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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A Fast Approach to Automotic Runner Balance
Runner balance is one of the most important issues to be addressed for multi-cavity mold in the mold design phase. Poor runner sizing will lead to Christmas tree filling pattern and hence different residence time of plastic melt on each cavity. This leads to excessive packing pressure on small cavity and part weight variation. This problem becomes more crucial for the so-called family mold. In this work, the concept of flow balance index (FBI) is proposed to address this problem. Real industrial cases are studied by this new approach and are verified by molding trial results.
CAE Approach to Relieve Notebook Connector Air-Trap Problems
Air trap problem is crucial to notebook connectors that have complicated rib-hole structure and thickness variation. Engineering experience is usually not enough to provide a suitable gate-runner system design for these intricate parts. In this work, various design proposals are examined via mold filling simulation in order to avoid potential air-trap and void problems. This approach is proved to be effective to notebook connector mold designer for verifying design on computer before mold is constructed.
Preventing Sink Marks of Injection Molded Parts Using CAE Analysis
Sink marks on injection molded parts were caused mainly by part geometric design, mold design, and molding process conditions. This paper describes the dominant factors causing sink marks on injection molded part that can be predicted using CAE injection molding simulation programs. Sink marks on injection molded parts should be prevented for a new part design or solved for an existing one based on simulation results. In this study, a Bearing Bur, Laser printer part was chosen to illustrate how sink mark problems were solved using a commercial available C-MOLD® simulation program. The predicted sink marks of the Bearing Bur were compared to the measurements of an actual production part. Predictions were in good agreement with the actual injection molded part.
Apparent Viscosity Measurements for Determining Injection Molding Dimensional Variations
Injection molders presently use the Apparent Viscosity Curve" to determine the optimum fill time for a particular mold. Once the fill time has been determined the Viscosity Curve is set aside and the goal of the molder is to maintain the fill time. The motivation for my work is not only to determine fill time but also to quantify the melt viscosity using an injection molding machine/mold combination. The ability to determine the melt viscosity would assist the molder with "root cause" analysis when evaluating small dimensional shifts. The study will focus on determining if the derived viscosity using traditional rheological equations is of value when compared to dimensional or cosmetic changes."
A Transparent Barrel for Study of Reciprocating Screw Injection Molding
A transparent barrel system has been developed to assist in the understanding of polymer behavior in a reciprocating screw injection molding machine. This system allows the dynamic status of the polymer inside the injection barrel to be conveniently visualized though photography and video recording, and the corresponding material conditions can be measured via a computerized data acquisition system. Effects of different processing conditions on the melting behavior are analyzed. This system can not only assist in the understanding of the process but also can be used to quantitatively verify the modeling and optimization of injection molding system.
Characterization of Biaxial Orientation in Polyolefin Films
Among the most widely used orientation processes are those involving films; they include both film blowing (with a low level of orientation) and biaxial orientation or tentering (with a high level of orientation). Polyolefins (polyethylene, polypropylene, polystyrene, and their copolymers) represent a significant proportion of the polymers commonly used in these processes. The knowledge of the orientation developed in these films is critical for establishing the process conditions and the final properties of the films. In this study, we investigate the biaxial orientation developed in blown and biaxially oriented polyethylene films using Fourier transform infrared (FTIR) spectroscopy and birefringence. Biaxial orientation factors are determined for both crystalline and amorphous phases and discussed in relation with process conditions.
Measuring the Low Frequency Linear Viscoelastic Properties of Polymer Melts: Trials with PDMS Using Sphere-Plane Squeeze Flow and Interferometry
The problem of measuring the linear viscoelastic (LVE) properties of polymers at low frequencies is a long-standing one, especially for polyolefins with broad relaxation times and small time-temperature shift factors. A squeeze flow apparatus utilizing Newton's interference rings has been devised to measure minute strains at very low stresses with a minimum resolution of ¼ wavelength of light. Its simplicity allows several samples to be run simultaneously under vacuum. This arrangment minimizes degradation, manhours and cost, all critical considerations for long experiments. The design and preliminary results for PDMS as measured by a prototype of the instrument will be discussed.
New Polypropylene for Differentiated Blown Films
New polypropylene resins have been developed which allow for the commercialization of novel, air-quenched blown films. The new resins have been developed using molecular design principles and provide significantly enhanced properties. Key performance properties include stiffness, seal strength, and higher service temperature for many applications as well as flexibility and toughness for other applications. This new breadth in product offerings and performance ranges provides significant new opportunities for PP resins in blown films. This paper will highlight properties and processability of the new resins.
Improvement of Pentium-II Connector Support Design by CAE Tool
Weld line problem is crucial to a Pentium-II connector support part on appearance and mechanical consideration. In this work, a CAE tool is adopted during the product-development in order to detect potential weld line problem of the design. Various design revisions are proposed and tried on the computer. This approach is proved to be cost-and-time-effective to shorten time-to-marketing and avoid molding problem by improving design in advance.
In-Situ Production of Electrically Conductive Fibres in Polyaniline-SBS Blends
Electrically conductive polyaniline (PANI) was thermally blended with polystyrene-polybutadiene-polystyrene (SBS) at different weight compositions. The resultant blends were capillary extruded in order to generate a drawing process in the PANI. Microscopic analysis of the extrudates revealed that the PANI was deformed during the process to produce elongated structures. Electrical measurements showed the relationship between the electrical conductivity and the weight fraction of PANI in the blends.
