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 Study of Cooling for Steady-State Injection Molding
Since many current CAE softwares assume the initial temperature condition of the mold to be constant, this research investigates how the initial temperature distribution condition of the mold affects the accuracy of the estimation of the cooling time. Two cases, a mold with uniform temperature and a mold with steady-state temperature distribution due to continuous molding, are analyzed, and indicate a 30% error in cycle time prediction. Finally, the effects of different insert materials on cooling time and the production cycle are discussed.
Polymer Alloys of Polyvinyl Butyral: A Viable Means of Recycling Windshield Interlayer
Polyvinyl butyral (PVB) sheet is used as the energy absorbing interlayer in most safety glass applications including automobile windshields. A large supply of industrial and post-consumer PVB scrap is currently being disposed of by burning and landfilling. Polymeric modifiers can be used to compatibilize blends of PVB with PVC and polyolefins. These alloys can have a wide range of useful properties ranging from super-tough thermoplastics to thermoplastic elastomers.
Applications of Successive Self-Nucleation and Annealing (SSA) in Polyolefin Blends Characterization
The technique of Successive Self-Nucleation and Annealing (SSA) has been applied to thermally fractionate two types of ethylene/ -olefin copolymers and their blends. The results demonstrate the usefulness of SSA to determine the distribution of lamellar thickness and short chain branching (SCB) in the neat polymers and the miscibility of their blends.
Design of a Data Acquisition System for Predictive Control of Melt Temperature
This paper presents the design of a data acquisition system for model predictive control of the injection molding process in particular, five zones of melt temperature. Factors influencing the selection of sensors, sensor failure modes and intelligence, and the data acquisition requirements are presented. The predictive control strategy for controlling these interactive zone temperatures with the energy input disturbance caused by screw recovery is discussed.
Study of the Characteristics of Cellular PVC and a Suitable Processing Aid
The morphology of cellular PVC and the results of model experiments compared with Polystyrene suggested that cellular PVC products contain a high ratio of open-cells, but PVC can retain foam-ability even after the cells are partly broken. This characteristic is enhanced by its high melt elasticity, which is strongly related to the molecular chain entanglement between PVC and Processing Aid dispersion. From this aspect, a suitable processing aid was designed and its remarkable foam-ability was confirmed.
Effect of Iron Compounds (Oxide, Salt or Complexes) on Poly(Vinyl Chloride) Thermal and Photochemical Stability
Iron has always been known to have a detrimental effect on PVC aging but was never systematically studied when present as an impurity or as a component of the additives used in PVC formulations. A quick weathering test was designed to evaluate the effect of iron in PVC formulations and clearly demonstrated the correlation between iron content and PVC photo and thermodegradation. A threshold concentration of iron above which PVC degradation is catalyzed was determined and a specific look was given to color pigments containing iron.
Extrusion of Engineering Thermoplastic Polyurethanes
The results of extrusion trials on several single and barrier-flighted screws which highlight the importance of proper screw design for engineering thermoplastic polyurethanes are presented. Fundamental properties of the resins, including solid bulk density, coefficients of dynamic friction, melting rates and thermal properties are included to demonstrate their use in screw design.
Master Molding Technician Training Program at Lucent Technologies, Omaha, Nebraska
Growing" Production Technicians in an injection molding shop takes quite a bit of time. Even with a strong curriculum a company can be encumbered when after the training takes place employees are in a position to retire. In order to promote a continuous flow of talent a program was created jointly among management and union resulting in a "fast track" to higher paying jobs. Everyone benefits from the new Master Molding Technician Program- a 2 1/2 year curriculum based on the moldmaker apprenticeship idea."
Master Molding Technician Training Program at Lucent Technologies, Omaha, Nebraska
Growing" Production Technicians in an injection molding shop takes quite a bit of time. Even with a strong curriculum a company can be encumbered after the training takes place when employees are in a position to retire. In order to promote a continuous flow of talent a program was created jointly among management and unionresulting in a "fast track" to higher paying jobs. Everyone benefits from the new Master Molding Technician Program- a 2 1/2 year curriculum based on the moldmaker apprenticeship idea."
Laser Beam Welding of Plastic Micro Parts
By means of laser beam welding it is possible to join plastic parts in micro system technology. Based on existing macroscopic process variants for laser beam welding a appropriate process technology for the joining of plastic micro parts has been developed at IKV. For welding of plastic parts the influences of material and process parameters on the quality of the weld line have been investigated. Apart from this investigation high influence is expected by using filling materials like carbon black. Investigations of microscopic melt zones produced by the focused laser beam are presented.
