The Experts below are selected from a list of 468 Experts worldwide ranked by ideXlab platform
Debes Bhattacharyya - One of the best experts on this subject based on the ideXlab platform.
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Mechanical Properties of Rotational Moulded Polyethylene Composites - Experiments and Theories
Composite Technologies for 2020, 2014Co-Authors: Debes BhattacharyyaAbstract:ABSTRACT The dominant usage of linear polyethylene as the raw material for Rotational Moulding, a fast growing industrial method, has shown insufficient mechanical properties for certain applications where the strength and stiffuess of a product are of importance. Worldwide Rotational moulders have an urgent need for stronger, stiffer materials to be available; therefore, the introduction of reinforcements into rotoMoulding process is attracting increasing attention. However, the incorporation of reinforcements in Rotational Moulding process has often shown difficulty of achieving a uniform distribution within the matrix material, which results in unsatisfactory mechanical properties. This paper describes an investigation using various particles of different volume fractions as the reinforcements, and verifying the various mechanical properties of rotomoulded products using different mathematical models. The results show that the Halpin-Tsai-Nielsen equation and the Nicolais-Narkis equation are well suited to predict the tensile modulus and tensile strength respectively for the rotomoulded particulate reinforced structure. A very good agreement can be achieved between the experimental results and the predictive models for the composites with particle volume fractions of 20% or less.
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Influence of surface treatment on hybrid wollastonite-polyethylene composite resins for Rotational Moulding
Journal of Materials Science, 2008Co-Authors: Xiaowen Yuan, Allan J. Easteal, Debes BhattacharyyaAbstract:The purpose of this research was to develop a reinforcing material for polyethylene-based composite manufacture by Rotational Moulding. Wollastonite, sisal fibres and PE are premixed by blending and compounding with a single screw extruder and then granulated to particles with diameter about 0.5 mm prior to Rotational Moulding, for which the mixture is placed in a mould that is heated from the outside to 250 °C for a period of about 10 min. Aminosilane was used as a surface treatment for wollastonite. It was found that incorporating wollastonite microfibres improved the tensile properties of the system. When wollastonite fibres were coated with aminosilane, the impact strength and processability were enhanced greatly. Sisal fibres were added to improve the impact properties. Scanning electron microscopy revealed good adhesion between the coated fibre reinforcement and the polyethylene matrix at the fracture surface. The mechanism of this phenomenon is discussed.
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MECHANICAL PERFORMANCE OF ROTOMOULDED WOLLASTONITE-REINFORCED POLYETHYLENE COMPOSITES
International Journal of Modern Physics B, 2007Co-Authors: Xiaowen Yuan, Allan J. Easteal, Debes BhattacharyyaAbstract:This paper describes the development of a new processing technology for Rotational Moulding of wollastonite microfibre (WE) reinforced polyethylene (PE). Manufacturing wollastonite-polyethylene composites involved blending, compounding by extrusion, and granulating prior to Rotational Moulding. The properties of the resulting composites were characterised by tensile and impact strength measurements. The results show that tensile strength increases monotonically with the addition of wollastonite fibres, but impact strength is decreased. In addition, the processability is also decreased after adding more than 12 vol% WE because of increased viscosity. The effects of a coupling agent, maleated polyethylene (MAPE), on the mechanical performance and processability were also investigated. SEM analysis reveals good adhesion between the fibre reinforcements and polyethylene matrix at the fracture surface with the addition of MAPE. It is proposed that fillers with small particles with high aspect ratio (such as wollastonite) provide a large interfacial area between the filler and the polymer matrix, and may influence the mobility of the molecular chains.
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Morphology of Rotationally Moulded Microfibril Reinforced Composites and its Effect on Product Performance
Key Engineering Materials, 2007Co-Authors: Debes Bhattacharyya, Stoyko FakirovAbstract:Rotational Moulding (rotoMoulding) is one of the fastest growing plastics manufacturing processes using linear polyethylenes dominantly as raw materials. However, due to their modest mechanical properties, Rotational moulders worldwide are keen to develop stronger and stiffer materials. In the present study, an attempt was undertaken to apply the concept of microfibril reinforced composites (MFCs) for improving the material performance. Melt blended and subsequently cold drawn and undrawn linear medium density polyethylene (LMDPE) with either poly(ethylene terephthalate) or poly(ethylene naphthalate) possessing MFC structure were mixed with neat LMDPE and thereafter processed via Rotational Moulding. The rotomoulded samples were characterised morphologically and tested mechanically. The obtained unsatisfactory mechanical characteristics led to the subsequent morphological study which revealed some interesting phenomena for the rotomoulded products containing MFC blends.
