Home About us Contact
|
Home About us Contact | ||
|
|
||
Plastic Materials (plastic + material)
Selected AbstractsGreenhouse Gas Profile of a Plastic Material Derived from a Genetically Modified PlantJOURNAL OF INDUSTRIAL ECOLOGY, Issue 3 2000Devdatt Kurdikar Abstract: This article reports an assessment of the global warming potential associated with the life cycle of a biopolymer (poly(hydroxyalkanoate) or PHA) produced in genetically engineered corn developed by Monsanto. The grain corn is harvested in a conventional manner, and the polymer is extracted from the corn stover (i.e., residues such as stalks, leaves and cobs), which would be otherwise left on the field. While corn farming was assessed based on current practice, four different hypothetical PHA production scenarios were tested for the extraction process. Each scenario differed in the energy source used for polymer extraction and compounding, and the results were compared to polyethylene (PE). The first scenario involved burning of the residual biomass (primarily cellulose) remaining after the polymer was extracted from the stover. In the three other scenarios, the use of conventional energy sources of coal, oil, and natural gas were investigated. This study indicates that an integrated system, wherein biomass energy from corn stover provides energy for polymer processing, would result in a better greenhouse gas profile for PHA than for PE. However, plant-based PHA production using fossil fuel sources provides no greenhouse gas advantage over PE, in fact scoring worse than PE. These results are based on a "cradle-to-pellet" modeling as the PHA end-of-life was not quantitatively studied due to complex issues surrounding the actual fate of postconsumer PHA. [source] Evaluation of poly(ethylene-co-vinyl acetate-co-carbon monoxide) and polydimethylsiloxane for equilibrium sampling of polar organic contaminants in waterENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 9 2009Jörgen A Magnér Abstract Abstract-The aim of the present study was to develop a passive a bsorptive equilibrium sampler that would enable the determination of the concentrations of polar organic compound (POC) in water more efficiently than existing techniques. To this end, a novel plastic material, poly(ethylene-co-vinyl acetate-co-carbon monoxide) (PEVAC), was evaluated and the results were compared with an existing silicone-based passive absorptive equilibrium device. Seven compounds (imidacloprid, carbendazim, metoprolol, atrazin, carbamazepine, diazinon, and chlorpyrifos), a mixture of pharmaceuticals, and pesticides with a logarithmic octanol-water partition coefficient ranging from 0.2 to 4.77 were selected as model substances for the experiments. The results showed that six of the seven selected POCs reached distribution equilibrium within 4 d in the two materials tested. A linear relation with a regression coefficient of more than 0.8906 between the established logarithmic absorbent-water partition coefficient and the calculated logarithmic dissociation partition coefficient of the selected compounds in the two polymers was observed. The correlation between these two coefficients was within one order of magnitude for the compounds that reached equilibrium in the two polymers, which demonstrates that both materials are suitable for mimicking biological uptake of POCs. The PEVAC material showed an enhanced sorption for all selected compounds compared to the silicone material and up to five times higher enrichment for the most polar compound. Fluorescence analysis of the sampler cross-section, following the uptake of fluoranthene, and proof that the sorption was independent of surface area variations demonstrated that the PEVAC polymer possessed absorptive rather than adsorptive enrichment of organic compounds. [source] Statical shakedown analysis with temperature-dependent yield conditionINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING, Issue 11 2004M. Heitzer Abstract This paper describes a general statical approach for shakedown analysis of structures of perfectly plastic material using non-linear optimization. The developed methods may be implemented with any displacement-based finite element code. The temperature-dependence of the yield limit is taken into account in shakedown analysis. Temperature-dependent shakedown analysis of a pipe-junction and a thick tube are performed by different methods. Copyright © 2004 John Wiley & Sons, Ltd. [source] Online control of the injection molding process based on process variablesADVANCES IN POLYMER TECHNOLOGY, Issue 2 2009Walter Michaeli Abstract The conventional control of the injection molding process is based on machine variables, which