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
Analysis of Rotational Moulding Process Parameters and Warpage on Cycle Times
Anton Ianakiev, K.K.Lim, May 2007
The analysis of heat transfer in the rotational moulding process is a non-linear multi-dimensional problem, which involves a number of process conditions and thermal parameters. This study, mostly involves dimensional analysis, the changing effects of the process parameters and conditions on the process times for different processing circumstances. The modelling helps to further identify and understand the dependence of key thermal parameters due to external heating, external cooling, external-internal cooling and warpage on cycle times of the rotational moulding. This study shows that for the external cooling process, the warpage formation for thicker parts does have a considerable influence on prolonging the total cycle time, also the external-internal cooling method significantly improves the cycle time.
A Constitutive Model for Creep Lifetime of PBO Braided Cord
W.J. Sterling, May 2007
A constitutive model to describe the creep lifetime of PBO braided cord has been developed and fit to laboratory data. The model follows an approach proposed for p-aramid cord in similar applications, and has an Arrhenius-type representation that arises from consideration of the failure phenomenon mechanism. The data were obtained using a hydraulic-type universal testing machine, and were analyzed according to Weibull statistics using commercially-available software. The application of concern to the author is NASA's Ultra- Long Duration Balloon and other gossamer spacecraft, but the motivations for the related p-aramid works suggest broader interest.
The Reinforcement of Poly(Lactic Acid) Using High Aspect Ratio Calcium Carbonate Based Mineral Additive
Zhiyong Xia, Dennis Prendes, Patrick Wernett, Richard C. Bopp, May 2007
As a sustainable alternative to petrochemical-derived products, poly(lactic acid) (PLA) is gaining a lot of interest in recent years. PLA has good optical clarity and high stiffness, but it is also intrinsically brittle. In this paper, the comparison between a specially engineered high aspect ratio mineral-EMforceTM Bio calcium carbonate, mica and talc in reinforcing PLA was performed. It was found that EMforceTM Bio calcium carbonate was extremely effective in improving the low temperature impact toughness as well as increasing the stiffness of PLA. Further the addition of EMforceTM Bio calcium carbonate to PLA does not hinder its compostability at elevated temperatures.
Adhesively Bonded Smart Composite Joints: An Overview
Jinquan Cheng, Guoqiang Li, Su-Seng Pang, May 2007
The peel/shear stress concentration is the principal reason to cause the catastrophic failure of adhesively bonded joints. Many traditional enhancement methods have been developed to mechanically improve the joint strength. Comparing to these traditional mechanical enhancement methods, a smart strength improvement concept for adhesive joint has been introduced to adaptively realize the reduction of peel/shear stress concentration by the integrated piezoelectric layers. Here, the current development of adhesively bonded smart joint systems is reviewed and summarized in detail.
Insert Coating as a Pre-Processing Approach for Improvement of Adhesive Bonding in Plastic-Metal Hybrid Structures
Ahmad Al-Sheyyab, Ines Kuehnert, Ernst Schmachtenberg, May 2007
Improvement of adhesive bonding between plastic and metal components by means of surface coating pretreatment has been investigated. Metal inserts have been coated with polymer-based film then overmolded with reinforced polyamide-6 in an injection molding process. Experimental work has included the characterization of the adhesive bonding strength and the influence of the coating film on the mechanical behavior. FE-Simulation has been conducted to analyze the local shear stresses. Aging influence has been evaluated using climate change test.
ION/Polymer Interactions in Polyelectrolyte Gels
Ferenc Horkay, May 2007
We report results from experimental studies performed on polyelectrolyte gels to understand the volume transition induced by multivalent cations. Macroscopic osmotic and mechanical measurements are made to determine the effect of ion binding on the elastic and mixing contributions of the network free energy. Small-angle neutron scattering is used to reveal the role of multivalent ions in the organization of the polymer segments. We demonstrate that combination of scattering and osmotic measurements allows us to determine the characteristic size of the structural elements that contribute to the osmotically driven concentration fluctuations, and yields important information on the effect of ions on the structure and thermodynamic properties at both molecular and supermolecular levels.
