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This study shows how the parison of a large (1000 liters) blow molded water container can be optimized (programmed) to improve its mechanical performance as related to hydrostatic loading while keeping the weight of the part to a minimum. This case study is composed of two parts. The first (baseline) case is aimed at validating the computational model by comparing the material distribution predicted by the model with available experiments. As an input to the baseline simulation, the initial thickness variation along the parison was obtained from direct measurements from the field and used for the baseline case. The final material distribution obtained from the blow molding simulation is then compared to those of the real part. A structural analysis is next performed using static implicit FEA to predict the container's performance when it is completely filled with water and enclosed in a steel cage. The objectives are to compute the total deformation, and the total (von-Mises) stresses. The variable material distribution obtained from the blow molding step is used in the structural model. In the second part of the case study, the initial parison thickness used in the field was challenged and optimized. The objective of the optimization (programming) was to find out the minimum initial thickness of the parison that will increase the minimum final thickness to a desired value. The optimized container is lighter than the original design by 10% while at the same time being more rigid.
In this study, we investigated the structure and properties of multilayer films with a nanocomposite core layer. The core layer materials considered were polypropylene (PP), polylactic acid (PLA) and polyamides (PA-6) and the side layers were polyethylenes (PE). The multilayer films were obtained from the extrusion cast or film blowing processes. The structure of the films was investigated using microscopy, X-ray diffraction and differential scanning calorimetry. The properties studied were the mechanical properties in terms of modulus, strength and elongation in addition to tear, haze and barrier properties of the films. The effect of nanoclay content in the range of 1 to 7.5 wt% was investigated. In terms of structure, it was found that the clay platelets aligned in the films plane. Exfoliation was observed for the PA nanocomposite systems, some intercalation was observed in the case of PLA-nanoclay and no change in the clay spacing was observed in the case of PP-nanoclay system. For the performances, it was generally found that the presence of clay enhanced the modulus, tear and barrier properties, but little change was observed in the other properties. The barrier properties correlated with the state of dispersion of the clay platelets. Multilayer films with PA nanocomposites showed the highest barrier to oxygen permeation.
Film insert moldings were fabricated by using PLA as film and POM copolymers with various oxyethylene repeating units. The interfacial adhesion properties between film and substrate were determined by micro-cutting analyses. POM containing high oxyethylene content shows superior adhesive strength than those with low oxyethylene content. The growth of the POM-PLA mix layer was explained by mechanism of “negative pressure” in POM phase attributed by POM crystallization and partial miscibility between POM and PLA.
A transparent, high temperature thermoplastic Polyetherimide (PEI) resin blend with improved impact resistance and enhanced hydrostability has been developed for healthcare applications. The two-phase resin blend can be sterilized using traditional methods such as high temperature autoclave, ethylene oxide, gamma radiation, as well as STERRAD® NX®, a low- temperature hydrogen peroxide plasma sterilization process. Injection molding of the new resin blend and mechanical property and color retention after sterilization is described and compared to polyphenylsulfone (PPSU).
In this study the effect of injection mold venting design combine with CAE simulation results to improve the product surface quality was verified. Various venting design (numbers and locations) and injection speed (100, 200, 300 mm/s) were used in the experiment. The melt flow evolution was verified by a numerical simulation method. The developed pressure of trapped air inside cavity was derived and associated with part surface quality. Highly compressed trapped air from high injection speeds led to poor surface quality due to burning of material. For solving the burning mark and surface quality improvement, venting locations and sizes could thus be determined from experimental and simulation results to offer adequate venting.
Coating operations such as spin coating, curtain coating, role coating, slide coating, slot coating, and etc. are dated from long time ago and still considered very important processing. Slot coating is considered very important specially for the manufacturing of liquid crystal display parts. Photo resistant is coated on the glass and is sent to next process to make TFT board. Coating quality such as uniformity of coating thickness can be divided into two categories, which are machine direction quality and transverse direction quality. Machine direction quality is related to die lip design and operation conditions whereas the transverse direction quality is related to flow uniformity inside of the die. The flow uniformity is governed by flow balance in the die. The most important design factors for the inside die geometry are manifold and land. Through this study the flow balance according to the manifold design has been examined by computer simulation. The design variables of manifold were manifold volume and manifold shape. Well designed manifold gives good flow balance in the die land and consequently gives good coating uniformity. Good manifold design has been investigated by computer simulation.
This study combines two processes. A one dimensional tube was used to investigate the gas penetration characteristics including penetration length and hollowed-core ratio under varied parameters including gas delay time, short shot and wax temperature. The wax properties were tested by importing the CAE software to simulate the wax filling and gas penetration length. The experimental results show gas-assisted injection molding is successfully applied to wax injection. Simulation results for wax filling and gas penetration are in agreement with the experimental results except for gas pressure, due to the viscosity deviation.
