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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Investigation of Optimum Conditions of Thin-Wall Injection Molding Process
Optimum conditions of thin-wall injection molding process of a cellular-phone cover are investigated via the use of computer-aided-engineering simulation and experimental measurements. CAE simulation using C-MOLD and a set of experimental tests based on design of experiments (Taguchi's method) scheduling are performed to determine optimum process conditions of an injection-molding machine by minimizing the shrinkage and warpage of the molded part. Effects of various process parameters of the injection-molding machine on the shrinkage and warpage of the molded part are also examined.
An Investigation of the Impact Behaviour of Rotomoulded Polyethylenes over a Wide Temperature Range
This paper examines the relationship between the impact strength of rotationally moulded polyethylene parts and the dynamic mechanical properties. A range of conventional linear low density polyethylene powders (LLDPE) and metallocene polyethylene powders (MPE) were rotationally moulded and tested. Falling weight impact tests were carried out over a temperature range from -60ºC to 20ºC. Dynamic mechanical thermal analysis (DMTA) was carried out from -100 to 90ºC, at different frequencies. Transitions evident in DMTA results are used to explain sub-zero maxima in the impact strength of the polymers tested.
Investigation of the Local Residence Time Distribution in Special Mixing Elements for Co-Rotating Twin Screw Extruders
Tightly intermeshing, co-rotating twin-screw extruders are commonly employed for tasks requiring good mixing. Mixing involves several mechanisms: longitudinal mixing laminar shear mixing and dispersive mixing. This work focuses on the longitudinal mixing behavior investigated for special twin screw mixing elements.We used a model extruder where two residence time probes were mounted to the barrel. For the experiments we varied throughput, screw speed and the material. By applying a deconvolution algorithm we were able to determine the local residence time distribution in the measuring section. The residence time distributions of the mixing elements were compared to those of standard elements (e.g. conveying elements).
Investigation of the Processing Characteristics and Mechanical Properties of Metallocene Polyethylene Foams for Rotational Moulding
The object of this work is to investigate the foaming characteristics of Metallocene-catalysed polyethylenes for rotational moulding. This paper reports on the results of ongoing experimental investigations in which rheological and thermal parameters are related to the polymer structure and mechanical properties of metallocene polyethylene foams. Through adjustments to moulding conditions, the significant processing and physical material parameters, which optimise metallocene polyethylene foam structure, have been identified. The results obtained from equivalent conventional grades of polyethylene (PE) are used as a basis for comparison.
Isotropic Residual Stresses in Thermosetting Resins: A New Instrument for Direct Measurement
The development of isotropic residual stresses is important in thermoset cure. These stresses are conventionally determined by curing the material in a cylindrical tube having a large length-to-diameter ratio. Despite its popularity, questions arise whether the stresses are isotropic or not in this method. To surmount this ambiguity, we propose a new method of measuring the build-up of isotropic residual stresses by confining the thermoset resin in a spherical geometry, thereby maintaining a truly hydrostatic deformation on the material. This paper describes the method and presents preliminary results on a model epoxy resin.
The Job Seeker Trilogy Preparation - Resume - Interview
While this trilogy is of value to anyone seeking a career change, it will be especially helpful to those now re-entering the job market after 10, 15 and 20 plus years, long-term career employees who are discovering that the process of job searching has dramatically changed, both good and bad over that time. The computer and the internet have created new and better tools; resources with new protocols and methodology. Many initially are overwhelmed; and, most find themselves unprepared, adding more stress and frustration to the emotional impact of an unexpected termination. Worse, the search process has also become increasingly more impersonal, requiring a different mindset to be successful. I know firsthand, having ‘been theredone that’, from being in the same situation less than five years ago, after closing a product design & development group I founded and managed for 20-years. If I knew then what I know now, I would have proceeded differently – and that is what I wish to share with you, hopefully making your career move easier, more effective and more successful in a shorter time-line. There are three major components to any search, and while books have been written on each, this trilogy will present the essence of all three – Job Search Tools for the New Millennium, will cover mental preparation and becoming informed on the expanded resources and options now available; the second, Your 30-Second Window of Opportunity – the Power Resume, will help you prepare an effective and dynamic resume and cover letter; and the last, The Interview – It’s a Mating Game, So Know the Rules of Engagement, explores mastering the phone and onsite interview, with the appropriate follow up.
