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

Migration of Surface Defects Thru Thickness of a Polymer Film during Thermoforming
A Venkateswara Gupta, Himanshu Asthana, Ashwit Dias, May 2007

Mechanism of defect migration from bottom to top surface of a sheet due to thermoforming has been investigated in this work. ABAQUS, a commercially available package was used to conduct finite-element analyses of point defects found on back surface of film/ sheet. It is postulated that these point defects are incorporated during sheet/ film extrusion process. In film/ sheet as manufactured they do not necessarily negatively impact Cl A surface finish. However, post-thermoforming they manifest themselves as dimples or craters on the first surface (exposed surface on final part, visible to eye). This may negatively impact Cl A surface finish of the thermoformed part. Recommendations to prevent such defects on the thermoformed part have been provided.

What Every Plastics Professional Should Know about Patents and Patenting- Part 3: Lawful Designing around Valid U.S. Patents
Amad Tayebi, May 2007

Claim elements and construction of claim terms define the intellectual property rights granted in a valid U.S. patent, Markman v. Westview Instruments, Inc., 517 U.S. 370 (1996). As such, based on a claim element-byelement comparison, one may determine whether an accused product or process infringes (literally or under the doctrine of equivalents) a patent claim. Conversely then, carefully designing a product, a process, an apparatus or a chemical composition so that it falls outside the scope of the allowed patent claims would likely avoid potential successful infringement actions. This article provides an overview of literal infringement requirements and the test employed by the courts in determining infringement under the doctrine of equivalents.

Mechanical and Physical Properties of High Strength, High Conductivity Copper-Nickel-Silicon-Chrome for Mold Tooling
Doug B. Veitch, John C. Kuli, Jr, Robert E. Kusner, May 2007

In the last 10 years, a CuNiSiCr alloy with thermal conductivity in excess of 100 W/m/K and a nominal hardness of 30HRC has been produced and marketed into the plastic injection and blow molding industries. The alloy is comprised of nominally 7% Ni, 2% Si, 1% Cr and a balance of Cu. We have tested wrought versions of this alloy produced by us as well as other manufacturers. We present the hardness, strength, conductivity and fracture resistance, and compare it with that of other high strength copper mold alloys. We also present actual cooling data for polycarbonate lenses molded in a 100 W/m/K copper insert vs. a tool steel insert as an illustration of the utility of high conductivity molds.

Failure Analysis of Gasoline Storage Assemblies
Jeffrey A. Jansen, May 2007

Failures occurred within tank assemblies used for the storage of gasoline. The cracking was observed in a significant number of assemblies that had been in service. The cracking was found within the injection molded spout in areas immediately adjacent to the surrounding blow molded tank body. The focus of this investigation was a determination of the nature and cause of the failures. The results obtained during the evaluation of the cracked components indicated that the failures occurred through slow crack initiation via a creep rupture mechanism. This paper will review some of the testing performed to characterize the failure mode and identify the cause of the cracking, while demonstrating the analytical procedures used in the investigation.

Reactor TPO: Innovations in Low Temperature Ductility and At-Press Dimensional Control
Frank Krabbenborg, Parvinder Walia, Tom Traugott, May 2007

Material specifications for exterior TPO applications require materials which are highly ductile at temperatures as low as - 40°C. Practical impact tests such as pendulum impact on large part moldings, are simulated by multi-axial impact tests according to ISO 6603 or ASTMD3763 standards. In such tests, molded discs with a prescribed thickness (2-3 mm) are impacted at low temperatures (0 to -40°C) and impact speeds (2 to 7 m/s). Injection molded 3 mm thick discs from compounded TPOs using ethylene –? olefin copolymer elastomers are known to have total energy absorption of > 60 Joules and fail in ductile manner down to -40°C. A compounded TPO must use a particular PP, and 30-35% added elastomer to obtain such ductile performance. Thus, manufacturing complexity and an additional heat history had to be added via compounding to meet these specifications.In response, Dow R&D has developed a natural reactor TPO (product name Dow PP D143.00) which is fully ductile at - 40°C. This performance is the result of a product design based on specific elastomer design and MWD distribution while still being produced in the reactor. The resulting flexural modulus is greater than 900 MPa and coefficients of linear thermal expansion (CLTE) = 90-100?m/m·°C. This reactor TPO will meet the functional requirements for many bumper fascia designs. In cases where higher modulus and/or lower CLTE is required, talc filled master-batches are developed to allow easy dispersion within an injection molding press.

