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

Hybrid Nanocomposites of Carbon Nanotubes (CNTs) Grown on Carbon Fiber in Polyester Matrix with Improved Thermomechanical Properties
Prabhat Agnihotri, Kamal K Kar, May 2007

Carbon nanotubes (CNTs) were grown on the surface of carbon fiber using thermal chemical vapor deposition (CVD) technique. Ni is used as a catalyst. The coating of catalyst on the surface of carbon fiber was done by electroless dip coating technique. By performing structural characterization of CNT coated carbon fiber using scanning electron microscope (SEM) and transmission electron microscopy (TEM), the length and diameter of CNTs were measured and found to be ~9000 nm and ~40 nm respectively. Thermo gravimetric analysis (TGA) of as received and CNT coated carbon fiber samples in nitrogen atmosphere indicates that the CNT coated carbon fiber samples are thermally more stable. The improvement in storage modulus in CNT coated carbon fiber samples is observed in dynamic mechanical analysis (DMA).

Influence of Part Thickness, Glass Fibre Content and Line Energy on Laser Transmission Welding of Polyamide mXD6
P.J. Bates, M-E Druart, M. Chen, G. Zak, J. Billiet, May 2007

Laser transmission welding is a process used to join two thermoplastic materials based on their abilities to transmit and absorb laser energy. The influence of part thickness, glass fibre content, and line energy on the laser welding of a semi-aromatic polyamide was examined. Plaques of polyamide mXD6 were moulded at three different thicknesses (0.5 mm 1 mm, and 2 mm), a range of glass fibre contents (0, 30, 50 and 60%) in both natural and black. Lap welds were made using a Rofin Sinar diode laser in a contour welding mode over a range of line energies. The assemblies were tested in shear and the fracture surfaces examined using scanning electron microscopy.

Shrinkage and Cooling Simulation of Injection Molded Parts in Melt Solidification Processes
Shiu-Wu Chau, Yin-Jie Juang, May 2007

The numerical prediction of three-dimensional warpage simulation during cooling process for injection molded parts before demolding is conducted in this paper. Similar to other warpage calculations, the energy equation for injection molded parts is solved together a thermal elastic models to investigate the shape deformation inside mold. Different from previous studies assuming melt cooling from solid state, the injection molded parts are cooled from fluidic state using a solidification model. Additionally, the influence of mold constrain is also taken into account.

Modeling the Rheology and Orientation Distribution of Short Glass Fibers Suspended in Polymeric Fluids: Simple Shear Flow
Aaron P.R. Eberle, Donald G. Baird, Peter Wapperom, May 2007

In this paper we present a constitutive relation for predicting the rheology of short glass fibers suspended in a polymeric matrix. The performance of the model is assessed through its ability to predict the steady-state and transient shear rheology as well as qualitatively predict the fiber orientation distribution of a short glass fiber (0.5 mm, L/D < 30) filled polypropylene. In this approach the total extra stress is equal to the sum of the contributions from the fibers (a special form of the Doi theory), the polymer and the rod-polymer interaction (multi-mode viscoelastic constitutive relation).

Ultrasound Assisted Single Screw Extrusion Process for Dispersion of Carbon Nanofibers in Polymers
Avraam I. Isayev, Changdo Jung, Kaan Gunes, May 2007

A novel method for the continuous dispersion of carbon nanofibers (CNFs) in a polymer matrix for manufacturing high performance nanocomposites was developed using an ultrasonically assisted single screw extrusion process. The effect of ultrasound on die pressure, electrical conductivity, rheological, morphological and mechanical properties of polyetherimide (PEI) filled with 1-20 wt% CNFs was studied. A reduction in the die pressure, percolation threshold and an increase in the viscosity, Young's modulus and electrical conductivity along with better CNF dispersion in nanocomposites was achieved through ultrasonic treatment.

Studies on the Thermomechanical Properties of Nickelphosphorous Coated Carbon Fiber Fabric/Polyester Laminates
Niranjan Patra, Kamal K Kar, May 2007

A systematic study was carried out to investigate the effects of nanoscaled electroless nickel-phosphorous alloy coating on the thermomechanical properties of woven carbon fiber fabric reinforced polyester matrix composites. The electroless nickel-phosphorous coated carbon fiber fabrics with different coating time interval (0, 5, 10, 15, 20, 25, 30mins) were prepared. The polyester matrix was then used to manufacture weave carbon fabric/polyester nanocomposites using wet lay-up process. Dynamic mechanical analysis (DMA) studies were carried out in bending and tensile mode. Experimental results showed Maximum improvements in modulus for 30mins coating time reinforced composites. Dynamic mechanical analysis showed enhancement in thermomechanical properties. The nickel-phosphorous coated carbon fiber fabric composites showed a considerable improvement in the glass transition temperature (Tg).

