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

Comparison of Results from a Simulated and Actual Design of Experiments

Erik E. Gatewood, James A. McQuown, May 2001

This study includes a design of experiments using a blow molding simulation software. An eight-run, four factor D.O.E. format was chosen. The response variable of interest is the variable wall thickness throughout an extrusion blow molded part. The simulation will help pinpoint the factors that have the largest effect on wall thickness variation throughout the part. The results will be implemented into an actual D.O.E. that will be completed in the future.

Study of Cast in Passages for Rotational Molds

Kristopher J. Ivie, May 2001

This paper discusses the theoretical effect of cast in passages on the wall thickness of rotationally molded part. Finite element analysis was used to determine temperature differences for given passage geometry and dimensions. Testing was done to determine the relationship between surface temperatures and melt thickness versus time. This information provides a theoretical model for construction of rotational molds using cast in passages.

Predicting Shrinkage for Injection Molds

Ben Bogdanski, Michael McMeans, Patrick Bogdanski, May 2001

Shrinkage of plastics materials can be significantly affected by both process and flow induced orientation in a cavity. This paper presents a study of the factors that affect shrinkage in a variety of different types of thermoplastic materials. These include process, flow type (linear versus radial), material and material fillers. Sensitivity of shrinkage to these factors is established and can assist mold designers in more accurately sizing their cavities to account for in-mold shrinkage

Warpage Index for Mold Designers and CAE Analysis

Michael McMeans, Benjamin Bogdanski, Patrick Bogdanski, May 2001

This paper presents the results of study directed toward developing a simplified technique of classifying plastics materials relative to their sensitivity to warpage as caused by non-uniform cooling and flow induced stresses. The materials are then rated on a relative scale of 1 to 10. This information will allow mold designers and injection molding simulators analyst to realize the relative sensitivity of a material to warpage from these factors and therefore more strategically design their molds to address these issues.

Process Window as Effected by Shear Induced Flow Imbalance in Multicavity Molds

Heath E. Casaldi, Timothy Michel, May 2001

The paper presents a study on the sensitivity of shear induced mold filling imbalance, found in multi-cavity molds, to process variations. A variety of materials are molded in an eight-cavity test mold using a variety of different runner designs. The materials are molded at four different flow rates. Two different runner designs are used - a conventional geometrically balanced runner and a geometrical balanced runner including a melt rotation technology that eliminates shear induced mold-filling imbalances.

Effects of Aqueous Medium on Long Term Creep Properties

James Kopchick, Jacob A. Rowley, May 2001

The determination of the physical properties of a polymer over time has long been a topic of speculation. It is not clear the effect of moisture on this mechanism. This research will attempt determine the interaction between percent humidity and the final creep properties, while the samples are completely immersed in an aqueous medium. This paper will attempt to bring together molecular interaction, secondary forces, and hydrolyzed components of them and how they interact with the final tensile, ultimately creep properties.

An Investigation of Part Variation in Multi-Cavity Injection Molds when Using Cavity Pressure Control

Robert Cooney, David Neill, Larry Pomorski, May 2001

The use of cavity pressure to control velocity to pressure transfer during the injection phase of the molding process is generally considered to be the most repeatable method. However, for multi-cavity molds, it is believed that the part variation may actually be worse in non-controlling cavities than it would be if position transfer were used. This study will look at how the balance of conditions between cavities effects the part variation for both cavity pressure and position transfer methods.

Effects of Annealing on the Crystallization Behavior of Nylon 6,6 in the Presence of Nucleating Agents

Jamie Hummer, Ken Woodruff, May 2001

Nucleating agents such as paraffin wax and MoS2 are known to vary the morphology and quality of crystals. Samples of unfilled Nylon 6,6, wax filled, and MoS2 filled were subjected to structured annealing conditions. Samples were then analyzed using Differential Scanning Calorimetry (DSC). Changes in tensile, flexural, and impact data were compared and correlated to the crystallinity data.

Orientation Effects on Thermoformed Parts at Different Temperatures

Scott D. Bemiss, J. Jacob Kennerknecht, May 2001

The orientation of a plastic part changes due to the processing temperature. The extent of these changes can be seen on thermoformed parts from the same mold, processed at different temperatures on a smooth surface.

Study of PVC Degradation Using a Fast Computer Scanning Procedure

Radu Bacaloglu, Ulrich Stewen, May 2001

A fast computer scanning procedure for the determination of total double bond concentration resulting from PVC thermal degradation is described. It allows the rapid estimation of rates of degradation and prediction of temperature and stabilizers effects on degradation.