A Method for Quantifying Relative Interfacial Shear Stress in Mwnt/Polymer Composites
R.K. Duncan, L.S. Schadler, R. Andrews, L.C. Brinson, X. Chen, I. Beyerlein, May 2007

In order to better understand the micromechanical behavior of carbon nanotube filled polymers, the load transfer behavior and interfacial shear stress must be quantified. This paper presents preliminary work on an experimental technique for quantifying the relative interfacial shear stress in multi-walled carbon nanotube / polycarbonate composites. The procedure provides a comparison of the aspect ratio of the nanotubes pulled from a fracture surface. In addition, the correlation with pullout angle is discussed. This work showed a decrease in the aspect ratio and thus an increase in interfacial shear as a result of chemical surface modification to multiwall nanotubes.

A Durability and Adhesion Test for Fabric Covered Plastic Parts
Theresa Hermel-Davidock, Mark A. Spalding, Mike E. Hus, John Buck, David A. Reuschle, May 2007

The cross-cut adhesion test provides a rating for the adhesion of a surface material to a plastic substrate. The original ASTM standard D3359-02 for the cross-cut adhesion test was developed to measure the adhesion between thin paint films and flat, metal substrates. This test, however, is not well suited for three dimensional plastic parts that are covered with fabric. It will be shown in this study that improper cross-cut testing protocol can result in false failures and artificially low adhesion performance scores. A modified cross-cut adhesion test procedure is documented here that is based on the ASTM method and is applicable to fabric covered parts.

Effect of Screw Type on Development of Polymer Blend Morphology along an Extruder during Compounding
Han-Xiong Huang, Xiao-Jing Li, May 2007

The morphology development of an immiscible polymer blend along a single screw extruder was investigated experimentally. Three different screw geometries were evaluated: one with conventional screw elements; the other two with a fluted and Pineapple mixing element, respectively. The experiments were conducted using a polypropylene/polyamide-6 (PP/PA6) blend. The samples of blends were collected from four different positions using specially designed sampling device along the extruder online during compounding and were then examined using scanning electron microscopy (SEM) to evaluate the morphology development. The results showed that the screw with a fluted mixing element appears to produce the finest morphology at the end of the extruder. The Pineapple mixing element, with a characteristic of chaotic mixing, facilitates to form thinner laminar layers of dispersed phase.

Visco-Elastic Polyurethane Foams Creep Behavior and Recoverability Analysis
Shaofu Wu, Bernard Obi, J. Wilchester, V. Juarez, May 2007

The creep behavior and mechanism of several visco-elastic foams were analyzed in this paper to understand the structure property relationship. The creep behavior and recoverability of these foams were characterized by the compression set, short time creep test, as well as hysteresis with an optical extensometer. The creep mechanism was analyzed and explained based on foam cell structure (cell orientation and uniformity) and material property. Material parameters and cell structure that possibly control the creep and recoverability of visco-elastic foams are also discussed.

Hybrid Nanoclay-Rigid PVC-Wood-Flour Composites
Laurent M. Matuana, Omar Faruk, May 2007

This study examined the use of nanoclay reinforced rigid PVC prepared with a novel melt-blending approach as a matrix for PVC/wood-flour composites. The effects of nanoclay contents and chitin as coupling agent on the properties of the composites were evaluated. The flexural, tensile and dynamic mechanical properties of composites made with nanoclay reinforced PVC matrix and chitin were measured and compared to their counterparts made with unreinforced PVC matrix. The experimental results indicate that wood-plastic composites with properties similar to solid wood could be manufactured by tailoring the formulation, i.e., combining nanoclay, rigid PVC, wood flour, and coupling agent.

