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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The Effect of Flow Channel Aspect Ratio on Layer Uniformity in Flat Extrusion Dies
Common extrusion systems used to produce multilayer structures include a coextrusion feedblock - which assembles individual melt streams into a narrow multilayer “sandwich”, and a flat die - whose primary purpose is to uniformly distribute this multilayer structure to the desired final width. Given the demand for improved layer uniformity, extrusion die distribution manifold features have been developed to reduce the distortion of coextrusion interfaces. This paper will discuss the effect of die manifold aspect ratio on coextrusion uniformity.
The Potental of Expanding Elongation Flows to Increase the Through-Plane Thermal Conductivity
Thermal conductive plastics are often used in electronical components for heat management or in heat exchangers. Often heat has to be conducted in thickness direction of a thermal conductive part (through-plane). Yet, conventional plastics processing techniques like injection molding or extrusion yield lower thermal conductivity in thickness direction, especially for thin parts. Therefore, a new method is presented, which significantly increases the through-plane thermal conductivity using expanding elongation flows. Medium expansion ratios of 4 to 5 already achieve high
Failure Analysis of a Plastic Toy Helicopter
A failure analysis was performed on a plastic toy helicopter that exhibited several fractures of both the rotor blades and the rotor hub sections. Fractography and flight testing were utilized to determine whether or not the toy helicopter fractures were due to operation and flight of the helicopter or due to other causes. The multiple fractures were found to be inconsistent with normal operation and flight of the helicopter and the analysis showed that the fractures were likely due to manual manipulation of the rotor blades and hub sections prior to use of the helicopter.
High Gloss “Piano Black” Acetal Copolymer
High gloss, piano black is an appearance that continues to grow as an accent color for automotive interior, cosmetic packaging, small appliances and other markets. The most common way to achieve a piano black look is by painting plastic parts using a two-coat or three-coat painting process which adds significant part cost and scrap. A molded-in-color solution is desirable to reduce cost without sacrificing quality. This paper discusses development of a molded-in-color solution in acetal copolymer resin and how that solution compares to other resins commercially available.
Predicting the Impact Puncture Response of Multilayer Flexible Food Packages Using Explicit Finite Element Models
In previously presented work (ANTEC 2015), the authors developed a laboratory test method capable of ranking the impact puncture resistance (IPR) of multilayer flexible packages. This paper describes the development of nonlinear finite element models capable of predicting the IPR of the same multilayer structures. Information about the method used to obtain material properties at relevant strain rates, and comparisons between predicted and experimental responses are presented.
The Effect of Viscous Encapsulation on Layer Uniformity and Rheology in Multilayer Coextrusion
Multilayer coextrusion is a process in which two or more polymers are extruded and joined together in a feedblock or die to form a single structure with multiple layers. This paper will discuss the effect of viscous encapsulation especially in a flow channel with a noncircular cross-section on layer re-arrangement and rheology of a coextruded structure.
Viscosity Measurement of Multilayer Structures via Parallel Plate Rheology
Parallel plate rheometry has been used to characterize the viscosity of multilayer polymer structures. It has been demonstrated that this technique is not a good substitute for performing such measurements using a coextrusion slit die rheometer. For the purpose of designing dies for producing multilayer structures, one needs good viscosity data that correctly represent the behavior of the intended structure under flow and for this reason, a coextrusion slit die rheometer is recommended.
PC/ABS Recovered from Shredded Waste Electrical and Electronic Equipment
Our industry leading separation technology enables us to recover a variety of plastics from complex mixed streams such as shredded waste electrical and electronic equipment (WEEE). Plastic flakes recovered using our process are compounded and sold as pellets suitable for use in injection molding applications. Polyolefin and styrenic plastics have been in our product portfolio for nearly a decade, but recently we have been expanding our range of plastic products. This paper looks at the challenges of recovering additional plastics and the properties of PC/ABS we have recovered from shredded WEEE.
Modeling and Simulation of the Foaming Process in Elastomers
A numerical simulation for elastomer foaming extrusion process was made. Energy equation coupled with unit cell model were used and solved by Radial Basis Function (RBF) and Finite Difference Method (FDM), respectively. The curing reaction, the change of viscosity and the concentration of the gas inside the rubber are also taking into account. The effect of processing parameters as temperature of vulcanization and the velocity of the profile inside the tunnel were evaluated and the resultant bubble size and its distribution were analyzed.
