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

New Developments in Co-Rotating Twin-Screw Extrusion for Production of Long Glass Fiber Composites

Daniel Schwendemann, September 2002

Long fibre reinforced thermoplastics have excellent mechanical properties and stiffness-weight ratio which is of particular interest to the automotive industry. The new Inline-Compounding processes for long fibre materials offer users more flexibility as they are able to both compound and process such materials in accordance with their own formulation and also use ready-made compounds. The following process combinations are possible: E-LFT; In-Line-Compounding and Direct Extrusion to Profile or Plate D-LFT; In-Line-Compounding and Compression Moulding S-LFT; In-Line-Compounding and Injection Moulding

FiberSIM: Advanced CAD software for composite engineering from racing to production automotive

Dr. Olivier Guillermin Vistagy, September 2002

The principal challenge in applying composite materials to automotive vehicles is to provide structural performance that allows for significant weight reductions over conventional materials such as steel. However the automotive market is quite different from the proven aerospace composite arena. Aircraft parts are typically produced in low volumes with few requiring very complex surface shaping. The automotive industry by contrast produces a variety of products comprising hundreds of basic structural forms. Dramatic changes in fiber orientation can occur inducing large thickness changes loss of laminate stack-up symmetry and balance. All of these issues can have a considerable effect on the behavior of the final part. This paper describes how the FiberSIM suite of software tools supports the entire composite engineering process by using a unique material simulation technology that predicts how composite material conform to complex surfaces. Engineers can quickly visualize ply shapes and fiber orientations and identify manufacturing problems during the design phase. Designers can also create and automatically update drawings and related manufacturing data directly from the master CAD model thus reducing opportunities for errors and delays on the manufacturing floor. Practical case studies from automotive highlight how composite engineering can be improved and risk can be reduced by the use of these new integrated simulation-driven tools.

Analysis of Resin Flow under Flexible cover in Vacuum Assisted Resin Infusion

Laurent Joubaud, September 2002

Techniques to simulate resin infusion using classical RTM simulation software are investigated. The difference in the filling behavior between “rigid” and “flexible” molds is evaluated and explained. A model describing the evolution of permeability with pressure is developed for flexible moulds. This model takes into account the changes in thickness of the cavity following deformations of the mold cover as well as the compressibility of the reinforcement. The model is validated by comparison of numerical simulations for a complex automobile part manufactured by resin infusion with actual test results obtained at the factory

No Postcure RRIM for Automotive Exteriors

Michael F. Hurley, September 2002

Reinforced reaction injection molding (RRIM) has reemerged as an important method in automotive exterior applications. Presently composite applications demand higher productivity and improved part performance. Stability at higher heat to endure E-coat oven bake improvements in fillers yielding easier processing at high loading improved toughness at high modulus and higher productivity have already been realized with RRIM in Europe and NAFTA. Now the kinetics of one new material Bayflex 190 is such that reaction is essentially complete at demold. In the past RRIM molded parts were required to be baked at 120oC and above to complete chemical reactions attain complete physical properties and de-gas parts prior to painting. In current E-coat applications postcure of 190oC is typical. Elimination of postcure means significant savings in energy increased productivity decreased handling and lower capital expense. Bayflex 190 polyurea attains virtually all properties at demold. After molding parts can be washed and primed directly. Dynamic mechanical analysis shows that further heating to 200oC anneals and strengthens the composite. Several very sensitive analytical methods have been employed to characterize the degree of cure at demold. Differential scanning calorimetry (DSC) shows no exothermic chemical reaction up to 200oC. Thermal gravimetric analysis (TGA) shows no CO2 loss from unreacted isocyanates. And Fourier transform infrared spectroscopy (FTIR) scans indicate no free isocyanate in freshly molded samples. Parts painted in production exhibit no defects associated with elimination of postcure.

Designing for Durability Using an E-Glass Reinforced SRIM Urethane Composite

Scott L. Coguill, September 2002

The durability of a SRIM Urethane composite are evaluated and the results are used to develop a design guide to aid in the use of this material. Test methods for static fatigue creep and impact testing are described in detail. The Oak Ridge National Laboratory developed these methods for durability testing. The raw test data from an earlier study are summarized and generalized in the form of design equations. The scope and limitations of these design equations are discussed. This material evaluation and data summary process provides a means for designing for durability using an E-glass reinforced SRIM Urethane composite.

