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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Study on Crystal Structures of Isotactic Polypropylene Processed by Injection Molding
The crystallinity and crystallite size of injection molded isotactic polypropylene was measured by wide angle X-ray diffraction(WAXD) and the distinct skin-core morphology was visible under a polarizing optical microscope. The results show that the crystal structures are dependent on the injection molding processing conditions. The crystallinity and crystallite size decreases with the distance from the gate. The skin layer thickness is thinner with the higher injection temperature.
In-Mold Part Shrinkage Rate Measurement
An on-line technique for quantifying part shrinkage rate in the mold has been developed. The technique consists of measuring post-hold cavity pressure decay rate inside the mold during the injection molding process. A comparison of the technique as applied to amorphous and semi-crystalline polymers will be presented.
Determination of Shear Viscosity and Shear Rate from Pressure Drop and Flow Rate Relationship in a Rectangular Channel
In this study, we present a unique approach to calculate the shear viscosity and shear rate with the pressure drop and flow rate data from a channel having a rectangular cross-section with a height-to-width ratio (H/W) of close to one. The derived equation was verified with experimental data from rectangular dies whose height-to-width ratio (H/W) ranges from 0.1 to 1. It was confirmed that the proposed approach is reliable for calculation of the shear viscosity and shear rate from the flow data in a rectangular channel.
Improvement of Transparency and Processing Properties of Hard TPU Materials
A statistical model is discussed which will help to understand the sequence length distribution of thermoplastic polyurethane block copolymers. Using this model processing range and transparency of some TPU materials were correlated to the theoretical segment length distribution.Considering this analysis some new Elastollan® 1200 materials (E 1200 materials) were developed. Due to the wide processing range and the high transparency of these new materials they are suitable to an increased number of applications.
Excimer Laser Ablation of Polystyrene-Clay Nanocomposites
The ablation behavior of injection molded polystyrene (PS)-Organically modified montmorillonite (OMMT) nanocomposites by 248 nm KrF excimer laser irradiation were investigated for different OMMT concentration and melt-blending conditions. The surface structures induced by excimer laser ablation were also studied using SEM. Results indicate that PS-OMMT nanocomposites show improved or decreased resistance to excimer laser irradiation depending on the OMMT concentration. The dispersion state of OMMT may play an important role in excimer laser ablation behavior of PSOMMT nanocomposites.
Effects of Process Conditions and Glass Fiber Content on Part Quality of Glass Fiber-Reinforced PP Part
Shrinkage and warpage are two important quality indexes of the plastic of fiber-reinforced injection molded parts. The effects of different processing parameters and the percentage of glass fiber on volumetric shrinkage and warpage of the parts have been investigated based CAE analysis. An L16(45) orthogonal array design was conducted analyze the influence of factors and fiber content on shrinkage and warpage, and improve the quality of the injection molded polypropylene part.
Designing Plastic Products for Injection Molding
Designing plastic products for injection molding requires knowledge about strength of materials, heat transfer, mold making, injection molding and costs.The product design can then be optimized for minimal mold and processing costs. Students of Industrial Design Engineering at the Delft University of Technology are educated in designing consumer products for small series till mass production. Cost awareness is important and in the lectures we present practical engineering design rules.
Effect of Thermal History on Surface Roughness and Light Transmission of Biaxially Oriented Polypropylene Films
The effect of preform thermal history on the transparency of biaxially-oriented polypropylene (BOPP) films was investigated. Preform sheets were prepared by compression molding with careful variation of cooling rates, and subsequently were oriented using a Brückner Karo IV stretcher. The small and large-scale surface roughnesses of oriented films were determined by atomic force microscopy (AFM) and optical microscopy, and correlated with light transmission measured by UV-Vis spectrometry.
An Experimental Investigation into Solids Feeding Characteristics of a Single Piece Barrel with Integral Feedport Design vs a Standard Two Piece Water Cooled Feedblock and Barrel Configuration.
Differences in solids conveying, screw pressure profile generation, output and melt temperature varies between single piece barrel with integral feedport design and two piece water cooled feedblock and barrel designs. Two different resins will be studied using the same screw design for each barrel configuration.
Removal of Oxygen Dissolved in Thermoplastic Resin for Gentle Processing
The effect of temperature and time on desorption of Oxygen dissolved in thermoplastic resin has been investigated. Exclusion of Oxygen is presently studied to reduce thermo-oxidative degradation in injection molding. A desorption fixture with an oxygen-sensor has been used to measure while a model has been implemented to calculate the amount of Oxygen dissolved in thermoplastic resins in dependence of desorption parameters. Results indicate a good match of experimentally attained and calculated values and a high potential for gentle processing by exclusion of Oxygen.
