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
Application of GRP for Chimney Liners Exposed to Sulfur Dioxide and Sulfur Trioxide
Valery G. Makarov, May 2004
Innovative development and application of a multilayer GRP structure for chimney liners exposed to sulfur dioxide and sulfur trioxide are described.The structure is made by winding. It includes a chemical proof layer, a constructional layer and an external layer.Inspections have shown no deterioration of GRP after three months of operation. GRP are affective constructional material of the universal purpose.
Novel Technique for Predicting Long Term Resistanse of Chemical Resistant GRP
Rakhil M. Sinelnikova, Valery G. Makarov, May 2004
A novel technique of estimating the lifetime of chemical resistant GRP is described.Destruction of GRP is considered as a heterogeneous chemical reaction of the first or zero order with constant energy of activation.Based on these estimations, it is recommended to use GRP for chimney liners exposed to sulfur dioxide and sulfur trioxide. Received results were used for forecasting of service life of GRP.
Rheological, Thermal and Mechanical Behavior of Polyolefins/Sea Shells Composites
J. González, M. Candal, C. Albano, M. Ichazo, M. Mayz, A. Martínez, May 2004
The rheological, thermal and mechanical behavior of polypropylene (PP) and high density polyethylene (HDPE) filled with sea shells composites at different concentrations of filler were investigated. The composites were prepared by extrusion and injection molding. Most filler addition to composites promoted a slightly increase on the melt viscosity, improve the tensile modulus and the thermal stability in all composites studied.
Study on the Characteristic of Axial Circular Flow Field in Co-Rotating Intermeshing Twin-Screw Extrusion
Xiuqing Ma, Xiaozheng Geng, Linjie Zhu, May 2004
In order to improve the mixing ability and elongate the mean residence time in twin-screw extruders, the axial circular flow was introduced in this study. A non-intermeshing section was set in the co-rotating twin-screw extruder, in which one screw was equipped with reverse conveying elements and the other with forward conveying elements. In the current work, a three-dimensional simulation of the flow in the axial circular flow section was developed by FEM package, ANSYS. Based on the calculated pressure and velocity profile, the pressure-throughput behavior and mixing ability of the axial circular flow section were discussed. Compared with the conventional conveying elements, the circular flow section has reduced ability to conveying but its distributive mixing capability was largely increased. Visualization experiments showed that the simulation results were in good agreement with the experimental outcomes.
3-D Modeling of Polymerization in Conveying Screw Element in Twin-Screw Extruder
Linjie Zhu, K.A. Narh, Kun S. Hyun, May 2004
The polymerization of ?-caprolactone in fully intermeshing conveying screw elements of co-rotating twin screw extruders was simulated with Fluent. The effects of the pitch on the element, temperature, flow rate, and screw rotating speed upon the reaction progression were investigated. It was found that the back-flow in the screw element affects the progress of polymerization. The simulation result from 3-D model differs significantly from 1-D model, especially in relation to slow reactions. This is because reaction is very sensitive to temperature change, and the value of heat transfer coefficient at the barrel and screw surface used in 1-D model may not represent the real conditions in extruders.
Investigation on Extrusion Property of PSE?Polygon Screw Element in Co-Rotating Twin Screw Extruder
Xiuqing Ma, Yanling Yin, Xiaozheng Geng, Linjie Zhu, May 2004
PSE (Polygon Screw Element) is a new screw element, designed to meet the development of co-rotating twin-screw extruders toward high rotating speed and excellent mixing capability. In the present study, a three-dimensional flow field simulation of PSE element was carried out by the ANSYS FEM package. Pressure profile and shear stress profile were obtained. The mixing ability of PSE element was also analyzed. The simulation results of the flow field in PSE element were verified by experiments. It was found that the energy consumed in PSE element is smaller, whereas its mixing ability is better than the kneading block. Furthermore, PSE element is suitable for the fiberglass reinforced processing.
A New Machine Conception for the Extrusion of Biodegradable Foams and the Influence of Process Parameters on Product Propert
H. Potente, W. Ernst, May 2004
Foamed products based on renewable raw material have a high application potential e.g. for packaging because of their biodegradeability. This may permit renewable raw materials to substitute polymers like polystyrene in some applications.A common way to process renewable raw material like starch is to produce starch based resins with twin screw extruders. These resins can be used on conventional polymer processing machines, but the step of compounding the starch on twin screw extruders causes costs which make these resins economically unattractive.Due to a new extrusion technology these costs can be reduced by a direct processing of starchy material like maize. A characteristic of this extruder is a very short (2 L/D), conic, multiple flighted screw in a barrel with spiral grooves. The energy for the plasticizing process is yielded just by the transfer of mechanical energy of the rotating screw into friction in a shear gap between screw and barrel.In order to understand the process different geometries of screw and barrel have been used in the experiments, additionally the process parameters have been varied. The results lead to an optimised configuration of the extruder and to a better understanding of the influence of process parameters on the product properties.
