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

Investigation of PPA Interactions with Polymer Melts in Coextrusion Flows

M. Zatloukal, J. De Witte, C. Lavallée, May 2006

Recently proposed new slip model based on 'effective continuum methods' was developed and used for investigation of process aids interactions with polymer melts in single as well as multi-layer flows. Specific attention has been paid to understanding the role of process aids on stabilization of the zig-zag type of interfacial instabilities in film blowing coextrusion.

Modeling of Viscoelastic Multi-Layer Flows for Different Polymer Melts

M. Zatloukal, M.T. Martyn, J. Vlcek, P.D. Coates, May 2006

Modified Leonov model has been employed in the modeling of the coextrusion flows with same as well as differerent polymer melts. Flow visualization measurements were used for verification of the used numerical scheme. Specific attention is paid here to the possible numerical difficulties which may occur during modeling of the merging area with different polymer materials. Both, measurements as well as FEM analysis of the coextrusion flows were discussed from the wave type of interfacial instabilities point of view.

Investigation of Advanced Constitutive Equations Under Different Flow Conditions

M. Zatloukal, R. Pivokonský, T. Gough, P.D. Coates, May 2006

The predictive capabilities of three models (eXtended Pom-Pom, PTT- XPP and modified Leonov model) are tested for both, steady as well as transient shear and uniaxial extensional flows of LDPE. In the second part of the paper, the modified Leonov model is employed in FEM modeling of the abrupt contraction flow and predicted stress fields are compared with the stress measurements from the flow visualization cell.

The Elimination of Weld Line Witness Marks in Injection Moulding

Peter S. Allan, Keith W. Rawson, Michael J. Bevis, May 2006

The surface witness marks of weld lines in injection mouldings can be particularly unsightly in certain resin compounds. This paper will describe a method that offers the potential to eliminate weld line witness marks. The process involves the combination of selectively heating the mould surface and the application of melt shearing in the mould cavity.

Shape Memory Binary Blends: Compositionally Tailored Fixing and Recovery

Cheryl J. Campo, Patrick T. Mather, May 2006

Semicrystalline-amorphous blends exhibit shape memory due to (1) the elastomeric nature imparted by crystallites that act as physical crosslinks and (2) temporary shape fixing made possible by the vitrification of a continuous, miscible amorphous phase. PVDF-containing binary blends were studied using calorimetry and rheology in order to characterize the morphological control afforded by subjecting such materials to different thermal histories. The sensitivity of the aforementioned techniques to changes in blend morphology will also be discussed.

Fracture Behaviour of Injection Moulding Post-Consumer Wood/Plastic Composite Foams

R. Gosselin, B. Riedl, D. Rodrigue, May 2006

This study investigates fibre reinforced microcellular foams produced via injection moulding using recycled polymers. The objective is to determine the effect of wood, blowing agent and coupling agent contents on impact and tensile properties. Birch wood fibres were blended with a post-consumer HDPE/PP matrix to produce the composites. Azodicarbonamide was used as a blowing agent while maleic anhydride polypropylene copolymer was used as a compatibilizer. Optimal results were obtained with 20 wt.% wood contents.

The Effect of Sharp Corners and Runner Length on Melt Flow Imbalances

Raymond W. McKee, Joshua A. Hoover, May 2006

This study revealed that the use of 90 degree sharp corners has virtually no effect on mold filling imbalance. The study also found that mold fill rates can have a significant impact on the shear induced imbalances found in multi-cavity molds. Further, the study found that increasing the length of the secondary runner will initially decrease the shear induced imbalance developed in the primary runner. Continuing to increase the length has a diminishing effect on the degree the imbalance decreases.

Film-Casting Behavior as a Function of Molecular Structure and Rheology

Christopher W. Seay, Donald G. Baird, May 2006

Polyethylene resins with different molecular structures and rheological properties are investigated in terms of their performance in film-casting. Four metallocene catalyzed polyethylene resins with different degrees of long-chain branching and two conventional polyethylene resins are analyzed in terms of their dimensional changes during film production. With an increase in long-chain branching, and thus strain hardening-behavior, an increase in the necking phenomenon is observed during film-casting.

Antimicrobial Additives in Medical Plastics Compounds

Lawrence A Acquarulo, Jr., Lawrence Johnson, Anthony Listro, Charles J. O’Neil, May 2006

Bacterial infections in hospitals are a leading cause of death in the U.S. and can be caused by bacterial growth on plastic medical devices. The purpose of this paper is to identify effects of microorganisms on plastics, discuss pros and cons of antimicrobial additives in medical plastics.

Measurement of Surface Properties of Polymeric Materials Using Nanosphere Embedment Measurements

Stephen A. Hutcheson, Gregory B. McKenna, May 2006

Here we report results from our ongoing investigation of the surface properties of polymers using a nanoparticle embedment method that was originally pioneered by Teichroeb and Forrest. We describe a viscoelastic contact mechanics solution that includes surface adhesive forces and a time dependent Poisson's ratio. The results show that, with properly designed experiments, both the surface adhesion properties and the surface rheological properties can be extracted from nanosphere embedment measurements.