Joining Applications in Exterior Automotive Panels Made of TPO (Thermoplastic Olefin)
Metallocene-catalyzed polyolefin thermoplastics became available to product designers when production was scaled up from pilot-plant levels to industrial-quantity production in the middle 1990s. The first large volume use of this material, referred to in industry as TPO, was exterior body parts for 2002 model year vehicles. As designers made decisions about where and how to use the material, it logically followed that an answer was needed to the question of how best to assemble these parts. This paper gives an overview of several new or improved applications of thermoplastic joining technologies to these parts, including ultrasonic spot welding, vibration welding, thermal staking, and ultrasonic inserting.
Key Elements in the Survival of Plastics Recycling Industries
The growth of the plastics recycling industry was spurred by increased resin prices and the landfill crisis of the 1980's. Many of the recycling companies that started in the 1980's and 1990's quickly learned that economic recycling of plastic waste was a difficult and challenging task. For many of these companies, the problems were overwhelming and they went out of business. Those that survived into the 21st century are a unique group of entrepreneurs. The bulk of the survivors are small companies with sales under $20 million.In this study, 36 plastic recycling companies in the U.S. and Europe were evaluated to determine the elements that aided their survival. Three elements that were present in the majority of these companies were: an ability to develop and maintain their own technology, financial or technical support from external sources, and strong leaders who were determined to make the business survive. These companies are the models for their industry. The stories of these companies could be of particular value to the emerging automotive and electronic post-consumer plastics recycling industry.
Keys to Customer Loyalty in the Engineering Plastics Industry
Traditionally, many resources are dedicated to the acquisition of new customers in the engineering plastics industry. While constant replenishment/expansion of the customer base is important, it is critical not to lose sight of the growth potential of existing customers. The costs (and risks) involved in maintaining and growing these accounts are typically much lower than new account acquisition.As a result of over 1000 recent interviews, BRG Townsend has been able to identify, by segment, the attributes that are prerequisites for new account penetration and those which drive existing customer loyalty. By aligning resources with customer loyalty preferences, suppliers can more profitably manage their marketing resources.
Laser Assembly Technology for Planar Microfluidic Devices
The assembly of plastic microfluidic devices, requiring high positioning and welding accuracy in the micrometer range, was successfully achieved using a new technology based on laser transmission welding combined with the mask technique. In this paper we present a high-end laser assembly system for the joining of microfluidic plastic parts with its main related process characteristics and its potential for low-cost and high volume manufacturing. The innovation is a special arrangement of diode laser with a mask to generate micro welding seams with freely definable geometry. A fully automated mask alignment system with a resolution of 2 ?m and a precise, non-contact energy input allows a fast welding of micro structured plastic parts with high reproducibility and excellent welding quality.
LFT-D-ILC - Innovative Process Technology Decreases the Costs of Large-Scale Production of Long-Fiber-Reinforced Thermoplastic Components
In the European industry fiber reinforced thermoplastics have been firmly established for years for the purpose of large-scale production of structural automotive components. In particular, the newly developed LFT direct processing method has increasingly achieved its objectives due to its cost saving potential and excellent material characteristics.As a manufacturer of LFT processing plants Dieffenbacher GmbH & Co. meets the high requirements regarding material quality in order to guarantee a process for safe part production including an acquisition and evaluation system (SPC) of process data.The effect of material quality control will be demonstrated and the process technology will be introduced in this paper. Influences of the in-line compounding on mechanical properties will be discussed.
Load-Carrying Ability of Bolted Connections in Glass Mat Thermoplastics
Compression molded samples of GMT (Azdel R300B01N) were connected to metal steel plates with a bolt M8. No metal inserts were applied. Metal washers were placed between GMT plate and steel plates both at one side and at two sides of the GMT plate. Tests with and without a bold pre-stressing force were carried out. The load-carrying ability was tested with in-plane loading at rates of 1 m/s and 1 mm/s. A nominal bearing stress of 200 MPa seems to be a safe lower bound. Pre-stressing increased the maximum force sometimes with more than 75%. However, it was shown, that it pre-stressing can change the fracture mechanism from bearing fracture into the brittle tensile fracture. Cleavage fracture occurred when a washer with a diameter of 30 mm was used without pre-stressing and a loading rate of 1 m/s was applied.