New Approaches for the Integration of Process Disturbances in Injection Molding Simulation
During the product development of injection molded parts, simulation software is used to predict process parameters and part quality during the production process. The integration of process disturbances into the injection molding simulation software leads the way to a prediction of the quality variation. Thus, the optimization regarding a robust process parameter set already during early stages of the product development process is possible.
Application of TRIZ Tools to Develop a New Plastic Chemical Dispenser
The application of several TRIZ (Theory of Inventive Problem Solving) tools to support the development of plastic products is presented. The considered tools are the Function Analysis, the Inventive principle application, the solution of Physical Contradictions and Trimming. A plastic chemical dispenser is used as study case. The design starts from a plastic fish feeder that is commercially available. After applying the TRIZ tools, the design evolves to a complete new concept, overcoming the original design limitations.
High Precision and Repeatability in Micro Injection Molding Using the Inverse Screw
For an economical production of micro components made of thermoplastics by injection molding a reproducible and precise process control is essential. An alternative to two-step plasticizing units, which are commonly used in micro injection molding, is the so-called inverse screw. This newly developed plasticizing principle enables the integration of a conventional three-zone-screw’s geometry in a miniaturized plasticizing unit drastically reducing the overall melt volume.
High Temperature and High Energy Density Nanolayer Film Capacitors
Improvement of the dielectric properties was achieved by combining two or more polymers in a layered geometry using film coextrusion process. In recent development, film production scale-up of thin nanolayered films, film metallization and capacitor winding capabilities were demonstrated to create the world’s first nanolayer film capacitor prototypes. Increased temperature use of the high energy density films was demonstrated in capacitors. The detailed results of the capacitors fabrication process and the corresponding properties are discussed in this paper.
Reduced Post Crystallization of Polyhydroxybutyrate (PHB)
Polyhydroxybutyrate (PHB) belongs to the family of polyhydroxyalkanoates (PHA) and is both, biobased and biodegradable. Due to its linear chain structure, PHB is highly crystalline and has a melting temperature close to its decomposition temperature. Pure PHB crystallizes very slowly, so that the use for some technical applications is not commercially viable. This paper describes the crystallization of pure and nucleated PHB by means of differential scanning calorimetry (DSC). The cooling curve and the metabolic rate as a function of temperature are elaborated.
Thermoplastic Semiconductive Power Cable Jacket
A new thermoplastic semiconductive power cable jacket compound is presented. The compound is designed by adding carbon blacks to a blend of linear low density polyethylene and elastomer to achieve overall excellent performance, including good electrical conductivity, excellent mechanical properties, superior environmental stress crack resistance, and low moisture vapor transmission rate as well as low temperature brittleness property. The compound meets wire and cable industrial specifications such as ICEA S-94-649-2013.
Effect of Extensional Viscosity, Elasticity and Die Exit Stress State on Neck-In Phenomenon during Extrusion Film Casting: Theoretical Study
In this work, viscoelastic, isothermal extrusion film casting modeling utilizing 1D membrane model and modified Leonov model was performed in order to understand the role of extensional viscosity, elasticity and viscoelastic stress state at the die exit, on the polymer melt film stretching in the post die area. Experimental data for LDPE and theoretical predictions based on the eXtended Pom-Pom (XPP) model taken from the open literature were used for the validation purposes.
Analysis of the Foam Injection Molding Process Using a Chemical Blowing Agent
This paper details the analysis of the foam injection molding process which uses a foaming gas generated from a chemical blowing agent. The analysis is done using a numerical simulation program developed in this study. The simulation analyzes the injection molding process with the calculation of bubble nucleation and growth. Some experiments were conducted to validate the simulation results. The experiments performed include viscosity measurement and molding experiments. The experiment and simulation results compare reasonably well.
Microcellular Foam Injection Molding of Thick Parts
Achieving uniform, microcellular injection molded foams with large cross sectional thicknesses and high void fractions is difficult, due to the large temperature gradient. To investigate this issue, a thick part mold cavity has been manufactured and the effects of injection flow rate and mold temperature have been investigated. Higher injection flow rate resulted in higher cell density; while higher mold temperature resulted in more uniform cell density.
SIGMASOFT® Virtual Molding: An Alternate Approach to Resin Selection
This paper explains a new approach taken by a thermoplastic supplier running virtual trials instead of floor trials to compare and evaluate the performance of different MFI grades. The evaluation results showed energy consumption reduction in high MFI grades due to lower injection pressures and lower clamping force requirements. The total cycle time was reduced when using high MFI grades in comparison to low MFI due to faster cooling rate of the part.
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