SPE Library
The SPE Library contains thousands of papers, presentations, journal briefs and recorded webinars from the best minds in the Plastics Industry. Spanning almost two decades, this collection of published research and development work in polymer science and plastics technology is a wealth of knowledge and information for anyone involved in plastics.
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Conference Proceedings
Failure Mechanism of Panel Leak Formation in Solution Containers
Large-volume flexible solution containers are gaining in popularity in the medical products arena in recent years. The composition of these products often involve materials other than PVC. These products present peculiar engineering challenges, particularly in relation to the formation of panel leaks during packaging, storage, and distribution, due in large part to the volume of solution in the container. An extensive investigation of these panel leaks led to the elucidation of a multi-step failure mechanism. Understanding the failure mechanism directed efforts to enhance the robustness of the final product.
Effect of Dynamic Melt Manipulation and Flow Induced Orientation on Biaxial Stress in an Injection Molded Coupon
This study investigates the effect of locally induced molecular orientation imparted by dynamic melt manipulation based injection molding has on the biaxial stress in an injection molded coupon. Melt manipulation refers to a process where the polymer melt is manipulated during molding beyond normally encountered in conventional injection molding. The technique studied in this paper is Vibration Assisted Injection Molding, where a conventional injection molding machine is augmented by oscillating the injection screw (in the axial direction) during the injection and packing phases. The localized final molecular orientation and morphology that results dictates the resultant product response. Typically improved mechanical properties are observed. For this study the ultimate tensile strength of injection molded polystyrene was investigated. A previous study showed a dramatic tensile strength increase in the regions of higher melt manipulation induced molecular orientation along the direction of flow. To elicit the effect on the strength in the transverse direction, smaller test specimens were machined uniformly perpendicular to the flow length and tested. Comparisons were made with specimens tested axial to the flow.
Surface Properties of Hydrosilylated Polyolefins Annealed in Supercritical Carbon Dioxide
Two hydrosilylated polyolefin compounds, a polydimethylsiloxane (PDMS) end-capped PP and a lightly crosslinked PE sample, are annealed in supercritical carbon dioxide (scCO2). The contact angle, instead of Si concentration, of both samples is found to increase with annealing temperature. Increasing the scCO2 pressure leads to higher Si concentration on the surfaces of both samples, but opposite trends in contact angle: an increase in contact angle on the hydrosilylated PP and a decrease on hydrosilylated PE. The hydrosilylated PP surface shows SiO2 particles after annealed in CO2 at 120 °C.
Distribution of Minor Phase Components and its Influence on the Film-Substrate Interface in Film Insert Moldings
In most cases, the injection molding conditions significantly affect the morphology and subsequently the bulk mechanical properties of the product. This effect is more pronounced when polymer blends or composites are used where the extent of dispersion and orientation of the disperse phases or reinforcements would affect the final property of the molding. In film insert moldings, it is important to ensure that the film is firmly attached to the substrate. Hence, the distribution of the disperse phases (Acrylonitrile-butadiene-styrene in polycarbonate) at the interface is investigated to establish correlations between phase anisotropy, film-substrate adhesion and bulk mechanical properties.
Enhancing the Performance of Polymeric Dyes in Polypropylene
Clarified polypropylene (PP) continues to find increasing uses as polymer and additive improvements allow for its incorporation into applications where resins such as polystyrene or acrylics have traditionally been used [1]. Second and third generation clarifiers have improved the clarity, processing properties, and the organoleptic properties (residual odor and taste), opening the way for more extensive food contact applications [2,3]. With the expanded use of clarified polypropylene comes the need appropriate colorants which will give high clarity, low haze, deep coloration, and no migration. Polymeric colorants have shown to possess these properties, further expanding the market potential for clarified polypropylene. This paper will explore the use of various modified wax compounds and their effects on the residual haze of clarified PP molded with GemToneTM Polymeric Colorants.
Development of an Extended Predictive Controller for Injection Speed
An approach for controlling the injection speed is developed using a new form of predictive control termed extended predictive control (EPC). EPC is a practical scheme that can be implemented on a wide range of industrial processes. The major contribution of EPC is that only one tuning parameter is used in a simple and effective way to tune the process closed-loop response. The main features of EPC are practically illustrated on controlling the injection speed of a 150 tonne machine and three temperature zones on a steel cylinder that used to melt the plastic material inside the barrel. The control performance of EPC is compared with other predictive controllers with improved results.
