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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Evaluation of Methodoligies Utilized to Determine the Pressure Drop throughout an Injection Mold
Two of the most common industry methods for evaluating the pressure drop through an injection mold during mold filling are investigated against an instrumented mold. The first is injection molding simulation and the second is the shop floor applied “Pressure Drop (Loss)” study method that is widely accepted as part of modern injection molding practices. The study finds that the shop floor method can significantly misrepresent the relative pressure developed through progressive regions of a mold. Injection molding simulation was found to provide a better agreement with the actual measured mold filling pressures.
Performance Enhancement of PEBAX Using Supercritical Fluid Extrusion for Biomedical Applications
An intravascular catheter system requires design specifications that needs to provide sufficient flexibility, to follow desired path required by the surgeon and adequate stiffness to travel along the curving path of vasculature. This paper presents the effects of sub-supercritical, near-supercritical and beyond supercritical carbon dioxide assisted extrusion process and their characterization to evaluate their thermal and dynamic mechanical properties using Pebax. A twin-screw-extruder using scCO2 can effectively generate foams, while providing excellent control over mechanical and thermal properties. The crystallization and melting behaviour of scCO2 assisted extrudates were investigated using differential scanning calorimeter technique (DSC) for various isothermal conditions. The mechanical performance was evaluated by using dynamic mechanical thermal analysis (DMA) and tensile test. A significant increase in dynamic modulus was observed for Pebax extruded at 800 psi and 1000psi, however, decreased resilience and toughness was noted for Pebax extruded at 1200psi.
Using ZeMac® Copolymers To Increase Performance and Processibility of High RV Nylon
Conventional polyamides with high relative viscosity called “high RV polyamides” or “high RV nylons” are prepared typically by a few large nylon-6 producers with solid state polymerization (SSP) process, which is time consuming and energy intensive and hence expensive. Such polyamides are linear molecules as are high RV polyamides produced by compounding with chain extenders with ?-? functional groups. However ZeMac® alternating copolymers of ethylene and maleic anhydride, which are unique with hundreds of pendant functional groups, can be compounded with low RV polyamides to form high RV polyamides which have a branched structure, confirmed by shear thinning rheology. The paper will cover this and performance and cost advantages of such branched polyamides over conventional SSP and linear polyamides for several high performance applications.
Energy-Efficient Processing of Rendered Animal Proteins as Value Added Bio-Crosslinkers in High-Strength Thermosets
Emergence of bovine spongiform encephalopathy (BSE) has inhibited the use of proteinaceous materials from rendering industry with regard to animal feed, pet food, and fertilizers. In recent times, extensive research has been done towards finding suitable, alternative, non-feed and non-fertilizer applications for these materials. In this regard, plastics from proteins, especially thermoplastics and derived composites, have emerged as a potentially suitable choice. However, poor mechanical properties, high moisture absorbing ability as well as inherit odor have limited their widespread application. In this study, we developed high-strength, and toughened thermoset polymers from proteinaceous material obtained from the rendering industry, such that they can be employed in high performance applications, such as automotive sector.
Improved Sand Erosion Resistance and Mechanical Properties of Multifunctional Carbon Nanofiber Nanopaper Enhanced Glass Fiber/Epoxy Composites
Multifunctional fiber reinforced epoxy composites with improved sand erosion resistance; mechanical properties and electromagnetic interference (EMI) shielding resistance have been fabricated and tested in this work. Preformed carbon nanofiber (CNF) thin film or nanopaper, made of dense and entangled nanofiber networks, was laminated on the surface of glass fiber reinforced epoxy composites (GFPRC) as a surface protection layer. Five times improvement in sand erosion resistance in terms of sand erosion rate, and up to 24% improvement in flexural strength was achieved after the incorporation of CNF nanopaper onto thin glass fiber/epoxy composite. The CNF nanopaper composite showed an EMI shielding resistance of 30–40 dB within a frequency range of 30 MHz to 1.5 GHz. This multifunctional composite material shows good potential for use in commercial electronics, housing, and the automotive industry.
