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
Explanation of Metal-Metal Contact in Hydraulic Cylinders
J.L. Spoormaker, A.H.J. Nijhof, A. van Beek, K. Kavelin, May 2005
Pistons and cylinders in hydraulically systems are separated using composite wear rings, positioned in grooves of the piston. Metal-metal contact is a serious failure mode in hydraulic cylinders.Metal-metal contact can occur due to more elastic deformation than predicted, wear, exceeding tolerances and too high radial loads.The paper is about failure analysis of damaged hydraulic cylinders for levelling a construction. The failure was not expected because data about the stiffness of the wear rings in the brochure were very much in error.The design curve about “average bearing pressure – compression” of wear rings were suspected and have been accurately measured in a laboratory of Delft University of Technology.Although the data in the design brochure about the stiffness of the wear rings was very much in error, metal-metal contact could then not be explained.It was also assumed that during the setting of our experiments some plastic compression could have occurred. The additional compression should be just enough to explain metal-metal contact if “worst case” of tolerances should have occurred.It was decided to use a probabilistic approach to predict the probability distribution of the radial clearance. Monte Carlo method was applied to determine the probability density function of the radial clearance. From this approach we learned that the probability of metal-metal contact was very low. The only remaining explanation was exceeding of the radial forces on the wear rings.
Novel Green Nanocomposites from Toughened Polyhydroxyalkanoate and Titanate Modified Montmorillonite Clay
Yashodhan S. Parulekar, Amar K. Mohanty, May 2005
The environmental regulations, societal concerns, and a growing environmental awareness have triggered the search for new products and processes that are compatible with the environment. Polyhydroxybutyrate (PHB) is a biodegradable polymer that has created significant interest recently because of its renewable resource-based origin. PHB shows susceptibility to fracture when subjected to high rates of deformation. This work investigates toughening mechanisms for PHB via incorporation of functionalizede lastomeric components into the PHB matrix. A compatibilizer was investigated to improve the interfacial adhesion between the incompatible elastomer and plastic phases. The toughened PHB was characterized through their thermo-mechanical, rheological and morphological analysis. The resulting toughened PHB showed more than5 times improvement in impact strength over virgin PHB with around 60 % loss in modulus. The loss of modulus was recovered to permissible extent through incorporation of titanate modified montmorillonite clay. The hydrophilic clay was modified by titanate-based treatment to make it organophilic and compatible with the polymer matrix. Nanocomposites with this modified clay exhibited more than 275% improvement in impact properties with around 40% reduction in modulus in comparison with the virgin PHB bioplastic.
Polynanomeric Composite Technology Applied to Environmental Filtration Processes
Laura Lu, Samra S. Sangari, Lambros Georgoulis, James C. Seferis, Daniel Luchtel, May 2005
Composite filtration technology can be implemented less expensively to prevent fossil fuel burning power plants and nonroad and highway heavy-duty engines from releasing green house gases and air pollutants directly into our environments. Carbon-carbon composites (CCCs) were investigated for CO2 filtration from flue gas streams and air pollution filtration such as nitrogen oxide and hydrocarbons from diesel fuel emission. The porous structure of CCC filters was made of chopped carbon fibers and phenolic resin going through curing, pyrolysis and activation. In this study, CCC filters were synthesized under different combinations of pyrolysis and activation times. The structural, physical as well as thermal properties of CCC filters were studied: Scanning Electron Microscopy (SEM) showed the porous structure of CCC filters. Sorption and thermal swing was used for the surface area and adsorption capacity measurements. From the thermal gravimetric analysis (TGA), the thermal properties of CCC filters were investigated. The gravimetric processing has been shown to impact significantly on the filtration performance of CCC filters.
Process Optimization to Improve Mechanical Properties of Thermophysically Adhered Composites
Sanjiv M. Bhatt, Charles W. Extrand, May 2005
Adhesion of (Poly)carbonate (PC) with a carbon fiber filled (Poly) ether ether ketone (PEEK) compound (SP3000) was evaluated for an insert molding application. Composite samples of PC and SP3000 were injection molded as a function of injection speed, packing pressure, nozzle and mold temperature. The composite samples were tested in tension. Modulus was invariant. Breaking stress showed the most change with process conditions. In general, injection speed and packing pressure had little effect on ultimate properties. Nozzle and mold temperature were the governing variables for adhesive strength.