Microstructural Characteristics of Micro-Injection Molded Thermoplastics
Jingsong Chu, Andy Hrymak, Musa R. Kamal, May 2007

A micro-injection molding machine was used to obtain micro-moldings of polyethylene, in order to study the effects of processing conditions on some microstructural characteristics of the moldings. The processing variables were estimated, based on experimental data and on simulation results. Polarized light microscopy was used to evaluate morphology. Three-dimensional distribution of shrinkage was measured. Micro-mechanical properties (modulus and hardness) were measured with a nanoindenter. The microstructure and properties will be explained in light of the thermo-mechanical history.

The Effect of Implementing Hybrid Mold Temperature Dependant Heat Characteristics on the Accuracy of 3D Injection Molding Simulation
Ludwig Cardon, Cristoph Hinse, May 2007

When analyzing the thermal behavior of hybrid molds, normally fixed values for thermal characteristics are implemented. This paper will discuss the underestimated effect of temperature dependant heat characteristics of hybrid mold materials on the accuracy of 3D injection molding simulation via obtained results of a former PhD work and implementation of this knowledge into Moldex3D (M3D).A hybrid mold of a technical part was designed to analyze this problem. It also resulted in a better understanding of the mold design strategy and 3D simulation advantages for multiple material molds related to filling, warpage, cooling and final part quality.

Influence of Process Parameters on the Weld Lines of a Micro Injection Molded Component
G. Tosello, A. Gava, H.N. Hansen, G. Lucchetta, May 2007

The insufficient entanglement of the molecular chains and the stress amplification at the v-notch of a weld line compromise the mechanical strength of a plastic product, also in the micro scale. To investigate the influence of process parameters on the weld lines formation, a special micro cavity was designed and manufactured by ?EDM (Electro Discharge Machining). Weld lines were quantitatively characterized both in the two-dimensional (direction and position) and three-dimensional range (surface topography characterization). Results showed that shape and position of weld lines are mainly influenced by mold temperature and injection speed.

Laser Transmission Welding of Electro-Pneumatic Valves
D. Hänsch, May 2007

Laser welding has proved an appropriate method for joining plastic parts. The increasing trend towards greater freedom of design, integration of ever more functions, and therefore more complex modules is putting increasing pressure on joining technology, and is thereby promoting the development and introduction of novel technologies.Laser welding of plastics is a suitable complement to established joining processes, and thereby opens up new fields of application. This has been demonstrated by numerous applications for small and even for larger components.Compared to alternative joining methods the contact free method has the advantage that hardly any flash or no flash is being produced, which means that joints with a high quality visual appearance can be produced. The laser is clearly superior to alternative processes, even for joining 3D geometries produced by coupling to a robot. The heat-affected zone is only a few #m deep and reduces the risk of surface flaws.The following paper is a case study for the introduction of the Laser welding process for electro-pneumatic valves. It describes the process development from the initial tests to the In-Line integration in mass production.

Birefringence Distribution in Gas-Assisted Tubular Injection Moldings: Simulation and Experiment
A.J. Carrillo, A.I. Isayev, May 2007

Measurements and simulation of three birefringence components and of the gas/polymer interface distribution in gas-assisted injection molding (GAIM) of a tubular geometry are presented. The governing equations of the process are derived using a nonlinear viscoelastic model and solved using a hybrid finite element/finite difference/control volume method (FEM/FD/CV). The measurements were carried out on polystyrene moldings before and after annealing. Simulation and experimental results indicate that the birefringence is high in the gas penetration region and low in the region where the gas did not penetrate.

Radiation Cross Linking Engineering Thermoplastics for Tribological Applications
Zaneta Brocka, Ernst Schmachtenberg, Gottfried W. Ehrenstein, May 2007

Electron beam irradiation primarily leads to cross linking in the amorphous fraction of semi-crystalline thermoplastics. As a result, there is a change in morphology and an improvement in mechanical and thermo dynamical properties. This effect can be utilized for tribologically stressed parts as micro parts and gear wheels. These parts feature an unfavorable relationship of part/volume leading to a disadvantageous formation of morphology and crystallinity. Experimental work shows the potentials of radiation cross linked polyamides. Due to cross linking in particular the thermal-mechanical and tribological properties are shifted into a range, which enables the employment of this substrate for application at elevated temperatures. Furthermore, the investigations on PA6 and PA66 show that a lower crystallinity degree leads to better results of cross linking via electron beam radiation and to an improvement of abrasion resistance.

Failure Analysis and Prevention – A New European SIG
Jan Spoormaker, Erik Andreassen, Anton Heidweiller, May 2007

The new European Failure Analysis and Prevention Special Interest Group (FAPSIG) is creating a database with failure cases. The members share this database and contribute with their own failure investigations. The two main groups are Failure Causes and Failure Mechanisms. Failure Causes are subdivided in: Stress concentrations, low mass and/or mould temperature, highly stressed weld lines, faulty ribbing; too high stiffness of construction elements, incorrect joining, and incorrect material selection.Failure Mechanisms are subdivided in: Creep and stress relaxation, wear, fatigue, UV degradation, chemical attack, environmental stress cracking.The paper will present some examples for designers of plastic products.