During the last decades, the food, pharmaceutical and many other industries have seen several changes in packaging technology and applications because of new consumer demands and market trends. These drivers can be summarized as requirements for high quality, freshness and extended shelf-life of products, with easy-to-use and resistant packaging made with lighter, cheaper and recyclable materials. On the other hand, public demand and awareness for food safety has become a significant concern. This has even intensified on the recent regular outbreak of Listeria and Salmonella bacteria in various area of the world, following the consumption of contaminated meat and cheese products. The outbreak has prompted the public awareness to question food quality in stores and technological solutions that could prevent contamination and/or alert consumers may provide better public protection. Finally, the global market for materials and films used in packaging is very large. When decomposed into various segments such as controlled, active, and smart or barrier packaging, the volumes used and annual growth rates are significant in addition to other concerns such as sustainability. The performance of polymer films and multilayer packages are the result of the microstructure that is imparted to the material as a result of complex interactions between the resin and the thermo- mechanical history that it experiences during processing. This microstructure is strongly influenced by molecular parameters of the resins used (molecular weight, molecular weight distribution, branching, co-monomer type and content, etc.), their layout in multilayer structures and the additives used as well as the rheological, thermodynamic, thermal properties and the crystallization kinetics under the processing conditions. In the past, most of the studies were directed to the improvement of structural properties of films and multilayer structures (mainly mechanical: strength, tear, toughness etc...) and muc
Polycarbonate (PC) is one of the engineering plastics and it has high mechanical properties and transparent characteristics. PC is widely used for the outer case of mobile electronic products and lamp covers for automobile, and so on. However it has a weakness in low surface hardness, which is a low scratch resistant property. Scratch resistant property is considered very important specially for the outer case usage. Scratch resistant property is evaluated by pencil hardness. It was observed that the pencil hardness of injection molded PC sheet was dependent of its surface roughness. The specimen having convex or concave shaped surface had high pencil hardness. Deformation and stress concentration on the specimen surface have been analyzed during the pencil hardness test through computer simulation. Convex and concave shaped surface showed small deformation compare with flat surface. This made pencil hardness high. The surface of injection molded product can be controlled by controlling mold surface. Consequently the high pencil hardness can be achieved by designing the surface roughness of mold surface.
The use of polylactic acid (PLA) in durable applications such as appliances and computers has been limited by PLA’s inherent property shortcomings, such as low impact strength, low heat distortion temperature, and lack of flame retardancy. These issues have been overcome via blending with engineering plastics, applying new compatibilization technology and using unique flame retardant additives. The resultant compositions have an excellent balance between heat resistance, impact resistance and flame retardancy. One such composition achieves a UL 94 rating of V-0 at 1.6 mm thickness, a notched Izod impact value at room temperature up to 11.6 ft-lbs/in and also exceeds a threshold of 100°C in heat distortion temperature (HDT) at 66 psi load. This bio-derived blend with >30% bio-content has exceptional properties and has taken PLA into the realm of engineering plastics. These enhancements will enable PLA to replace petrochemical- based materials in many demanding durable applications.
Various models of foam deformation have been formulated during last decade, but most of the models make use of basic concepts of continuum mechanics in combination with finite element method with limited consideration of specific micro-mechanisms of foam deformation and fracture. Three types of deformation and fracture mechanisms of oriented foams were classified: 1) Large reversible deformation, 2) Large elasto-plastic deformation and 3) Brittle fracture of faces and/or edges of individual cells. In this paper, five polymeric materials which have completely different deformation behaviors are selected and their fracture behavior was observed by scanning electron microscope. Among them, three polymeric foams with distinctively different deformation and fracture mechanisms are selected based on the classification for detail analyses.
The Method of Ellipses has been applied to short and long fiber polymer composites to evaluate fiber orientation. The resulting orientation distributions are compared at various percentages of fill for injection molded center-gated discs. Preliminary results suggest that an increase in magnitude in fiber length leads to significantly reduced fiber orientation in the radial direction (Arr). There is little effect on the Arz component of the orientation tensor, however, except at large percentages of fill.
