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
Intermittent Extrusion Blow Molding Using a Reciprocating Screw
Nathan A. Mancine, May 2000
The intermittent type of extrusion blow molding is different from continuous blow molding in that it is not a continuous cycle. An intermittent blow molder can be very useful when processing plastics that have a low melt strength, like Polycarbonate. This project began with the donation of a partially finished prototype of a continuous blow molder. This blow molder will use a reciprocating screw injection unit that had been donated. The hydraulic pumps, the clamping system and the frame are still part of the design. This paper will discuss the design and construction of this intermittent extrusion blow molder that will be used in the Penn State University's plastics processing lab in Erie, Pennsylvania.
Sequential Valve Gating for Thin Wall Injection Molding Comparison between Experimental Results and Filling Software
Ronak Shah, May 2000
The objective of this study was to investigate the sequential and concurrent filling patterns of a U-shaped thin walled cavity and to evaluate the weld line location, shifting of weld line location and retention of weld line strength. The experimental results were also compared with the predicted results obtained from a computer filling simulation software. The opening of the gates was sequenced to achieve the desired fill pattern, thereby eliminating hesitation effects which cause the flow front freeze-off and also to control the wall thickness to flow length ratio. The paper discusses the effect of critical processing parameters that affect the shifting of weld line location such as, fill pressure, fill time and gate opening-closing time.
Self-Assembly of Chromophoric Arrays on Conducting Polymers
Brian Bergman, Patrick Dillon, Timothy W. Hanks, May 2000
The study of self-assembled mono- and multilayers has advanced rapidly in recent years. One promising area that has received little attention to date is the assembly of molecular devices" on the surface of electrically conducting polymers. We previously developed an effective coating procedure for attachment of various alkane thiols to the surface of thin films of polyaniline polypyrrole polythiophene and poly(ethylenedioxy-thiophene) which were electrochemically grown on indium-tin oxide-coated (ITO) glass plates. Similarly alkane thiols that are derivatized at the terminal end with a porphyrin also assemble on polymer surfaces. The use of porphyrins containing an acetylene "handle" trans to the thiol enables the sequential attachment of additional porphyrin units leading to oligomeric arrays. Similar arrays can be constructed on polystyrene resins. This is useful for preparing larger quantities of the oligomers for characterization and for optimizing the solid-phase reaction parameters. If necessary chromophores can be assembled on the polystyrene resins and then transferred to other polymers that might be sensitive to some of the reactions used in the synthesis of arrays."
Advances in Modular Tool Design Coupled with the in Mold Process Control of Dynamic Feed Provides Lower Tooling Costs, Shorter Lead Times, High Level Part Quality and Improved Machine Utilization
Curt Watkins, William J. Hume, May 2000
The concept of modular tooling offers many advantages to the molder. Shorter lead-times on tooling, lower tooling costs, and better operational efficiency are all benefits which can be realized with the modular tooling concept. Complex part geometries often have limited the use and value of modular tooling. With an advanced modular tool design complex geometries requiring slides and lifters can now be successfully produced in modular tools. One of the limitations of modular tooling has also been that of molding differing size and geometry's of parts within the same frame. By incorporating the Dynamic system this is no longer a limitation. Dynamic Feed is a leading edge technology, which provides real time closed loop pressure control to each cavity independently. Thus Dynamic Feed allows each cavity to have its own injection and pack pressure profile, providing tight dimensional control to each part regardless of the cavity mix. Advanced Modular Tool designs combined with Dynamic Feed carry modular tool molding to the next level of dimensional control and versatility.