Experimental Co-relation of Induction Welded Bead’s Burst Pressure using Finite Element Techniques
This report describes the results of a project focused on obtaining the yield stress at the weld bead of a vibration welded pressure vessel. The burst pressure of 0.508 bar was obtained from the hydrostatic pressure test data performed experimentally. The aim of this project is to verify the amount of stress generated at the weld bead as it is observed in the hydrostatic pressure test that the rupture occurs in this region and formulate a failure criterion. Additionally, the project investigates the best methodology of mesh by playing with the various parameters like geometric modelling, order of elements and type of contact in Hyper mesh 13.0 in order to obtain maximum correlation with experimental data. The material used for the vessel is Thermylene (a polypropylene composite material which is proprietary to Asahi Kasei Plastics NA) and a bonding resin compound for the bead. The analysis consists of Non-Linear Geometric Static simulation of applying 0.075 MPa of pressure (to get more data points in yield condition and observe geometric behavior) to the vessel using Finite Element Analysis. Both the full and quarter model was Meshed using Hypermesh and analyzed in ABAQUS. The results obtained from the analysis were displayed using stress plots.
The Effect of High Solvating Plasticizers on Fusion Behavior and Mechanical Properties of PVC-Based Luxury Floor Tiles
Growing year by year in use as a general purpose plasticizer phthalate replacement, 1,2 cyclohexanedicarboxylic acid diisononylphthalate (referred to generically as DIDC) has limitations in both processing and final product performance. A project was undertaken recently to demonstrate how DIDC’s performance can be improved through the utilization of propylene glycol dibenzoate (PG) in vinyl floor tiles. To demonstrate the effectiveness of adding PG to DIDC for increased compatibility, formulations were prepared containing diisononylphthalate (DINP), DIDC, PG, and blends containing DIDC and PG. The results indicate a marked improvement using DIDC/PG blends in fusion temperature and dry point over standalone DIDC formulations, as well as tensile strength and elongation properties that are comparable to DINP.
Investigation of the Influence of Color on Plastic Product Failure
The color of a polymeric compound must be engineered just like any other desired resin property such as mechanical or thermal. Reaching the desired color can be adversely affected by processing or the combination with modifiers and additives in the resin system. Even if colors can be achieved by increasing the amount of pigment used in the formulation, other performance attributes such as mechanical properties may be adversely affected as well. This paper discusses these color matching concerns.
Rebuilding Screws for Injection Molding Processes
Improper rebuilding of screws for injection molding plasticators can lead to screws with high wear rates and the formation of resin degradation products. Resin degradation can cause black specks and color streaks in injection molded parts, reducing the yield and profitability of an injection molding process. This paper presents two problems that occur when injection molding screws are not rebuilt properly.
Study on Interphase Transfer of the Liquid Tackifier between Immiscible Rubber Pair
The transfer phenomenon of a third component between immiscible rubber pair was studied using natural rubber (NR) and poly(isobutylene) (PIB). The coumarone-indene tackifier was employed as the third component. After the laminated rubber sheets were annealed at various temperatures, the tackifier distribution was characterized by the dynamic mechanical analysis (DMA) and differential scanning calorimetry (DSC). It was found that the tackifier transfer between the rubbers occurs. Furthermore, the amount of the tackifier in each rubber depends on the ambient temperature.
Structure and Acoustical Property of Polyolefin Film/Foam Alternating Multilayer Composites
A novel alternating film/foam multilayer sheet was prepared through multilayer co-extrusion. The film layer was a blend of LLDPE with poly(ethylene-octene) elastomer (POE) and the foam layer was cross-linked and foamed POE. The multilayer film/foam sheet exhibited advantaged acoustical properties. In select wavelength regions, the sound absorption coefficient of the multilayer film/foam structure improved 2-3 times compared with conventional single-layer materials.