A Test Method for Rolling Resistance of Rubber Compounds

A.N. Gent, May 2006

A test method is described for measuring energy losses in rolling, using the damped oscillations of a pendulum. The amplitude of oscillation decays initially at a constant rate, and changes to a decreasing rate as the swings become small. In principle, the two processes provide separate measures of energy dissipation. The proposed method could be used for studying the effects of surface features of tire treads and roads on tire rolling resistance, in addition to characterizing the dissipative properties of tread compounds.

Mechanical Properties of Foamed PP Sheet

Yasuhiro NISHIKAWA, Xinyu YANG, Seiichiro HISAKA, Asami NAKAI, Hiroyuki HAMADA, May 2006

Mechanical properties of foamed polypropylene sheet having different foaming ratios (2.0, 2.4 and 3.0) were investigated. Tensile strengths and ultimate strains of polypropylene sheet with 3.0 foaming ratio were lower than those of polypropylene sheet with 2.0 and 2.4 foaming ratios. The ultimate strain increased with an increase in the aspect ratio of the cell shape in the polypropylene sheet. The ultimate strain of the foamed polypropylene sheet was affected by the cell shape.

Thermal and Morphological Properties of Polyethylene Crystals Formed in N-Pentane Under High Pressure

Wei Zhang, Erdogan Kiran, May 2006

The thermal and morphological properties of PE crystals formed in n-pentane at selected pressures from 10 to 54 MPa were studied using DSC and SEM. The results show that the PE crystals that form from these high-pressure conditions display a plate-like morphology which tends to aggregate into ellipsoid-shape structures. DSC studies show that the PE crystals show higher crystallinity and display multiple melting peaks during the first heating scan. This process can be an alternative method for the thermal fractionation.

Blown Films From LDPE-Organoclay and Ionomer-Organoclay Nanocomposites

Rhutesh K. Shah, Rajendra K. Krishnaswamy, Donald R. Paul, May 2006

Mechanical and barrier properties of LDPE and poly(ethylene-co-methacrylic acid) ionomers were improved by melt mixing them with montmorillonite based organoclays. Organoclay structure was optimized to form nanocomposites with good exfoliation, from which films were blown under different conditions.

Modeling the Transient Rheology of a Polypropylene Melt Reinforced with Long And Short Glass Fibers

Aaron P.R. Eberle, Donald G. Baird, Peter Wapperom, May 2006

In this paper we investigate the transient shear rheology of a polypropylene containing long fibers (2.75 to 11 mm, L/D > 150) and short fibers (1 mm, L/D < 50). The objectives of this work are to determine the relationship between stress growth and relaxation behavior of fiber orientation and determine the feasibility of extending Doi's theory for the rheology of rod-like molecules to fiber reinforced materials.

Chemical Attack of UV-Cure Adhesives Involving Polycarbonate

Jessee McCanna, May 2006

UV-cure adhesives are commonly used to assemble a variety of devices molded out of polycarbonate. This paper investigates the effect of uncured or partially cured UV adhesives on elongation-to-break performance of polycarbonate samples, both stressed and unstressed. In addition, the effect of cure time and vapor exposure on elongation-to-break is also summarized.

The Effect of Orientation on Perfluorosulfonate Ionomer Based IPMC Actuation

Joel M. Carr, May 2006

This paper discusses recent findings in the enhancement of actuation properties in ionic polymer metal composites through systematic manipulations of molecular organization and morphology. The preliminary results showed that there is a direct correlation between the morphology of the material and the mechanical properties.

Scratch Behavior of Model Polypropylene Thin Sheets

E. Moghbelli, R.L. Browning, S.F. Hahn, H.-J. Sue, May 2006

The effects of molecular weight (MW) and surface morphology on scratch behavior of model polypropylenes (PP) were investigated. The results suggest that scratch performance is improved when the MW and surface crystallinity of PP are high. Correlation between surface properties and scratch resistance of PP is established and discussed.

Stresses, Adhesion and the Mechanics of Polymer Coatings

Richard John Farris, May 2006

Novel and powerful methods of characterizing the state of stress, the orthotropic elastic coefficients and the energy of adhesion of thin coatings are described. These methods were developed by my research group to help understand the mechanical behavior of coating materials. The systems studied include epoxies, polyimides, photoresists and even some paints and metals. The techniques address issues such as the origin of coating stresses, the influence of the degree of constraint, determining anisotropic elasticity coefficients, and problems associated with adhesion testing.

Working with Organic Pigments in Yellow Color Space

Damien T. Cole, Roger A. Reinicker, May 2006

Formulators coloring plastics and synthetic fibers can select from a variety of organic colorants in order to achieve a final desired color. The choices can be confusing unless the colorants are previously specified or are well known to the formulator. This paper will deal with a subset of the colorants in yellow color space while clarifying the selection process with respect to some of the most important properties of the colorants for plastics and fibers.