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

Practical Relationships for Calculating Pressure Drop in Injection Molds
Natti S. Rao, Günter Schumacher, Nick R. Schott, Ray Edwards, May 2002

The flow of melt in runner systems of injection molds takes place in channels whose cross section can be either circular, square, rectangular or of any other geometrical form. In order to obtain a uniform distribution of the melt at low pressures, knowledge of the pressure drop along the flow path is important. Based on the modern developments in rheology, this paper presents easily applicable relationships for calculating pressure drop in the flow channels of different geometry taking flow rate, resin type and melt temperature into account. Worked-out examples illustrate the use of the equations presented, which were found to agree well with the results in the practice.

Prediction of Anisotropic Shrinkage Behavior of Plastic Injection Molded Parts by Experimental Design Approach
Tao C. Chang, Ananth U. Gadiyar, May 2002

The shrinkage behavior plays an important role in the determination of the final dimensions of plastic injection molded parts. Materials used, mold and part designs, and processing conditions all can have great influence on parts' final dimensions. In this study, the experimental design approach of L27 array is used to study the effects of three processing parameters (melt temperature, mold temperature, and holding pressure) on the shrinkage behavior (along-the-flow and across-the-flow directions) of injection molded parts of polystyrene. A multiple regression model is set up to predict the dimensions and the goodness of the model is verified by the confirmation data. Previous research results are reviewed and compared with.

Prediction of the Mechanical Properties with Part Weight Reduction for Injection Molding Microcellular Foam Parts
Jingyi Xu, Levi Kishbaugh, Mike Casale, May 2002

A microcellular plastic part with an injection molding method can be treated as a sandwich structure in which a foamed core encased by a skin frame. It is unique characteristics for microcellular plastic injection molding part because of a uniform cell distribution across the foamed section except the skin. The simple models based on this structure for prediction of mechanical properties of microcellular plastics are proposed and verified by the injection molding microcellular sample tests. The weight reduction percentage of the whole part and the skin thickness are used as input data to calculate the mechanical properties. The effect of skin-core ratio for the mechanical properties of foamed part is also discussed in this paper.

The Prep Virtual Factory: A Suite of Processing Simulators
Kirk Cantor, Timothy Weston, Stanley Baczek, May 2002

The Plastics Resources for Educators Program (PREP) has produced a vast array of multimedia training materials for plastics educators and the plastics industry. Products completed so far include graphics, animations, and teaching modules. The latest product is a suite of plastics processing simulators called the PREP Virtual Factory." This fully interactive teaching facility includes "machines" for extrusion injection molding and blow molding. Using these tools learners can discover proper operating procedures and investigate the influence of various process parameters on product properties."

Pressurization and Energy Characteristics of Strainer Disk Elements CFD Calculations and Experimental Results
Ralf Kühn, Peter Heidemeyer, May 2002

A study of pressurization and energy characteristics of strainer disk elements for different sizes of ZSK twin-screw extruder with PE-HD are presented. The work compares the results of a complex 3D CFD model of ZSK40 strainer disks with some experimental results. As the manual setup of such a complex CFD model is rather expensive, a method has been developed to decompose the complete model into two simple parts. These parts can be set up easily in a batch procedure. Finally the effect on the pressurization and energy characteristics is discussed when doing a scale up from a ZSK40 to a ZSK92 or a ZSK250.

A Procedure for the Design Optimization of Injection Molded Plastic Parts Using CAD/CAE Softwares
M.V. Candal, R.A. Morales, O. González, May 2002

The objective of this work was the development of a procedure to establish the optimization design basis of plastic parts by using Computer Aided Design (CAD)/Computer Aided Engineering (CAE) software. An example is show applying the procedure on a specific problem where the part evaluated was a commercial compact disk (CD) case. The simulation results were obtained through a filling/cooling simulation program for the injection molding process and a three-dimension solid modeler program. After modifying the process conditions, gate dimensions and part design, a new case design was evaluated. The simulation results, maximum wall shear stress and shear stress in service showed a best behavior in use for the new proposal.

Process Capability Comparison of Various Switchover Modes from the Filling to Packing Stages in Injection Molding
Tao C. Chang, May 2002

Many sources of variation in the process can contribute to product inconsistencies among a batch of molded parts in the injection molding process. These sources include materials, machine control capability and conditions, human factors, and environment. This paper provides an overview of the means for measuring process capability and the methods for maintaining process robustness in injection molding. Furthermore, an experimental study utilizing statistical methods provides a simple and effective means of identifying capable switchover methods in the injection molding cycle to maintain the shot-to-shot process repeatability for injection molding operation. Five switchover modes are compared.