Micro-Injection Molding of High Aspect Ratio Features with Thermoplastic Polyurethanes
Sung-hwan Yoon, Michael W. Alabran, Jun S. Lee, Joey L. Mead, Carol M.F. Barry, David Carter, May 2007

High aspect ratio (4:1) microscale features were injection molded using thermoplastic polyurethanes and silicon tooling and measured using atomic force and scanning electron microscopy. Direct filling of the features enhanced replication when compared to indirect filling (i.e., filling during melt pressurization). With direct filling, mold temperature and melt temperature equally impacted replication. For good replication, mold temperatures must selected to balance filling, stretching of molded features during ejection, and shrinkage of the features.

Chemiluminescence and Fluorescence Imaging of Virgin and Reprocessed Grades of Nylon 6,6 and Polycarbonate
Timothy L. Hoeller, May 2007

Chemiluminescence and Fluorescence Imaging can be used as novel quality control techniques applied to reprocessed resins. Chemiluminescence measurements of Nylon 6,6 in both air and nitrogen atmosphere reveal increased sample oxidation with increased number of molding cycle. Fluorescence imaging of reprocessed polycarbonate pellets compared to virgin shows significantly greater intensity from reprocessed resins. GPC and Raman Spectroscopy confirm disorder in reprocessed resins. Both Chemiluminescence and Fluorescence imaging techniques performed in combination yield information related to sample morphology and contamination. By careful selection of excitation and emission filters, Fluorescence imaging can discern regrind amounts in plastics to better than 5% resolution.

Effect of Cell Shape on Mechanical Properties of Polyurethane Foams Molded under Several Conditions
Kazumi YAMAGUCHI, Akihiko GOTO, Asami NAKAI, Hiroyuki HAMADA, May 2007

Polyurethane foam is formed by various molds. The internal structure of rigid polyurethane foam is very complex. Moreover, the cell shape showes elongated shape in foaming direction, so that rigid polyurethane foams exhibit anisotropy in mechanical properties. Therefore, the effect of cell shape on the mechanical properties of polyurethane foams have been investigated on various molded condition and different mold shapes. The cell shape was evaluated by the ratio of the longitudinal diameter to the transverse diameter . The relationship among density, cell shape and compressive properties of many kinds of rigid polyurethane foams were investigated. It was found that compressive properties depended on cell shape in compared with density.

Effect of the Clay Treatment on Cure and Morphology of Epoxypolysulfone- Montmorillonite Hybrid Nanocomposites
Martin Arellano, Juan A. Martínez-Sánchez, May 2007

The effect of the addition of two different organically treated clays montmorillonite on the cure and morphology of an epoxy-polysulfone (PSF) blend (5, 10 and 15 phr PSF) is studied. The epoxy system was based on diglycidyl ether of bisphenol A and diaminodiphenylsulfone. The clays used were Nanomer I.30E (NI30E) and Cloisite 15A (C15A). The curing reaction was followed by differential scanning calorimetry and the morphology was analyzed by scanning electron microscopy. The presence of NI30E accelerates the curing reaction, decreases the glass transition temperature (Tg) and increases the PSF domain size. On the other hand, there is a negligible change on the curing reaction and blend morphology for C15A modified systems.

Synthesis and Characterization of Some Novel Polyurethanes Based on Rigid or Flexible Aromatic Diisocyanates and Mixtures of Them
Cristina Prisacariu, C. Paul Buckley, May 2007

Polyurethane elastomers were synthesized with ethylene glycol as chain extender. The macrodiol was poly(ethylene adipate) MW = 2000 ± 50. Two isocyanates were employed: 4,4- diphenylmethane diisocyanate (MDI) and 4,4’ - dibenzyl diisocyanate (DBDI), alone or as mixtures. Materials were characterized by DMA, DSC and WAXS. Changes induced by varying the type and the number of isocyanates and the order of their introduction were followed. Crystallinity was strongly reduced when DBDI was mixed with MDI.

