SPE Library

Fabrication of Hybrid Polymeric-Metallic Foams as Scaffolds for Bone Tissue Engineering

Anil Mahapatro, Lipi Malladi, May 2016

Thermoplastic foams have been explored for their use as scaffolds for bone tissue engineering. Challenges exist in their applicability and strategies for enhancement in mechanical properties are needed. In this paper we report the fabrication of hybrid polymeric-metallic foams where magnesium was electrodeposited on polyurethane foams with the goal to enhance the mechanical properties of polyurethane foams. The foams were characterized using visual methods and optical microscopy techniques, which clearly showed the presence of magnesium fused foams.

Weld Lines in Injection Molded Parts: Strength, Morphology and Improvement

I. Kuehnert, Y. Spoerer, M. Zimmermann, May 2016

Weld lines are rather well known as optical and/or mechanical blemishes in plastics products that can be avoided barely by mold design or process control. Although many publications show single solutions to optimize weld line strength in injection molded parts, there is no complete comparison of thermoplastic polymer materials available. Therefore, an overview about formation, morphology and strength of weld lines for amorphous, semicrystalline and filled polymer materials is given.

How to Add Value to Capillary Rheometers

Tim Haake, May 2016

Capillary Rheology has been around for many years. As technology moves on, this has opened doors to use the capillary rheometer as a base on which to build a sophisticated R&D platform to perform a wide range of other tests, which help rheologists and their colleagues. We look at extensional rheology, elasticity, pressure- volume-temperature (PVT), thermal conductivity (TC), sharkskin analysis and the effects of counter pressure measurements. Those are but a few of available options to lab managers who try to squeeze out extra capabilities from their budgets.

Single Pellet Extrusion

D.O. Kazmer, May 2016

Analysis and results are presented to model the melting of a single pellet in an extrusion screw. The analysis considers transient heat conduction with a convention boundary condition and three sources of internal generation. The results suggest that the theoretical melting time for a pellet is on the order of seconds and more optimal extrusion screw designs are possible.

The Effect of Flow Channel Aspect Ratio on Layer Uniformity in Flat Extrusion Dies

Sam Iuliano, Andrew Svenningsen, May 2016

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.

High Gloss “Piano Black” Acetal Copolymer

Bruce M. Mulholland, Coralie M. Richard, May 2016

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.

The Effect of Viscous Encapsulation on Layer Uniformity and Rheology in Multilayer Coextrusion

Hyunwoo Kim, Kurt A. Koppi, Robert Wrisley, Joseph Dooley, May 2016

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

Kurt A. Koppi, Christopher M. Thurber, Hyunwoo Kim, Joseph Dooley, May 2016

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.

Study on Nano Polyacrylonitrile Fiber by Cotton Candy Method

Ryo Takematsu, Masayuki Okoshi, Hiroyuki Inoya, Hiroyuki Hamada, Akihiro Tada, Yoshifumi Aoi, May 2016

New Approaches for the Integration of Process Disturbances in Injection Molding Simulation

Christian Hopmann, Benjamin Grümer, May 2016

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

Iván D. López, Juan C. Ortiz, Alberto Naranjo, May 2016

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

Ch. Hopmann, T. Fischer, May 2016

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

Deepak Langhe, Michael Ponting, May 2016

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)

Linda Goebel, Christian Bonten, May 2016

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

Jianmin Liu, Sathish Kumar Ranganathan, Sean Culligan, May 2016

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

Martin Zatloukal, Tomas Barborik, May 2016

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

Sejin Han, Franco Costa, Edwin Klompen, May 2016

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

Lun Howe Mark, Raymond K.M. Chu, Guilong Wang, Chul. B. Park, May 2016

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

Gabriel Geyne, Matt Proske, Laura Florez, May 2016

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.

New Synergistic GRAS Stabilizer for Polyolefins

Robert L. Sherman, Jr., Kimberly E. Kern, Steven R. Torchia, May 2016

Baerlocher has developed a new family of polymer stabilizers called Baeropol® RST (Resin Stabilization Technology). Baeropol® RST works synergistically with standard antioxidants to improve color, stability, and performance of polyethylene and polypropylene resins, while maintaining GRAS FDA food contact regulations. This synergy can allow for a reduction in the amount of both phosphite and antacid used in current resin formulations, while giving equal or better performance.