An In-Process Ultrasonic Approach to Investigating the Relaxation of Orientation and Disorientation of Polymer Melts
The orientation and relaxation behaviors of a low density polyethylene melt after undergoing a shear flow in a restricted channel were investigated by using ultrasound. A capillary rheometer was used to force the polymer melt through a slit die equipped with pressure, temperature, and ultrasound sensors, and the variation of ultrasound velocity traversing the melt was measured. Experimental results revealed that due to different mechanisms involved, the relaxations of orientation and disorientation processes show different dependences on temperature and shear rate.
Hierarchical Structure Developed in PC/ABS Closed Spiral Flow Injection Molding
The internal structures of the injection molded parts are complex and greatly affect on the mechanical properties. The closed-spiral flow injection molded technique was used to observe the microstructure development. Through thickness direction, different morphological structures were observed. The changes in morphology can be abrupt, especially at the regions closest to the external surface of the specimen, while a more gradual transition was observed with increasing depth of the specimen. The width of each layer and the characteristics (i.e. shapes and sizes) of the cavities are believed to have a direct impact on the final mechanical properties of the moldings. Hence, it is essential to understand the morphology of the moldings in order to effectively predict the final properties at different molding conditions.
Production of Novel Sound Absorption Microcellular Foams Using High Internal Phase Emulsion Polymerization
High internal phase emulsion (HIPE) polymerization foaming process is controlled for production of novel foams with various microcellular structures and morphologies. The objective is to produce lighter weight sound insulation packages with superior acoustical performance for passive noise control in automotive structures using microcellular foams. This was achieved through the control of the foaming process for production of variable microcellular structures and morphologies for the novel foams under investigation. As an attempt to reduce the cell size and increase microcellular density and open cell content without sacrificing the mechanical prosperities, the microcellular foams combining viscosity improvers into the conventional formulation of styrene and water system were prepared via high internal phase emulsion polymerization.
A Test Apparatus for Characterizing High Strain Rate Properties of Natural Rubber
Elastomers are used to dampen vibrations and minimize structural damage caused by impact loads because of their low modulus, high damping and large extensibility. Applications include isolation bearings, engine mounts and shock pads, where the loads are dynamic in nature. A testing apparatus is developed to obtain the deformation and fracture properties of carbon-black filled natural rubber under impact loading in pure shear. The specimen and the grips are designed to be interchangeable with other existing test machinery such as an MTS servo hydraulic machine. Piezoelectric load cells and a high-speed video camera are used to measure forces and displacements, respectively.
Manufacturing of Plastic Lens Mold Conformal Cooling Channel Using Direct Metal Laser Sintering and Spray-Formed Tooling Process
The development of plastic lens is advancing not only in the direction of micro size lenses but also for larger dimensions. Because of an excessive thickness of product, the cooling time for large lenses is much needed and dimensional accuracy of difficult to achieve. In this study, we produce molds for plastic lens using 3 kinds of methods, (a)using traditional method, (b)the process of Direct Metal Laser Sintering(DMLS), and (c)the Spray Formed Tooling(SFT), where conformal cooling channels are designed inside the molds of DMLS" and "SFT". The cooling efficiency of manufactured molds is then compared through injection molding experiments. We also analyzed the application potential of manufacturing mold in the industry field."
Effect of Molding Conditions on Morphology and Structure of Recycled-PET
Mechanical and morphological properties of injection moldings are known to be highly dependant on molding conditions, e.g. barrel and mold temperatures, injection speed, and injection pressure. However, the not all conditions impart the same degree of influence on the final properties of the moldings. Here, the properties of recycled poly(ethylene terephthalate) (RPET) were gauged based on accurately measured injection molding conditions, i.e. transducers embedded in the mold cavity were used to measure the resin pressure and speed. Initial investigations have shown that injection speed exerts more influence on the properties of RPET than injection pressure.
Effect of Temperature and Pressure on Surface Tension of Polystyrene in Supercritical Carbon Dioxide
The surface tension of polystyrene in supercritical carbon dioxide is determined experimentally by Axisymmetric Drop Shape Analysis-Profile (ADSA-P), where a high pressure and temperature cell is designed and constructed to facilitate the formation of a pendant drop of polystyrene melt. As pressures and temperatures increase, the surface tension of polystyrene decreases. A linear relationship is found between surface tension and temperature, and between surface tension and pressure. The slope of surface tension change with temperature is dependent on pressure.