Effect of Strain Rate on Tensile Properties of Carbon Nanofiber-Reinforced SC-15 Epoxy
Sajedur Rahman Akanda, Yuanxin Zhou, Shaik Jeelani, May 2007
In this study, tensile tests were performed on carbon nanofiber reinforced epoxy at different strain rates. Tests results showed that both the elastic modulus and the tensile strength of the materials increased with higher strain rates, but the failure strain decreased with higher strain rates, indicating that the composite is a strain rate-dependent material. Experiment results also showed an even distribution of CNFs in the 1 wt% and 2 wt% systems and an agglomeration of CNFs in the 3 wt% system. Therefore, the 2 wt% CNF-infusion system exhibited maximum enhancement, compared to other systems.
Clear Barrier at Atmospheric Pressure – the Second Phase
Rory A. Wolf, Rick E. Elwanger, May 2007
The barrier properties of transparent layers deposited on flexible plastic substrates are of interest to many in the packaging industry. Numerous methods have been used to manufacture transparent barrier coatings with varying degrees of success to address evolving environmental laws requiring the reduction or elimination of volatile organic compounds (VOCs), which are the byproduct of curing liquid topcoats. There is also a consumer preference to visually inspect packaged products through packaging prior to purchase. This paper will present new evidence since the 2006 SPE FlexPack Conference of the potential for clear barrier at atmospheric pressure through the use of plasma processing as integral steps in a composite, or several stage, process for deposition and polymerization of functional barrier coatings. XPS analysis of polymerized film showed presence of silicon, carbon and oxygen in ratios different from the monomer, and in fact approaching a Si:O atomic ratio of 1:2 confirming cross linking effects, and the plasma polymerized organo-silicon films displayed good functional barrier properties without the environmental concerns of VOCs.
Mini Mixing Devices for Specialty Nano-Strucured Blends and Composites: Evaluation of Flow, Mixing and Morphology
Uttandaraman Sundararaj, Orna Breuer, May 2007
A 1:20 downscale of an internal batch mixer (60mL total volume), the Minibatch mixer (3 mL total volume), requiring only 2g per blend sample, has been developed for small-scale blending of specialty polymers and nanocomposites. The morphology of samples processed by this new miniature mixer is compared to other labscale equipment such as the 60mL internal batch mixer and the Alberta Polymer Asymmetric Minimixer (APAM). Immiscible blends showed a spherical dispersed phase structure and uniform distribution throughout the blend; however, the dispersed phase particle size was large in comparison to the other mixers. Vapor grown carbon fiber (VGCF) nanocomposites were better dispersed and more homogeneous compared to those prepared using the 60mL batch mixer and the APAM. The large surface to volume ratio of this new mixer plays an important role in the heat transfer mechanisms and thus may affect flow patterns occurring in the Minibatch mixer. Simulations using Polyflow software showed that the flow pattern in the 3mL Minibatch is similar to the 60mL batch mixer but that the temperature rise due to viscous dissipation is not as large for the new miniature mixer.
Comparison between Amorphous Metallic Alloy and Silicon as Molding Insert for Micro Injection Molding of Polymers
Yew Weng Loke, Shu Beng Tor, Jung-Hoon Chun, Ngiap Hiang Loh, David E. Hardt, May 2007
The mass-production of microfluidic devices must be done in a reliable manner. In this study, toolings used to reproduce microfluidic features on cyclic-olefincopolymer (COC) and polymethyl-methacrylate (PMMA) polymers by amorphous metallic alloy and silicon inserts were compared. Both toolings were used in micro injection molding. Findings indicate that the alloy was mechanically more suitable as mold inserts, whereas silicon had better surface roughness. COC samples showed comparable geometrical replication of microfluidic features compared to PMMA.
