Phase behavior and mechanical properties of poly-p-phenylene terephthalamide/amorphous nylon molecular composites

Jen-Chang Yang, Tomohiro Fukai, Thein Kyu

Research output: Contribution to journalArticle

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Abstract

Poly(p-phenylene terephthalamide) (PPTA)/amorphous nylon (AN) molecular composites were prepared from sulfuric acid solution by rapidly coagulating in distilled water. The regenerated films appear homogeneous and transparent. However, the rod-like and flexible macromolecules are probably entrapped in a single phase during rapid coagulation, thus thermodynamically unstable and undergoing phase segregation upon thermal treatment. The miscibility between PPTA/AN was identified by a dielectric relaxation method. Phase behavior and kinetics of phase separation in PPTA/AN mixtures were thoroughly investigated by time-resolved light scattering as well as optical microscope. A pseudo phase diagram reminiscent of a lower critical solution temperature (LCST) was established by a cloud point measurement. Several temperature-jump experiments were undertaken from ambient to a two-phase temperature region. The low PPTA content molecular composites were prepared by coagulating in a non-solvent, then by compression molding below the phase separation temperatures. The 30 wt% PPTA molecular composite exhibits over three-fold increase in tensile modulus relative to that of the neat AN, however, there is little or no improvement in the tensile strength. On the other hand, by a slight addition of AN into PPTA, the tensile and compressive failures of spun fibers may be improved.
Original languageEnglish
Pages (from-to)699-704
Number of pages6
JournalPolymer Engineering and Science
Volume31
Issue number10
DOIs
Publication statusPublished - 1991

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Nylons
Phase behavior
Mechanical properties
Composite materials
Phase separation
Temperature
Compression molding
Dielectric relaxation
Coagulation
Macromolecules
Sulfuric acid
Light scattering
Phase diagrams
Microscopes
Tensile strength
Solubility
Elastic moduli
Heat treatment
poly(4-phenylene terephthalamide)
Kinetics

Cite this

Phase behavior and mechanical properties of poly-p-phenylene terephthalamide/amorphous nylon molecular composites. / Yang, Jen-Chang; Fukai, Tomohiro; Kyu, Thein.

In: Polymer Engineering and Science, Vol. 31, No. 10, 1991, p. 699-704.

Research output: Contribution to journalArticle

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abstract = "Poly(p-phenylene terephthalamide) (PPTA)/amorphous nylon (AN) molecular composites were prepared from sulfuric acid solution by rapidly coagulating in distilled water. The regenerated films appear homogeneous and transparent. However, the rod-like and flexible macromolecules are probably entrapped in a single phase during rapid coagulation, thus thermodynamically unstable and undergoing phase segregation upon thermal treatment. The miscibility between PPTA/AN was identified by a dielectric relaxation method. Phase behavior and kinetics of phase separation in PPTA/AN mixtures were thoroughly investigated by time-resolved light scattering as well as optical microscope. A pseudo phase diagram reminiscent of a lower critical solution temperature (LCST) was established by a cloud point measurement. Several temperature-jump experiments were undertaken from ambient to a two-phase temperature region. The low PPTA content molecular composites were prepared by coagulating in a non-solvent, then by compression molding below the phase separation temperatures. The 30 wt{\%} PPTA molecular composite exhibits over three-fold increase in tensile modulus relative to that of the neat AN, however, there is little or no improvement in the tensile strength. On the other hand, by a slight addition of AN into PPTA, the tensile and compressive failures of spun fibers may be improved.",
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N2 - Poly(p-phenylene terephthalamide) (PPTA)/amorphous nylon (AN) molecular composites were prepared from sulfuric acid solution by rapidly coagulating in distilled water. The regenerated films appear homogeneous and transparent. However, the rod-like and flexible macromolecules are probably entrapped in a single phase during rapid coagulation, thus thermodynamically unstable and undergoing phase segregation upon thermal treatment. The miscibility between PPTA/AN was identified by a dielectric relaxation method. Phase behavior and kinetics of phase separation in PPTA/AN mixtures were thoroughly investigated by time-resolved light scattering as well as optical microscope. A pseudo phase diagram reminiscent of a lower critical solution temperature (LCST) was established by a cloud point measurement. Several temperature-jump experiments were undertaken from ambient to a two-phase temperature region. The low PPTA content molecular composites were prepared by coagulating in a non-solvent, then by compression molding below the phase separation temperatures. The 30 wt% PPTA molecular composite exhibits over three-fold increase in tensile modulus relative to that of the neat AN, however, there is little or no improvement in the tensile strength. On the other hand, by a slight addition of AN into PPTA, the tensile and compressive failures of spun fibers may be improved.

AB - Poly(p-phenylene terephthalamide) (PPTA)/amorphous nylon (AN) molecular composites were prepared from sulfuric acid solution by rapidly coagulating in distilled water. The regenerated films appear homogeneous and transparent. However, the rod-like and flexible macromolecules are probably entrapped in a single phase during rapid coagulation, thus thermodynamically unstable and undergoing phase segregation upon thermal treatment. The miscibility between PPTA/AN was identified by a dielectric relaxation method. Phase behavior and kinetics of phase separation in PPTA/AN mixtures were thoroughly investigated by time-resolved light scattering as well as optical microscope. A pseudo phase diagram reminiscent of a lower critical solution temperature (LCST) was established by a cloud point measurement. Several temperature-jump experiments were undertaken from ambient to a two-phase temperature region. The low PPTA content molecular composites were prepared by coagulating in a non-solvent, then by compression molding below the phase separation temperatures. The 30 wt% PPTA molecular composite exhibits over three-fold increase in tensile modulus relative to that of the neat AN, however, there is little or no improvement in the tensile strength. On the other hand, by a slight addition of AN into PPTA, the tensile and compressive failures of spun fibers may be improved.

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