Long Glass Fiber Composites: Rapid Growth and Change
Long fiber reinforced thermoplastic composites (LFRT) are one of the fastest growing segments in the plastics markets in North America and Europe, experiencing 30% per year growth, over the last decade. Development of new large part applications in the automotive market will continue to drive the growth of these materials.This paper will review the history of the LFRT composite market and give an up-to-date overview. It will also cover the new emerging in-line compounding technologies and what role they will play in this market. An overview of the current technologies will also be covered. The information presented is a brief excerpt from a more detailed study conducted by BRG, at the end of 2001.
Long-Term Creep and Recovery of Polypropylene Impact Copolymer
Effect of temperature on impact PP copolymer was studied during long-term creep and recovery (time duration-840 hrs) at two different stress levels. The experiments were performed at different temperature above glass transition (Tg) to probe the effect of temperature on the entropic nature of the impact PP copolymer due to presence of physical entanglements (networks). The recovery tests were performed in the absence of external forces. This provides accurate information with regard to the effect of temperature on the statistical behavior of the material. Those data were successfully used for finite elements model and packaging applications.
Luster Measurement of Single Textile Fibers by Aspecular Laser Scattering and Image Analysis
Luster is a key appearance attribute of textile fibers that may be defined by how glossy they appear. In textiles made from synthetic polymers, it is typically desirable to have low luster fibers that emulate the appearance of natural fibers such as cotton or wool. Assessment of luster for fibers is often qualitative in nature. A simple quantitative technique based upon laser scattering from a single fiber at an aspecular angle (75 degrees) combined with charge coupled device detection and image analysis was developed. A strong correlation was shown between a defined scattering ratio, obtained from the laser scattering data, and a five level panel luster test. A second correlation based upon fiber standards impregnated with titanium dioxide particles was also made.
Material Challenges in Medical Micromolding Applications
Processors in the medical field are being challenged to mold parts with smaller and smaller features. Many new lab-on-a-chip devices are designed to move biological fluids with micro liter volumes. This requires flow channels and other features that are on the order of microns. Molding parts with features of this size and with the tolerances required for medical applications presents several unique challenges in the selection and processing of the appropriate material. This paper discusses some general principles for material selection in the medical micro-molding field. In addition, several case studies are provided to illustrate solutions on real parts.
Mathematical Modeling of the In-Mold Coating Process for Injection Molded Thermoplastic Parts
In-mold coating (IMC) for thermoplastic parts is employed either to protect products from outdoor exposure or to improve the surface appearance as in automotive applications, or both. The coating material is injected into the closed mold and advances by compressing the thermoplastic substrate. This paper presents a mathematical model for the process. The compressibility of the thermoplastic substrate is taken into account. The corresponding computer code for the coating material filling and packing in a simple geometry has been developed and the results have been verified by experiments.
Measurement of Peroxide Content of Crosslinkable Polyethylene by Differential Scanning Calorimetry
The first rotational molding grades of polyethylene appeared in the 1950's. In subsequent years considerable effort was expended to improve the performance of these polyethylenes through peroxide-initiated crosslinking. Success was achieved due to the availability of peroxides with sufficient stability to be processed at elevated temperatures without significant scorching or pre-curing of the resin. The performance of crosslinkable polyethylene is strongly dependent upon the level of peroxide in the resin. This paper presents data showing that peroxide levels can be quantitatively and reproducibly characterized using differential scanning calorimetry. This method can be used for quality control in determining peroxide loss when grinding the resin into powder for rotational molding.
Measuring Dart Impact Strength of Polyethylene Films
Dart impact strength is widely used by resin manufacturers and film converters for quality control and for selecting the appropriate resin for a desired application. ASTM D 1709, Method A and B are generally used in the industry for dart impact strength measurement. This standard allows a surprising amount of latitude in the details of the test. This paper will describe a systematic study of the dart impact strength measurement technique. Some of the variables that have been explored are the material of construction of the dart head, age of the dart head and the diameter of the incremental weights. Variations of this type, all within the limits set in ASTM procedure D 1709, revealed significant influence on the measured dart impact strength values.
Mechanical Hole Burning Spectroscopy: A Nonlinear Viscoelastic Analysis
A mechanical hole-burning scheme was constructed to compare the analogous observations to those from dielectric non-resonant spectral hole burning (NSHB) for glass forming liquids near their glass transitions. Within the framework of the BKZ nonlinear viscoelastic constitutive equation and without invoking an explicit heterogeneous or homogeneous nature of the relaxation of supercooled materials, the calculated modified shear moduli shift non-uniformly with pump frequency. Mechanical holes were burned in the loss response and exhibited most of the apparent features of those reported from dielectric NSHB.
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