Novel Fiber Surface Treatment for Use in Engineering Thermoplastic Composites
A water-soluble polymer (Polyoxazoline) was used to treat nickel coated graphite (NCG) fiber and the treated fiber was then used to reinforce ABS, Polycarbonate and Polyetherimide. The water-soluble polymer improves the compatibility of the fiber in the thermoplastic resin matrix thereby providing an improved thermoplastic composite material with optimum mechanical and electrical performance.
Physical Model of Polymer Pellets Melting in Co-Rotating Twin-Screw Extrusion
The melting of polymer in co-rotating twin-screw extruder depends not only on screw configurations and operational conditions, but on the properties of the polymer as well. The melting progressing is too various to be described by single melting model. Only in the past few years (1-9), some attention has been paid to the research of polymer melting in co-rotating twin-screw extrusion. In present study, based on experimental results, the conception of melting sub-stage was defined to describe the complex polymer melting progressing in co-rotating twin-screw extrusion. Ten melting sub-stages were concluded and defined. It was found that the complicate polymer melting progressing can be modeled by combining some of these ten melting sub-stages. It showed that the definition of melting sub-stages would provide an important way to the research of polymer melting in twin-screw extrusion.
Numerical Analysis on the Melt Conveying Properties of Wave Screw Element in Intermeshing Counter Rotating Twin-Screw Extruder
In this paper, one new kind screw element, wave screw element in intermeshing counter-rotating twin screw extruder, is designed. Three-dimensional Non-Newtonian model is established to investigate the melt conveying properties of this new screw elements. The model consists of all the gaps between the screws and the barrel such as the side gap, the calender gap, the flight gap, and the tetrahedron gap, which is in accordance with the true extrusion process. With the finite element software ANSYS, velocity, pressure and viscosity field are obtained respectively. Experiments are used to verify the results of simulation. It shows that the calculated results such as output is nearly the same as the experimental results.
Morphology/Property Relationships in Thermoplastic Starch/Poly(hydroxy ester ether) Biodegradable Blends
The effect of moisture level during processing on the mechanical properties of biodegradable blends of thermoplastic starch and poly (hydroxy ester ether) (PHEE) was studied. The morphology of the blends changed with the moisture content of starch. The dispersed phase was significantly deformed under high moisture conditions, leading to fibrillar and laminar types of morphologies at 50-80% starch level. A low moisture level produced a more dispersed morphology. Improved tensile properties were observed for the blends processed at high moisture levels due to the presence of elongated morphologies.
Mechanical Properties of Starch Filled Poly(hydroxy ester ether) Biodegradable Composites
The mechanical properties of starch filled biodegradable composites have been investigated. The strength was found to be independent of the filler content below 10 vol% and above approximately 30 vol%. This behavior is due to the failure mechanism operating in these composites. The matrix, poly(hydroxy ester ether) (PHEE), adheres well to starch and as a result the granules do not dewet during deformation. Instead the composites behave as a quasi-homogeneous material with increased brittleness as the filler content increases. The deformation mechanism was investigated by acoustic emission analysis and by a post-mortem examination of the fracture surfaces.
Mold-Making Apprenticeship Program in Georgia
This paper will trace the development of the Mold-Making Apprenticeship Program in Georgia's technical institutes, developed to support the plastics industry within the state. It will explain why the program was developed, how it was developed, the content of the program and the results to date. The purpose of the poster presentation is to explain the process and outline the program with the goal of assisting other states with similar programs and ultimately addressing the shortage of trained and available mold-makers. The poster presentation will include three sections: industry growth and potential, team process and program outline.
Regulatory and Experimental Approaches to FDA Food Contact Compliance
Tests to determine the migration of indirect additives into actual foods are essential in order to ensure food safety. Recent changes in regulatory protocols and evolving analytical technologies have helped define new ways to receive regulatory clearance for food contact polymers. This poster summarizes the issues to be addressed when designing a test plan and outlines regulatory considerations and experimental approaches applicable to both Food and Drug Administration (FDA) and European compliance. In addition, the proper use of food simulants, available extraction cells, and analytical techniques are discussed.
Optimising Nano Filler Performance in Selected Nylons
A class of polymer materials having significantly improved properties has emerged. This class of material is being referred to as polymer nano composites. Typical of this class is the nano clay filled Nylon 6 family. We have recently found that by exposing the nano clay filled Nylon 6 materials to ionizing irradiation at low levels, 3 - 5 megarads that we further improve the flex-modulus. We have also found that this technology can be applied to Nylon 12. This technology is new to the 12.
Analytical System for Measuring Thermally Generated VOC Emissions from Polymers
An analytical instrument and procedures were developed to investigate the thermally generated VOC emissions from different polymers with a flame ionization detector (FID). This system was applied to estimate the upper limit of VOC emissions from recyclable 100% carpet residue by exaggerating its thermal exposure at a predetermined temperature. The pattern of VOC emissions was also studied for the 100% carpet residue as well as its composite (80% carpet residue + 20% virgin LDPE), and virgin resins (PP and LDPE).
Load-Carrying Ability of Injection Molded Products with Holes
The mechanical loadability distribution around a molded-in hole in a polystyrene plate has been analyzed using flatwise bending. Four different injection molding conditions have been applied. Birefringence measurements have been carried out to analyze the molecular orientation. The weld line is the weakest point, but the loadability reduction is small when it is related to the loadability perpendicular to the molecular orientation. Almost no effect of variation of process conditions was found.
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