Effects of Barrel and Screw Heating in Rubber Extrusion
This paper deals with the effects of barrel and screw heating in rubber extrusion particularly with regard to the throughput and the melt temperature. To determine exactly the impact of heating on throughput behavior during extrusion, experimental investigations were conducted on two rubber extruders of different sizes. In addition, numerical flow simulations were carried out for non-isothermal shear thinning melt flows, under consideration of dissipative heating in the screw channel.
Novel Poly (Lactic Acid) Foams: Micro to Sub-Micron Size Transition
Chemical modification of poly(lactic acid) (PLA) through a reactive extrusion process was performed in the presence of a free-radical initiator and multi-functional chain extenders. Batch foaming, using nitrogen as the blowing agent, was done at various temperatures to differentiate the effect of chain branching and nucleation on the cell size of reactively modified foams. Depending on the conditions very fine, sub-micron size foams were obtained in reactively modified PLA.
Process Optimization of Single-Screw Extrusion Systems for Polyolefin Resins
Many existing extruders running polyethylene (PE) resins can be optimized to operate at higher production rates and also with higher qualities by the mitigation of gels. This paper provides an assessment process where the extruder is studied for potential rate increases and quality improvements. It is recommended that such an assessment be made prior to purchasing new screws or when a line is close to becoming sold out and more product is required.
Testing Fused PVC Water Pipe with the ISO 13477 S4 Method for Critcal Pressure
While a test method for thermoplastic pipe to determine resistance to rapid crack propagation has been standardized for nearly 20 years, very little testing of PVC for water use has been done. Test methodology and results are presented in this paper for the S4 testing for water for fused PVC manufactured to the AWWA C900 PVC pipe standard, Critical pressure, crack speed, and decompression wave speed are discussed..
Characterizing an Extrusion Process Using Design of Experiment (DOE)
Including an explanation of design of experiment (DOE) principles, this paper describes the procedures and results of a designed extrusion experiment. The goals were to understand and model the influence of key process variables (barrel zone temperatures and screw speed) on several performance indicators, such as output, pressure variation, and temperature variation. One important finding was a quadratic model of melt temperature variation, primarily as a function of screw speed and barrel zone 1 temperature.
Reduced Adhesion Strippable Insulation Shields Using Nano-Scale Mineral Fillers for TRXLPE Insulated Medium Voltage Power Cables
Semiconducting insulation shield compounds with reduced adhesion to tree retardant cross-linked polyethylene (TRXLPE) are presented. Through a combination of additives comprising 5% by weight of the formulation or less, adhesion force can be reduced by 40% or more without compromising other critical properties such as volume resistivity, cure kinetics, and physical characteristics including tear strength.
Estimate of Astm Melt Flow Rates from Oscillatory Shear Rheology
ASTM Melt Flow Rate is one of the most common product specifications and is widely used by resin manufacturers and users. Small Amplitude Oscillatory Shear (SAOS), on the other hand, is the preferred rheology data for researchers. A one-to-one correlation between these two kinds of rheology data has not been observed or reported in the past. With a new approach of applying the Cox-Merz Rule, excellent estimates of ASTM melt flow rates were obtained from the SAOS data for a wide range of linear polyethylene resins.
Improvements in Processing Semi-Crystalline Polymers for Thermoforming Sheet in Multiple Nip Systems
Covering higher output rates in the production of thermoforming sheet motivated the development of a new roll-stack design. While amorphous materials like HIPS and A-PET are not sensitive to cooling parameters, the quality of sheet made of semi-crystalline polymers like PP and PE is showing a great dependency on their cooling history. In the daily production environment not only higher outputs were achieved, but improvements in quality and performance were obtained.
A DSC Method to Determine Temperature Uniformity in BOPA Annealing Oven at Transverse Direction
A DSC method was demonstrated to determine the temperature uniformity at transverse direction in BOPA annealing oven by utilizing the existence of small endothermic peak before the melting of alpha-form (221 øC) and /or gamma-form (214 øC) nylon 6 on 1st heating thermograph.
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