Process Control by NMR at Basell Polyolefins
Ronald A. Grinsted, May 2002

Basell currently has over 25 polyolefin production lines at our various plants throughout the world utilizing NMR for advanced process control. These units include online units, which provide virtually continuous process feedback control as well as offline and laboratory units to provide checks of the various processes. Correlations have been developed to monitor a number of process variables of interest. The use of NMR for advanced process control has reduced the need for frequent wet" tests has reduced "off-spec" materials has improved product transition times and has allowed the reallocation of resources to other parts of the plants. The intent of this paper is to give a general overview of process control by NMR and in particular at Basell and how it is implemented."

Processing and Cell Structure of Nano-Clay Modified Microcellular Foams
Xiangmin Han, Changchun Zeng, L. James Lee, Kurt W. Koelling, David L. Tomasko, May 2002

Applications of nanometer-sized particles can facilitate the formation of microcellular foams in the continuous extrusion foaming process. Both intercalated and exfoliated polystyrene/nanoclay composites were foamed using CO2 as the foaming agent. The resulting foam structure is compared with that of pure polystyrene and polystyrene/talc composite. It is found that unique foam structure can be created by changing the content and the dispersion of nanoclay particles. The effects of nanoclay dispersion on the polymer melt rheology and the foaming process are discussed. Combining nanoclay compounding with microcellular foaming provides a new technique for the design and control of foam structure.

Processing and Characterization of Recycled PC/ABS Blends with High Recycle Content
Ruifeng Liang, Rakesh K. Gupta, May 2002

In order to develop a polycarbonate (PC)/ acrylonitrile-butadiene-styrene (ABS) product with a high content of recycled PC, a low molecular weight virgin PC was added to recycled PC to minimize batch-to-batch property variations in the compounded product. Six PC/ABS blends were prepared on a twin screw extruder by mixing 50 wt% virgin ABS and 0-25 wt% low molecular weight virgin PC with 25-50 wt% high purity recycled PC recovered from end-of-life electronics. These blends were characterized rheologically and mechanically. Results showed that this strategy could yield consistent quality resin blends with a high recycle content.

Processing Properties of Some Ethylene and ?-Olefin Copolymers
L. Halász, K. Belina, O. Vorster, I. Tincul, May 2002

Ethylene-1-butene, ethylene-1-pentene, ethylene-1-hexene, ethylene-1-heptene, ethylene-octene and ethylene-1-nonene random copolymers were prepared by Ziegler-Natta catalyst system and their rheological and thermal properties were determined. The rheological properties (zero shear viscosity, zero shear first normal stress coefficient, steady state viscosities and components of complex modulus are decreasing with the increase of co-unit size because the entanglement density decreases with the increase of co unit side group length. The melting point, heat of fusion also decrease with the increase of co-unit side group length because of the decrease of crystallinity.

Processing-Structure Relationship Using Rheological Constitutive Equations for Immiscible Polymer Blends
Bushra I. Chaudhry, Mosto Bousmina, Rosario E.S. Bretas, May 2002

This works tries to correlate the influence of the thermal and deformation histories that the polymer blend undergoes during its manufacturing on its microstructure. This is done by using a rheological model for polymer blends in the numerical simulation of this deformational field. The applied model is a modification of Bousmina et al in the Grmela's [1] model for two immiscible viscoelastic fluids and allows to obtain the size and shape of the dispersed particle of these heterogeneous systems through the deformational parameters, as shear rate and physical properties, as interfacial tension and viscosity of the polymers.

Production, Research and University Courses in the Field of Plastics in Croatia
Igor Catic, Maja Rujnic-Sokele, Gordana Baric, May 2002

Plastics are undivided parts of today's human life and their possibilities in new applications are growing almost every day. Production and processing of plastics are very promising industries and research fields. In this work it will be presented history and present situation, and future possibilities in Croatian plastics industry. It will be also presented educational and research institutions that are concentrated at four Croatian Universities in: Zagreb (the biggest one), Osijek, Rijeka and Split, their field of interests, research results and knowledge that they are offering to students and industry experts.

Properties of Expanded PTFE Sheet Gasket for Fluid Sealing Applications
Lei-Ti Huang, Shia-Chung Chen, James Huang, Walter Lee, May 2002

Advances in plastic expansion technology have created a new class of gasket material, called expanded polytetrafluoroethylene (ePTFE). The material comprises a highly fibrillated and porous microstructure that contributes to its excellent sealing capability. Its mechanical and sealing properties have been studied by the room temperature tightness test. The results suggest that ePTFE has better compressibility, creep resistance and sealability than other PTFE-based gaskets. These properties combined with excellent chemical resistance and thermal stability make ePTFE one of the most versatile gasket materials available today. The key factor that leads ePTFE to its excellent properties is the specialized process technology.