The Use of UV Light for Surface Cleaning for Painting and Adhesive Bonding of Composites and Metals

Michael J. Rich, September 2002

Contemporary vehicles utilize a mix of materials in their construction consisting of metals plastics and composites. These materials must possess suitable surface properties to achieve desired performance when these parts are adhesively bonding or painted for field service. Surface preparation methods now in place oftentimes use solvents or caustics an increasingly unacceptable approach in an era of mounting environmental regulations. New methods of surface preparation are called for that are environmentally benign and economically feasible while meeting the stringent quality standards of the automotive industry. The use of energetic ultraviolet light is emerging as a promising technology to compete with the old methods of surface preparation. This paper reports the utility of using energetic UV light to generate appropriate surface chemical composition on plastics composites and metals for subsequent painting or adhesive bonding operations. UV treatments have the potential to replace the old methods of treating assorted materials used in the automotive industry in an environmentally responsible and cost-effective manner.

Enhanced Bonding of Polypropylene to Polypropylene and other Materials with Novel Thermoplastic Heat Activated Adhesives

S.W.Tsui, September 2002

It is commonly accepted that bonding polypropylene to itself or other adherends is difficult and the options available for cost-effective bonding using adhesives are very limited. The aim of the presentation will be to describe a new range of heat-activated adhesives recently developed in our research laboratories and their applications. These adhesives which are now commercially available offer numerous advantages for the rapid manufacture of composite materials in addition to promoting new or improved assembly methods in a wide range of market sectors. e.g. automobile aerospace construction textiles footwear and packaging to mention but a few. The main focus of the presentation will be to outline various ways in which the film strand or pellet forms of the new adhesives may be used to solve a variety of industrial problems. The range of materials to which polypropylene can be successfully bonded (e.g. to itself to many metals and to a range of other materials notably cellulosics) will be outlined together with their associated manufacturing methodologies such as hot compression lasers and induction heating. An indication of the mechanical bond strengths which can be achieved at various temperatures will also be outlined.

Electrochemical and Stack Evaluation of Composite Bipolar Plate Materials

Joachim Scherer, September 2002

Composite plate materials for use as bipolar plates in a fuel cell stack must meet certain performance criteria namely high surface and through-plane electrical conductivity very low gas permeability and chemical resistance to both coolants and reactants. In addition to these performance criteria it is necessary from a cost viewpoint that the bipolar plates are easy to manufacture. One category of materials being used for bipolar plates are carbon composites where carbon additives are mixed with a thermoset resin for net-shape compression molding of bipolar plates. A study of the corrosion resistance (via electrochemical testing) helium permeation stack performance and electrical conductivity of a variety of composite materials designed for bipolar plate applications will be presented.

Polymeric Composite Bipolar Plates for Vehicle Applications

Richard Blunk, September 2002

At present membrane electrode assembly performance levels and stack operating conditions of PEM fuel cells a plate area specific resistance of less than approximately 20 mohm cm2 and a plate thickness of less than 2 mm are required to meet the vehicular volumetric power density target (> 2 kW/l). It is however difficult to meet these aggressive requirements and simultaneously obtain good mechanical properties when using polymeric plate materials. Polymers become brittle and break frequently at the high conductive filler loadings (e.g. > 50 v/o graphite) required for high conductivity. This study investigates a potential approach for obtaining high plate conductivity at low conductive filler loadings thus enabling high volumes of thin and ductile plates to be manufactured at low scrap rates.

3D FEM Simulation of Feed-Block Profiling for Flat Die Coextrusion

John Perdikoulias, Jiri Svabik, May 2002

This paper presents the results of a 3D FEM analysis of some layer spreading experiments performed on flat die with a coextrusion feed-block. The complete feed-block and die assembly was simulated using a commercially available 3D FEM software package and a path-line analysis was used to determine the interface position and the degree the of layer spreading. The results obtained were in good agreement with the experimental data. The simulation also provided a better insight into the flow development within these types of systems.

Adhesive Bonding of Polymers and Composites with Microwave Mode-Switching Method

Shirley Zhou, Martin C. Hawley, May 2002

Microwaves provide rapid, selective and volumetric heating in processing polymers and polymer composites. A variable frequency mode-switching method was studied to uniformly bond two polymer composites with an epoxy-based adhesive. Results were compared with thermal process. For one substrate, microwave method reduced the bonding time and enhanced the bonding strength significantly. For the other substrate, microwaves reduced the bonding time and achieved equal bonding strength as that in thermal process.

