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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Interlayer Adhesion of Co-Extruded Sheets before and after Biaxial Stretching
In order to quantify interlayer adhesion of co-extruded sheets with strong interlayer adhesion, a test method was developed to first initiate delamination by uniaxial stretching and then measure interlayer adhesion by peel test. The method was applied to co-extruded sheets before and after biaxial stretching. Interlayer adhesion with peel force as high as 5330N/m (30lb/in) have been measured for the as co-extruded sheets. Reduction of interlayer adhesion as a function of biaxial stretching was revealed.
Continuous Compounding of EPDM Formulations on Co-rotating, Intermeshing Twin Screw Extruders
A 58 mm twin screw trial was run to evaluate machine design, shear and heat transfer effects in a generic EPDM formulation. The effects of product rate, screw speed, screw design, barrel temperature, and screw cooling were evaluated on product temperature, Mooney viscosity, and cure time. Scale up is evaluated in terms of heat transfer (cooling), volumetric and torque limits. Operation at high specific rate, low barrel temperatures, and the use of screw cooling provide improvements for rate. Commercially viable throughput rates were achieved in the trial.
Ultrasonic Monitoring of Barrel Wear and Screw Status
Four types of high temperature (HT) ultrasonic sensors have been installed at barrels and a flange of a 30-mm twin-screw extruder to non-intrusively and non-destructively measure barrel and screw wear, as well as screw misalignment and deflection during polymer extrusion. The sensors included sol-gel sprayed ultrasonic transducers (UTs), non-clad and clad buffer rod sensors, and stand-alone HTUTs. This study has demonstrated the capability of these ultrasonic sensors in monitoring the barrel and screw statuses at the pumping, mixing and melting zones of the extruder.
Development of a Stiff, Void Free, Low Density Plastic Wood Replacement
Process studies attempting to produce a low density, wood like replacement involving Kenaf, Polypropylene and hollow glass spheres (bubbles") blends along with processing aids and compatibilizers have been investigated using a counter-rotating non-intermeshing (CRNI) twin screw extruder. Bubble breakage was higher than anticipated based on related work but in spite of the fairly low bubble survival rates nailability of the boards was improved. Bubble breakage and mechanical properties are presented along with a discussion of the narrow process window."
Hydraulic Conveying of Plastic Pellets
Today’s plastic production plants can have a yearly capacity of more than 400,000 t. New catalysts enable them to produce a great variety of increasingly softer product grades in the same reactor. Together with logistic concepts that increase conveying distances, the polymer industry has reached the limits of traditional dilute and dense phase pneumatic conveying systems.This paper presents a new concept to convey plastic pellets as water slurry to overcome the limitations of pneumatic conveying. A further benefit of this technology is the gentle handling of attrition sensitive plastics like Polycarbonate and Polyester.
PTFE Paste Extrusion: Effect of Physical Properties of Lubricants
Preforming and the physical properties of the lubricants play a crucial role on PTFE paste extrusion. Since the most significant effects on liquid migration are due to viscosity and the wettability, the lubricants were characterized in terms of both flow and surface properties. These two properties were altered independently to study their relative effects on PTFE paste processing. Based on this study, it was concluded that preform quality and the extrusion pressure increase with increase of viscosity and improvement in the wettability characteristics of the lubricant.
The Determination of the Best" Viscosity Model for Shear Thinning Fluids from Capillary Rheology Experiments"
This paper describes an algorithm used to determine a single viscosity correlation from capillary rheometer experiments. One can choose any one of seven commonly used models for shear thinning fluids. The program then determines the constants in the chosen model which best describes all of the experimental data in a statistical (i.e., least sum of squares) sense. By comparing the results from several different models, one can determine in a matter of minutes the model, which best describes the measured rheology data.
High Performance Polyethylene Resins for the Thin Wall Injection Molding Market
A new single-site catalyst and process technology has been used to produce resins for thin wall injection molding lid applications. The performance of the single-site resins is compared with conventional Ziegler-Natta resins. The single-site polyethylenes provide superior processability with less mold deposit and organoleptic concerns. Additionally, these resins possess equivalent or better stiffness and toughness versus competitor products along with an unusually high level of clarity in the final parts.
Effect of Cyclic Cooling on Power Consumption of the Injection Moulding Process
The performance of a cyclic mold cooling system has been investigated with particular emphasis on process power consumption. A highly instrumented proportional-hydraulic injection molding machine was used to produce tensile test specimens from HDPE. Mold temperature was monitored at high frequency during each cycle, as was nozzle melt pressure, temperature and power consumption. Reduced cycle times were achieved with cyclic cooling and savings in power consumption of up to 23% were recorded over conventional methods.