Identification of Composite Beam Parameters from Vibration Data
Kumar Vikram Singh, Guoqiang Li, Su-Seng Pang, Yitshak M. Ram, May 2005
In dynamic analysis of composite structures the characteristic polynomials, associated with the discrete model (FEM/FDM), lack the ability to approximate the transcendental functions (continuous systems) accurately and they introduce error in evaluating the higher eigenvalues. Due to such dissimilar asymptotic behavior of the eigenvalues, higher frequencies of the discrete models deteriorate the reconstruction process. A low-dimensional mathematical model is developed here such that the non-uniform composite beam is approximated by another beam with piecewise constant physical parameters. Such approximation preserves the spectral consistency between the asymptotic behaviors of the original system and approximated system. The solution of corresponding inverse transcendental eigenvalue problems is developed and small scale vibration tests are conducted. A finite number of experimental spectral data is used for the reconstruction of non-uniform composite beams.
NIR Radiation Management Part II – NIR Transparent Organic Blacks for Plastics
Arno J. Boehm, Oliver Seeger, May 2005
Last year (ANTEC 2004) we presented a new class of highly efficient organic Near Infrared (NIR) absorbers with a unique performance profile especially suited for laser transmission welding and transparent heat management applications. In this paper we want to introduce novel perylene based high performance black pigments with extraordinary high NIR transparencies. Their excellent thermo- and photostabilities, in combination with a neutral hue, high transparency and color strength make them the ideal candidates for black laser weldable formulations and opaque heat management applications. We present models for the explanation of the unique thermostability and weatherability of this class of compounds, as well as recent advances in the synthesis of those materials, and examples for state-of- the-art plastics applications
Comparision of Measurement Techniques and Methods to Evaluate Irradiated Polymers
Sanjiv Bhatt, Robert Dobrick, May 2005
Electron Beam irradiated high density polyethylene (HDPE) and ethylene tetra fluoro ethylene (ETFE) was studied using dynamic rheology. The objective of this work was to compare and critique different modes and methods of dynamic mechanical testing, determine the best method or test to characterize the structural changes, and verify the governing phenomenon for structural changes in irradiated injection molded HDPE and ETFE. The predominant response to radiation in HDPE and ETFE is that of cross-linking. The tests were conducted in tension, bending, and shear.This study is limited to comparing the response of electron beam irradiated materials to the aforementioned tests. Effects of radiation levels and aging are beyond the scope of this work.It was found that dynamic shear testing at temperatures above the melting point of the materials is the best mode and method to finger print the structural changes in radiated HDPE and ETFE. The flexure test modulus results were higher than that from the tensile test.
Impact of UV Cured Inks and UV Exposure on Physical Properties of BOPP Films
Kunal Shrotri, Tejas Upasani, Scott Williams, Seung Kim, Kamaran Rab, May 2005
Biaxially oriented Poly (propylene) [BOPP] films are extensively used in food packaging industry primarily because of their good barrier properties, machinability and printability1. We investigated the effect of flexographic UV-cured acrylic inks on to BOPP films with a focus on permeability towards oxygen and moisture. Temperature dependence on mechanical properties of the printed films was studied. Instron tensile strength, Mocon permeability tests, and thermodynamic results were obtained that suggest that there is no appreciable change in the physical properties when the films are printed with UV curing inks.
Rheological Investigation of Entangled Hybrid Copolymers of Polystyrene (PS) with Polyhedral Oligosilsesquioxane (POSS)
Jian Wu, Timothy S. Haddad, Patrick T. Mather, May 2005
The thermal properties and rheological behaviors of polystyrene (PS)-based thermoplastics bearing polyhedral oligosilsesquioxane (POSS) were investigated with variation of isobutyl (iBu)-POSS weight percentage. The incorporation of POSS-group significantly decreases the glass transition temperature and the rubbery plateau modulus. These findings are attributed to an influence of the nanometer-scale POSS pendant group on the microscopic topology of the host polymeric chains and negligible interactions between POSS and PS matrix.
Thermal and Rheological Characterization of Feedstocks for Powder Injection Molding
Juan Adames, Leonov Arkady, May 2005
The rheological and thermal behavior of a powder injection molding feedstock (highly filled polymer blend) was studied using rheometry, and thermal techniques. The feedstocks were prepared using two mixing schemes. In the first scheme, an internal mixer and a twin-screw extruder were used. In the second scheme the blends were prepared in a laboratory internal mixer. The filler material was stainless steel and its content in the samples is above 90 % by weight. The rheological behavior of the feedstock was studied in dynamic mode. The techniques used and the results obtained are presented.
