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

Designing the Cooling System: What's the Relationship between Mold Material Selection, Water Line Spacing and Mold Surface Temperature Variation

Jay Shoemaker, Kurt Hayden, Paul Engelmann, Patricia Miller, May 2004

Cooling system design is important for making injection-molding tools that have short cycles and produce high quality parts. Guidelines for waterline placement vary widely and don’t satisfy the above requirements. This research used Moldflow to investigate the effects of mold material and waterline spacing on mold temperature variation.

Runner Diameter and Length Effects on Molded-In Stresses of Injection Molded Parts

Scott Robert Cleveland, Joseph Philip Latchaw, May 2004

Molded-in stresses are present in all injection molded parts and can be altered by the melt delivery system of a mold. The length and diameter of runners will have a direct effect on the amount of shear the material is exposed to prior to entering the part cavity and its melt conditions as it flows through the cavity. Various runner diameters and flow lengths are evaluated as to their influence on, and relationship to, the development of residual stresses in a molded part.

Rotofoamability of Polyolefin Resins

Remon Pop-Iliev, Chul B. Park, May 2004

A statistical method was used to analyze experimental data and identify the best-suited polyolefin resins for rotational foam molding operations. The average cell sizes of the skinless foams that occupy the mold to its full volumetric capacity were used as the measured response.

DSC-OIT Studies of Antioxidants in Rotomolded HDPE Tanks

Brian L. Weick, Raed S. Al-Zubi, May 2004

Differential scanning calorimetry (DSC) was used to perform oxidation induction time (OIT) studies using surface samples from three rotomolded high-density polyethylene (HDPE) tanks. Three different processing times were used to rotomold undercooked, ideal, and overcooked tanks. Graphical and statistical methods were used to study the presence and characteristics of antioxidants at the inside and outside surfaces of the tanks.

Improving the Prediction of Thermoforming Sag in Simulations through Experimental Validation of the Transition Model

Patricia Debergue, Patrick Girard, Christian de Grandpré, May 2004

Sag is a critical parameter to control in thermoforming. It is however very difficult to predict sag accurately through simulation. A series of numerical models for sag prediction are evaluated by comparison with experimental results. Some of the main process modeling parameters are identified and quantified experimentally.

New Capillary Viscometers for the Compounding Industry

Giancarlo Locati, Enrico Corazza, May 2004

New Capillary Viscometers, beyond offering remarkable precision, may also broaden the characterisation of polymer compounds.After a short review of the features of recent equipment, some selected examples of applications will be shown. They range from improved quality control of incoming and outgoing products, to recycling management, masterbatches characterisation, and evaluation of dispersion effects on filled materials.

The Effect of Movement during Cure of a Silicone Sealant

C.C. White, D.L. Hunston, May 2004

Movement of a building joint sealant during cure is believed to affect the fully cured" mechanical properties and the durability. A one part silicone was cured for 10 h to 168 h before the onset of physical deformation cycles. These cure times fall between the proposed RILEM TC-139 technical recommendation of 5 min and the ASTM C719 durability standard of 21 d. Apparently enough cross-linking occurred prior to testing such that neither the overall movement history of the sample nor the deformation regime shapes affected subsequent curing or mechanical properties of the sealant."

Rheological Characterization of Liquid Crystal Polymers (Xydar-300, Xydar-400 and Xydar-900) Measured in ARES Spectrometer

Kamal K. Kar, Joshua U. Otaigbe, May 2004

An in-depth experimental and theoretical study of many important factors governing the rheological properties of liquid crystal polymers, Xydars (SRT-300, SRT-400, and SRT-900) is carried out by Advanced Rheometric Expansion System (ARES Spectrometer) in the parallel plate-plate configuration over a wide range of frequency, temp and strain level in the steady shear and dynamic conditions.

Rheological Methods for the Detection of Low Levels of Long-Chain Branching in Polyolefins

T.P. Karjala, R.L. Sammler, W. Huang, M.A. Mangnus, M.S. Johnson, May 2004

Several published rheological approaches to detect the presence of long-chain branching (LCB) in commercial polyolefin resins were assessed. In particular, the suitability, feasibility, and applicability of these approaches in detecting low levels of LCB (( 0.01 LCB/1000C) were the basis of the assessment. Nine methods were evaluated using two sets of metallocene polyethylenes.

Investigation of Torque and Normal Force Responses in Double-Step Strain Histories for Branched Polyethylenes

Changping Sui, May 2004

Experiments of single-step and reversing double-step strain histories were performed on branched polyethylene and the torque and normal force responses were analyzed within the framework of the K-BKZ theory. The results validate the findings of Venerus that K-BKZ model correctly predicts the responses in the reversing histories for branched polymers.