Advances in the Stabilization of Flexible PVC Using a Liquid Calcium-Zinc Technology

James E. Reddy, Jeremy A. Hackett, May 2002

The global market for liquid mixed metal stabilizers is migrating toward heavy-metal-free products. Historically, these systems have not been performance and cost competitive. High efficiency calcium-zinc stabilizers have the potential to replace heavy-metal-based products. The intrinsic value of non-phenolic lubricating calcium intermediates and calcium-zinc stabilizers are discussed within the following report.

AFM Study of Ultrathin Tri-Block Copolymer Films on Tailored Grafted Polymer Layer

Igor Luzinov, Vladimir V. Tsukruk, May 2002

AFM was used to study the morphology of ultrathin poly[styrene -b- butadiene -b-styrene] copolymer (SBS) films deposited on polystyrene brushes. The grafting density and molecular weight of the grafted polymer layers were varied to reveal the relationship between the parameters of the brush interface and the structure of the film. We found a strong effect of the underlying brushes on the formation of the SBS films.

Analysis of Large Diameter Polyethylene Piping Failures

Donald E. Duvall, May 2002

Large diameter high density polyethylene (HDPE) pipe, typically with diameters greater than 300 mm (12 inches) often have very different failure modes than smaller diameter pipe of the same materials. Heavier wall thicknesses, sometimes greater than 50 mm (two inches), are more susceptible to oxidation during manufacture. The aqueous media transported in such pipes may also oxidize the pipe wall. Such pipes are also often more susceptible to excessive deformation by soil settlement. In this paper, failures in three different large diameter HDPE systems will be investigated.

An Analysis of the Fiber-Fiber Interactions Using the Fragmentation Test and Optical Coherence Tomography

Walter G. McDonough, Gale A. Holmes, Joy P. Dunkers, May 2002

Multi-fiber model composites are being used in studies into the nucleation of failure in composites. Results have revealed that the nucleation of critical flaws in unidirectional fibrous composites may rely on the time-dependent redistribution of stress by the viscoelastic matrix. Although their role in flaw nucleation is not clearly understood, shear deformation bands have been detected between fiber breaks. Furthermore, interfacial phenomena have been detected in the matrix by Optical Coherence Tomography.

Analysis of the Polymer-Pellet-Flow into the First Section of a Single Screw

H. Potente, T.C. Pohl, May 2002

The flow of plastics pellets between the first flights of a single screw can lead to conveying problems. As a result, the throughput varies or not enough material reaches the following screw sections. In order to gain a better insight in the correlations that exist between pellet properties, barrel and screw geometry, a physico-analytical model is worked out. On the basis of this model, the pellet flow behavior can be analyzed relatively accurately.

Analysis of Tiger Striping in Injection Molded TPO

K. Jayaraman, P. Papworth, Chichang Shu, M.D. Wolkowicz, May 2002

Tiger striping in injection molded bars made of thermoplastic olefin (TPO) blends has been examined by a detailed analysis of the disperse phase morphology. This is evaluated in flow mark regions and out of flow mark regions on the part surface and near the wall, and also just behind the flow front but away from the wall. The results point to a way to control the rheology of the components for avoiding or delaying the onset of flow lines.

Annealing of a Co-Continuous Polystyrene/Polylactide Blend and its Influence on the Morphology

Zhenhua Yuan, Basil D. Favis, May 2002

In this paper, polystyrene and polylactide were blended at a composition of 50/50 to form a co-continuous morphology. The influence of annealing on the final morphologies of the blend is investigated using SEM and Mercury Intrusion Porosimetry. It is demonstrated that a series of co-continuous networks with pore sizes ranging from 1 to 80 microns and higher have been achieved by varying the annealing conditions. A mechanism of coalescence is discussed in order to account for the said morphologies.

Application of Ultrasound in the Determination of Fundamental Extrusion Performance: Barrel and Screw Wear Measurement

C.-K. Jen, Z. Sun, M . Kobayashi, M . Sayer, C.-K. Shih, May 2002

Ultrasonic stand-alone and film-type high temperature sensors and system have been used to measure in-line the barrel and screw wear during low-density polyethylene extrusion. These sensors are nonintrusive and non-destructive. For the screw wear measurement the system is equipped with fast data acquisition. Measurement accuracy of better than 50 ?m can be achieved.

Application of a Single Screw Extruder Simulation towards Design

Jiri Vlcek, John Perdikoulias, May 2002

This paper provides an overview of the application of extrusion simulation towards process analysis and screw design. The paper discusses some of what is possible today with computer aided screw design; what can be obtained from simulation results, what the limitations are, and shows a couple of examples of how to apply simulation towards design.