Effect of the Full-Slip Condition along Rotors on the Mixing Efficiency of Internal Mixers
B. Alsteens, Th. Avalosse, V. Legat, Th. Marchal, E. Slachmuylders, May 2004
The importance of slip for applications such as extrusion, cable coating, thermoforming, etc. has been widely discussed in the literature. Recent experimental works suggested that slipping along the rotors also impacts the quality of the mixing in batch mixers typically used for Carbon Black dispersion. In batch applications, the slip reduces the mixing efficiency, hence requiring a longer process to get a given mixing quality.Recent developments in CFD allow to include the slip in the numerical models. The advantage of numerical simulation is the ability to turn on or off this phenomenon. Also, the effect of particles behavior along the rotors on both the flow pattern and the mixing efficiency of internal mixer is studied. Two 3D transient simulations are performed with the POLYFLOW package: one simulation assumes sticking boundary conditions along the rotors whereas the other involves a full slip condition.The results obtained in both simulations are compared and validated against experimental results: the slip condition modifies dramatically both the velocity and the shear rate fields. Therefore, the distributive and dispersive mixings generated by the two models are significantly different. Eventually, we observe a better match between numerical and experimental results when the slip condition is taken into account.
Effect of Morpholgy on Mechanical Properties of Composites Prepared by Reaction-Induced Phase Separation
Amit Chandra, Sadhan C. Jana, May 2004
A new class of fiber-reinforced composite materials was designed in our laboratory by using a hybrid of thermoplastic and thermosetting polymers. The thermosetting polymer phase separates upon curing reaction and creates morphology on the fiber surfaces. Effect of the morphology is studied on the fracture toughness of the composite, with the aim of enhancing the mechanical properties of the resulting fiber reinforced composite.
NMR Analysis for a Secret Ingredient
P.R. Lewis, May 2004
Finding very small amounts of a secret compound in complex mixtures presents a big challenge for analysts. A dispute between two companies involved building plasters with a polymer viscosity modifier. The case hinged on confidential information about the exact structure of the polymer, which one company had apparently taken illicitly from the other. FTIR revealed little, so NMR was used to identify the compound in deuterated DMF extracts from the plasters. They showed that the plasters possessed compounds of identical structure. The case was settled without trial.
Polymer-Clay Nanocomposites: Tailoring Structures with Processing Conditions
C.Y. Lew, W.R. Murphy, G.M. McNally, S. Yanai, K. Abe, May 2004
Nanocomposites based on nylon-12 and synthetic fluoromica were compounded using a single-screw extruder at different combination of shear and residence time and analysed with respect to their morphology, rheological, mechanical, and thermal properties. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) revealed unique structural arrays of the exfoliated layers which were found to be dependent on the extent of shear and residence time during processing. Rheological analysis showed that the melt viscosity of the nanocomposites was considerably lower compared to the unfilled polymer. Furthermore the melt viscosity and properties of each nanocomposite varied depending on orientation of the exfoliated layers. The results show that it may be possible to tailor the structures and properties of the nanocomposites using controlled extrusion conditions.
Some New Observations Relative to Melting in Single Screw Extruders
Gregory A. Campbell, Zirong Tang, Chicheng Wang, Matthew Bullwinkel, May 2004
The focus of this investigation was to evaluate literature and run experiments to help understand the mechanism of melting in single screw extruders. Literature data was re-analyzed using video capture and analysis programs to determine the rate of loss of material in the cross channel and solid bed thickness directions. The analysis demonstrates that the polymer solid bed goes to zero dimension in the thickness direction well before the solid bed width is consumed. This observation was confirmed in our laboratory using a specially built glass barrel extruder. These results suggest that the melting in single screw extruders is dominated by the loss of bed thickness and not bed width as predicted by current literature.
The Influence of Morphology on the Failure of Polyethylene Pipes in Hydrostatic Pressure Tests
Rajendra K. Krishnaswamy, Mark J. Lamborn, May 2004
Failure times of plastic and metal pipes subjected to hydrostatic pressure at various levels assist pipe manufacturers to not only design pipes for certain applications, but also to give them an indication of the useful service life-times of these pipes. In order to understand the influence exerted by semicrystalline morphology on the failure of polyethylene pipes under hydrostatic pressure, a medium-density polyethylene resin was converted into various pipes by altering the extrusion processing conditions. These pipes were subsequently subjected to hydrostatic pressure at a constant hoop stress and the failure times were recorded. The failure times were observed to depend strongly on the morphology of the pipes.