Rheological Studies of Injection-Molded Polyolefin Foams

Xue Chen, Marie-Claude Heuzey, Pierre J. Carreau, May 2004

The rheological properties of molten LDPE and mPE foams were measured in small amplitude oscillatory shear flow. The foam samples were prepared by injection molding and the effect of injection conditions on the resultant cell structure is discussed. The linear viscoelastic behavior of the foams is well described by the Palierne emulsion model (1) without the use of any fitting parameter. It is shown that the linear viscoelastic properties of LDPE and mPE foams depend only on the properties of the polymer matrix and on the gas volume fraction.

Computer Modeling of Gas Permeation in Flexible Packages

Paul E. Koch, Brian A. Young, Michael W. Alabran, May 2004

The shelf life of oxygen and moisture sensitive products is limited by a plastic package's ability to restrict or control the permeation of small molecules through the package's walls. Mass transfer and thermal transfer equations have the same theoretical basis, and therefore heat transfer modeling programs can be adapted to model permeation. This paper models and validates this concept.

Improvements to Laser Processing of Thin Polymer Films - Using Non-Standard Novel Laser Wavelengths

Tony Hoult, Bill Dinauer, May 2004

Highly reliable high power carbon dioxide lasers are being increasingly employed in the converting industry. New laser sources with different wavelengths are available to allow more controlled laser cutting and perforating processes. These process advantages are thought to be due to enhanced absorption of certain thermoplastics at these shorter wavelengths and this paper investigates these.

Force Measurement during Vibration Welding of Nylon 66

X.Y. Dai, G. Park, P.J. Bates, May 2004

An experimental technique for measuring the shear forces generated during vibration welding is presented. It involves the use of piezoelectric shear force transducers mounted under the fixture on the lifting table. Using unreinforced and 30% glass fibre reinforced nylon 66 T-welds, the force was measured in real time under a range of weld pressures and weld amplitudes. The shear stress amplitude is observed to depend strongly on the type of material, the welding parameters and the specific phase of the vibration welding process.

Automotive Plastic Fuel Tank Systems

Kenneth W. Albaugh, May 2004

The manufacturing of Plastic Fuel Systems is an ever changing and technology driven field. The field is influenced by governmental emission standards that are becoming tougher to meet with plastic fuel tanks. Several new technologies have been developed to accommodate the environmental legislative changes.

Through-Transmission Laser Welding of Nylon - Breaking the Moisture Barrier

Steven A. Kocheny, Val A. Kagan, John Macur, May 2004

For through-transmission laser welding (TTLW), basic studies include optical and mechanical data of nylon at dry-as molded conditions". Recent developments have been oriented toward the influence of accumulated moisture on optical and mechanical characterization of laser welded nylon 6. Results from this report provide supporting data that moisture in nylon is not a barrier for laser technology and the mechanical performance of welded parts."

Design Flexibility in Waveguides and Lightpipes for TTIr Plastics Welding

Scott Caldwell, Paul Rooney, May 2004

Waveguides and lightpipes can be used for simultaneous TTIr plastics welding. There are various new improvements in the waveguide and lightpipe technology, including optical horned, tapered, lensed, side looking, and part incorporating waveguides and lightpipes, that enhance weldability, weld quality, and cycle times.

Practical Joint Designs for Laser Welding of Thermoplastics

Thomas R. Kirkland, May 2004

In recent years, much work has been done on laser welding of thermoplastics. The process has been well characterized through the use of test plaques. This paper discusses practical considerations of laser joint design, including an examination of the advantages and disadvantages of collapse-type joints and non-collapse or contained welding joints. Issues such as reflection and low transmissibility and low absorption materials are discussed from the part designer's point of view.

Industrial Applications for Laser Welding of Plastics

Michael Cherdron, May 2004

The possibility for laser welding of plastics has been researched over the past years with the results of the technology going in various directions. The Approach of laser welding plastic components in Industrial applications utilizing the Quasi-simultaneous laser welding (QSLS) has been quite successful.

In-Process Temperature Measurement in Extrusion Using Continuous Wave Ultrasound

K. Trivedi, D. Cuff, Charles L. Thomas, May 2004

In this work a continuous wave ultrasound system was investigated for application to in process temperature measurement for extrusion. Work to date includes preliminary studies of the feasibility and initial laboratory based tests showing sensitivity of the signal to temperature changes.