Properties of Hydrosilylated Polypropylene Blends
Mercy P. Bulsari, Costas Tzoganakis, May 2002

Low molecular weight polypropylene (Eastman, Epolene N-15) has been chemically modified during reactive processing using a catalytic hydrosilylation reaction in a batch mixer under various processing conditions (1,2). The hydrosilylated PP (Si-PP) has been blended with a commodity polypropylene resin (Montell, KF 6100) in a batch mixer at concentrations ranging from 5-20 wt%. This PP blends have been characterized in terms of their rheological properties as well as their thermal and impact properties. Addition of the hydrosilylated PP reduces the processing torque and the shear viscosity, while the impact properties depend on the crystallinity, Si-PP content and dispersed phase morphology.

Properties of mLLDPE Blown Films Extruded Utilizing Boron Nitride Based Polymer Process Aids
Eugene A. Pruss, Stuart K. Randa, Stephen S. Lyle, Thomas M. Clere, May 2002

The Saint-Gobain Advanced Ceramics Corp. of Amherst, N.Y. introduces, CarboGlide™, a new family of polymer process aids for thermoplastic resins. These boron nitride based polymer process aids eliminate shark skin melt fracture and postpone, to much higher shear rates, the onset of gross melt fracture. Extrusions of CarboGlide™ and mLLDPE into blown film have resulted in a three-fold increase in rate. In addition, improvements in film quality, such as, better caliper control, mitigation of film streaking, control of coefficient of friction, enhanced gloss, reduced haze and enhanced heat seal-ability are realized with CarboGlide™. Mechanical properties of the film, such as yield strength and Graves tear, are not debased. This unique combination of both process and product improvements, at equivalent to fluoroelastomer process aid costs, demonstrates that CarboGlide™ is the next generation of polymer process aids.

Property Comparison for Talc, Glass Fiber, Mineral Fiber and Mica Filled Polypropylene
Amit Dharia, John O. Rud, May 2002

The performance of muscovite mica as a reinforcing agent is compared with chopped glass fiber (CGF), milled glass fiber (MGF), the processed mineral fiber (PMF®FIBER), and talc in polypropylene. The effect of type, particle size, mixing energy, surface treatment, and coupling agent on physical properties and weld line strength is evaluated.Due to its high hardness, large area to thickness ratio, polar surface, and lubricating nature, mica reinforced polypropylene has higher rigidity, lower shrinkage, the highest surface hardness, lighter color and better processability than the reinforcing agents.

Pultrusion Compounding of Commingled Glass and Polypropylene Fibers
Iyobosa Ekhator, Philip Bates, May 2002

Much of the recent interest in commingled glass and polymer rovings has centered on woven materials. These commingled rovings can also be used in pultrusion forming, or filament winding. However, these processes require that the commingled material be in a tape form and that the glass fibers be well wetted with polymer. An instrumented pultrusion compounding process was developed to perform this wetting and forming operation. It consisted of an unwinding station, preheater guide, impregnation chamber, shaping die, cooling chamber, puller guide, and pulling station.The quality of the pultruded tape as a function of process parameters was assessed using short span flexural testing, glass fiber weight content, and scanning electron microscopy.

Qualitative and Quantitative Methods Used to Satisfy ISO 10993-18: Biological Evaluation of Medical Devices-Material and Chemical Characterization
David E. Albert, Paul J. Upman, May 2002

The international standard 10993 has been and continues to be the driving force behind the biological safety evaluation of biomaterials and medical devices. An important step in the process is that of characterizing the materials and the chemicals that can migrate or extract from the polymer components to the patient. Such basic information is critical to understanding biological response and risk management of the device. Whether to evaluate the polymer, simulated extracts, or degradation products will be discussed. Appropriate testing to do at the raw material, component part and final device stages will be presented.

Rapid Tooling – What Works and What Doesn't
Barbara J. Arnold-Feret, May 2002

This paper is third in a series of updates on rapid and alternative tooling technology for plastic molding and manufacturing. Examination of LENS, sintered metal, allow embedding technology, as well as newer processes using LSA and layer deposition is detailed. Tolerance, cosmetics, cost and lead times are update for users of commercial processes so expert decision can be made on best use for various molding and processing applications.Overall, during the last year, the leaps and bounds of the past progress in rapid tooling slowed almost as much as the economy. The lack of progress can be attributed to various factors including lack of funds, lack of interest, lack of defined goals, and lack of diversity of R&D efforts.

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