cannot sufficiently characterize the course of the process. Hence, a system that controls the injection molding process based on process variables has been developed at the Institute of Plastics Processing at RWTH Aachen University during the last years. It controls the quality determining process variable cavity pressure directly and realizes a desired course of cavity pressure in the injection and holding pressure phases. The cavity pressure course in the holding pressure phase is controlled online on the basis of pvT behavior of the processed plastic material. Thus, an optimal course of the process in the pvT diagram can be guaranteed and the quality constancy of the molded parts can be clearly increased. Using the pvT-based process control, the effect of varying mold and melt temperatures on the molded part weight can be decreased by about 90% compared with the conventional process control. © 2009 Wiley Periodicals, Inc. Adv Polym Techn 28:65,76, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20153 [source] Effect of culturing processes and copper addition on laccase production by the white-rot fungus Fomes fomentarius MUCL 35117LETTERS IN APPLIED MICROBIOLOGY, Issue 1 2009M. Neifar Abstract Aim:, To produce high laccase activities from the white-rot fungus Fomes fomentarius. Methods and Results:, Different culturing methods, viz, cell immobilization on stainless steel sponges and plastic material and solid-state fermentation (SSF) using wheat bran as substrate were used for laccase production by the white-rot fungus F. fomentarius. The SSF study expresses the highest laccase activities, nearly to 6400 U l,1 after 13 days of laboratory flasks cultivation. When the wheat bran medium was supplemented with 2 mmol l,1 copper sulfate, laccase activity increased by threefold in comparison to control cultures, reaching 27 864 U l,1. With the medium thus optimized, further experiments were performed in a 3 l fixed-bed bioreactor (working volume 1·5 l) leading to a laccase activity of about 6230 U l,1 on day 13. Conclusions:, The results obtained clearly showed the superiority of wheat bran for laccase production over stainless steel sponges and plastic material. Supplementing the wheat bran solid medium with 2 mmol l,1 copper sulfate allowed obtaining high activities at flask scale. The system was scaled to fixed-bed laboratory reactor. Significance and Impact of the Study:, The high enzyme production along with the low-cost of the substrate, showed the suitability of the system F. fomentarius, SSF for industrial purposes. [source] "Plastic Trash goes Biohybrid",Rapid and Selective Functionalization of Inert Plastic Surfaces with Biomolecules,MACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 2 2010Stefan M. Schiller Abstract The covalent functionalization of "inert" polymers such as polypropylene with biomolecules for biocompatible or biosensor surfaces is challenging. Here we present a powerful approach to covalently modify "inert" macromolecular surfaces with biomacromolecules reusing old plastic material. A special emphasis was placed on easily accessible materials and a process which is easy, fast, efficient, cheap, and reliable. "Plastic trash" (lids from Eppendorf® pipet tip containers) was used as a polymer substrate to demonstrate the use/reuse of commercial packing material to covalently modify this material with a thin reactive plasma polymerized maleic anhydride nanolayer network, which can be subsequently modified with biomolecules for various applications, e.g., in tissue engineering and as biochips. [source] A Study on Modern High Effective Random Packings for Ethanol-Water RectificationCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 7 2008S. Darakchiev Abstract Raschig Super-Ring is a modern and high-efficient packing used for intensification of absorption and distillation processes. The aim of this work is to characterize the efficiency of this packing applied to rectification of an important industrial system, ethanol-water, and to compare its efficiency to that of some random packings of the third generation as well as to the structured packing, HOLPACK, which is used in the ethanol production industry. The experiments were carried out in a column installation, 0.213,m in diameter with a packing height of 2.8,m. The column is heated by a number of electrical heaters (total power 45,kW), which can be switched gradually. Operation at total and partial reflux is possible. Eight types of random packings were studied: five types of Raschig Super-Ring, four metallic (with characteristic dimensions 0.5, 0.6, 0.7, and 1") and one of plastic material 0.6"; two types of packing IMTP and one plastic Ralu