Fiberoptic Evanescent Wave Spectroscopy(FEWS) for the Real Time Investigation of Diffusion Processes in Amorphous Polymers: The Use of AgClBr Infrared Fibers for Studying the Penetration of Water & Or
Edward Bormashenko, Joseph Reichlin, Roman Pogreb, Irena Wasserman, Abraham Katzir, May 2000
Advanced optical methods have already been used for the investigation of the mechanisms of diffusion in amorphous polymers. In this work Fiber Optic Evanescent Wave Spectroscopy has been used for the real time investigation of diffusion processes in glassy polymers. Unclad AgClBr fibers of diameter 0.9 mm were dip coated by polystyrene layers of thickness 1-30 ?m. The transmission of the fibers in the mid - IR was measured using by a Fourier Transform Infrared (FTIR) spectrometer. The penetration of liquids into these layers gave rise to significant changes in the measured spectrum. These changes were used for diffusion studies in situ. The sensitivity of the method was sufficient for studying the penetration of small concentrations (up to 5 ppm) of organic liquids through polymer layers. It must to be emphasized that the cylindrical symmetry of our fibers render them especially suitable for the diffusion study and allows to obviate the difficulties caused by end effects. Fickian and non-Fickian cases were observed and the mathematical model of the process was proposed.
Investigating the Effect of Coupling Agent on the Structural Properties of Glass Fiber Reinforced HDPE
B.P. Duffey, May 2000
Plastic lumber used to be a poorly regarded material. In the past decade advances in processing and materials have allowed plastic lumber to become a competitive material in the construction industry.1 This study evaluates the effectiveness of three coupling agents on the properties of glass fiber filled HDPE lumber. The coupling agents to be studied are titanate, zirconate and silane. Test samples will be manufactured from compounds that utilize various concentrations of coupling agent. They will be tested for flexural and tensile modulus and impact strength. The results will be compared to data gathered from samples made with the industry standard silane loading and sample with no coupling agent.
Building Soft Tooling Molds Using Rapid Prototyping and Different Methods of Construction in a University Environment
Kevin Bussard, May 2000
The objective of this investigation is to determine an optimal and efficient method of building soft tooling molds for injection molding in a university environment. The procedure for this investigation will involve using rapid prototype models and different methods of construction. Because the soft tooling will be intended for universal use between multiple university injection molding machines, the molds will be designed for direct use with a small machine or as a cavity for a large insert mold. Each construction method will be evaluated on multiple properties, such as cost, production time, surface finish, quantity of parts, and thermal conductivity.
Investigation of the Phase Morphology Development in PA-6/PP Blends Using a Reactive Compatibilizer (Glycidyl Methacrylate Grafted Polypropylene)
G. De Belder, V. Schiepers, G. Groeninckx, May 2000
This paper deals with the in-situ reactive compatibilization of polypropylene(PP) / Polyamide-6( PA-6) using a third polymer, glycidyl methacrylate grafted polypropylene (GMA-g-PP). This new compatibilizer was prepared by functionalizing PP with GMA in the presence of styrene. Several factors were altered in order to evaluate their effect on the grafting yield, which was investigated by means of Fourrier Transform Infrared Spectroscopy (FTIR). The phase morphology of compatibilized PP/PA-6 blends was investigated by means of scanning electron microscopy (SEM). The morphology of these blends after optimizing processing parameters was studied, the co-continuous region was determined and the effect of annealing was investigated. From differential scanning calorimetry (DSC) measurements, it was found that coincident crystallization can occur in the presence of a compatibilizer.
Economics of Plastics Materials over the Last Few Decades
Nishith Chasmawala, May 2000
Polymers are used in almost every imaginable application today, such as simple bags and pouches, medical and mechanical packaging, aerospace and automobile application and everyday application such as refrigerator or coffee makers etc. This paper discusses the economics of these polymers over the past few decades in the United States. The growth and fall of these materials are discussed, comparing them to various factors such as GDP, OPEC, Processing Technologies, Imports and even applications. The information will not only provide an overview of the industry in past and present but will also provide insight on areas that hold promise for the future.
