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
Understanding Why Adhesion in Extrusion Coating Decreases with Diminishing Coating Thickness, Part III: Analysis of Peel Test
Barry A. Morris, May 2007
It is well known that in the extrusion coating process, peel strength to aluminum foil and other non-porous substrates decreases with decreasing coating thickness. The peel strength is found to be more sensitive to changes in thickness as the adhesion between the coating and substrate improves. An analysis of the peel test shows that changes in the critical dimension of the deformation region at the peel front may be responsible.
Novel Polycarbonate Blends with Improved Environmental Stress Cracking Resistance (ESCR) to Hospital Cleaners and Household Disinfectants
Srinivas Siripurapu, Asima Chakravorty, Naveen Singh, May 2007
Impact modified Polycarbonate blends are preferred for medical housings due to their excellent balance of mechanical properties, flame resistance and processability. These housings are increasingly subject to aggressive cleaners and disinfectants to meet heightened sanitation requirements. New flame retardant polycarbonate blends using tailored silicone copolymers exhibit improved environmental stress cracking resistance (ESCR) to many classes of these cleaners.
Numerical Investigation of the Effect of Screw Temperature on the Melting Profile in a Single-Screw Extruder
Atakan Alt?nkaynak, Mahesh Gupta, Mark A. Spalding, Sam L. Crabtree, May 2007
Sensitivity of the melting profile to the screw temperature in a single-screw, plasticating extruder was analyzed using a three-dimensional finite element simulation of the melting process. Numerical predictions are compared with the corresponding experimental data from screw freezing experiments. Against the conventional intuition, the predicted melting rate in the compression section of the extruder was found to decrease with increasing screw temperature.
Viscoelastic Flow Model Applied to Tubing Extrusion
Ming Li, William C. Hurley, May 2007
Two designs of tube tooling with different draw down ratios were analyzed using a multi-mode viscoelastic flow model to reduce the post-extrusion shrinkage in a cable jacketing process with polyvinylidene diflouride (PVDF). The analysis focused on reducing both elongation and hoop stresses, which were believed to correlate most closely with the shrinkage. Results showed both elongation and hoop stresses were reduced. Cable tensile tests were conducted to compare with the numerical findings.
Purification Procedures to Obtain Chitin Whiskers Employing Shrimp Shells
M. Marquez, M. Matos, M.L. Arnal, F. López-Carrasquero, C. Rosales, A.J. Müller, May 2007
Two routes for purification of shrimp shells to obtain chitin whiskers were evaluated. The best result was found when demineralization was performed with 1M HCL followed by sample deproteinization with 5% w/v KOH. In order to obtain chitin whiskers an acidic hydrolysis was performed with several acids: HCL, H2SO4 and H3PO4. Chitin whiskers with lengths between 90 and 170 nm were obtained with phosphoric acid. The process was evaluated by FTIR, TGA and TEM.
Analysis of Viscous Heating Effects in a Pressure Slit Rheometer Using Radial Functions Method (RFM)
Ivan D. Lopez, Fritz Klaiber, Tim A. Osswald, May 2007
A pressure rheometer was built to measure rheological properties of polymers at elevated pressures and temperatures. However the viscosity at high deformation rates decreases more than the predicted theoretical value represented by the Cross-WLF model. This paper studies the role of viscous heating in the resulting viscosity deviations by means of simulation using the Radial Functions Method (RFM).
Optical and Mechanical Durability of Polymeric Materials for Solar Collectors
Gary J. Jorgensen, May 2007
The cost of solar collectors can be reduced by using polymeric glazing and absorber materials, but the durability of their optical and mechanical properties must be demonstrated. Polycarbonate glazings with ultraviolet screening layers have been shown to survive accelerated light intensity for an equivalent 20 years outdoor exposure in Miami, FL. The mechanical properties of two candidate absorber materials—metallocene-based multi-density polyethylene and polypropylene—have been measured as a function of wet and dry thermal exposure.
Surface Damage Threshold in Laser Transmission Welding of Polycarbonate
M. Chen, G. Zak, P.J. Bates, M. McLeod, D. Rouison, May 2007
Paper identifies experimentally the process conditions leading to specimen surface damage of laser-transparent polycarbonate during laser transmission welding. Influence of surface finish, defects and contamination is determined. Surface damage mechanisms are discussed. The surface damage threshold (SDT) is measured over a range of laser speeds and powers. Suggestions are provided for increasing the SDT.
Fiber Jamming and Fiber Matrix Separation during processing of fiber reinforced composites
Alejandro Londoño-Hurtado, Tim Osswald, May 2007
Fiber jamming is perhaps the least understood defect in molding of polymer composites. This paper presents a dimensional analysis developed to predict fiber distribution in ribbed sections. The model shows that parameters like mold closing speed and polymer viscosity can be optimized to decrease fiber matrix separation.
Influence of a Triangular Stress Concentrator on the Mechanical Properties of Plastic Parts
M. Candal, H. Rojas, J. Jiménez, May 2007
The influence of a stress concentrator on the mechanical properties of injected plastic parts was studied. Polystyrene plaques with different dimensions of a triangular concentrator were injected. Melt temperature, injection and holding/packing pressures and injection speed were modified in order to determine their influence on the stress concentrator factor (Kt). The experimental results were compared with the simulation ones. It was verified that Kt depends on geometrical parameters and process conditions of the injected plastic parts.