Solids Compaction and Conveying in a Single-Screw Extruder by Discrete Particle Modeling
P.A. Moysey, M.R. Thompson, May 2007
To improve our understanding of granular flow in the solids-conveying zone of a single-screw extruder, a discrete particle model has been developed. The discrete particle approach allowed us to simulate polymer compaction without using the isotropic stress assumption used by continuum models. An elastic-fully plastic contact force displacement model was validated by simulating HDPE and PS under compaction in a batch cell and comparing against reported data in the literature. The particle model and experimental results showed good agreement for PS which exhibited elastic behavior up to the tested limit of 12 MPa. The simulation for HDPE showed marked deviation above 4 MPa, over predicting the plastic dissipative losses. The extruder simulations showed exponential pressure development along the axial length of the screw, similar to continuum models, but indicated that bulk density in the screw was affected by attributes of the flow field besides just pressure. The nonisotropic stress distribution of the solids in the screw was examined, with the stresses found to be concentrated at different boundaries depending on pressure development.
Scale up Rules for Profile Geometries in Extrusion Dies and Options to Adjust Surrounding Flow Channels to Avoid Transverse Flow
Helmut Potente, Hans-Peter Heim, Ralf Schlottmann, May 2007
The design of extrusion dies is frequently based on knowledge and experience of the designers. One very simple, rapid and low-cost means of designing a profile die is the use of scale-up rules. This paper deals with an approach to develop scale-up rules which make it possible to scale-up or scale-down existing profile geometries by means of simple equations. The following profiles are observed: rectangular channel, annular gap and pipe channel. Allowance is also made for a change in material properties in order to achieve the greatest possible variability in the die design. Neighboring areas are examined and revised by iterative procedures to avoid transverse flow between the flow channels.
Effects of Structural Constraint and Impact Energy on Fracture Behavior of a Flexible Composite Tubing
Xiaoping Guo, May 2007
By using scanning electron microscopic analysis, we fractographically examine failure modes of flexible, braiding-reinforced composite tubes under impact energy pulses. The tubes are subjected to different extents of structural constraint imposed by other catheter components. The effects of impact energy pulses and structural constraints on failure modes are qualitatively evaluated. It is practically shown that under certain extents of structural constraint, minimal impact energy input can introduce catastrophic, brittle fracture mode dominant over either fatigue fracture mode or ductile failure behavior. In an attempt to identify the root causes for the formation of observed brittle fracture phenomena, various material characterizations, including differential scanning calorimetry (DSC), thermo-gravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FTIR) are conducted on the thermoplastic elastomer material of the tubes to attest material integrity after fabrication.
Melting Behavior of a Poly(Ether-Block-Amide) Copolymer Melt-Crystallized under Isothermal, Quiescent Condition
Xiaoping Guo, May 2007
The melting behavior of a poly(ether-block-amide) copolymer melt-crystallized under various quiescent, isothermal conditions was studied using differential scanning calorimetry (DSC). The structure of the crystallized copolymer was characterized at ambient temperature using wide-angle X-ray diffraction (WAXD). It was found that the hard, crystalline microdomain of the melt-crystallized copolymer only exhibited ?- or (???) crystal form associated with hexagonal habits. It was determined based on the DSC and WAXD results that the multiple melting endotherms were attributive to different origins, including the short-range ordering effect at the late stage of crystallization and the melting-crystallization event that occurred during the DSC heating scan.
Generic Circuits by Conductive Epoxy/Ni Adhesives: Geometric Effects
Jianguo Zhou, Erol Sancaktar, May 2007
Epoxy/Ni adhesives can be used as integrated circuit (IC) packaging materials due to their lower cost than epoxy/Ag adhesives with acceptable electrical conductivity. In this work, conductive epoxy/Ni adhesives were prepared by solution method and filled into holes connecting the multilayers of a novel prototype designed to be used in electronic components in circuit boards, in order to study the geometrical effects on the prototype's electrical resistance. An empirical equation was obtained for the contact resistance (Rc) measured after cure. We also show that Ohm's law adequately describes the effects of the bulk adhesive resistance (Rb) on prototype's electrical resistance.