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Effect of Coupling Agents and Particle Size on Mechanical Performance of Polyethylene Composites Comprising Wollastonite Micro-Fibres
Key Engineering Materials, 2007Co-Authors: Xiaowen Yuan, Debes Bhattacharyya, Allan J. EastealAbstract:The usefulness of Rotational Moulding (rotoMoulding) as a polymer processing technique is often limited by the selection of polymers, which in most cases happens to be polyethylene (PE). In the present study, PE polyethylene was blended with wollastonite microfibres and maleated polyethylene (as a coupling agent) with the purpose of developing an improved material for Rotational Moulding. The incorporation of wollastonite fibres without any coupling agent improved the tensile strength, but showed a reduction in impact strength. As expected, the most significant enhancement due to wollastonite was in the tensile modulus.. The addition of a coupling agent improved both the impact strength and the processability, especially when wollastonite was coated with aminosilane. Scanning electron microscopy revealed good adhesion between the coated fibre reinforcement and the polyethylene matrix at the fracture surface.
Abbas Tcharkhtchi - One of the best experts on this subject based on the ideXlab platform.
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modelling of sintering during Rotational Moulding of the thermoplastic polymers
International Journal of Material Forming, 2016Co-Authors: A. Hamidi, Mario D Monzon, Fabien Nony, Sofiane Khelladi, Farid Bakir, Zaida Ortega, Sedigheh Farzaneh, Abbas TcharkhtchiAbstract:This paper concerns the study of sintering phenomenon during Rotational molding of polypropylene(PP),Polyvinylidenefluoride (PVDF) and Polymethyl methacrylate (PMMA). First, the coalescence (first step of sintering) of two grains has been followed. Bellehumeur’s model has been tested as a model to explain this phenomenon. In order to study the effect of neighboring grains on coalescence of two grains, a third grain has been put in contact with these two grains. For modeling the phenomenon in this case, Bellehumeur’s model has been modified by a geometric parameter called Farz Factor (FF), being this model validated by experimental test. Concerning densification, two different stages have been observed. In the first stage, before welding of the grains and formation of interphases between them, the grains are not stuck yet. The air trapped between the grains escapes through free ways between grains. This first step of densification is directly related to the coalescence where the density of the polymer varies very quickly. A new tridimensional model, based on a Body Centered Tetragonal (BCT) configuration, has been proposed to explain the densification during this first stage. In the second stage, the migration of air is controlled by diffusion.
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Modelling surface tension with smoothed particle hydrodynamics in reactive Rotational Moulding
Computers & Fluids, 2015Co-Authors: A. Hamidi, Sofiane Khelladi, Lounès Illoul, Mohammadali Shirinbayan, Farid Bakir, Abbas TcharkhtchiAbstract:Abstract Reactive Rotational Moulding (RRM) is the best process for producing large hollow plastic parts without weld lines. Constant quality in technical parts requires the process to be mastered by controlling on-line the main physical phenomena. However, the main drawback of RRM is poor control of the process due to the high number of influent parameters. In these conditions, the optimization of the process is quite complex. The aim of this work is to simulate the reactive fluid flow during RRM with Smoothed Particle Hydrodynamics (SPH) solver in two dimensions (2D) and three dimensions (3D) taking into account surface tension force. To implement this force, the interface is tracked explicitly using algorithm developed by Barecasco et al. (2013) and Terissa et al. (2013) and the reconstruction of curve or surface boundary by different interpolation or surface construction technique with Lagrangian interpolation and fitting circle methods in 2D and spherical regression in 3D, respectively.
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Thermal transfer simulation regarding the Rotational Moulding of polyamide 11
Journal of Thermal Analysis and Calorimetry, 2013Co-Authors: Said Lotfi Hafsaoui, Mokhtar Benziane, Abbas TcharkhtchiAbstract:Simulation of thermal phenomena in Rotational Moulding is very important to follow the evolution of the temperature in various zones of this process. It was a question of modelling heat gradients developing in Rotational Moulding part. Thermal model tested take into account the temperature change (thermal transfer mechanism) of melting and crystallization pseudo-stages (enthalpy method). Series of tests in polyamide 11 (PA11) were carried out by means of Rotational Moulding STP LAB, and non-isothermal crystallization kinetics of Rotational Moulding PA11 grade are measured and analysed by DSC technique type TAQ20. A result of non-isothermal crystallization of the studied polyamide was confronted with Ozawa model. In order to test the validity degree of enthalpy method (layer to layer), another approach based on Ozawa model has also been used in the case of cooling pseudo-stage. As results, the Rotational Moulding of PA11 was successfully carried out. The simulation of the fusion and crystallization stages, by application of Ozawa model coupled with enthalpy method gave a good representation of experimental data.
