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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Solvent Effects on the Mechanical Properties of Peek: An In-Situ Dynamic Mechanical Analysis Technique
Amorphous poly(ether ether ketone)(PEEK) plasticizes and/or crystallizes in the presence of common organic solvents. In-situ Dynamic Mechanical Analysis techniques have been employed to study the effects of solvent-induced crystallization on the storage modulus (stiffness) of amorphous PEEK. Preliminary results indicate that the Tg of PEEK is depressed below 20°C allowing for room temperature crystallization. Real-time immersion at room temperature shows the competing effects of plasticization and crystallization on the mechanical response of PEEK.
Cavity Pressure Studies for Stereolithography Produced Tooling
The objectives of the study are to: 1)Determine the relationship between cavity pressure and tool failure; 2)Evaluate the feasibility and effectiveness of cavity pressure transfer from first to second stage for stereolithography (SLA) produced tooling; and 3)Evaluate the effectiveness of computer simulation in determining the startup conditions for the AIM* injection molding process.
Investigation of the Reaction Kinetics within Expandable Mixtures Used for Preparing Injection-Molded Polyolefin Foams
In this study, expandable polyolefin elastomer mixtures used for preparing cross-linked polyolefin foams were studied by Differential Scanning Calorimetry (DSC) to determine the reaction rate constants for azodicarbonamide (AZDC) decomposition. Activation energies and rate constants were computed from results obtained by variable heating rate DSC experiments. Predictions made from the kinetic equations were compared with results from isothermal aging experiments as well as observations made during injection molding of cross-linked foams.
Effect of Applied External Pressure on the Surface Concentration of Erucamide in LLDPE Films
External pressure was applied to extruded LLDPE films with an average thickness of 70 microns at 35°C and 50°C for prescribed periods of time. The final surface concentration of the slip agent (erucamide) was then compared to the initial concentration. Three applied pressures were used and diffusion profiles were determined using FTIR-ATR spectroscopy.
Experimental Comparison of Floating Ring Mixing Devices
Experiments were performed to determine the performance of three floating ring mixing devices. The mixers studied were 1) a Twente mixing ring, 2) a Barr sleeve mixer, and 3) a Barr ring mixer. Performance was measured using extrudate sampling, extruder performance, and extrusion solidification experiments.
An Optical Determination of Melt Viscosity through Particle Kinematics
Melt viscosity is calculated by observing contaminant flow in a low density polyethylene melt stream. The melt stream is radiated by visible light and images of flowing particles are captured and processed. Particle flow rates are measured across the stream, and a velocity profile is then determined. Viscosity is calculated from this profile.
Studies of Sharkskin Melt Fracture Using a Model Polymer
Sharkskin melt fracture (SSMF) of, especially, LLDPE has been studied for several decades because of its economic importance and scientific interest. SSMF occurs on extrusion of some--but not all--polymer melts; examples include LLDPE, PDMS and polybutadiene (PBD). PBD exhibits remarkably similar flow and SSMF behavior to LLDPE, but is easier to work with. Evidence for the origin of SSMF inside the die was sought, but not found, leaving the exit as the probable source of SSMF for this resin.
Effect of Metallocene Polyethylene on Heat Sealing Properties of Low Density Polyethylene Blends
Laminations made with blends of metallocene Polyethylene (m-PE) and high-pressure low density Polyethylene (LDPE) were prepared to investigate the effect of the former resin on heat sealing performance. According to various experimental studies of seal strength, hot tack and differential scanning calorimeter (DSC), it could be concluded that percentages around 15% of m-PE allow to obtain the optimal balance for heat sealing properties and cost. Using the interdiffusion theory of heat sealing, a thorough discussion of the results was done.
The Color Image Coding Analysis of Progressively Degrading Polymers
Many an industrial polymer product reveals, once its quality diverts from set standards, either a change in color or an increase in fluorescence. After their accelerated ageing, various products are scanned on special flatbed scanners and their filed images are then color coded to determine with high accuracy their color composition, fluorescence intensity and the extent of their discoloration during processing.
The Effect of Salt Absorption on Nylon
One of the most common environmental exposures that nylon undergoes when used for automotive applications is that of salt splash, which commonly occurs during winter driving. This study looks at the effect of various salts (NaCl, KCl, CaCl2) on the mechanical and thermal properties of nylon when exposed to one and four molar aqueous salt solutions. Also, the partition of the salt/water solutions was studied, as well as the preferential absorption of one salt over another.