Sacrificial Material Assisted Laser Welding of Polymeric Microfluidic Devices
Chunmeng Lu, L. James Lee, David Grewell, Avraham Benatar, May 2005
A critical phase in fabricating microfluidic polymer chips is welding of a cover to a channel in order to produce tube type geometry. A possible method to weld such a cover is by through transmission laser welding of polymer components. The major issue in welding of microstructured parts is blockage of the flow path by molten polymer (flash) resulting from a typical welding process. In this study, a sacrificial material technique is developed, in which a water-soluble material is used as a mold material to prevent weld flash from being allowed to flow into the channels. In detail, a sacrificial mold remains in the embossed parts instead of being separated from the part (De-embossing) after molding. A cover or other embossed part is then welded to this part. In this study, through transmission laser welding was used to fabricate such parts. The sacrificial material was then removed by dissolution in an appropriate solvent. Different mold preparation methods are discussed and examples of welded structures are given here.
Finite Element Analysis of Cell Coarsening in Polymer Foaming
Zhenjin Zhu, Donglai Xu, Chul B. Park, R. Fenton, May 2005
In this work, cell coarsening in polymer foaming was investigated through numerical simulation. Cell coarsening occurring on two adjacent bubbles of different sizes in a finite volume of polymer melt was considered to be representative of the whole foaming system. A quadratic triangle-based finite element analysis with an implicit scheme for time evolution was utilized to solve the governing diffusion equation in the axisymmetric coordinate system. The effects of the bulk gas concentration, the intercellular distance, and the initial bubble sizes on cell coarsening were estimated. Efforts were made to improve a fundamental understanding of cell coarsening in polymer foaming.
Quantitative Mixing Uniformity Assessment in Two Laboratory Scale Devices
Parvinder Walia, Mark Barger, M. McKelvy, May 2005
A technique is described to quantitatively assess mixing effectiveness. The technique utilizes infrared (IR) analysis of dissimilar polymer blends. The rheology of the blend system can be tuned through temperature to easily derive a spectrum of viscosity ratios. The technique has been applied to two common laboratory mixing apparatus, a batch mixer and a mini-twin screw extruder. Mixing effectiveness of these two devices will be described within both spatial and temporal considerations. The relative merits of the different mixing techniques will be additionally discussed.
A Unique Surface Modification Technique for Extending Surface Activation of Flexible Packaging Substrates
Rory A. Wolf, May 2005
Flexible packaging polyolefin materials such as polypropylene and polyethylene have low levels of polar functional groups on the surface and have poor wettability and adhesion properties, making it difficult to apply other functional layers such as inks, adhesives and coatings. To enhance surface polarity, surface treatments such as flame, corona or plasma can be applied to improve wettability and adhesion. To improve the stability of achieved surface polarities which can be impaired by the effects of aging, humidity and heat, the combination of a unique molecular grafting technology with atmospheric plasma treatment significantly enhanced treatment longevity and surface adhesion.
Optimizing Performance of Benzoate and Phthalate Blends for Vinyl Applications
William D. Arendt, Arron M. Strepka, Danielle C. Petrovich, Makarand Joshi, May 2005
To achieve required performance, blends of plasticizers are commonly used in flexible vinyl applications. Typically, when fast fusion is required high solvating phthalates have been utilized in plasticizer blends. Benzoate esters are high solvators and can also be used in these blends. However, eventhough benzoate plasticizers offer additional performance benefits that can complement general purpose phthalate performance most published literature does not include the use of benzoate plasticizers in blends with phthalates. The purpose of this paper is to demonstrate the performance benefits of blending benzoate and phthalate plasticizers. The approach selected to accomplish this was to develop performance data utilizing a mixture design approach with DOE software. A resilient flooring plastisol formulation was selected as the model. The following properties were obtained: degassing, low and high shear viscosity, viscosity stability of the plastisol, gel and fustion characteristics, tensile strength vs temperature, vinyl heat staiblity, stain resistance, volatility and UV stability. The data indicates how to utilize the advantage of benzoates as “process aides” to speed production rates and improve product quality.
