Effect of Nanoclay on Thermal Properties of Polylacticacid-Kenaf Hybrid Bio-composite

An alternative composite material which is a mixture of bio-fiber with nano filler and polymer known as hybrid bio-composite has become a state of the art in composite research and development. The hybrid bio-composite has been widely studied with different combinations for the application of secondary structure in automotive industry, packaging, aerospace, sports, armour proucts and others. The availability of natural fiber (such as kenaf fiber) makes the hybrid bio-composite competetively lower cost and feasible to be produced industrially for wide range of applications. The main objectives of this paper are to fabricate and the effect of nanoclay on thermal properties of hybrid bio-composite. A comprehensive database was developed to determine the thermal property of PLA, PLA-20KF-3Clay, PLA-20KF-5Clay and PLA-20KF-7Clay. Three point bend Dynamic mechanical analysis (DMA) tests were carried out on standard specimens at temperature ranging from -900C to 1000C whereas frequency was 1Hz. The result revealed that with addition of nanoclay glass transition temperature (Tg) increased 50C. The storage modulus (E’), loss modulus (E”) and damping (tanδ) also increased with addition of nanoclay which is an indication of better thermal properties

Supporting students improve their academic writing through online collaboration

This thesis report is submitted in partial fulfillment of the requirements for the degree of Masters of Arts in Teaching to Speakers of Other Languages, 2015.Cataloged from PDF version of Internship report.Includes bibliographical references (page 40-43).This study examines how students can be supported online with their writing while they are outside classroom. Coming from different backgrounds and media of study, many of the undergraduate students of BRAC University face difficulties while writing in English which results in poor grades at the end of the semester. In this research, 25 undergraduate students from six different departments were selected based on a diagnostic test taken in the beginning of the semester. They all were added on three online groups (Wiki, blog and FB) where they have practiced, in addition to the class works, more on basics of academic writing so that they get additional support to bridge up the existing learning gap with their other classmates. Results have shown that students using the online groups have gotten advantages out of the activities. They also have mentioned that they were benefitted by the comments by their peers, though, according to them, a teacher must be monitoring the whole system to optimize the outcome and increase students’ participation. This type of research can be replicated in many other institutions provided they have all required facilities in place. Through this study, English language teaching and learning takes a new form and hundreds of students learn English language with supports from their teacher and peers online.Mohammad Rejaul KarimM. in TESO

Eco-friendly PLA-kenaf fibre biocomposite for food packaging

From a statistics accounted in 1999, 48% of plastic bottle that used is made from PET. Among them a huge percentage are end up as garbage and caused the landfills. This toxic waste pollutes our subsurface water label through leaching. PLA is a strong candidate to substitute conventional petroleum based polymer. Kenaf fiber was added to reduce the cost as well as to increase properties. The mechanical and thermal properties shows that PLA-Kenaf biocomposite shows better properties than conventional food packaging polymer

Fabrication of biodegradable composite – an implication of plasticizer

This paper aims on the fabrication of fully biodegradable composite with the addition of plasticizer. For the fabrication of biodegradable composite, a twin screw extruder was used which provides a good blending of matrix, fiber and plasticizer. The percentage is varied from 5% to 40% for fiber and for plasticizer it is 5% to 20%. Higher percentage of plasticizer shows more difficulty during fabrication process of bio-composite. The results also showed that the addition of plasticizer reduces the melting and glass transition temperature of the composite which affects the processing parameter such as, temperature of different zones, rotation of the extruder screw, feed rate and production rate of the extruder. This paper also discussed on the suitable processing parameters for production of plasticized biodegradable composite