Flow. Some experiments were conducted at total reflux operation at vapor velocity, 0.253,0.936,m/s, and liquid superficial velocity, 4.44,·,10,4,1.63,·,10,3,m3/(m2s). Experiments at partial reflux were carried out at constant liquid superficial velocity and changeable vapor velocity as well as at constant vapor velocity and changeable liquid velocity. The results are presented as height of transfer unit, HTU, and height equivalent to a theoretical plate, HETP, as a function of the velocity of phases. [source] Localized failure of fibre-reinforced elastic,plastic materials subjected to plane strain loadingINTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 7 2007Dunja Peri Abstract We consider discontinuous bifurcations as the indicator of a localized failure for a class of composites that are characterized by elastic fibres reinforcing an elastic,plastic matrix. A macroscopic tangent stiffness tensor for the fibre-reinforced composite is developed by consistently homogenizing the contribution of fibres in a spherical representative volume element. Analytical solutions are derived for the critical hardening modulus and corresponding bifurcation directions for the case of plane strain loading. Properties of the solutions are further illustrated on the example of the non-associated Drucker,Prager model at onset of yielding. Results show that presence of fibres decreases the critical hardening modulus, thus inhibiting the onset of strain localization. The rate of decrease in the critical hardening modulus is the highest for pure shear, followed by uniaxial tension, uniaxial compression, biaxial tension and biaxial compression. The main fibre parameters that control the onset of strain localization are their volumetric content and their stiffness modulus whereby very stiff fibres can produce the most significant decrease in the critical hardening modulus, especially for the state of biaxial tension. The critical hardening modulus for the non-associated Drucker,Prager model exhibits a full range of localization modes including compaction bands, dilation bands, and transition in the form of shear bands regardless of the presence of fibres. Presence of fibres affects bifurcation directions, except in the case when Poisson's ratio of the matrix is equal to 0.25. The results demonstrate stabilizing effects of fibres by which they provide the control against the onset of strain localization. Copyright © 2006 John Wiley & Sons, Ltd. [source] Ground response curves for rock masses exhibiting strain-softening behaviourINTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 13 2003E. Alonso Abstract A literature review has shown that there exist adequate techniques to obtain ground reaction curves for tunnels excavated in elastic-brittle and perfectly plastic materials. However, for strain-softening materials it seems that the problem has not been sufficiently analysed. In this paper, a one-dimensional numerical solution to obtain the ground reaction curve (GRC) for circular tunnels excavated in strain-softening materials is presented. The problem is formulated in a very general form and leads to a system of ordinary differential equations. By adequately defining a fictitious ,time' variable and re-scaling some variables the problem is converted into an initial value one, which can be solved numerically by a Runge,Kutta,Fehlberg method, which is implemented in MATLAB environment. The method has been developed for various common particular behaviour models including Tresca, Mohr,Coulomb and Hoek,Brown failure criteria, in all cases with non-associative flow rules and two-segment piecewise linear functions related to a principal strain-dependent plastic parameter to model the transition between peak and residual failure criteria. Some particular examples for the different failure criteria have been run, which agree well with closed-form solutions,if existing,or with FDM-based code results. Parametric studies and specific charts are created to highlight the influence of different parameters. The proposed methodology intends to be a wider and general numerical basis where standard and newly featured behaviour modes focusing on obtaining GRC for tunnels excavated in strain-softening materials can be implemented. This way of solving such problems has proved to be more efficient and less time consuming than using FEM- or FDM-based numerical 2D codes. Copyright © 2003 John Wiley & Sons, Ltd. [source] Locking-free finite elements for shear deformable orthotropic thin-walled beamsINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 7 2007F. Minghini Abstract Numerical models for finite element analyses of assemblages of thin-walled open-section