Polylactides. A New Era of Biodegradable Polymers for Packaging Application
Rafael Auras, Bruce Harte, Susan Selke, May 2005
Polylactide polymers have garnered enormous attention as a replacement for conventional synthetic packaging materials since they are biodegradable, compostable, and recyclable. In this study, commercially available PLA films, bottles, and trays were evaluated. PLA films show better ultraviolet light barrier properties than polyethylene, but were slightly worse than polystyrene (PS) and polyethylene terephthalate (PET). PLA films show better mechanical properties than PS, and comparable to those of PET. PLA has lower melting and glass transition temperature than PET and PS. Solubility parameter predictions indicate that PLA will interact with nitrogen compounds, anhydrides, and some alcohols, and it will not interact with aromatic hydrocarbons, ketones, esters, and water. In terms of barrier, PLA showed O2 and CO2 permeability coefficients lower than PS and higher than PET. The amount of lactic acid and its derivatives that migrate to food simulant solutions from PLA was much lower than any of the current average dietary lactic acid intake values reported by governmental organizations.
Synthesis and Characterization of Polypropylene Nanocomposite Fibers
C.Y. Lew, W.R. Murphy, G.M. McNally, K. Abe, S. Yanai, May 2005
Nanocomposite fibers were produced by the melt spinning of a polypropylene/organoclay compound, maleated with maleic anhydride functionalised propylene oligomers. XRD and TEM analyses showed that the organoclay exfoliation associated with property improvement was enhanced significantly by the elongational melt deformation during the melt spinning process. SEM and FTIR results revealed the preservation of a homogeneous monodispersed phase in the nanocomposite fibers. In addition, there was an overall improvement in the mechanical properties, including tenacity, when the organoclay were optimally delaminated. Rheological analysis and polarizing optical microscopy study showed a significant enhancement in the melt spinability and optical birefringence of the nanocomposites. The DMA results suggested the fiber matrix was simultaneously reinforced and plasticized by the exfoliated organoclay layers. A simple model was also proposed to illustrate the organoclay exfoliation mechanism during the melt spinning process.
Observation and Modeling of Stress Corrosion Cracking in Plastic Pipes
Byoung-Ho Choi, Alexander Chudnovsky, Kalyan Sehanobish, May 2005
There are four stages of stress corrosion crack (SCC) such as initiation, individual SC crack propagation, many crack interaction and clusters of crack formation, and finally crack or cluster instability and dynamic growth leading to the ultimate failure. The second stage is critical in determining the lifetime of pipe. Crack Layer model is adopted in this study to predict the individual SC crack propagation kinetics and the time interval from crack initiation to instability and break through. In addition, numerical simulation of Stress Corrosion Crack Layer (SCCL) and comparison with experimental observations of SCCL propagation in various thermoplastics is presented.
Polymorphism and Crystallisation in Metallocene PP-Copolymer Nanocomposites
C.Y. Lew, W.R. Murphy, I.M. Major, G.M. McNally, May 2005
The structures, polymorphism and crystallisation behaviour of a range of maleated and acrylated polypropylene (PP) layered-silicate nanocomposites were studied using wide-angle X-ray diffraction (WAXD), small-angle X-ray diffraction (SAXD), transmission electron microscopy (TEM), differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) techniques. The dispersed silicate layers were shown to restrict the ?-crystalline phase and selectively suppress the (220), (040) and (060) crystallographic planes of the PP. The PP crystallinity and crystallisation temperature decreased with an increasing degree of layered-silicate intercalation and exfoliation, by up to 26 % and 10 degC respectively. This is attributed partly to interaction of the polymer and layered-silicate with the compatibiliser. The unique damping mechanism of the silicate layers reduced the PP ?-phase glass transition temperature (Tg). The endothermic crystalline peak pattern of the compatibiliser, determined by DSC was found to be a novel technique for characterising the degree of layeredsilicate exfoliation in the PP matrix.
Dimensional Stability in LDPE Foams
Hua Yang, Chien-Yueh Huang, Chi-Tai Yang, S.T. Lee, May 2005
Unbalance between the effusion rate of the blowing agent and the infusion rate of air in post-extrusion LDPE foam sheets causes dimensional instability of the sheets. A one-dimensional diffusion model coupled with a constitutive Voigt equation was proposed to study the time-dependent dimension in LDPE foams. The features of shrinkage-restoration or swell-relaxation were captured by varying the permeability ratio of gases. Comparisons with experimental results were made to retrieve the parameters used in the model. These parameters are related to the physical properties of the materials used and are expected to correlate to the structures of the foams such as the global porosity and cell size distribution.
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