Individual polymers are known to exhibit a wide range of characteristics that can be manipulated physically, thermally, and chemically. Furthermore, combining these materials through various mixtures can extend the ranges in properties offered by polymers. An interpenetrating polymer network (IPN) is a typical example of a multi-component polymer material. These polymers are closely related to other multi-component materials, containing completely entangled chains, such as polymer blends, grafts and blocks copolymers. IPN is a multiphase polymer material comprising of two or more networks which are at least partially interlaced on a molecular scale but are not covalently bonded to each other and cannot be separated unless chemical bonds are broken. The most common classifications of IPNs are full- or semi-IPNs. Compositions in which one or more polymers are crosslinked and one or more polymers are linear or branched are semi-IPNs, when both polymers are crosslinked in full are full-IPNs. These concepts were developed in the 70’s, when several research groups studied different systems in some detail [1-4]. For example, the important commercial system developed by Fischer  in the early 1970s involved ethylene-propylene-diene monomers (EPDM) in combination with isotactic polypropylene. The result was a material with excellent energy- absorption capacity In recent years only limited research has been reported in this area. From the available literature it is possible to infer that IPNs possess several interesting characteristics when compared to normal polymer blends, because the varied synthetic techniques yield IPNs of such diverse properties that their engineering potential is vast. These networks exhibit dual phase continuity, meaning two or more polymers in the system form phases that are continuous on a macroscopic scale and the kinetics of formation of the individual networks and the process of phase formation (phase separation) influence the final properties
Failure criteria of the heat sealed part of aluminum (Al) and linear low density polyethylene (LLDPE) laminates made by an impulse type heat-sealing machine were investigated. Heat-sealing was performed in the machine and transverse directions with reference to the orientation of the aluminum sheet. The Al/LLDPE laminates consist of three layers, i.e. one sheet of aluminum as the outermost layer, which provides the strength and rigidity, and two sheets of LLDPE oriented in perpendicular directions, which make the laminates heat-sealable. Despite the presence of LLDPE films oriented in both directions, the direction of heat-sealing was found to affect the seal strength. This indicates that the heat-seal strength is primarily dependent on the molecular orientation of the LLDPE films at the seal interface.
In the recent years, with the increasing demand of energy and the rapid consumption of fossil fuels, a variety of alternative energy are rapid development to replace traditional energy. Solar power, is one of the best sustainable energy and nowadays widely used for generating electrical power. In this study, the solar condenser of converted efficiency is investigated into conventional and injection compression molding process with various parameters. The experimental results show that the higher mold and melt temperature can increase converted efficiency of condenser during conventional injection molding (CIM) process. In all conventional molding parameters, the best converted efficiency can enhanced 51.4 W/m2 (7.60%). The injection compression molding (CIM) can achieve better efficient performance than conventional molding process.
In this study, a gas-assisted heating system for mold surface temperature control was established. Two gap size control modes (A and B) of the gas channel and the heating results of both cavity and core sides were investigated, moreover, the effective heating area for gas heating expansion angle were determined as well by using gas flow rate 300l/min. The results show that the mold temperature difference on the gas inlet of core and cavity surface can be reduced from 39.8 °C to 1.4 °C under 5mm gap size with B mode. For the hot gas heating expansion angle, it directly affected heating area, and being relative with the entrance of gas channel. A case study of micro-molding for double sides 0.4mm thin wall plat (L/t=200) with micro-dot arrays shows that replication accuracies reach higher than 90% when molding at a mold temperature of 150 °C, an improvement of 25.3% over injection molding at the regular mold temperature of 90 °C.
Polyoxymethylene (POM) or polyacetal is an engineering thermoplastic resin used for the past 50 years, primarily in injection molded articles. POM’s benefit is derived from its strength, stiffness, toughness, lubricity and inherent chemical resistance. This combination of properties makes POM a preferred material for fuel exposure applications — both gasoline and diesel. This paper explores the influence of aggressive fuels on the properties of several commercial POM grades. Specifically, this work reports on the performance of POM exposed to different hydrocarbon-ethanol blends and to various low-sulfur diesel-biodiesel blends.
The purpose of this study is to develop a foaming control for Gas Counter Pressure (GCP) combined with mold temperature control technology during the MuCell process and to investigate its influence on mechanical properties. The results show that under GCP control alone, foam qualities and the thickness of frozen layer may be affected. Further, the tensile strength increases, but impact strength falls. The lower the mold temperature control for the frozen layer, the more obvious is the increase in bubble size, while the greater the average bubble size, the lower the tensile strength. Using both GCP and the mold temperature control, when mold temperature was higher while get average bubble size small and uniform, resulting in improved tensile strength.
Next to the established packaging market the interest for biopolymers in technical application increases more and more. Especially the technical industry is interested in substituting oil-based polymers with biopolymers. In view of that, the focus of the work described here was on optimization of injection molding of polylactide (PLA) in order to improve material performance for technical applications. Furthermore, the effects of poly-D-lactide (PDLA) as nucleating agent, fibers and modifiers on material properties (e.g. heat resistance, mechanical properties) are reported.
The foremost reason of incorporating pigments in polymers is to introduce color either for aesthetic reason or because of functional needs. For dispersion of these pigments, the optimization of extrusion process parameters is required. In present study, a regression model was generated to illuminate the effect of processing parameter on the color properties of polymers by employing a 3 level full factorial design for response surface. The three processing parameters were temperature; speed and feed rate during extrusion of polymer compounding. Design expert software was employed to carry out the experimental designs, statistical and numerical optimization. The analysis of variance (ANOVA) reveals that the color parameters L*, a* and b* are significantly influenced by the considered parameters. The optimization of L*, a* and b* indicates that they are closer to the required target values at 241.9°C, 737.6 rpm and 25.3 kg/hr.
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