Crystallinity Development during Spinning of Polypropylene Part I: On-Line Measurements Using Raman
Application of Raman spectroscopy to obtain crystallinity data, on-line, during fiber spininning of polypropylene polymers is described. These data were obtained to develop validated fundamental fiber spinning models. These validated fiber spinning models will be used to guide fiber spinning for rapid product development.
Biopharmaceutical Manufacturing – an Unseen Plastics Market
Plastics engineers are very aware of the use of polymeric materials in the medical field but little is known about a technically interesting and rapidly growing application that is totally dependent on polymers, biopharmaceutical manufacturing. Since 1990, producers have been replacing their traditional stainless steel tanks and pipes in both new construction and retrofit situations with sterile pre-engineered single use plastic bags equipped with the necessary inlet and outlet ports, tubing, filters, valves, and manifolds.
Resolving Stress Cracks by Injection Molding Simulation and Birefringence Analysis
CAE injection molding simulation software combined with birefringence analysis was used for resolving stress cracks and non-uniform stress distribution on an injection molded part. The part with a two-pin gate runner system was molded and cracked after molding. The birefringence showed high stresses on the part, which was in good agreement with part cracks. Based on the recommendation of the injection molding simulation, the part cracks were resolved by optimized gate location and runner system design. The birefringence shows low stresses on the final injection molded part.
Rotational Molding of Low Viscosity Metallocene PP Resins
Rotational molding is virtually a shear and pressure free process. The number of materials suitable for rotational molding is limited. This paper gives a summary of a fundamental study on newly developed low viscosity metallocene catalyzed PP resin for rotational molding applications. The influence of viscosity, surface tension and thermal properties on the sintering behavior of the polymers was investigated. Rotational molding experiments were carried out and mechanical properties of the molded parts were characterized.
The Effect of Density Profile on the Flexural Modulus of Polymer Foams
It is known that bulk or average density is the major parameter controlling the mechanical properties of polymer foams. Nevertheless, density profile has also a major impact especially for structural foams where an unfoamed skin is enclosing a foamed core. In this study, the effect of density profile on the flexural modulus of a structural foam is discussed in terms of skin thickness and taking into account the local variation of density (related to void fraction) with position.
Balancing of a Profile Die for Glass Run Seal of a Car Using Three-Dimensional Flow Simulation
Experimental data and three-dimensional finite element simulations of the flow in two different profile dies for glass run seal of a car are presented. The flow in one of the two dies, a plate die, is found to be highly unbalanced. Using a feeder plate in the second die (a stepped die configuration) the flow at the exit of the die was properly balanced.
Development of New PC/ABS Products for Chrome Plating Applications
There continues to be a strong demand for chrome-plated plastic parts in exterior and interior automotive components. In this paper, we present two new PC/ABS products suitable for use in these applications. A high-heat product is designed to meet the growing need for improved heat stability, impact and flow in addition to good plate adhesion. A medium-heat product is designed for improved flow, impact and excellent plate adhesion. Effects of key material variables on processing and plating performance are examined.
The Assessment of Uncertainty in Spectrophotometric Measurements of the Color of Plastics
The subject of uncertainty of measurement in spectrophotometric measurements of the color of plastics is reviewed. Definitions of the components of uncertainty are offered, and methods of assessment and calculation of the components of uncertainty are revealed so that the user might prepare an uncertainty budget for one's own measurement system. The practical applications of total measurement system uncertainty in industrial applications are addressed. Finally, example data sets are presented from measurements of several colored plastic materials
Gap Bridging in Laser Transmission Welding of PA6
Gaps in weld seams are an obstacle for applying the contour welding strategy in laser transmission welding of polymers. This paper examines the effect of laser (power) and material (carbon black level) and geometric (gap thickness) parameters on the shear strength of PA6 lap welds. Assemblies were made using a continuous wave diode laser in a contour welding mode.
Understanding Why Adhesion in Extrusion Coating Decreases with Diminishing Coating Thickness, Part III: Analysis of Peel Test
It is well known that in the extrusion coating process, peel strength to aluminum foil and other non-porous substrates decreases with decreasing coating thickness. The peel strength is found to be more sensitive to changes in thickness as the adhesion between the coating and substrate improves. An analysis of the peel test shows that changes in the critical dimension of the deformation region at the peel front may be responsible.
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