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

Acoustic Telemetry in Injection Molding

Charles Burton Theurer, Li Zhang, Robert Gao, David O. Kazmer, May 2001

The characterization of acoustic noise present in an injection mold during operation is presented for a remote in-cavity pressure sensor. This analysis is necessary to evaluate the use of ultrasound to carry process information out of the mold cavity. Experimental results are presented consisting of amplitude and frequency analysis of acoustic noise present in an injection mold as well as first attempts at transmission and demodulation of acoustic data.

Injection Nozzle Ultrasound Measurements

E.C. Brown, A.J. Dawson, P.D. Coates, May 2001

Ultrasonic measurements are a rich source of information during polymer processing. Difficulties in applying sensors to injection moulding nozzles have been overcome, and ultrasonic velocity measurements are being used to indicate process dynamics in terms of temperature and pressure change during injection. This work describes employment of a novel nozzle in which an ultrasonic signal is propagated along a path angled to the direction of melt flow, such that flow rate effects contribute to the received signal.

Creep Crack Growth in Oriented Polypropylene

J.B. Slay, Z.-Y. Xia, H.-J. Sue, May 2001

Creep (slow) crack growth resistance in oriented polypropylene (PP) is investigated using a fracture mechanics approach. The equal channel angular extrusion (ECAE) process is used to induce structural anisotropy. A constant load single edge notched bend (SENB) test is performed at an elevated temperature on isotropic (unprocessed) and anisotropic (processed) PP. This test generates stress intensity (K) vs. crack growth rate (da/dt) relationships. The da/dt = Kn relationship reveals that the creep crack growth resistance and mechanical properties of PP can be greatly improved by ECAE.

Plastics Education in the Delft University Industrial Design Engineering Curriculm

Rolf Koster, Anton Heidweiller, May 2001

Industrial Design Engineering graduates from Delft University have a background in a wide range of subjects, including plastics. They have been prepared for industrial product development practice by design exercises throughout the curriculum. In these exercises the students apply various subjects, including design of plastics components. The students' general technical and plastics background is expected to improve by curriculum adjustments currently being prepared. Product Design graduates have received additional training in designing with plastics.

Measurement of Entrance Pressure Drop of Polystyrene/Supercritical CO2 Solutions

Anle Xue, Costas Tzoganakis, May 2001

Two slit dies with sudden contraction ratios of 4:1 and 18:1 were designed to investigate the effects of pressure and supercritical carbon dioxide (scCO2) content on the entrance pressure drop and rheological properties of PS/CO2 solutions. scCO2 was found to decrease the entrance pressure drop as well as the shear and extensional viscosities of PS.

Compatibilizing EPDM and Degraded PP through Hydrosilylation Reaction

Claudio Villas-Boas, Luiz Mario Nelson de Goes, Costas Tzoganakis, May 2001

A hydride-terminated PDMS was used as a coupling agent for EPDM and degraded PP (previously generated all the way in melt phase by peroxide initiated degradation) through a hydrosilylation reaction in the melt-phase. Different concentrations of PP with different degrees of degradation were used, and different amounts of catalysts were employed. Melt viscosity, blend morphology and gel were evaluated. The reaction was found to increase viscosity and to improve blend morphology.

Simulation and Analyses of the Polymer-Pellet-Flow into the First Section of a Single Screw

H. Potente, T.C. Pohl, May 2001

The flow of plastics pellets into the first flights of the screw is frequently neglected when analyzing the solids conveying process in single-screw extruders. In order to gain better insight into the complex correlations that exist between pellet properties, barrel and screw geometry, the inflow process is simulated and investigated in experimental terms. Based on these findings a simple physico-mathematical model is worked out. The aim is to develop an optimum filling geometry in respect of feed behavior and solids conveyance.

Scratch Behavior in Molecularly Oriented Polycarbonate

Zhiyong Xia, Chen Xiang, Masaya Kotaki, Hung-Jue Sue, May 2001

In this paper the scratch behavior of molecularly oriented polycarbonate (PC) is investigated. Controlled molecular orientation is achieved through the equal channel angular extrusion (ECAE) process. Ford five-finger scratch test is used to investigate the orientation effect on the scratch resistance (in terms of scratch depth) in the ECAE-oriented PC. This study shows that controlled molecular orientation can improve the scratch resistance in polymers.

Investigation of the Volume Recovery of Glass-Forming Polymers

Hung-Jue Sue, Sindee L. Simon, May 2001

Up to now, the time dependent behavior of glass-forming polymers has been modeled with only moderate success. This could be explained by the fact that the relaxation times depend on the time-temperature- pressure history of the material rather than on the instantaneous state as is generally assumed. We have developed new volume recovery experiments to examine this assumption. The impact of our results on the current theoretical models will be discussed.

Full 3-D Prediction of Warpage of Injection Molded Parts

Y. Inoue, K. Imai, M. Takahara, Y. Murayama, T. Matsuoka, K. Shinoda, Y. Mori, May 2001

A full 3-D CAE system has been developed to predict warpage of thermoplastic injection molded parts. The system consists of pre/post processors and full 3-D solvers of mold cooling, polymer filling, packing and warpage. The validity of the warpage prediction was verified by using a box-shaped part and a L-shaped one. Although they were thin-walled parts, it was confirmed that the full 3-D simulation was necessary for the accurate prediction of their warpage.