Polylactide, A New Thermoplastic for Extrusion Coating

Mark Hartmann, Nicole Whiteman, May 2001

Polylactide (PLA), a new thermoplastic derived from corn, has been developed for extrusion coating applications. Polylactides can be rheology modified to run on high-speed commercial extrusion coating lines to produce packages with unique properties. New packaging systems will be described based on PLA's combination of adhesion, flavor/aroma barrier and heat seal/hot tack strength.

The Use of Encapsulation Dies for Processing Linear Polyolefin Resins in Extrusion Coating

Kelly R. Frey, Gary D. Jerdee, Clint D. Cleaver, May 2001

Traditionally highly branched autoclave low-density polyethylene resins have been ideal for extrusion coating due to their inherent melt strength characteristics. Encapsulation coating dies have been used with other polymers to overcome melt strength deficiencies and improve processing. This study evaluates the effectiveness of encapsulation with linear materials such as high-density polyethylene and linear low-density polyethylene.

Joseph P. McCaul, May 2001

The SEEK Risk© Model was developed as a screening device to identify critical inputs to a firm and assess the effectiveness of countermeasures against potential disruptions. It is also a tool for comparing suppliers. The risk, both mitigated and unmitigated, is evaluated on a logarithmic scale. The assessment considers threats to both supply and technical competitiveness of the organization. The overall risk is scaled to resemble the well-known Richter Scale.

TiO2 Photochemistry and Color Applications

Dwight A. Holtzen, Philipp M. Niedenzu, Michael Diebold, May 2001

TiO2 is one of the most commonly used pigments in the coloring of plastics. TiO2 not only provides opacity but it is an excellent UV absorber. Hence, the pigment provides opacity and protection for plastics. This paper reviews the sources of TiO2 photochemistry and methods to control photoactivity.

A Next Generation Color Management Tool

Richard Johnston, May 2001

A knowledge-based system allowing for more effective use of color concentrates in plastics has been developed. Software and portable spectrophotometers utilized during processing present a color matching system that functions as a significant new color management tool to both injection molders and machine extruders. Used this way, as a quality or process monitor, the system can manage color consistency and product stability, because the deleterious effects of fluctuations in colorant loading on the physical properties of molded parts can be eliminated.

Biaxial Orientation of Blown Films Using an 80/20 LLDPE/LDPE Blend

Renata O. Pimentel, Rosario E.S. Bretas, May 2001

The Hermans orientation function and the White-Spruiell biaxial orientation factors [1, 2] of blown films of blends constituted of linear low density polyethylene (LLDPE) and low density polyethylene (LDPE), with 90% [3] and 80% of LLDPE, were calculated by infrared spectroscopy and differential scanning calorimetry. These films were produced by using a industrial equipment, controlling the following processing conditions: BUR=Rf/Ri, where Rf and Ri are the final and initial radius of the blown films, the temperature and the thickness of the sample.

Phenomenological and Morphological Characterization of Shear Induced Crystallization of Isotactic Polypropylene

M. Farah, R.E.S. Bretas, May 2001

The Flow Induced Crystallization (FIC) of polypropylene was studied in a slit die coupled to a twin screw extruder in several ranges of temperature and flow rate. FIC layers were measured and characterized and fitted to the Janeschitz-Kriegl model (1). A morphological investigation using TEM, SEM and WAXS were also done. Morphological results showed that the FIC layers are composed by extended lamellae in the ? phase. The ? phase was observed in the neighborhood of FIC layer generated probably by a transcrystallization effect.

Decorating Polyolefins: The Color of Change

May 2001

Processability, performance and cost make TPO’S a popular choice in various applications. Decorating polyolefins is still a challenge, but the advantages can out weigh the disadvantages if engineered with care.

Property Separation Based on Inversion of Micro-Mechanics

Zhenfeng Zhao, Xiaoshi Jin, May 2001

An inverse method to separate the matrix thermo-mechanical properties from the fiber-filled composite properties is suggested. The Tandon-Weng micro-mechanics model [1] and an orientation averaging method with orthotropic closure are used for the calculation of the anisotropic, heterogeneous properties on both a layer and element basis[2], then a combination of Newton's and least square methods are employed to solve the inverse problem. In comparison with a previously used separation method based on pvT model, the inverse method gives more accurate and reliable results.

Transfer Efficiency - Issues & Methods

Steve Stalker, May 2001

Many manufacturers of industrial coating application equipment often cite efficiencies of their spray equipment in terms of transfer efficiency (TE). While useful in comparing different types of equipment (conventional, HVLP, airless, etc.), its value as a tool in evaluating real-world situations is questionable. This article is not intended to be a full discussion of the methods for testing spray equipment efficiency. More at heart is what are the primary methods of testing and what are the issues.