Effect of the Process Conditions over the Adhesion between Two Overmolded Polymers
M.V. Candal, A. Gordillo, G. Terife, O.O. Santana, May 2007
The effect of the injection molding process conditions (melt and mold temperatures, holding/packing pressure and injection velocity) over the adhesion resistance of two overmolded materials was studied. The materials used were a Thermoplastic Vulcanized Elastomer (TPV) (Santoprene 8211-55) and a Polypropylene (PP) (Moplen HP501H). The measurement of the adhesion resistance was done by Tensile Test and it was observed that the melt and mold temperature are the parameters that affect in greater degree the adhesion resistance.
Aspects of Electrospinning Process Control from Fundamental Mechanisms
Jonathan Jeffery Stanger, Nick Tucker, Nigel Larsen, Mark Staiger, Roger Reeves, May 2007
For large-scale application of electrospinning technology, it is important to know how to maximise and control the deposition rate of spun fibre. Driving polarity, substrate material and current flow were examined to quantify their effect on fibre deposition rate. Conductivity of the substrate and polarity of driving electric charge were found to affect the mass deposition rate. Higher deposition rates were the result of the production of thicker fibres and an increase in deposition speed.
Influence of Processing Parameters on Shrinkage of LDPE Parts in Gas-Assisted Injection Molding
Qian Li, Xiaofeng Wang, Changyu Shen, Jing Jiang, Shusen Hou, May 2007
The part properties are determined by quality of gas penetration in gas-assisted injection molding (GAIM), while processing conditions determine gas penetration. This research aimed to investigate some of the processing parameters, such as shot size, gas delay time and gas pressure. The effect of processing parameters on shrinkage ratio was discussed, as well as that how they influenced the part performance.
A New Approach for the Injection of Physical Blowing Agents in Foam Extrusion
Walter Michaeli, Holger Schumacher, May 2007
A new injection technique for introducing physical blowing agents into molten polymer is studied for its application in foam extrusion. Therefore, a special injection device is mounted on a standard laboratory scale single screw extruder. By means of this device, CO2 is injected into PS melt. In this paper first results of these preliminary tests are shown. The foams produced with this new technique exhibit a cell size in the range of 100 microns.
Reduction of Cooling Time by Using Atomized Water in Blow Molding
Walter Michaeli, Thomas Brümmer, May 2007
In the blow molding process, the blown part is primarily cooled by contact to the mold. Using internal cooling it is possible to reduce the cooling time. Using atomized water, is a new method to increase the heat flow at the internal surface. At the IKV the blow mandrel and the blow molding machine are modified to inject atomized water. The achievable cooling time reduction depends on the amount of the injected atomized water. The test series show that a reduction of cooling time up to 41% is achievable.
Crash-Simulation for Short-Fiber Reinforced Thermoplastic Parts
Walter Michaeli, Markus Brinkmann, May 2007
The anisotropic material behavior of injection-molded, short-fiber reinforced thermoplastic parts can be taken into account in mechanical simulation today by linking process simulation and structural analysis. However, the prediction of the crashworthiness of short-fiber reinforced parts is still performed predominantly using isotropic material models as a substitute. An approach to include anisotropic material behavior into crash-simulation has been developed at the Institute of Plastics Processing in order to advance simulation quality.
Wood Fiber Reinforced Polyamides
John Muzzy, Xiaolin Xu, Art Ragauskas, May 2007
Wood fibers are often used to reinforce polyolefins but not high temperature polymers like polyamide 6 and 66. These polyamides melt above 200 °C, which is often considered the maximum processing temperature for wood fibers. A variety of techniques for compounding and molding wood fiber/polyamide composites will be presented. These techniques are evaluated by examining fiber dispersion, fiber attrition and composite mechanical properties.
A Novel Approach for Measuring the Specific Volume of (Semi-Crystalline) Polymers at Elevated Cooling Rates Using X-Rays
Walter Michaeli, Manfred P. Hentschel, Oliver Lingk, May 2007
A new method to determine the specific volume of polymers over a wide range of temperature and pressure based on X-ray attenuation was developed. This method allows the application of different cooling rates enabling the investigation of the density depending on the thermal history. Experiments were performed to investigate the devolution of the specific volume of an isotactic polypropylene at elevated pressures and cooling rates.
Effect of Die Geometry and Extensional Rheological Properties on Vortex Development in Rectangular Dies
M. Zatloukal, K. Chaloupkova, D. Hertel, H. Münstedt, May 2007
The vortex development of a low-density polyethylene in different flat dies under various processing conditions has been analyzed by the Finite Element Method employing the modified White-Metzner model as constitutive equation. The theoretical results are compared with the velocity distributions measured by Laser-Doppler Velocimetry (LDV).
Optimization of Rotational Molding Cycle through Thermal Data Acquisition
Adam C. Barilla, Zachariah M. Ranck, May 2007
The DataPaq Rotomolding Telemetry System in conjunction with the Medkeff/Nye Shuttle PD developmental rotational molder was used to study and monitor internal mold and oven temperatures. Continuous internal temperature readout along with the software package were used to optimize the cycle of linear low density polyethylene (LLDPE). Designed experiments were employed to investigate process parameters and select physical and mechanical properties.
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