glass fiber (GF) reinforced polyimide (PL) composites filled with graphite powders were fabricated by means of hot press molding technique. The friction and wear properties of the resulting composites sliding against GCr15 steel were investigated on a model ring-on-block test rig at dry sliding condition. The wear mechanisms were also discussed, based on scanning electron microscopic examination of the worn surface of the PL composites and the transfer film formed on the counterpart. With the increasing normal loads, the friction coefficient of the composites increased under the dry sliding, owing to inconsistent influences of shear strength and real contact areas. Experimental results revealed that the incorporation of graphite significantly improve the wear resistance of the glass fibers reinforced polyimide composites. For best combination of friction coefficient and wear rate, the optimal volume content of graphite in the composites appears to be 45 %. It was also found that the tribological properties of the glass fiber reinforced PL composites filled with graphite powders were closely related with the sliding condition such as sliding rate and applied load.

Keywords: composites, fiber, friction, wear

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