Blends of a bottle-grade polyethylene terephthalate copolymer with a liquid crystalline polymer. Part II: Thermal and transport properties

2002 ◽  
Vol 42 (8) ◽  
pp. 1694-1709 ◽  
Author(s):  
L. B. Da Silva ◽  
A. L. Marinelli ◽  
R. E. S. Bretas ◽  
A. Rúvolo-filho
Keyword(s):  
Transport Properties ◽  
Polyethylene Terephthalate ◽  
Liquid Crystalline Polymer ◽  
Liquid Crystalline ◽  
Crystalline Polymer ◽  
Polymer Part

Effects of State Change of Liquid Crystalline Polymer on Dynamic Visco-Elasticity of its Blends with Polyethylene-Terephthalate

2007 ◽  
Vol 17 (6) ◽  
pp. 64510-1-64510-7
Author(s):  
S.A.R. Hashmi ◽  
Takeshi Kitano
Keyword(s):  
Polyethylene Terephthalate ◽  
Viscoelastic Properties ◽  
Liquid Crystalline Polymer ◽  
Liquid Crystalline ◽  
Loss Modulus ◽  
Crystalline Polymer ◽  
State Change ◽  
Molten State ◽  
Different Temperatures ◽  
Scanning Electron

Abstract The dynamic viscoelastic properties of liquid crystalline polymer (LCP) and polyethylene terephthalate (PET) blends were studied at two different temperatures: 265°C at which LCP was in solid state and 285°C at which LCP was in molten state. The PET was in molten state at both the temperatures. The storage modulus, G’, loss modulus, G’’, dynamic viscosity, h’, of blends with different compositions were evaluated and compared. The morphology of these samples was studied using scanning electron microscope, which exhibited composition dependency. A maxima was observed in the viscosity versus composition plot corresponding to 90/10 LCP/PET blend at 285°C. The G’ versus G’’ plots demonstrated the composition dependency of LCP/PET blends.

Observing the relaxation of molecular orientation in sheared liquid crystalline polymer solutions

1990 ◽  
Vol 48 (4) ◽  
pp. 1092-1093
Author(s):  
Wendy Putnam ◽  
Christopher Viney
Keyword(s):  
Molecular Orientation ◽  
Liquid Crystalline Polymer ◽  
Liquid Crystalline ◽  
Crystalline Polymer ◽  
Polymer Processing ◽  
Molecular Alignment ◽  
Global Alignment ◽  
Shear Direction ◽  
Axial Strength ◽  
Strength And Stiffness

Liquid crystalline polymers (solutions or melts) can be spun into fibers and films that have a higher axial strength and stiffness than conventionally processed polymers. These superior properties are due to the spontaneous molecular extension and alignment that is characteristic of liquid crystalline phases. Much of the effort in processing conventional polymers goes into extending and aligning the chains, while, in liquid crystalline polymer processing, the primary microstructural rearrangement involves converting local molecular alignment into global molecular alignment. Unfortunately, the global alignment introduced by processing relaxes quickly upon cessation of shear, and the molecular orientation develops a periodic misalignment relative to the shear direction. The axial strength and stiffness are reduced by this relaxation.Clearly there is a need to solidify the liquid crystalline state (i.e. remove heat or solvent) before significant relaxation occurs. Several researchers have observed this relaxation, mainly in solutions of hydroxypropyl cellulose (HPC) because they are lyotropic under ambient conditions.

Phase Separation in Liquid-Crystalline Copolymer/Poly(methyl methacrylate) Blends

1995 ◽  
Vol 60 (11) ◽  
pp. 1869-1874 ◽  
Author(s):  
Anatoly E. Nesterov ◽  
Yuri S. Lipatov ◽  
Vitaly V. Horichko
Keyword(s):  
Phase Separation ◽  
Methyl Methacrylate ◽  
Liquid Crystalline Polymer ◽  
Liquid Crystalline ◽  
Ethylene Terephthalate ◽  
Crystalline Polymer ◽  
Scattering Method ◽  
Thermally Induced ◽  
Poly Methyl Methacrylate ◽  
Copolymer Poly

The phase separation in the blends of poly(methyl methacrylate) and liquid-crystalline polymer (copolymer of ethylene terephthalate and p-hydroxybenzoic acid) has been studied by the light scattering method and the cloud point curves have been obtained. Simultaneously some morphological features of the blends have been observed. It was found that the initial blends are in the state of forced compatibility and that thermally induced phase separation occurs by the mechanism of spinodal decomposition but presumably in the non-linear regime.

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