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Rotational Moulding of Thermosets: Understanding of a Reactive Forming Process
International Journal of Material Forming, 2008Co-Authors: Jérémy Viale, Abbas Tcharkhtchi, Fabien Nony, Philippe Mazabraud, Jean-françois Gérard, Gwenael DoulinAbstract:Physical and chemical transformations of polyurethane thermoset are studied by means of thermal analysis, infrared spectrophotometer and dynamic rheology. Gel point, which limits the material flow, is given as a function of conversion and as a function of time by kinetic law. Glass transition corresponding to a dramatic transformation of the material is also explored and connected to conversion and time. These ex situ characterizations are then exploited in terms of Rotational Moulding process parameters to improve the understanding and thus the control of the process. Therefore in situ thermal analyses are handled to confirm first results. Final parts thickness distribution is examined as a quantitative parameter of process quality. Finally, as a perspective, ultrasonic response is also studied as a new way to follow material evolution directly in the forming mould.
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structure processibility relationships during Rotational Moulding of plastics
Advanced Engineering Materials, 2004Co-Authors: Abbas Tcharkhtchi, J VerduAbstract:During the Rotational Moulding of plastics there are a number of key temperatures that influence to a large extent the production of good quality parts. Using well established relationships between the structure and processibility of plastics, this paper explains why polyethylene is much easier to process by Rotational Moulding than other polymers such as polyamides, poly(ethylene terephtalate), poly(vinylchloride) or polypropylene.
Aabbas Tcharkhatchi - One of the best experts on this subject based on the ideXlab platform.
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Poly(methyl methacrylate)-modified epoxy/amine system for reactive Rotational Moulding: crosslinking kinetics and rheological properties
Polymer International, 2009Co-Authors: Eskandar Mounif, Genhai G. Liang, Veronique Bellenger, Wayne D. Cook, Aabbas TcharkhatchiAbstract:BACKGROUND: The Rotational Moulding of thermosetting resins is hampered by their low viscosity and the abrupt increase in their viscosity as they polymerize. This study investigates the use of poly(methylmethacrylate) (PMMA) as a rheological processing aid in reactive blends of an aromatic diepoxy resin (diglycidyl ether of bisphenol-A, DGEBA) and an aromatic diamine (diethyltoluenediamine, DETDA) by studying the miscibility, curing, rheology, dynamic properties and morphology of the uncured solutions and of the resulting highly crosslinked polymer blends. RESULTS: The PMMA was miscible in the uncured resins as expected from consideration of their solubility parameters, and the effect of PMMA concentration on the glass transition temperature, measured via differential scanning calorimetry (DSC), was fitted to several models. Addition of PMMA significantly increased the viscosity of the uncured blend which obeyed the log-additivity rule. The curing behaviour was monitored using DSC, infrared spectroscopy and dynamic rheology and it was found that addition of PMMA caused a small reduction in rate due to a dilution effect. The dynamic and steady shear rheologies were used to determine the gel point and gel relaxation index. Dynamic mechanical thermal analysis provided evidence for phase separation of the components into PMMA-rich domains and an epoxy-rich matrix and this was confirmed with electron microscopy studies. CONCLUSION: These results indicate that addition of small amounts of PMMA to DGEBA/DETDA enlarges the processing window with regards to the Rotational Moulding of thermosets. In addition, the blending of small amounts (ca 10 wt%) of PMMA with the DGEBA/DETDA resin appears to cause only a modest sacrifice in thermal resistance. Copyright © 2009 Society of Chemical Industry
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poly methyl methacrylate modified epoxy amine system for reactive Rotational Moulding crosslinking kinetics and rheological properties