Reactive Extrusion Process Characterization: Q/N Mapping Method
Reactive extrusion is an important industrial compounding process. Usually, a product is manufactured by the product by process" approach without direct monitoring or control of the critical in-situ chemical reaction. By means of a rapid steady state throughput (Q) and screw speed (N) mapping method described in previous publicat mean residence time and physical properties. The reactions examined include polymer degradation (peroxide cracking of Polypropyleneions a reactive extrusion processes is characterized by several model parameters derived from the on-line monitoring of the mixing intensity and time as measured or estimated from power consumption Polyester degradation) and in-situ grafting (Polyamide 6/SMA). In this study the effects of Q and N on melting mixing and rates and extent of reactions that change viscosity were quantified process changes in reactive extrusion systems with linear models of power consumption and mean residence time. Since these reaction systems tend to be controlled by interfacial area generation the effects of mixing intensity and time were captured. Using the proposed method such as rate optimization can be made without compromising product quality e.g. extent of reaction."
Dynamic Mechanical, Thermal and Fracture Toughness Properties of PC/ABS Blend System with Incorporation of Pcoligomer
The successful blending of polycarbonate (PC) and acrylonitrile butadiene styrene (ABS) has led to its many commercial applications such as electronic housings and automotive accessories. The presence of low molecular weight components in any resin is usually avoided due to their detrimental effects on mechanical performance of the final part. In this case, however, the incorporation of PC-oligomer was found to have enhanced the toughness and deformability of the molded product, even though the miscibility between the PC and ABS phases were poorer judging from the increased differences in terms of their glass transition temperatures.
Extrusion Compounding Fundamentals: An Industrial Perspective on Melting and Mixing of Polymer Blends
The classical explanation that melting and mixing take place sequentially in an extruder will be examined in view of the melting mechanisms existing in the literature, most notably laminar conductive and mixed melting models. Recent results utilizing the pulse perturbation technique suggest that phenomena such as lubricated melting, and morphological development involving phase inversion take place during dissipative mix-melting of polymer blends when the onset and rates of melting of each ingredient are different. Traditional polymer dispersion principles based on melt mixing of non-interacting particles can still be used to some extent, but with modifications, in view of the complications brought upon by the high concentration of the minor ingredient present.The melting and mixing principles thus derived have a profound influence on many commercially important compounding processes, especially plastic and rubber blending with in-situ grafting, or with in-situ rubber crosslinking, and compounding of polymers and plasticizers. The morphological development schemes during compounding introduced in the literature can now be viewed using the derived mixing principles in conjunction with the melting mechanisms described above.
Comparison of Shear and Butt Joint Designs for Vibration Welding of Polypropylene-Based Nanoclay Composites
Polymer/clay nanocomposites are attractive because addition of small amounts of clay platelets increases the modulus, strength, and reduces permeability of the material. Previous studies showed that for hot plate, vibration and ultrasonic welding, the weld strength decreases with increasing nanoclay content. It was theorized that squeeze flow during welding produced adverse orientation of the clay platelets weakening the weld. Therefore, vibration welding of butt and shear joints that produce different flow patterns were evaluated. Test results for vibration welds show that even shear joints had significant reductions in weld strength probably due to vibration induced flow and orientation.
Processing of Nanocomposites with Gradient Architectures in Twin Screw Extrusion for a Novel Combinatorial Approach
Nanocomposites, with superior material properties, have promising potential applications in almost every field. Using the dynamic characteristics of the TSE, the present works aims at developing a novel combinatorial approach for rapidly and efficiently assessing the processing-structure-property relationships for polymer nanocomposites. This approach is based on creating gradient architectures through step changes in the feed input. These gradient architectures are then predicted by convolving the step input with the Residence Volume Distribution (RVD) of the TSE process.
Causes of Melt Temperature Variatons Observed in the Nozzle during Injection Molding
Injection molders often assume that the temperature of the melt prior to injection is either equal to the barrel temperature or the temperature measured from a purge shot. Data obtained via an intrusive temperature probe in the nozzle showed a sharp increase in the melt temperature during injection followed by gradually decaying temperatures during holding and cooling. The effects that adiabatic compression, shear heating, and the initial thermal variation have on the observed temperature increase were determined through experimentation. It was found that adiabatic compression had a significant affect on the temperature increase, but the majority of the observed variation occurred as hot melt from the barrel flushed cooler melt out of the nozzle.
Comparing Laser Transmission Principles
In this paper simulation results of the simultaneous-, contour- and quasi-simultaneous laser welding processes will be presented. The calculations of this paper were performed by using a finite element analysis to understand the influence of the welding parameters: scanning velocity, frequency of scans, pressure and laser power. It will be shown how the process parameters affect the temperature distribution in the joining area. The FEA-model includes the heating phase and cooling phase and uses temperature dependent material data. Absorption in the transparent part and the convective cooling and emissivity at the surface of the weld interface were considered.
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