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

Dimensional Analysis and Scaling Approach for Thin-Wall Injection Molding

Sylvana García, Alejandro Roldán, Juan P. Hernández, Tim Osswald, May 2004

In thin - wall injection molding processes, parts thinner than 1 mm are produced using high injection pressures and velocities. Modeling has not been successful in predicting process physics during molding. A dimensional analysis is performed, considering the most relevant variables of the process, the geometry and the non – linear material properties. Using similarity analysis with the material and process related dimensionless groups, the process is scaled by reducing the thickness. The scaled dimensionless groups are used to find relations between process conditions, material properties and other physical parameters, which lead to reasonable conclusions.

Time Scales of Coalescence in Processing Flows: Investigation of Flow through Runners and Strip Molds

Jairo E. Perilla, Sadhan C. Jana, May 2004

The time scales of coalescence in several processing flows were determined from a mechanistic model based on ballistic aproximation and drainage of partially mobile interfaces and compared with the characteristic times of flow through runners and filling of strip molds. It was found that coalescence takes place in a zone between the centerline and the walls of runner of circular cross-section and far away from the injection point in the filling of the strip mold. Qualitative agreement was found between model predictions and experiments carried out in a capillary die and in an injection mold.

Residual Orientation in Injection Molding: A SANS study

John Healy, Graham H. Edward, Robert B. Knott, May 2004

The orientation of polymer chains after Injection Molding is usually studied using techniques that measure the average orientation of a polymer segment. Small-angle neutron scattering (SANS) is a technique for measuring orientation at molecular scales and is very sensitive to molecular anisotropy. The residual orientation and conformation of polyethylene and polystyrene chains after injection micro-molding has been measured using SANS. We have found that, for micro-moldings, the residual orientation decreases with increasing injection speed and that the residual chain orientation at the molecular scale is not necessarily related to the average orientation of short chain segments.

New Method of Designing Runner System for Injection Mold using CAO Technique

Shinichi Nagaoka, Tomoo Hirota, Yoshiaki Togawa, May 2004

Today it is popular to evaluate injection molding process using computational analysis in advance. Designing runner system is important to control flow balance and weld positions for molds of large parts with multi gates. If designers use conventional injection molding analysis, they need to evaluate many runner systems by trial and error for obtaining solution, which is optimum only within the tried runner systems.In this paper, we propose an automatic method of designing runner system using Computer Aided Optimization (CAO) technique in order to control weld positions, and show an example of this method with Variable Complexity Model (VCM) approach to reduce optimization time maintaining accuracy of analysis.

Grafting of 12-Aminododecanamide to EAA Copolymer Film to Reduce COF

Ning Luo, Amol V. Janorkar, Scott M. Husson, Douglas E. Hirt, May 2004

The effect of covalently bound 12- aminododecanamide on the surface coefficient of friction (COF) of ethylene-acrylic acid copolymer (EAA) films was investigated. The reaction involved grafting 12- aminododecanoic acid to the inherent carboxylic acid groups on the film, followed by amidation of the grafted amino acid. Conversion of film carboxylic acid groups to primary amide groups was also conducted to compare the impact of direct surface amidation. Subsequent measurements showed that both surface amidation schemes reduced the kinetic COF from 0.30 to 0.15~0.18. Repetitive COF testing revealed that amide-modified EAA films maintained low COF values that were independent of the number of COF test runs. However, control experiments showed that COF values also depended greatly on simply exposing film to the various reaction solvents, which increased surface roughness.

Selection of Process and Design Variable Settings under Multiple Performance Measures in Injection Molding

Carlos E. Castro, Mauricio Cabrera Ríos, Blaine Lilly, José M. Castro, May 2004

Injection molding (IM) is one of the most prominent processes for mass-producing plastic products. Selecting the proper settings for an IM process is crucial because the behavior of the polymeric material during shaping is highly influenced by the process variables. Consequently, the process variables govern the quality of the part produced. In order to obtain the variable settings that result in the best balances between key quality performance measures, Data Envelopment Analysis (DEA) was used to solve the respective multiple objective criteria problem using empirical models as surrogates. In addition, a DEA modification is explained here with the objective to further screen efficient solutions. Finally, practical cases containing only a subset of performance measures were analyzed to illustrate customized analysis and to illustrate how to identify robust process settings.

Thermal Stability Characterization of Plasticized PVC Compounds Using Calcium and Zinc Stearates

M. Guadalupe Rodríguez-Serrano, Saúl Gallegos Castillo, Martin Arellano, Luis J. González-Ortiz, May 2004

Thermal stability of plasticized PVC compounds (50 phr di(2-ethyl hexyl) phthalate and 0 or 5 phr of epoxidized soybean oil) was studied. The effect of Ca/Zn stearate ratio (0.0/1.0, 0.2/0.8, 0.4/0.6, 0.6/0.4, 0.2/0.8 and 1.0/0.0) and total amount of stearates (0.25, 0.5, 1.0 and 2.0 phr) was considered. The effect of presence of epoxidized soybean oil was evaluated only in formulations containing 2.0 phr of stearates. Degradation behavior was followed by color evolution (yellow index and L a b color coordinates), measurement of gel content, total amount of HCl and polyene produced and mass loss rate.