Polymer International, 2009Co-Authors: Eskandar Mounif, Genhai G. Liang, Veronique Bellenger, Wayne D. Cook, Aabbas TcharkhatchiAbstract:BACKGROUND: The Rotational Moulding of thermosetting resins is hampered by their low viscosity and the abrupt increase in their viscosity as they polymerize. This study investigates the use of poly(methylmethacrylate) (PMMA) as a rheological processing aid in reactive blends of an aromatic diepoxy resin (diglycidyl ether of bisphenol-A, DGEBA) and an aromatic diamine (diethyltoluenediamine, DETDA) by studying the miscibility, curing, rheology, dynamic properties and morphology of the uncured solutions and of the resulting highly crosslinked polymer blends. RESULTS: The PMMA was miscible in the uncured resins as expected from consideration of their solubility parameters, and the effect of PMMA concentration on the glass transition temperature, measured via differential scanning calorimetry (DSC), was fitted to several models. Addition of PMMA significantly increased the viscosity of the uncured blend which obeyed the log-additivity rule. The curing behaviour was monitored using DSC, infrared spectroscopy and dynamic rheology and it was found that addition of PMMA caused a small reduction in rate due to a dilution effect. The dynamic and steady shear rheologies were used to determine the gel point and gel relaxation index. Dynamic mechanical thermal analysis provided evidence for phase separation of the components into PMMA-rich domains and an epoxy-rich matrix and this was confirmed with electron microscopy studies. CONCLUSION: These results indicate that addition of small amounts of PMMA to DGEBA/DETDA enlarges the processing window with regards to the Rotational Moulding of thermosets. In addition, the blending of small amounts (ca 10 wt%) of PMMA with the DGEBA/DETDA resin appears to cause only a modest sacrifice in thermal resistance. Copyright © 2009 Society of Chemical Industry
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Poly(methyl methacrylate)-modified epoxy/amine system for reactive Rotational Moulding: Crosslinking kinetics and rheological properties
Polymer International, 2009Co-Authors: Eskandar Mounif, Genhai G. Liang, Veronique Bellenger, Wayne D. Cook, Aabbas TcharkhatchiAbstract:Background: The Rotational Moulding of thermosetting resins is hampered by their low viscosity and the abrupt increase in their viscosity as they polymerize. This study investigates the use of poly(methylmethacrylate) (PMMA) as a rheological processing aid in reactive blends of an aromatic diepoxy resin (diglycidyl ether of bisphenol-A, DGEBA) and an aromatic diamine (diethyltoluenediamine, DETDA) by studying the miscibility, curing, rheology, dynamic properties and morphology of the uncured solutions and of the resulting highly crosslinked polymer blends. Results: The PMMA was miscible in the uncured resins as expected from consideration of their solubility parameters, and the effect of PMMA concentration on the glass transition temperature, measured via differential scanning calorimetry (DSC), was fitted to several models. Addition of PMMA significantly increased the viscosity of the uncured blend which obeyed the log-additivity rule. The curing behaviour was monitored using DSC, infrared spectroscopy and dynamic rheology and it was found that addition of PMMA caused a small reduction in rate due to a dilution effect. The dynamic and steady shear rheologies were used to determine the gel point and gel relaxation index. Dynamic mechanical thermal analysis provided evidence for phase separation of the components into PMMA-rich domains and an epoxy-rich matrix and this was confirmed with electron microscopy studies. Conclusion: These results indicate that addition of small amounts of PMMA to DGEBA/DETDA enlarges the processing window with regards to the Rotational Moulding of thermosets. In addition, the blending of small amounts (ca 10 wt%) of PMMA with the DGEBA/DETDA resin appears to cause only amodest sacrifice in thermal resistance. © 2009 Society of Chemical Industry.
Krishnan Jayaraman - One of the best experts on this subject based on the ideXlab platform.
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Rotational Moulding and Mechanical Characterisation of Micron-Sized and Nano-Sized Reinforced High Density Polyethylene
Key Engineering Materials, 2019Co-Authors: Günther Höfler, Krishnan JayaramanAbstract:Rotational Moulding (RM) of plastics is predominantly used to produce hollow, singlepiece products. Polyethylene (PE) in its various forms, is the most commonly used material for this process. Researchers have been conducting numerous experiments trying to incorporate reinforcements attempting to improve the mechanical performance of RM products and overcome the material limitations posed by design parameters. One of the most common problems with reinforcement in RM is the migration of the filler towards the inside of the mould and agglomerations. In order to find a competitive material which is desirable by industry, RM experiments were conducted with various composite reinforcements; high density polyethylene (HDPE), numerous types of glass fibres (GF), carbon fibres (CF) and carbon nanotubes (CNT). In particular, the influence of low weight fractions of reinforcement on the mechanical performance, tensile, flexural and impact properties of HDPE were investigated.