Difference in Integral Aggregate Structure for Co-Neutralized Carboxylate Ionomers
The purpose of this study was to determine the arrangement of atoms inside ionic aggregates for ethylene-acrylic acid copolymers and ethylene-methacrylic acid copolymers neutralized with a combination of sodium and zinc. Significant qualitative differences were found as a function of sodium:zinc ratio. The implications of the differences in aggregate structure on the rheological behavior of these mixed-cation systems is discussed.
High Speed Toolholders
High Speed Milling requires many considerations for the toolholder. Cleanliness, Balance and Accuracy become even more important as the spindle RPM rises. With milling speeds rising through ten, thirty, and fifty thousand RPM, and with 100,000 RPM lurking on the horizon the ordinary toolholder and features may no longer be adequate. This paper deals with selecting the toolholder that will assure optimum performance.
Distribution of Material in an Injection-Molded Container
The distribution of material (weight) in an injection-molded container was quantified by cutting the container precisely into segments. Molding conditions were varied, and different polypropylene grades were used. The material distribution remained nearly uniform when increasing the packing pressure. Increasing the packing time above a certain limit, however, mainly packed material close to the gate. The material distribution was also affected by material parameters such as melt flow rate and nucleation. The shrinkage and the compressive strength of the container were related to the material distribution.
Flow Patterns in Special Twin Screw Mixing Elements
The flow behavior of a Newtonian fluid through special mixing enhancers in a modular intermeshing co-rotating twin screw extruder has been examined. The mixing enhancers are slotted screws and gear mixing elements. In addition to pressure and drag flow characteristics, particular attention has been directed to residence time distribution in such devices. The data obtained are useful for guidance in the selection of appropriate mixing elements and the validation of flow simulation models for twin screw extruders.
Hygrothermal Effects on Physical Aging and Structural Recovery of an Epoxy Thermoset
We have investigated the hygrothermal effects on thin epoxy films (c.a. 60 µm thick) using mass uptake, swelling and uniaxial creep compliance measurements inside a dew formation-free transparent chamber capable of arbitrary relative humidity and temperature controls. We show that the physical aging behavior in humidity down-jumps in RH are the first demonstration of an asymmetry of approach induced by moisture changes in a material. Preliminary efforts to extend the TNM-KAHR models of structural recovery to account for moisture induced aging effects are presented.
Roll Design: A Review of the Basics
Over the years many advances have been made in the production of flat sheet in the areas of die design, screw design, and polymers. However the design of a critical part, the cooling roll, is often given little consideration by the processor. The intent of this paper is to review some of the parameters that the roll designer uses to determine the design of the roll. The basic equations for calculating PLI (pounds per linear inch), and deflection of the roll, the heat removal rate required, and a method for approximating the required flow rate through the roll are explained.
Thermosetting Resins from Vegetable Oils
A range of polyols and thermosetting polyurethanes was prepared from soybean, corn, sunflower, safflower, canola, peanut, olive and castor oils. The products were rigid plastics if the polyol hydroxyl number was 160 mgKOH/g or above, or rubbers when the OH number was below that value. Tg of the resins showed linear dependence with the hydroxyl number. The exception was castor oil, which was rubbery, although the OH number was 164 mgKOH/g, which was attributed to the presence of double bonds.
Does Color Memory Exist?
While the scientific literature contains information about how the brain stores and retrieves memory, there are no references in the recent literature about the ability to remember a color. Data collected over a several year period shows that this ability is rather poor, even after short periods of time. Only thirty percent of participants at plastics coloring seminars were able to correctly identify a color observed only an hour earlier.
Performance Optimization of Transparent PS Packaging with Clear Elastomers
Clear, high styrenic elastomers (HSE) are commonly extruder blended with general purpose polystyrene (GPPS) to make sheet, which is thermoformed into articles for packaging and single service applications. The ability to adjust the blend parameters gives the processor an advantage over other clear polymers in meeting customer cost and performance demands. Transparency and impact resistance of such blends are affected by the HSE and GPPS selection, and the blend ratio. This paper discusses the influence of these parameters, with emphasis on GPPS selection.
Influence of Molecular Weight and Polydispersity on Interfacial Tension between Polystyrene and Polyethylene
The influence of temperature, molecular weight and polydispersity on interfacial tension between polyethylene and polystyrene was studied in this work. The molecular weight of monodisperse samples of polystyrene was varied from 13,000 g/mol to 400,000 g/mol. The effect of polidispersity was studied using bimodal, trimodal and multimodal polystyrene samples prepared by solvent evaporation. It was shown that the interfacial tension increases as a function of molecular weight and decreases as a function of polydispersity.
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