Added Value for Long-Fiber Reinforced Thermoplastic Components by In-Line-Compounding in the LFT-D-ILC Process

Stefan Troester, Oliver Geiger, Frank Henning, Peter Eyerer, May 2004

The relevance of long fiber reinforced thermoplastics in the automotive sector has grown significantly during the last years. State of the art technologies are processing of semi-finished products like glass mat reinforced thermoplastics (GMT) and long fiber granulates (LFTG). However, the so called long fiber direct process technologies (LFT-D) are about to gain growing market shares. These technologies enable manufacturers to produce components based on the raw materials glass fibers, thermoplastic resin and additives by using a compression molding technique.An important characteristic of long-fiber reinforced composites is the effect of fiber-orientation and thus anisotropic material properties within the components. The implementation of a new characterization procedure, the analysis of circular tensile specimen (so called “Zugronden”) to obtain the integral fiber-orientation will be introduced.The second focus of this paper is the presentation of some selected results of the material development related to the LFT-D-ILC process technology. The interaction between the different material components polymer, fibers and additives were well-investigated to achieve fundamental understanding of the LFT-D-ILC-Process. This enables optimised material compositions for specific applications.

Injection Molding Short Air Ducts Using TPVs

Sigenori Sasaki, Daniel J. Collins, Brendan Chase, May 2004

This paper presents comparisons between three primary process methods for the production of short air ducts for the automotive air induction market with a focus on thermoplastic vulcanizates (TPVs). Cost comparisons between rubber injection molding, extrusion blow molding and thermoplastic injection molding are presented. Injection molded short air ducts using TPVs offer recyclability and a lower air duct weight when compared to a thermoset rubber (TSR) air duct. Additionally, TPV injection molded short air ducts offer a lower cost alternative to blow molding by allowing simplified part consolidation and reduced finishing cost. Part design and process recommendations for injection molded TPV short air ducts are discussed.

In-Line Compounding and Molding of Long-Fiber Reinforced Thermoplastics (D-LFT) - Insight into a Rapid Growing Technology

Maël Garnier, May 2004

Long-Fiber reinforced Thermoplastics (LFT) encounter an increasing success in the molding of structural parts, especially in the automotive industry where LFT applications are experiencing tremendous growth. The following paper discusses the different LFT processing technologies – GMT, LFT-pellets and D-LFT – and exposes their distinctive trend for the near future. It also discusses the average fiber-length inside the parts involved by each technology and shows its distinctive influence on stiffness, tensile strength and impact strength. The paper focuses particularly on the Direct-processing of LFT (D-LFT) and shows how this technology can improve the economics although involving technological risks and high investment costs. This paper provides an impartial understanding of the different LFT technologies and highlights the cases in which benefits could be got from the D-LFT processing. In covering both D-LFT injection and compression molding, it also provides information that help the reader to decide which of them could be the most appropriate.

A New Mass Production Process for Lightweight Structural Parts and their Application-Field

Andreas Rüegg, Norbert Stötzner, Diego Jaggi, Stefan Ziegler, May 2004

A new mass production process combining unidirectional endless and long fiber thermoplastic (E-LFT) has been developed. This one-shot production process is a combination of the well-established LFT process with the direct implementation of unidirectional endless fibers and enables low cost mass production of complex structural lightweight parts. The unidirectional endless fiber tapes (EF) provide excellent mechanical characteristics and can be inserted three-dimensionally, following exactly the paths of load, while the LFT provides high design freedom. First prototype parts have been produced and show that this process allows the substitution of components previously manufactured as metal structures only.

One Piece DLFT Automotive Running Boards

Charles D. Weber, Scott Ledebuhr, Garek Barum, May 2004

Decoma International has developed a one piece composite running board utilizing Composite Products’ patented Advantage™ inline compounding technology. Running boards are currently in production on the F250/350 Regular, Super and Crew cabs, Explorer and Mountaineer vehicles. The replacement of the 43 piece metal and plastic assembly translates into a running board that meets or exceeds performance requirements at a significant cost savings to the OEM at half the weight. Composite Products, Inc. has commercialized this in-line compounding technology to produce long fiber thermoplastic composite solutions for various automotive applications. Advantage™ systems continuously compound thermoplastic resin with fiber reinforcements such as chopped fiber glass, carbon or natural fibers to produce finished composites with outstanding toughness and excellent exterior appearance characteristics.

Static Charging Methods and Graphic Material Properties for Low Scrap In-Mold Decoration

Robert Travis, May 2004

The use of static charging techniques has been investigated to understand which methods produce the most highly repeatable results for in-mold decoration. The techniques studied were the direct and remote charging methods.In addition to charging methods, the study evaluated material properties, gate location and environmental conditions that contribute to the success and repeatability of in-mold decoration.The optimal method, environmental conditions and material properties were found that produce low scrap results. Conclusions were made regarding optimal charging methods and graphic label constructions.