Flow Visualization of Polymer Processing Additives Effects

K.B. Migler, C. Lavallée, M.P. Dillon, S.S. Woods, C.L. Gettinger, May 2001

Flow visualization was used to understand how polymer-processing additives (PPA) eliminate sharkskin in linear low-density polyethylene (LLDPE). A sapphire capillary die was used to image the coating of the PPA onto the die wall. Depth resolved optical microscopy was used to measure the velocity profiles. When added, the PPA migrates to and coats the die wall, induces slippage, and eliminates sharkskin. The interface between the PPA and LLDPE is characterized by long stripes in the flow direction.

Structure-Property Relationships in HMW-HDPE Blown Films

Rajendra K. Krishnaswamy, May 2001

The influence of processing conditions on the performance of HMW-HDPE blown films was investigated in relation to their molecular orientation characteristics. The presence of two distinct populations of lamellar stacks in such HMW-HDPE blown films and their influence on the physical properties was also considered. Finally, the dart impact strength of certain HMW-HDPE blown films was observed to increase with increasing draw-down ratios (decreasing film thickness); the morphological features that drive this unique structure-property relationship was explored as well.

Forward to Better Understanding of Optical Characterization and Development of Colored Polyamides for the Infra-Red/Laser Welding: Part I-Efficiency of Polyamides for Infra-Red Welding

Val Kagan, Robert Bray, Al Chambers, May 2001

The influence of a wide range of the infrared (IR) wavelengths (from 830 to 1,064 nm) on the optical properties of welded thermoplastics was evaluated for unfilled, filled and reinforced polyamide 6, 66 and amorphous grades. Presented results and developed recommendations will help, designers, technologists and materials scientists in welded parts design, materials selection and new materials development for various laser welding (LW) applications.

Ethylene Styrene Interpolymers for Injection Molded Toys

Dane Chang, Y. Wilson Cheung, May 2001

Due to increasing regulatory pressure, the toy industry has found itself being challenged to find suitable replacements for flexible PVC in flexible injection molded toys. Plasticized PVC is typically used for flexible toys where design requires painting of the molded toy. A new family of compounds suitable for such toy applications has been developed. These compounds are based on ethylene styrene interpolymers and exhibit short cycle time, high tensile strength, and excellent paintability.

Rheology as a Tool for the Polymer Scientist

Montgomery T. Shaw, May 2001

Rheology is a discipline that has applications both for analysis of polymer structure and for correlation and prediction of processing behavior. As such, rheology has impact over the entire development of a commercial resin. Described are several projects in the areas of polymer blending, aging and fabrication that illustrate the important role that rheology has played in their execution.

Processing Ignition-Resistant Polystyrene Resins in Injection Molding Machines

Mark A. Spalding, Robert G. Nelb, James A. Patterson, Chris Youngson, Melissa J. Zawisza, May 2001

The demand for ignition-resistant polystyrene resins (IRPS) continues to increase. Moreover, economics at the molder are requiring that these materials cycle faster and still produce high-quality parts. A new high-flow IRPS resin was developed to meet these needs, and this paper describes a plasticating screw design and the process conditions for enhanced performance and improved economics for this resin.

The Effect of a Worn Feed Casing on Plasticating Extrusion

Mark A. Spalding, Kevin R. Hughes, John L. Sugden, Phillip A. Wagner, Kun Sup Hyun, May 2001

With continued use, a worn feed casing can cause severe rate reductions and unstable operation of plasticating extruders. This paper will present the performance of a commercial extruder with a worn feed casing, and laboratory experiments that show the factors that affect plasticating performance.

Influencing the Foam Structure of CO2-Blown Polypropylene Sheets

Robert Heinz, Walter Michaeli, May 2001

An investigation has been conducted to analyze the influence of different process parameters as well as material properties on the structure of CO2-foamed polypropylene sheets. The use of a linear and a branched polypropylene shows the influence of the rheological melt properties on the foam density and the structure. Using the branched polypropylene, densities down to 140 kg/m3 have been achieved. These samples also show a finer and more homogeneous foam structure than the samples made with the linear polypropylene.

Control of Morphology of Polypropylene and Noryl Blend via Melt Mixing

Yanmei Li, Hung-Jue Sue, Brian Coleman, May 2001

Morphological development of polypropylene/Noryl blends as a function of composition and processing conditions is studied. Effects of processing conditions such as screw speed and residence time, on the morphology and mechanical properties of PP/Noryl blends are investigated. The processing-morphology-property relationship in PP blends is discussed.

Application of Fused Deposition Modelling in Spray Metal Tooling for Injection Moulding

S.H. Masood, M. Bahri, I. Harianton, May 2001

This paper presents a modified spray metal tooling procedure based on FDM rapid prototyping process, where parting lines were defined in the design stage to simplify and accelerate the spray metal tooling. Core and cavity inserts for injection moulding of a gas turbine blade were created using the modified procedure and successfully injected using LDPE. The procedure significantly shortens and simplifies the tool fabrication process, particularly for complex shapes, when manual parting lines establishment is too complicated and time consuming.