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Effect of Thermal History on Viscoelastic Properties of Thermotropic Liquid Crystalline Copolyesters

  • T. Masuda , K. Fujiwara and M. Takahashi
Published/Copyright: May 27, 2013
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International Polymer Processing
From the journal International Polymer Processing Volume 6 Issue 3

Abstract

Dynamic viscoelastic properties of two samples of co-polyesters, PHB60 and PHB28, were measured over a wide range of temperatures. The copolyesters had been synthesized from polyethylene terephthalate (PET) and p-hydroxybenzoic acid (PHB). PHB60 and PHB28 contain 60 and 28 mol.-% PHB as the comonomer, respectively. PHB60 is well known as a thermotropic liquid crystalline copolyester. The effect of thermal histories on viscoelastic behavior of the copolyesters are discussed in terms of structure and liquid crystallinity of the copolyesters. A rheological transition in viscoelastic properties of the copolyester PHB60 was observed at about 270°C in the fluid state. The viscoelastic properties of the copolyester PHB60 strongly depend on thermal histories below the transition temperature, but not above the temperature. The transition behavior was attributed to a crystal-nematic transition by wide angle X-ray diffraction and differential scanning calorimetry. The attainable crystallinity was fairly low. Thermal history behavior found below the transition temperature is caused by slow crystallization and supercooling of the sample. PHB28 forms no liquid crystal phase, and is thermorheologically simple in the molten state: the sample showed no effect of thermal history in viscoelastic properties.

* Mail address: Prof. Dr. T. Masuda, Research Center for Biomedical Engineering, Kyoto University, Shogin, Sakyo-ku, Kyoto 606, Japan.
Received: 1990-2-25
Accepted: 1990-5-11
Published Online: 2013-05-27
Published in Print: 1991-09-01

© 1991, Carl Hanser Verlag, Munich

Articles in the same Issue

  1. Contents
  2. Contents
  3. Die Extrusion
  4. Finite Element Analysis of Polymer Melt Flow in Profile Extrusion Coating Die
  5. Simultaneous Diameter and Thickness Control in Tube Extrusion
  6. A Stick-Slip Problem Related to Melt Fracture in Polymer Processing Operations
  7. Effects of Plasticizers on Extrusion of Dry Blended PVC
  8. Flow-Induced Crystallization and Self-Reinforcement During Extrusion
  9. Molding
  10. A Fundamental Experimental Study of the Mechanisms of Warpage and Shrinkage of Polyethylene in Rotational Molding
  11. Closed Loop Control of Parison Dimension Profiles in Extrusion Blow Molding
  12. Liquid Crystal Polyesters
  13. Effect of Thermal History on Viscoelastic Properties of Thermotropic Liquid Crystalline Copolyesters
  14. Molecular Orientation and Modulus of a Thermotropic Liquid Crystalline Copolyester
  15. Production and Characterization of Fine-dispersed Mixtures of Liquid Crystalline with Conventional Polymers
  16. Processing and Properties of Polycarbonate/Liquid Crystal Polymer Blends
  17. Rapid Communication of Recent Advances
  18. Generation of Corners in Profile Extrusion**
  19. Coextruded Infrared Reflecting Films
https://doi.org/10.3139/217.910225

Articles in the same Issue

  1. Contents
  2. Contents
  3. Die Extrusion
  4. Finite Element Analysis of Polymer Melt Flow in Profile Extrusion Coating Die
  5. Simultaneous Diameter and Thickness Control in Tube Extrusion
  6. A Stick-Slip Problem Related to Melt Fracture in Polymer Processing Operations
  7. Effects of Plasticizers on Extrusion of Dry Blended PVC
  8. Flow-Induced Crystallization and Self-Reinforcement During Extrusion
  9. Molding
  10. A Fundamental Experimental Study of the Mechanisms of Warpage and Shrinkage of Polyethylene in Rotational Molding
  11. Closed Loop Control of Parison Dimension Profiles in Extrusion Blow Molding
  12. Liquid Crystal Polyesters
  13. Effect of Thermal History on Viscoelastic Properties of Thermotropic Liquid Crystalline Copolyesters
  14. Molecular Orientation and Modulus of a Thermotropic Liquid Crystalline Copolyester
  15. Production and Characterization of Fine-dispersed Mixtures of Liquid Crystalline with Conventional Polymers
  16. Processing and Properties of Polycarbonate/Liquid Crystal Polymer Blends
  17. Rapid Communication of Recent Advances
  18. Generation of Corners in Profile Extrusion**
  19. Coextruded Infrared Reflecting Films
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