profiles are presented. The assumed kinematical model is based on Timoshenko,Reissner theory so as to take shear strain effects of non-uniform bending and torsion into account. Hence, strain elastic-energy coupling terms arise between bending in the two principal planes and between bending and torsion. The adopted model holds for both isotropic and orthotropic beams. Several displacement interpolation fields are compared with the available numerical examples. In particular, some shape functions are obtained from ,modified' Hermitian polynomials that produce a locking-free Timoshenko beam element. Analogously, numerical interpolation for torsional rotation and cross-section warping are proposed resorting to one Hermitian and six Lagrangian formulation. Analyses of beams with mono-symmetric and non-symmetric cross-sections are performed to verify convergence rate and accuracy of the proposed formulations, especially in the presence of coupling terms due to shear deformations, pointing out the decay length of end effects. Profiles made of both isotropic and fibre-reinforced plastic materials are considered. The presented beam models are compared with results given by plate-shell models. Copyright © 2007 John Wiley & Sons, Ltd. [source] Smart blending technology enabled by chaotic advectionADVANCES IN POLYMER TECHNOLOGY, Issue 3 2006D. A. Zumbrunnen Abstract Polymer blending has been typically regarded as a mixing process rather than a structuring process so polymer blends and composites are not necessarily optimized with regard to structure, properties, and composition. In this article, a new smart blending technology is described whereby melt components and solid additives are more controllably organized into micrometer-scale and sub-micrometer-scale shapes and arrangements to improve properties or impart functionality to extruded plastics. Chaotic advection is an enabling recent subfield of fluid mechanics for smart blending. It provides a method to controllably stretch and fold melt domains and evolve a multilayered structure leading to derivative morphologies, or indirectly manipulate solid additives. Recent advances in fluid mechanics have thereby been implemented to reconsider how blending is done. A variety of structured plastic materials are producible with a single smart blending device with no device alterations. Several examples and their improved physical properties are shown or discussed. © 2006 Wiley Periodicals, Inc. Adv Polym Techn 25:152,169, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20073 [source] Safety and quality of plastic food contact materials.PACKAGING TECHNOLOGY AND SCIENCE, Issue 5 2003Optimization of extraction time, based on arithmetic rules derived from mathematical description of diffusion., extraction yield Abstract Migration of packaging constituents into food may raise concerns about food safety. This paper describes the conclusions of a EU research project (AIR 941025), aiming to facilitate the introduction of migration control into good manufacturing practice and into enforcement policies. The first part describes a re-evaluation of analytical approaches to extract and identify potential migrants released by plastic materials, viz. comparison of analytical methods, choice of extraction solvents and of fat simulants. Here we focus on the extraction time needed to achieve a given extraction yield. By correlating these parameters with simple and practical equations, it is possible to design alternative tests for control of compliance of packaging plastics. Using a reference experiment (where there is good agreement between experimental and calculated kinetic curves), it is possible to calculate the percentage of extraction which can be achieved in a given time, or the time necessary to reach a target extraction level for other polymer/solvent combinations. A global control scheme is proposed, which indicates whether and when calculation and testing should be applied. Guidelines are proposed, and can be adapted to both industrial control and to enforcement laboratories. Copyright © 2003 John Wiley & Sons, Ltd. [source] Effect of temperature on the cushioning properties of some foamed plastic materialsPACKAGING TECHNOLOGY AND SCIENCE, Issue 2 2003Jorge Marcondes Abstract Foamed plastics are used to cushion products to protect them from shock and vibration. Design data is in most cases derived from laboratory tests, performed under standard conditions. However, during distribution, most shock and vibration events occur under conditions different from those under which the materials were evaluated. Two commonly used foams in packaging, expanded polyethylene and expanded polystyrene, were used to