Comparison of Crystallization between Water-Assisted and Gas-Assisted Injection Molding Part of Semicrystalline Polymer Based on Numerical Simulation
Shen Changyu, Zhou Yingguo, Chen Jingbo, May 2007
Water-assisted injection molding (WAIM) and gas-assisted injection molding (GAIM) are two innovative process based on the conventional injection molding. Because of the difference between water and gas, the crystallization of part manufactured by WAIM and GAIM has a discrepancy. In order to compare the difference, a simplified mathematics model was created. Moreover, the simulation code was completed and numerical simulation was carried out. The simulation result shows the WAIM parts of the semi-crystallizing polymer will scarcely crystallize and have a short cooling time because of the fast cooling effects of water.
The Effect of Temperature on the Modulus of Elasticity of Non-Linear Viscoelastic Materials
C. Dallner, E. Schmachtenberg, May 2007
Understanding the effect of temperature is decisive to describe the deformation behaviour of viscoelastic materials. There is still no unambiguous evidence whether the elastic part of the deformation is influenced by temperature. Within the scope of this paper both viscoelastic properties and elastic deformation are investigated separately. Therefore, thermoreversible rearrangements (time-, temperature-, strain- and stress-dependent) based on dynamic, creep and relaxation experiments up to the nonlinear viscoelastic range are measured and modeled. A significant difference in the limit of linear viscoelasticity below and above the glass transition temperature is shown. These investigations can be the basis for a more effective use of thermoplastics in the future.
Recycled Vinyl Wallpaper- A New Composite
Karnik Tarverdi, May 2007
Mechanical recycling of waste polymeric based composites allows production of same or similar products, but in the case of vinyl wallpaper the quality of recovered material combines the cellulose component with the vinyl PVC resulting in a new composite which can have completely different applications compared with the original vinyl wallpaper.Vinyl wallpaper is generally composed of Polyvinyl chloride combined with cellulose fibre and with certain formulations a small percentage of different polymer based additives.It has been demonstrated and described in a previous presentation that this post industrial waste material can be recycled, the present paper will demonstrate that this recyclate can be claimed to be a new vinyl based composite. The present paper will also demonstrate advantages of using modified extrusion technology to recycle wallpaper continuously without degradation of base components. With properties characterisation and evaluation it will be demonstrated that this material can have different applications compared with vinyl wallpaper.
Highly Conductive Epoxy Composites for Application as Bipolar Plates in Proton Exchange Membrane Fuel Cells (PEMFCS)
Ling Du, Sadhan C. Jana, May 2007
Electrically conductive graphite-filled epoxy composites were developed by solution intercalation mixing of epoxy resins with expanded graphite (EG) and carbon black (CB), followed by compression molding and curing for application as bipolar plates in proton exchange membrane fuel cells (PEMFCs). High in-plane conductivity of 200-500 S/cm compared to DOE target value of 100 S/cm was achieved with good mechanical properties. The flexural modulus, flexural strength and impact strength were 2.08×104 MPa, 72 MPa, and 173 J/m respectively. The composites also showed high glass transition temperatures (Tg ~ 141°C) and high thermal degradation temperatures (T2 ~ 415°C). Hygrothermal effects on electrical, thermal, mechanical, and chemical properties were evaluated especially under acidic conditions. The maximum water absorption was found to be 1-2 % by weight for these composites, compared to 4-5% for cured EP resins without fillers. SEM micrographs suggested no change in morphology due to reflux in water and acid.
Production of a Tractor Cab Roof Module Using Direct In-Line Compounding of Long Glass Fiber Thermoplastics
Scott Ledebuhr, Darin Grinsteinner, Scott Snowberger, May 2007
Composite Products, Inc. continually adapts their Advantage In-Line Compounding Process to produce products that use novel composite molding tools and methods. In a recent agricultural application, a tractor cab roof combined long glass fiber thermoplastics with innovative tooling and molding methods to simultaneously maximize structure and aesthetic appearance. Additionally, significant cost and performance advantages were realized through part consolidation, material waste reduction, reduction in manufacturing steps at the OEM, and corrosion resistance. The launch of this product was achieved through the successful combination of materials, tooling and process.
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