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

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.

Summary Results of a Novel Single Screw Compounder

Keith Luker, May 2007

A novel single screw mixer is described having multiple elongational flow fields, upstream axial mixing, and thin film degassing. SEMs show high magnification examples of mixing including a PS/PE immiscible polymer blend, ceramic nano particles, and iscrete carbon nano tubes. Novel degassing over the mixer is cited using three vents in a 36/1 L/D single screw to process undried PETG.

Fundamental Structure-Property Relationship of Polymer Nanocomposites

W.-J. Boo, L. Y. Sun, S.-M. Lee, E. Moghbelli, G. Warren, A. Clearfield, H.-J. Sue, May 2007

The structure-property relationship of a set of model polymer nanocomposite systems has been investigated. The findings suggest that degree of exfoliation and aspect ratio of nanoplatelets in polymer matrices can greatly influence physical, mechanical and rheological behaviors of polymers. Most importantly, there appears to be a limit to which polymer nanocomposites can be applied for structural applications.

The Role of Chain Branching in Extrusion Blow Molding of Polyvinylidene Fluoride

Nafaa Mekhilef, Lotfi Hedhli, May 2007

The effect of long chain branching in polyvinylidene fluoride in extrusion blow molding is investigated in light of the enhanced rheological properties. The presence of long chain branching increased the melt strength; melt elasticity and strain hardening of the branched samples as opposed to their linear counterparts. These enhanced properties suggest better sag resistance during blow molding and higher blow-up ratio while achieving uniform wall thickness.

Full 3D Injection Molding Analysis and Modeling Tips for Complex Models

Byung-Gi Pyo, May 2007

3D injection molding analysis is getting popular to get accurate result in the industry. However, mesh generation time and memory size for complex models are being demanded more than those of general model or conventional 2.5D analysis. This paper adopts simulation technology such as CVFEM(Control Volume Finite Element Method) or fast multipole method based on BEM(Boundary Element Method) and shows real case for large models. It does not only develop effective method to reduce modeling time, but it also performs analysis with significant performance enhancement.

A Comparative Study of Simulation Softwares for Stretch Blow Moulding

D.U. Erbulut, S.H. Masood, I. Sbarski, May 2007

Blow moulding simulation softwares are effective tools for blow moulders to predict and improve the performance of blow moulding process. Not many such software are available in the market. This paper presents a comparative study of two blow moulding software - B-SIM and Blow View – for specific application of stretch blow moulding process. Features and capabilities are compared based on the simulation study of a plastic bottle.

Plastic Integral Hinges; Design, Processing, and Failure Analysis

Rabeh H. Elleithy, May 2007

This paper addresses the design issues and processing conditions that affect the performance of integral hinges. For example, the relation between the material properties and the design of the hinge is addressed. An answer will be given to the question why does the increase in the melt temperature improve the performance of hinges?" Some case studies of failed hinges are discussed to practically show the effect of processing material and design on hinges performance. Microscopy was used to investigate the failure mechanism of these hinges."

Effect of Die Design and Wall Slip on Die Drool Phenomenon for Metallocene Based LLDPE: Theoretical and Experimental Investigation

M. Zatloukal, K. Chaloupkova, May 2007

The effect of die design and wall slip on the die drool phenomenon was investigated for metallocene based LLDPE. It has been found that die exit opening and wall slip can significantly reduce the die drool phenomenon. Moreover, theoretical research has revealed that die drool onset can be explained by the negative/non-monotonic pressure profile generated inside the die and/or at the die exit region due to melt elasticity.

Determination of Uniaxial Extensional Viscosity for Polyolefins by Improved Entrance Pressure Drop Measurements

M. Zatloukal, J. Musil, May 2007

In this work, specially designed zero-length dies were used for the entrance pressure drop measurements with the aim to determine uniaxial extensional viscosity of polyolefin melts by using effective entry length correction and Cogswell/Binding models and the results were compared with the extensional rheology determined with the Sentmanat extensional rheometer. Reasonable agreement between these two techniques has been obtained.