Designing Sustainable Products Using Bio-Based Nanocomposites
Emre Tufekcioglu, Rolf Koster, Daniël Vlasveld, Remy Jongboom, May 2007

Environmental materials-related factors can be best addressed in the design stage. Conversion of materials to products is critically important in dealing with new and partly unknown challenges and opportunities. Experiments to explore bio-based nanocomposites included investigating injection molding processability and product properties. Several nanocompounds with modified poly(lactic acid) were prepared and geometries were molded with typical product characteristics, including flow weld lines. Further molding optimization is needed, preferably in conjunction with new mold design principles and dedicated molding machines.

The Effects of Secondary Angle Length and Thickness on Pinchoff Strength
Michael Vandeveer, Clint Badowski, Matthew Loeffler, May 2007

A properly designed pinch-off can mean the difference between a strong or weak weld in extrusion blow molding. There are few guidelines to use as when designing the pinch-off of a mold. The pinch-off area of a blow molded part is usually the weakest area the part. It is important to look at what affects the strength of the weld line in order to maximize the strength of the bottle. This experiment studies the effects of changing the depth and length in a compression type pinch-off of the compression region of the flash pocket while keeping the other dimensions of the insert constant. This will help mold designers in the future by giving them some guidelines when designing this part of the flash pocket. The results obtained from this experiment show that generally when the compression pocket length increases and compression thickness decreases, the weld strength increases. Some of the results were inaccurate, and the experiment needs to be run again with better dimensional control over the inserts.

New Polyurethanic Materials Derived from Dibenzyl Monomers: Elastomers, Films and Blends
Cristina Prisacariu, May 2007

New segmented polyurethanes have been designed and synthesized based on flexible DBDI (4,4’-dibenzyl diisocyanate) with internal –C-C- rotation axis. PUs structural and mechanical properties were investigated. DBDI giving rise to a special hard segment conformational mobility induces a specific physicalmechanical behaviour in PU and leads to a high tendency of crystallization and hard segment block phase separations in dibenzyl–based PU. The preliminary results of the structural study on such polymers have shown significant changes which are brought about by changing the geometry of the isocyanate.

Fabrication of Porous PCL Fiber with Co-Continuous and Size Adjustable Porous Structures from Immiscible Polymer Blends
Pratapkumar Nagarajan, Kathryn Abbott, Donggang Yao, May 2007

Porous polymer fibers can be fabricated using different methods including hollow fiber extrusion, multicomponent fiber extrusion (e.g. with islands-in-sea morphology), and solution processing. However, with the current technology, it is difficult to achieve a continuous porous structure across the entire fiber cross-section and control the pore size. This greatly limits potential applications of such fibers in many emerging biochemical and biomedical applications. We report here a filament extrusion process of immiscible polymer blends for fabrication of highly porous fibers with continuous and size adjustable porous structures.

Predicting Shelf Life of Medical Grade Polymers Using Accelerated Heat Aging
Eric S. Nachreiner, Adam J. Miloser, May 2007

Part failure after radiation sterilization in medical parts is a concern in the plastics industry. When the sterilization phase is complete damage to the part does not cease, but continues in a dark reaction for a period of time, often years.Damage can be noticed when melt flow index tests are performed and the reduction in molecular weight causes a higher melt flow value. Also, damage can be noticed when tensile tests are performed and decreases in ultimate elongation are noticed. The intention of this research is to derive a new Q10 constant for the Arrhenius Equation to better predict shelf life of medical polymers.Conclusions will be drawn by comparing results from the tensile and melt flow index tests.

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