Computer Aided Troubleshooting of Extrusion Problems
Chris Rauwendaal, May 2004
When a problem occurs in an extrusion operation it is important to diagnose the problem, determine possible solutions, and implement the best solution in the shortest possible time. In-house personnel are often not well trained in efficient troubleshooting techniques and problem solving. Outside technical assistance may not be immediately available and may not lead to an expedient solution of the problem. As a result, it is important for extrusion companies to have tools available in-house that can help in the troubleshooting and problem solving process.A new tool available to the plastics industry is an expert system that allows computer aided troubleshooting of extrusion problems. This program allows the user to systematically analyze a large number of extrusion problems. In the end the program presents the user with a number of possible solutions to the problem. This paper will describe the capabilities of the program.
Study of the Micropelletization Process
Claude Y.F. Xi, Elizabeth Takacs, Mark Tate, Michael R. Thompson, John Vlachopoulos, May 2004
A study has been performed to examine the rheological impact of micropelletization on several polyethylene grades with melt index values between 1-5 g/10 min. The experiments were done on a 50 mm 30:1 L/D extruder with an underwater micropelletizer attached. A 2-D finite element simulation was used to assist in the analysis by comparing the observed results to the predicted shear stresses in the die. The average micropellet size collected was 0.525 mm diameter. Minor sharkskin was observed on the surface of micropellets due to the high stresses experienced in the pelletizer die. However, the rheological properties of the micropellets did not change in comparison to the virgin resins.
Detecting Defects and the Onset of Failure of Adhesive Bonds Using Electrochemical Impedance Spectroscopy
Suresh Mani, Michael J. Rich, Robert J. Jurek, Lawrence T. Drzal, Guy D. Davis, May 2004
Tape sensors were mounted on the adherends and the health of the adhesive bonds was studied by electrochemical impedance spectroscopy. Results show that EIS measurements can discriminate bonded and unbonded areas in CFRP-Al systems. The EIS measurements are also sensitive to the weakening of adhesive bonds caused by exposure to humidity at high temperatures.
Microscopy and X-Ray Elemental Spectroscopy in Failure Analysis: Case Studies
Kevin P. Battjes, May 2004
Optical and Scanning electron microscopy (SEM) techniques, coupled with energy dispersive X-ray analysis (EDS) are effective tools in investigating the cause of failures in articles made from plastics. Practical examples and findings are reviewed that have been used to solve customer problems in real world applications.
Thermal Properties of ? Nucleated Polypropylenes
Martin Obadal, Roman ?ermák, Roman ?abla, Karel Stoklasa, May 2004
Commercially available isotactic polypropylene (iPP) was modified by various amounts of a specific ?- nucleating agent. Isothermal crystallization and subsequent melting behavior were analyzed using differential scanning calorimetry (DSC). The findings resulting from this work (such as crystallization halftimes, other kinetics parameters, glass transition temperatures, etc.) can significantly assist to explain not a few open questions concerning ?-nucleated polypropylenes and their processing.
High Thermal Conductivity Shape Memory Polymers
Changdeng Liu, Patrick T. Mather, May 2004
The ability for shape memory polymers (SMPs) to quickly actuate upon exposure to a heat transfer fluid or radiative heating depends significantly on thermal conductivity and heat capacity. Recognizing this, we have pursued the enhancement of thermal conductivity of several SMPs - developed previously in our laboratory - through the addition of thermally conductive inorganic filler. Our presentation will focus on both thermal and thermomechanical analyses for filled and crosslinked polycyclooctene, revealing the dependence of thermal conductivity and shape memory response on filler loading.
Processing Nanocomposites on a Kneader Reciprocating Single Screw Compounding System
Paul G. Andersen, May 2004
Interest in nanocomposites is based on the premise that with a relatively small loading of properly dispersed treated clay, polymers can exhibit substantial improvement in properties. These include thermal properties such as HDT, mechanical properties such as flexural strength and modulus (without significant loss of impact), barrier properties, flame resistance, and abrasion resistance. While the concept behind nanocomposites is sound, implementation has been flawed. Dispersion of 8 micron clay particles into a million or so high aspect ratio platelets is a difficult task. Both chemical modification of the clay for improved compatibility, and development of specific compounding technology have shown promise but not been fully successful. In previous work (1) unit operations that have significant impact on clay dispersion in the co-rotation twin-screw extruder were identified. This presentation will review the design flexibility associated with the reciprocating single screw, or kneader, compounding system and discuss key unit operations necessary to obtain well dispersed clay. It will also compare results from the reciprocating single screw system with those obtained from previous work on a twin-screw extruder.


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