Reaction-Induced Phase Separation of Polymer/LC Blends
G.M. Hostetter, G. Beaucage, B.L. Farmer, T.J. Bunning, May 2000
Polymer-dispersed liquid crystals (PDLC) are useful as optical components and have potential uses in display and switchable holographic applications. We have been investigating the kinetics of morphological development in a PDLC system based on a syrup composed of a multifunctional acrylate matrix and low molecular weight liquid crystal where phase separation is induced through UV or visible light initiated photo-polymerization. Polarized optical microscopy (POM) has been used to analyze the kinetics of the process while low voltage scanning electron microscope (LVSEM) measurements have been used to characterize the resulting morphology. Two different polymer systems, an optical adhesive and a penta-acrylate, were studied to show the range of the techniques and the differences in the gelation and phase separation processes. The primary difference between monomers lies in the polymerization mechanism; one is a step-growth reaction, while the other is a free-radical polymerization. We show that there are tremendous differences in the times of gelation and phase separation and large differences in the final morphologies.
Comparing Ultrasonic and Cavity Pressure Sensors for In-the-Mold Process Monitoring in Injection Molding
Seung Yoon Baek, Russell Edwards, Charles L. Thomas, Rob Peterson, May 2000
An ultrasonic transducer was installed on a simple plaque injection mold such that the sound pulse could propagate into the mold cavity and reflect back to the transducer. The sound velocity in the plastic and the attenuation of the signal traveling through the plastic were measured as process indicators. A cavity pressure transducer was installed behind an ejector pin exactly opposite the ultrasound sensor. parts were molded under a variety of molding conditions and the two sensors' signals were compared. Both sensors were quite sensitive to changing conditions inside the mold, with the results indicating a complementary sensitivity where each sensor was more sensitive under certain conditions.
Viscoelastic Behavior of Ethylene-Styrene Interpolymers
H.Y. Chen, E.V. Stepanov, M. Guest, S.P. Chum, A. Hiltner, E. Baer, May 2000
The linear relaxation master curves of Ethylene-Styrene Interpolymers, ESIs, were correlated with the molecular weight distribution by using double reptation theory. From this modeling, the plateau modulus was obtained. The entanglement molecular weight of the ESIs calculated from plateau modulus was much closer to that of polyethylene than to that of polystyrene. This was attributed to the unique chain microstructure of the ESIs in this study which have no styrene-styrene dyads. The large strain nonlinear stress relaxation behavior was also studied and the experimental data were successfully described by the Doi-Edwards theory. The instantaneous recovery after stress relaxation was investigated. The recovery was correlated with stress relaxation by newly developed model of two coexisting networks.
Fundamental Morphology-Property Studies of Reactor Grade Thermal-Plastic Olefins (RTPO)
C.K.-Y. Li, J. Wang, C.J. Chen, H. Sittertz-Bhatkar, May 2000
The relationships between morphology and several physical properties, namely, flexural, cryogenic Izod impact strength, and dynamic mechanical properties of reactor grade thermal-plastic-olefins (RTPO), were examined as a function of ethylene-propylene (EP) rubber phase content. It is shown that the cryogenic Izod impact strength is greatly enhanced as the rubber phase increases without sacrificing critical physical properties. Dynamic mechanical thermal analysis (DMTA) and transmission electron microscopy (TEM) results indicate that a good compatibility is achieved between isotactic polypropylene (iPP) matrix and rubber phase, which contributes to balanced physical properties.
Verification Studies of Blow Molding Software on Ovalized Parisons in Extrusion Blow Molding
Thomas J. Pfleger, Gilbert W. Munz II, May 2000
This paper is a study of ovalized parisons in extrusion blow molding simulation software. The software being used is BlowView. BlowView can be used to simulate the extrusion blow molding process and aids in reducing design time for accurate product thickness. BlowView is utilized to lower the development time when used correctly. This paper will compare the output from the simulated process to the actual manufacturing setup and results. Currently extrusion dies are being built using previous standards and educated guesses. Dies are originally built and usually needing of modification to produce the desired profile. With the use of the computer simulations, giving all the design considerations will accelerate the developing of the die and necessary process.