A Novel Microcellular Co-Injection Molding Process
This paper presents the development of a novel microcellular co-injection molding process that combines aesthetic and processing advantages of injection molding with the benefits and property attributes of microcellular plastics (MCPs). While eliminating the swirling patterns seen on surface of microcellular plastic parts, this process is capable of producing lightweight parts with lower energy requirements, better dimensional stability, reduced sink marks, and desirable microcellular structure with fine cells and high cell density.
Real-Time, Non-Intrusive and Non-Destructive Ultrasonic Monitoring of Injection and Co-Injection Molding Processes
Integrated ultrasonic sensors directly coated onto mold inserts of a molding machine together with rugged ultrasonic system are used for real- time, non- intrusive and non- destructive monitoring of injection and co- injection molding processes. Monitoring of flow front arrival, flow speed, filling completion, solidification, part detachment and thickness of skin and core inside the mold has been demonstrated.
In-Line Activation with Atmospheric-Plasma Makes a Strong Bond in Multi-Component Injection Moulding
In-line-activation of polymer surfaces by atmospheric-pressure plasma-treatment directly in the injection mould enables positive-joint composites to be made from polymer combinations that were hitherto unable to adhere to each other, significantly improves adhesion of compatible combinations and can be easily integrated into the process chain. The paper presents the technology, its advantages, and shows results for new compatible material-combinations.
Co-Injection Molding in Metal Injection Molding
Metal Injection Molding (MIM) is a process to manufacture metal parts, combining powder metallurgy with plastic injection molding. With MIM process, it is possible to produce highly functional composite metal structures by insert molding, co-injection or double injection molding. In this study, co-injection molding was applied to manufacture composite component of dissimilar metals. The effect of injection speed on flow behavior of dissimilar metal powder was experimentally investigated.
Localized Material Effects Associated with Flow Control during Multi-Cavity Injection Molding Processes
This paper describes a numerical simulation based study of a new injection molding concept focused on locally controlling the filling of multi-cavity molds in real time. The concept is applicable to all runner system types and involves the utilization of controllable mechanical valves. Several types of valve designs in cold runners were modeled and the effects of various control scenarios on localized material conditions throughout the mold are presented.
Optimization of Injection Molding Process Parameters by the Combining ANN/GA method
The process conditions in injection molding have important influence on the part quality, so how to get the optimum process parameters is the key to improving the part quality. In this paper, a combining ANN/GA method is proposed to optimize the process parameters so as to improve the part quality. Application of the method in an industrial part indicates it is an effective tool for the process optimization of injection molding.
Velocity Analysis in Recovery Process for Reciprocating-Screw of Injection Molding
A reciprocating-screw of injection molding not only rotates like extrusion screw but also moves axially during recovery process. A velocity analysis establishes a relationship among melt velocity to barrel, melt velocity to screw, and screw velocity to barrel in axial direction. As the application of this velocity analysis a liquid agent dosing is discussed in this paper.
Performance of a Distributive Melt-Mixing Screw with an Advanced Mixing Tip
The DM2 high-performance screw combined with an Eagle mixer on the tip can be used in injection molding processes to decrease cycle times, reduce scrap rates, and provide high levels of mixing for coloring natural resins using color concentrates. The screw combination works by increasing the melting capacity and eliminating solid polymer particles from the discharge. The performance of this screw combination is presented along with the performance of a conventional screw.
Approximate Maximum Flow Length Ratio of Plastic Parts
In this paper, an efficient algorithm is proposed for calculating the approximate maximum flow length ratio of parts. The method mainly uses approximate shortest path algorithm on a weighted triangle mesh model to calculate flow length ratio of part. Although the algorithm is an approximation, it has high approximation accuracy and is numerically robust. An applications of this algorithm is discussed.
Use of In-Line Viscosity Control Method to Stabilise Part Quality during Regrind Variation
In the injection molding process, variation of material viscosity through a change in the material behaviour and environment may lead to production problems such as poor process control and defective parts. To correct these problems, an in-line viscosity control method has been developed for use in the production environment. The method utilises melt temperature to control the material's viscosity, ensuring that its response remains consistent. The method and the quality improvements obtained are presented in this paper.
Minimizing Warpage of Injection Molded Part by Systematical Simulation Analysis
A systematic simulation approach was used for minimizing warpage of an injection molded part. An example was given to illustrate the approach. The complete simulation analysis was able to reproduce the existing warpage for the sample part. Then it was used to optimize the process conditions, modify the runner system design, and check the cooling line layout design for minimizing the part warp. The analysis final results showed very good filling balance, lower injection pressure, fairly uniform cooling and lower warpage for the part.
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