Measurement of the High Frequency Viscoelastic Properties of Polypropylene Using a Sliding Plate Rheometer
Chelsea A. Braybrook, Jennifer A. Lee, Philip J. Bates, Marianna Kontopoulou, May 2007

A newly constructed sliding plate rheometer (SPR) is used to investigate the high frequency linear viscoelastic properties of two polypropylene (PP) resins with widely differing melt flow rates. Extrapolation of rheological measurements obtained on a traditional parallel plate rheometer to frequencies obtained on the SPR, through use of the generalized Maxwell and Cross models, was used to assess the performance of the high frequency SPR. Good agreement between the extrapolated and measured data demonstrates the ability of the SPR to measure the high frequency rheological properties of PP.

Development of Rubber Mould Inline Process and Offline Process Inspection by Touch Probe
Suchada Rianmora, Chana Raksiri, Supasit Rodkwan, Kunnayut Eiamsa-ard, May 2007

Development in design of mould using reverse engineering can reduce lead time and increase the quality of mould inspection. For two methods used: touch probe on machining center and portable arm coordinate measuring machine, these are used along software that is capable of measuring three-dimensional coordinate and analyzing the results. The first inspection is done on the machine during production (inline) then another is examined after production (offline). The experiment result demonstrates in terms of accuracy there is no significant difference between two measurement methods. Nevertheless, the portable arm CMM has an advantage in its simplicity, and require less operation and lead time.

Optimization of Quality and Throughput at Low Revolution Speeds in an Advanced Two Stage Compounding System
Ralf Kühn, U. Burkhardt, Peter Heidemeyer, May 2007

Melting and incorporation of high viscous particles into a low molecular matrix is a difficult process due to differing requirements for melting and homogenizing. Melting is preferably done by using high shear rate and stress in combination with a small residence time. These facts lead to a fast turning small machine. Homogenizing on the other hand requires elongational flow, high viscosity and a significant amount of residence time which leads to a low revolution speed. By using a two step compounding system one can meet the differing constraints at the same time. Optimization of efficiency in pressure build-up can be done effectively by using state of the art CFD calculation methods.

Numerical Balancing of Coextrusion Dies : A Validation Study with a TPV-Based Hose
T. Marchal, T. Burton, G. Franceschetti, J. De rijcke, C. Chauvin, H.M. Metwally, May 2007

In some industrial applications, like hydraulic hoses, a two-layer structure may be produced from the coextrusion of a soft Engineering Polyamide Alloy and a Thermoplastic Vulcanizate (TPV), like Santoprene™ Thermoplastic Rubber. As the inner layer, the polyamide component provides a barrier against oil at high temperatures; the TPV provides flexibility, resistance to abrasion as well as adhesion to the inner layer.Reaching a die design that yields the required concentricity and homogeneous material distribution in each layer is a challenge. The following two-step approach is here proposed. First a 3D numerical simulation using the POLYFLOW code confirms the current unsatisfactory extruded profile quality. A second extrusion simulation is next carried on a modified geometry to ensure proper flow balancing. A validation is performed for the coextrusion of a relevant Thermoplastic Rubber grade compatible with an Engineering Polyamide Alloy.

Engineering Plastics for Laser Welding
Eric van der Vegte, Marnix van Gurp, Hans Hoekstra, Alexander Stroeks, May 2007

The use of laser light energy to very locally weld plastic surfaces together has opened new possibilities for flexible design and assembly of plastics parts. However, this poses the challenge of applying a combination of transparent and absorbing plastic parts in order to use the laser light efficiently for local melting at the interface. Transparency is still a challenge in some cases, due to the scattering nature of certain plastics. This paper will focus on the optical requirements of the welded parts, but also on the physical aspects of the interface to form a strong weld.

Plane Stress Rapid Fracture Resistance of Pipe Grade PE: Estimation from Tensile Drawing Data
Pemra Ozbek, Patrick Leevers, May 2007

The Rapid Crack Propagation régime in pressurised polyethylene pipe is limited by a critical temperature, which is determined mainly by the increasing resistance of the material to plane stress fracture. The Reversed Charpy and ASTM F2231 ‘Thin Charpy’ test methods are designed to index this property, at appropriately high rates, for quality control and material development purposes. This paper demonstrates that equivalent information can be derived from a procedure based on basic tensile drawing tests, via material properties which are more accessible to material design.

Heat-Aging Performance of Metallized Thermoplastics for Automotive Lighting
Adam Zerda, Kathryn Guggenheim, Beatrice Grau, Theo Hoeks, May 2007

Driven by weight savings, design freedom, manufacturing economics and pedestrian impact considerations, the use of plastics in automotive lighting has grown over the last decade to include all aspects of forward and rear lighting. Among these is the use of plastics in reflector applications where the molded plastic part is metallized, heated and expected to maintain high reflectivity and tight dimensional stability over time at use temperatures. In addition to the thermal properties of the plastic, other factors can affect the use temperature in such an application. The effects of metallization conditions, moisture and post-metallization aging are discussed as they affect the use temperature of a variety of high temperature thermoplastics.










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