investigate how changes in temperature affect the performance properties of these materials. The materials were tested for shock and vibration under four different temperatures (,17°C, 3°C, 23°C and 43°C). The results show that the properties of expanded polystyrene were the least influenced and those of expanded polyethylene were the most influenced by changes in temperature. Copyright © 2003 John Wiley & Sons, Ltd. [source] Evaluation of plastic packages for guava refrigerated preservationPACKAGING TECHNOLOGY AND SCIENCE, Issue 1 2001Angelo Pedro Jacomino Abstract Guavas cv. ,Kumagai' were packed in several plastic materials and stored at 10°C and 85,90% relative humidity (RH) for 7, 14, 21 and 28 days (+3 days at 25°C). The plastic materials studied were: multilayer co-extruded polyolephine film with selective permeability (PSP), low-density polyethylene film (LDPE), LDPE film with mineral incorporation (LDPEm) and heat-shrinkable polyolephine film (SHR). Guavas not packed were taken as control samples. The physicochemical characteristics of the fruits, O2 and CO2 transmission rates of the packaging materials and gas composition at the package headspace were evaluated. The LDPE film, 69,µm in thickness, with the lowest permeability to both O2 and CO2, led to anaerobiosis and high CO2 concentration inside the packages and promoted physiological disturbances and changes in fruit flavour. The SHR film, 15,µm in thickness, was the most permeable to CO2 and had quite high O2 transmission, which modified the inner atmosphere of the packages slightly. The fruits packed in this film showed a poorer quality than the controls, possibly due to the heat produced during the shrinking of the film. The LDPEm film, 24,µm in thickness, was almost as permeable to CO2 but had reduced O2 transmission, promoting an atmosphere of equilibrium of 3% O2 and 4.5% CO2. Fruits packed in this film kept their skin colour and pulp firmness, suitable for consumption up to 14 days. The PSP film, 35,µm in thickness, had the greatest O2 transmission but just over half of the CO2 transmission of LDPEm, promoting an atmosphere of equilibrium of 0.5% O2 and 4.5% CO2 inside the packages. Fruits packed in such packages kept their physicochemical characteristics up to 21 days. Copyright © 2001 John Wiley & Sons, Ltd. [source] Use of Turkish huntite/hydromagnesite mineral in plastic materials as a flame retardantPOLYMER COMPOSITES, Issue 10 2010Hüsnügül Y, lmaz Atay In this study, the flame retardancy properties of huntite/hydromagnesite mineral in plastic compounds were investigated for potential electrical applications. Before the production of composite materials, huntite/hydromagnesite minerals were ground to particle sizes of 10, 1, and 0.1 ,m. Phase and microstructural analysis of huntite/hydromagnesite mineral powders were undertaken using XRD and SEM-EDS preceding the fabrication of the composite materials. The ground minerals with different particle size and content levels were subsequently added to ethylene vinyl acetate copolymer to produce composite materials. After fabrication of huntite/hydromagnesite reinforced plastic composite samples, they were characterized using DTA-TG, FTIR, and SEM-EDS. Flame retardancy tests were undertaken as a main objective of this research. The size distribution and the mineral content effects are measured regarding the flame retardancy of the polymer composites It was concluded that the flame retardant properties of plastic composites were improved as the mineral content increased and the size was reduced. POLYM. COMPOS., 31:1692,1700, 2010. © 2010 Society of Plastics Engineers. [source] Replication of sub-micron features using amorphous thermoplasticsPOLYMER ENGINEERING & SCIENCE, Issue 7 2002Kari mönkkönen A comprehensive experimental study was carried out to replicate sub-micron features using the injection molding technique. For the experiments, five different plastic materials were selected according to their flow properties. The materials were polycarbonate (PC), styrene-butadiene block copolymer (SBS), impact modified poly(methyl methacrylate), methyl methacrylate-acrylonitrile-butadiene-styrene polymer (MABS), and cyclic olefin copolymer (COC). Nanofeatures down to 200-nm line width and with aspect ratios (aspect ratio = depth/width) of 1:1 could be replicated. In all selected materials, the greatest differences between the materials emerged when the aspect ratio increased to 2:1. The most favorable results were obtained with the use of high flow polycarbonate as the molding material. The best replication results were achieved when melt and mold temperatures were higher than normal values. [source] | |||||||||||||||||||