An Injection Molding Process Capability Comparison between Position and Hydraulic Transfer Modes across Various Degrees of Check Ring Wear
Jeffrey D. Nicolia, Matthew D. Roth, May 2000
The purpose of this study was to determine whether using the traditional position transfer mode or the hydraulic pressure transfer mode produces parts with less variation under the conditions of successively greater check ring wear. The process capability characteristics that were used were the standard deviations of the part weights, part diameters, cushion values and pressure at transfer values for each of the various molding conditions. The hypothesis of the study was that a process set-up in a three-stage hydraulic transfer mode will be more resistant to process variations caused by molding with a worn check ring and therefore more capable than a three-stage position transfer mode process.
An Injection Molding Dimensional Capability Comparison of Three Molding Transfer Modes Each Run under Both a Two and a Three-Stage Molding Strategy
Michael J. Christie, Michael D. Leatherman, May 2000
The main focus of this study was to determine whether or not the hydraulic pressure transfer mode would produce more consistent parts than the screw position transfer mode would under simulated machine wear. The comparison was made across both two-stage and three-stage process set-ups. The three modes tested included screw position, hydraulic pressure, and cavity pressure transfer. The comparisons were made across both a two-stage and a three-stage process set-up. All of the molding trials were completed under the conditions of a mildly worn check ring that was used to simulate a portion of the normal shot size inconsistency found in a traditional production molding environment. The results showed that the cavity pressure transfer mode produced the most consistent parts. The hydraulic pressure transfer mode resulted in less variation than the screw position transfer mode.
Practitioner Training Program for Troubleshooting Injection Molded Part Defects
Michael Shanor, Dan Swantner, David T. Baird, May 2000
The main objective of this paper is to develop a program for teaching plant floor molding personal how to solve injection molded part problems and defects. A prioritized troubleshooting guide was developed using 12 common defects. The four defects that a case study was successfully performed on were vacuum voids, struck parts, color streaks, and discoloration. These four will be further discussed in this paper. Each defect was produced using different combinations of mold, material, and process conditions. The case study was performed to verify what actually causes each defect and to what degree.
Non-Destructive Means of Measuring the Glass Density of a Fiberglass Preform
Filip J. Salusky, May 2000
The purpose of this experiment is to determine a non-destructive means of measuring the glass density of a fiberglass preform. This study includes two techniques: using a concentrated light source with a light meter and by using a thickness gage. The light meter measurement is taken by placing a concentrated light source on one side of the preform and the light meter on the opposite side. The thickness gage measurement is taken by pushing a pin through the preform and by using a dial gage to measure the thickness of the preform. Both of these measurements are believed to be related to the density of the fiberglass.
Improving Mechanical and Organoleptic Properties of Polypropylene
Tara S. Campbell, Jaime L. Clarke, May 2000
In an attempt to find a long term heat stable grade of polypropylene this project is designed to take pure flake polypropylene directly from the reactor and add specific fibers, fillers and additives with a minimal amount of processing. Polypropylene is not the usual material in potable water applications due to organoleptics and mechanical property weaknesses, which occur at elevated temperatures. With materials and additives, it is postulated that organoleptic issues can be lessened or eliminated from the finished product. Testing for mechanical properties such as heat deflection temperature (HDT), tensile strength, and taste and odor characteristics, will be conducted in order to create the ideal material for this application.
Development of Crosslinkable Binder System for Metal Injection Molding Using Urethane Technology
Alicyn M. Haney, May 2000
Shape retention of Metal Injection Molding (MIM) parts throughout the debinding and sintering stages of production is a common problem among molders. Slum ping of parts often causes distortion in complex shapes, minimizing surface details. Challenges in development of a binder system include powder compatibility, powder wetability, and polymer compatibility. A mix of coupling agents, surfactants, anti-oxidants, plasticizers and compatibilizers must be determined. The feedstock must not cure during com pounding or injection molding. Sample batches will be com pounded and molded. Successful candidates will be tested for shape retention and mechanical properties.

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