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

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.

The Effects of Shear Imbalances on Intra-Cavity Melt Flow Using Varying Melt Flow Rates in Thermoplastic Elastomers and Vulcanizates

Eric D. Baluh, Mikael S. Wagner, May 2007

The high shear developed in a runner creates significant melt variations and is the source of shear induced mold filling imbalances in geometrically balanced runner runners. These same shear induced melt variations can also create unexpected filling patterns in a single cavity mold. If this uneven filling pattern could be manipulated then shear induced melt variations can be used as a tool in industry. The focus of this paper is to find if the filling pattern with thermoplastic elastomers (TPE) and thermoplastic vulcanizates (TPV) can be manipulated by varying injection flow rate.

Analysis of the Relative Effects of Loading Agents and Their Interactions as a Function of Core Resistivity in Thermoset Polyurethane Foam Parts

Daniel Brittingham, May 2007

While there has been an increase in the use of certain polymers for electrically conductive applications [5], thermoset polyurethane foams have been primarily used in applications that do not require any electrical conductivity. The electrically insulative properties of these materials can be accentuated by the presence of air pockets inside of the foam parts [4]. This investigation analyzes the effect loading agents have on electrical conductivity on thermoset polyurethane foam containing a conductive core. This paper discusses the relative effects of two loading agents – carbon black and graphite – on resistivity of a thermoset urethane part containing a conductive core as determined by statistical analysis through designed experiments.

Penetration Length, Thickness and Crystallization Behavior of Water-Assisted Injection Molded Part

Han-Xiong Huang, Zhi-Wu Deng, Xu-Hui Liu, May 2007

Water-assisted injection molding experiments were carried out on newly developed equipment in our lab. The effects of four processing parameters, short-shot size, melt temperature, water injection delay time, and water pressure, on the water penetration length and residual wall thickness of water-assisted injection molded polypropylene curved pipe were investigated. The crystallization behavior difference between the beginning and the end of the water channel of the curved pipe was analyzed using differential scanning calorimetry.

Predicting Processing Parameters for Water-Assisted Injection Molding Based on Inverse GA-LMBP Neural Network

Jian-Min He, Han-Xiong Huang, May 2007

The water-assisted injection molding (WAIM) is a new injection molding technique. It is difficult to describe the WAIM process using mathematical method due to its complexity. In this work, a predicting model for the WAIM process was developed via an inverse hybrid algorithm combining genetic algorithm (GA) with Levenberg-Marquardt back propagation (LMBP) neural network. By adopting the model, processing parameters, such as melt temperature, water pressure, water injection delay time, and short-shot size, can be predicted quickly and accurately for desired residual wall thickness of molded parts.

Selection of Colorants and Other Additives for Durable Products

James J. Bal, May 2007

Polyolefins are utilized frequently in durable products that call for extended life in a variety of environmental conditions. Many of these products require color and almost all require and enhanced degree of resistance to the stresses of an exterior environment. The selection of plastic colorants that can withstand harsh environmental conditions is critical to ensuring the long term appearance of a polyolefin based durable product. Likewise, the correct choice of plastic additives for exterior applications must be made in order to ensure acceptable product appearance and performance over time.This paper examines key design considerations for durable polyolefin products in terms of additive selection. Special consideration is made in terms of selecting colorants that are considered non-toxic. A practical example is presented.

Appraisement of the Engineering Properties of the Chemical Resistant Laminate in Products

Rakhil M. Sinelnikova, Valery G. Makarov, May 2007

Polymer composites on epoxy vinyl ester resins serve the needs of wide range of industrial chemical processes with the final products, such as coverings, coverings of floors, etc.To provide a good corrosion barrier over concrete, metal etc, it is necessary to use a chemical resistant laminate (CRL). The practice of FRP application shows the existence of an optimum ratio between numbers of powder bonded chopped strand mat layers and engineering properties of CRL.Analyses of scale (size) effect of strength and permeability are carried out.The analytical dependence of tensile strength and permeability from a thickness is used for appraisement of the engineering properties of CRL in products.

New Transparent Copolycarbonate Compositions with Low OSU Heat Release Values

Jianbo Di, Gary Davis, Katherine Jackson, Ahmed El Kassmi, Brian Mullen, Laura Schultz, Moitreyee Sinha, Paul D. Sybert, Jenny Zhang, May 2007

New polyester carbonate copolymers afford the first resins with low color, high transmission and low haze combined with low OSU Heat Release values. In addition, the fabricated articles can be hard coated to provide improved levels of scratch resistance. These compositions can be varied to maximize the various mechanical properties depending on the needs of the application. The excellent clarity combined with OSU 65/65 compliance allow for applications such as interior transportation windows/dust covers, partitions, mirrors and lighting lenses. The excellent colorability also allows for the fabrication of interior opaque components for the transportation industry.

In-Situ Formation of Microfibrillar Morphology in Polymer Blends

Roman Cermák, Martina Polášková, Jakub Kalus, Jana Výchop?ová, Martin Obadal, May 2007

The work focuses on microfibrillar-phase formation in polymer blends during extrusion through a die with semihyperbolic-converging channel. For these purposes, three polyethylene/polypropylene blends with the mixing ratios (wt./wt.) 80/20, 70/30 and 60/40 were prepared. Final structure and properties of extruded blends were examined using electron microscopy, wide-angle X-ray scattering, differential scanning calorimetry and tensile testing. It is demonstrated that the formation of microfibrillar-phase morphology is achieved in all blends, independent of their mixing ratios. However, the structure and properties of these microfibrillar-phase composites are strongly influenced by mixing parameters.