Switching Equipment Location/Allocation in hybrid PONs

Our research goal is to investigate the FTTX (Fiber-to-the Home/Premises/Curb) passive optical network (PON) for the deployment of BISAN (Broadband Internet Subscriber Access Network) to exploit the opportunities of optical fiber enabled technologies as well as of passive switching equipment. Indeed, the deployment of FTTX PON is the most OPEX-friendly scenario, because it allows for completely passive access networks through minimizing the number of active components in the network. Previously, most FTTX PON architectures are designed based on the principle of either time division multiplexing (TDM) technology or wavelength division multiplexing (WDM) technology. We focus on designing the best possible architectures of FTTX PON, specifically hybrid PONs, which embraces both TDM and WDM technology. A hybrid PON architecture is very efficient as it is not limited to any specific PON technology, rather it is flexible enough to deploy TDM/WDM technology depending on the type (i.e unicast/multicast) and amount of traffic demand of the end-users. The advantages of a hybrid PON are of two folds: (i) it can offer increased data rate to each user by employing WDM technology, (ii) it can provide flexible bandwidth utilization by employing TDM technology. In this thesis, we concentrate on determining the optimized covering of a geographical area by a set of cost-effective hybrid PONs. We also focus on the greenfield deployment of a single hybrid PON. It should be worthy to mention that while investigating the deployment of hybrid PONs, the research community around the world considers the specifications of either the physical layer or the optical layer. But an efficient planning for PON deployment should take into account the constraints of the physical and optical layers in order that both layers can work together harmoniously. We concentrate our research on the network dimensioning and the selection as well as the placement of the switching equipment in hybrid PONs with the intention of considering the constraints of both physical and optical layers. We determine the layout of an optimized PON architecture while provisioning wavelengths in a hybrid PON. We also propose to select the switching equipment depending on the type (unicast/multicast) of traffic demand. Finally, we determine the best set of hybrid PONs along with their cascading architecture, type and location of their switching equipment while satisfying the network design constraints such as the number of output ports of the switching equipment and maximum allowed signal power loss experienced at each end user’s premises. In this thesis, we propose two novel schemes for the greenfield deployment of a single hybrid PON. The first scheme consists of two phases in which a heuristic algorithm and a novel column generation (CG) based integer linear programming (ILP) optimization model are proposed in the 1st and 2nd phase respectively. In the second scheme, a novel integrated CG based ILP cross layer optimization model is proposed for the designing of a single hybrid PON. We also propose two novel schemes to deal with the greenfield deployment of multiple hybrid PONs in a given geographical area. These two schemes determine the best set of cost-effective hybrid PONs in order to serve all the end users in a given neighborhood. The first scheme executes in four phases in which two heuristic algorithms, a CG based ILP model and an ILP optimization model are proposed in the 1st, 2nd, 3rd and 4th phase respectively. In the second scheme, an ILP model as well as a CG based ILP model, another ILP model as well as another CG based ILP model, a CG based ILP model and an ILP optimization model are proposed during four consecutive phases. Our proposed scheme can optimize the design of a set of hybrid PONs covering a given geographic area as well as the selection of the best cascading architecture 1/2/mixedstage) for each selected PON. It minimizes the overall network deployment cost based on the location of the OLT and the ONUs while granting all traffic demands. The scheme emphasizes on the optimum placement of equipment in a hybrid PON infrastructure due to the critical dependency between the network performances and a proper deployment of its equipment, which, in turn depends on the locations of the users. It is a quite powerful scheme as it can handle data instances with up to several thousands ONUs. On the basis of the computational results, the proposed scheme leads to an efficient automated tool for network design, planning, and performance evaluation which can be beneficial for the network designers

Effect of Non-newtonian Behaviour on Fluid Structural Interaction for Flow Through a Model Stenosed Artery

AbstractThe cause and development of many cardiovascular diseases are related to the nature of blood flow and the mechanical behaviour of the blood vessel. Moreover, the plaque (stenosis) rapture can be occurred as a result of interaction between the blood and plaque, leading to the clot formation and stroke. In the present study, the interaction of blood flow with plaque (stenosis) was numerically modelled. A pulsatile flow was used to mimic the real blood flow through the artery. The rheological properties of blood are considered as Newtonian as well as non-Newtonian. Fibrous cap thickness was varied from 0.1mm to 2.0mm. Many vortex rings are appeared at the pre- and post-stenotic region in the Newtonian model than in the non-Newtonian model. Deformation of stenosis, wall shear stress (WSS) and vomises stress all are found high in non-Newtonian model for the fibrous cap thicknesses studied here. Moreover, in Newtonian model, the vonmises stress was found to be 6500 pa for the case of 50% stenosis with 0.1mm fibrous cap thickness on the other hand it was around 10500 pa in case of non-Newtonian model

Effect of processing routes on the mechanical, thermal and morphological properties of PLA-based hybrid biocomposite

Due to environmental awareness and depletion of petroleum oil, bioplastics and their composites are one of the most researchable topics throughout the world. Polymers that are produced from renewable sources are expected to be the best alternative to replace conventional polymers. The bottles neck of these bioplastics is its cost which limits its application in certain purposes. Bioplastics filled or reinforced with natural fibers can reduce cost and improve properties, like stiffness, strength and toughness of biocomposites. Impact strength and fracture toughness are the main demerits of short fiber-filled biocomposite. On the other hand, when nanoclay, having a very high aspect ratio, is mixed with bioplastics it may significantly affect the thermal and mechanical properties of the final composites. A composite may also suffer dispersion inefficiency, which is considered the key factor to improve the properties. The aim of this paper was to hybridize nanoclay and short kenaf fiber in polylactic acid (PLA) by double extrusion method and followed by mechanical, thermal and morphological characterizations. Mechanical properties showed improvement with nanoclay, specifically the impact strength increased more than 50 % compared with unreinforced PLA. A double extruded composite showed 3–10 % better tensile and flexural properties than the single extruded composite. Similarly, addition of nanoclay increased decomposition and melting temperatures (T m) from 198 to 225 �C and 152 to 155 �C, respectively. Crystallization temperature (Tc ), however, dropped with nanoclay from 116 to 106 �C and storage modulus (E’) increased by about 1 GPa. These findings were also supported by scanning electron micrograph (SEM) and transmission electron micrograph (TEM) where in double extruded composite a better dispersion of nanoclay was observed. By employing X-ray diffraction (XRD) it was found that higher percentage of crystallinity was obtained while Fourier transform infrared (FTIR) displayed new bond formation. The presence of nanoclay enhanced thermal and mechanical properties of the hybrid composite