Detailed Investigations of Structural Layering Phenomena in Injection Molded Thermotropic LCP
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C. M. Hsiung
Abstract
Effects of processing variables on the structural gradients developed in the injection molding of thermotropic wholly aromatic copolyester parts were investigated using optical macro and microscopy combined with image analysis techniques at various sections of the molded LCP parts.
The studies indicate the existence of a multi-layer structure from skin to core of the parts. These include: a skin layer, a transition zone composed of a sub-skin layer, a shear layer and a core region. The effects of processing conditions including injection speed, mold temperature, and mold size on the structural features were evaluated. An interesting buckling phenomenon resembling features observed in jetting at core regions near the end of the cavity after the divergence section was observed for the samples molded at the lowest injection speed and mold temperature.
Digital image analysis of the images of the sectioned parts revealed that there are more layers than one observes macroscopically. In certain instances as many as 15 layers were detected. Orientation behavior and the positional light reflection intensity appear to correlate with each other particularly away from the skin regions. This may be the manifestation of high visible light absorption anisotropy exhibited by these aromatic polymers.
© 1993, Carl Hanser Verlag, Munich
Articles in the same Issue
- Contents
- Contents
- Internal Mixers
- Estimation of Quality of Mixing
- Screw Extrusion and Continuous Mixing
- An In-line Rheometer for Molten Plastics
- Melting of Plastics in Kneading Blocks
- Development of Phase Morphology of a Polyethylene-Polyamide 6-Blend in a Modular Co-rotating Twin Screw Extruder
- Microstructure Formation in Extruded and Drawn Polyblends of PC with a Thermotropic LCP
- Die Extrusion
- A Slip Model for Linear Polymers Based on Adhesive Failure
- Film
- Effect of Biaxial Stretching on Mechanical Properties and Surface Roughness of PMMA Films
- Molding
- Dynamics and Control of Surface and Mold Temperatures in Injection Molding
- A Study on Flexural Properties of Sandwich Injection Moldings
- Detailed Investigations of Structural Layering Phenomena in Injection Molded Thermotropic LCP
- Computer Controlled Rotational Molding of Liquid Silicone Polymer
Articles in the same Issue
- Contents
- Contents
- Internal Mixers
- Estimation of Quality of Mixing
- Screw Extrusion and Continuous Mixing
- An In-line Rheometer for Molten Plastics
- Melting of Plastics in Kneading Blocks
- Development of Phase Morphology of a Polyethylene-Polyamide 6-Blend in a Modular Co-rotating Twin Screw Extruder
- Microstructure Formation in Extruded and Drawn Polyblends of PC with a Thermotropic LCP
- Die Extrusion
- A Slip Model for Linear Polymers Based on Adhesive Failure
- Film
- Effect of Biaxial Stretching on Mechanical Properties and Surface Roughness of PMMA Films
- Molding
- Dynamics and Control of Surface and Mold Temperatures in Injection Molding
- A Study on Flexural Properties of Sandwich Injection Moldings
- Detailed Investigations of Structural Layering Phenomena in Injection Molded Thermotropic LCP
- Computer Controlled Rotational Molding of Liquid Silicone Polymer