Precision Printed Films & In-Mold Decorating Technologies

May 2004

There are a multitude of definitions and processes associated with the decoration of plastic components within the injection molding cycle. In-mold decorating is otherwise known as IMD and either term can be used loosely to describe any process where a part is decorated in some manner “in-mold” or within an injection tool. There are many process names associated with IMD including; in-mold labeling (IML), in-mold priming, the injection of paints into a mold (In-Mold Paint), printing in-mold, et cetera. Many of these have variations between processes from one company to the next. Combining the various trade names and generic process names can form a veritable manufacturing and injection molding alphabet soup.

A Study on the Influence of Surface Roughness and Injection Moulding Parameters on the Gloss of ABS Parts

M.J. Oliveira, A.M. Brito, L.F. Costa, M.C. Costa, May 2004

Plates from ABS, with surface texture varying from very smooth to very rough, were injection molded. They were used for studying the influence of the processing parameters on the morphology, topography and gloss of the surface. It was observed that the mold temperature is the more influent parameter on the final roughness of the moldings. The injection temperature and hold pressure follow next. Higher values of these parameters improve the replication accuracy that causes a decrease in roughness (and increase in gloss) of the very smooth surfaces and the opposite effect in the rougher surfaces.

Accelerated Weathering Characteristics of Inorganic Pigments in Various Thermoplastic Applications Systems

James E. Rediske, May 2004

Iron oxide pigments have been around as a coloring agent for thousands of years. Despite this amazing longevity the question is frequently asked, “What is the UV stability of your iron oxide?” This question has always been answered in a lighthearted if somewhat cynical fashion, “Has your car ever spontaneously unrusted while sitting in your driveway?”The goal of the work represented by this paper is to try to remove the comedic quality of the answer by establishing an experimental set of parameters and providing a quantitative response to this question.

Understanding the Effects of a Compounding Process on the Production of Co-Extruded Vinyl through the Utilization of Design of Experiments (Part II)

Keith Effertz, May 2004

There are many ways to add color to the windows of your home. For many window companies, a weatherable PVC is used on the outside of the window to provide for a durable, low maintenance, and weatherable exterior. The market demands a variety of different colors within a short time; thus an understanding of rapid adaptability to the market demand is needed. This paper is a continuation of a project presented last year. This paper will discuss the results of a Designed Experiment (DOE) conducted to determine the variables for successfully developing a process window model. This model can be used for current and future colors; thus shortening the development time.

Using a Hierarchical Model of Cognition to Enhance Polymer Education

Douglas E. Hirt, Christopher L. Cox, David A. Bruce, Charles H. Gooding, Graham M. Harrison, Scott M. Husson, S. Michael Kilbey II, Richard W. Rice, Deborah M. Switzer, May 2004

A hierarchical model of mental growth can be used as the basis for developing critical thinking skills in polymer science and engineering undergraduates. Specifically, mental growth constitutes a progression through a hierarchy of cognition. The critical thinking and judgment required of scientists and engineers lies at an upper level in the hierarchy, and to reach high levels, an individual must master cognitive skills and reorganize knowledge gained at lower levels. Teaching and learning devices that exercise low-level cognitive skills and that support effective development of critical thinking are presented. Assessment instruments that monitor student growth and evaluate the effectiveness of these teaching and learning devices are also described.

An Innovative Alternative for Plastics Training & Certification

Peter M. Myers, May 2004

Training and certification have been hot topics in the plastics industry for a number of years, but we have had little success in establishing a relevant certification strategy or making major improvements in the way we train employees. We all seem to recognize the need for a welltrained and highly skilled workforce in order to compete in today’s knowledge-based economy but our approach to training hasn’t changed much over the years.This paper presents a new competency-based training and certification model which can provide a framework that leverages the collective knowledge of the industry and empowers the learner to clearly identify their own learning needs. This unique approach also ensures that learning takes place within the work context of the learner, ensuring maximum retention and application on the job.It will review the work that has gone into the development of this model including the completion of an in-depth industry needs assessment and a Master’s degree in advanced educational techniques and technologies. Individuals who have a stake in ensuring we have a well-trained workforce will find this session of great interest. Copies of the original thesis, which expands on the points brought forward here, is available by email request.

How to Tell when the Emperor is Naked

Stephen DeHoff, May 2004

A near-fad mentality to source in China has developed in buyers of plastic products. Major company senior managements are declaring that sourcing should only be done in China in a near-total absence of strategic comparison data that is relevant to their products. Their employees then stop thinking critically and do as they are told regardless of the impact. Many of these off-shore sourcing decisions are inappropriate and very costly both for the buyer and for the North American suppliers they didn't but probably should have used. A review of case studies permits some understanding of the key elements that both suppliers and buyers need to assess in making intelligent sourcing decisions. Further strategic assessment reveals some specific differences in strategy and methods that should be considered by mold builders, molders, and buyers to know when the emperor is naked.