Comparison of the Morphologies of Hot-Tool and Vibration Welds of Thermoplastics
Because the heating rates in hot-tool and vibration welding are very different, and the higher weld pressures used in vibration welding induce more squeeze flow, the weld zones in these two processes see very different flows and cooling rates, resulting in different morphologies. The weld morphologies of bisphenol-A polycarbonate and poly(butylene terephthalate) for these two processes are discussed in relation to these differences.
Injection Mold's Problems Solved by CAE Analysis
The use of CAE1 as a powerful tool to analyze injection mold quality has given encouraging results. CAE is used to deal with mold troubleshooting and to solve problems concerning Filling Time, Injection Pressure, Gate Position and Dimensions, Warpage, Coolant Efficiency, etc. This paper focuses some of these parameters to its weightiness for Mold Technologies Division. Therefore CAE is a powerful tool to assure quality, price and time delivery.
Effect of Pressure on Crystallization of Polyethylene
The morphology and crystallinity of plastics articles are influenced by several parameters, in particular the pressure and the temperature history during solidification. In this study, the crystallization kinetics and the PVT behavior of a high-density and linear low-density polyethylene resins were evaluated and compared using a high-pressure dilatometer under both isothermal and isobaric conditions. Also, the PVT behavior was compared to the predictions of the Tait equation of state. It was found that the induction time increases with increasing pressure, suggesting that pressure delays crystallization.
Flexural Properties of Dental Composites
Effect of specimen thickness on flexural properties of particulate filled and continuous fiber reinforced composites was investigated by 3-point bending test according to ISO10477. Results showed that flexural strengths and moduli decreased with the increase in specimen thickness. Loss of flexural properties in thicker specimens compared to those in thinner specimens was higher in fiber reinforced composite than in particulate filled composite.
Rheology and its Relationship to Applications of Ethylene/Styrene Interpolymers
The rheological properties of ethylene/styrene interpolymer (ESI) systems ranging in styrene content up to 80 wt% (50 mol%) and in melt index from 0.5 - 10 are discussed. Dynamic mechanical spectroscopy, melt strength, and pressure-volume-temperature data will be presented along with corresponding relationships between these data and applications of ESI.
Injection Molding by Direct Compounding
Direct compounding has long since been eastablished in sheet-, profile- and pipe-extrusion, where the high cost-advantages of single-stage article production are appreciated . Compared to extrusion applications, direct compounding of injection molded articles is comparitively unknown territory. The IMC-process (Injection Molding Compounding) enables filled or reinforced plastics to be direct-compounded immediately before injection molding. This offers two advantages to the molder: his material costs are reduced and he gains in flexibility.
Spatial Variation of Structural Hierarchy in Injection Molded Polypropylene
The structural hierarchies in injection molded isotactic polypropylene are mapped at two different mold temperatures and injection speeds in order to quantitatively understand their spatial variation. The mechanisms of formation of structure in various locations of three-dimensional objects and their quantitative representations are addressed at different levels of size hierarchy (superstructure, lamellar, and unit cell) using Optical Microscopy, Hot Stage Video Microscopy, SALS, SAXS, and Microbeam WAXD. A structural model describing the overall behavior is presented.
Motors and Drives for Extrusion Applications
There are many choices and options available for motors and drives for extruders and other machinery used in extrusion lines. This paper provides an in-depth explanation of DC, AC Vector, Servo, Brushless DC, and other common drive and motor technologies. It covers how they work, their major differences, their pros and cons, and some guidelines in how best to apply them. This knowledge should help plastics engineers in the selection of extrusion equipment.
Velocity Distributions in the Nip and Translational Regions of a Co-Rotating Twin-Screw Extruder
The positive displacement characteristics of a twin-screw extruder are often attributed to the intermesh of the two screws. Our objective was to measure velocity distributions in the nip and the translational regions of a co-rotating twin-screw extruder. The variation of axial and tangential velocity with screw rotation changed significantly from the translational to the nip region. Much higher axial velocity values were measured in the nip when compared with those measured in the translational region.
Effect of Thermal Degradation on the Impact Properties of PVC Compounds
Instrumented drop weight impact test was used to study the effect of thermal degradation on the impact properties of PVC compounds. The impact resistance of the aged compounds related well with their weight loss and hence thermal degradation. Each compound showed a specific weight loss percentage that correlates with a 50% loss in its impact properties (failure point) irrespective of the aging temperature. The results were also used to estimate a thermal index (TI) of each compound in a rapid and reliable way.
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