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Rotational Moulding and mechanical characterisation of halloysite reinforced polyethylenes
Journal of Polymer Research, 2018Co-Authors: Günther Höfler, Krishnan JayaramanAbstract:Extensive experiments with Rotationally moulded polyethylene halloysite nanocomposites have been conducted. Previous studies regarding the use of filler materials in Rotational Moulding often report problems with agglomerations or inward migration of the filler. Despite the previous advances in machine adaptations and mould configurations to apply internal pressure, this study has focused mainly on non-pressurized composite production. Halloysite is a natural, nano-size, mineral clay with different reactivities from the internal aluminol and external siloxane surfaces. Due to its morphology and chemical nature, halloysite is easier to process compared to other fillers and achieves good particle dispersion, making it a potential candidate for reinforcing Rotationally moulded products. In this study, nanoparticle-reinforced composites containing halloysite with medium density or high density polyethylene were produced by Rotational Moulding. The influence of halloysite on the melt flow index and mechanical performance, tensile, flexural and impact properties, were investigated.
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natural fibre reinforced thermoplastics processed by Rotational Moulding
Advanced Materials Research, 2007Co-Authors: Krishnan Jayaraman, D Bose, M MaaroufAbstract:Rotational Moulding or rotoMoulding is a manufacturing process best suited for producing one-piece, hollow plastic products. The raw materials can be in powder or liquid form with linear polyethylene of varying densities being dominant worldwide. Due to the modest material properties of polyethylene, reinforcement in various forms have been incorporated within the rotomoulded components to improve the performance of these products. With the abundance and eco-friendliness of natural fibre resources, this study has focused on the use of sisal and woodfibres along with linear medium density polyethylene (LMDPE) powder to produce rotomoulded composite components. Tensile and impact properties of the rotomoulded natural fibre-reinforced composites have been determined as a function of fibre content.
Conchur M O Bradaigh - One of the best experts on this subject based on the ideXlab platform.
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Rotational Moulding of peek polymer liners with carbon fibre peek over tape placement for space cryogenic fuel tanks
Materials & Design, 2017Co-Authors: Brendan R Murray, A Doyle, Patrick Feerick, Christopher Semprimoschnig, S B Leen, Conchur M O BradaighAbstract:Abstract PEEK polymers are investigated as replacement materials for metallic liners in composite overwrapped pressure vessels (COPVs) for fuel tank applications in space. A novel, integrally heated, Rotational Moulding tool has been developed to produce PEEK polymer liners, samples of which have then been overwrapped using CF/PEEK in a laser assisted tape-placement (LATP) process to produce demonstrator samples of a polymer lined COPV. Helium permeability testing has shown that the designs are capable of resisting leakage to acceptable levels for fuel storage, while X-ray CT scanning and cryogenic cycling have shown that the current design is capable of resisting crack growth over multiple cycles. Nano-indentation testing has shown that the LATP process has created a region of reduced modulus in the PEEK polymer at the surface of the liner where the CF/PEEK has been tape-laid. This laser-affected zone of reduced polymer modulus in the composite interface region has enabled an enhanced resistance to crack growth formations from thermal residual stresses in comparison to hot plate moulded test samples.
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Rotational Moulding of PEEK polymer liners with carbon fibre/PEEK over tape-placement for space cryogenic fuel tanks
Materials & Design, 2017Co-Authors: Brendan R Murray, A Doyle, Patrick Feerick, Christopher Semprimoschnig, S B Leen, Conchur M O BradaighAbstract:Abstract PEEK polymers are investigated as replacement materials for metallic liners in composite overwrapped pressure vessels (COPVs) for fuel tank applications in space. A novel, integrally heated, Rotational Moulding tool has been developed to produce PEEK polymer liners, samples of which have then been overwrapped using CF/PEEK in a laser assisted tape-placement (LATP) process to produce demonstrator samples of a polymer lined COPV. Helium permeability testing has shown that the designs are capable of resisting leakage to acceptable levels for fuel storage, while X-ray CT scanning and cryogenic cycling have shown that the current design is capable of resisting crack growth over multiple cycles. Nano-indentation testing has shown that the LATP process has created a region of reduced modulus in the PEEK polymer at the surface of the liner where the CF/PEEK has been tape-laid. This laser-affected zone of reduced polymer modulus in the composite interface region has enabled an enhanced resistance to crack growth formations from thermal residual stresses in comparison to hot plate moulded test samples.
