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Title: Investigation of the Rigid Amorphous Fraction in Nylon-6

Abstract

A three-phase model, comprising crystalline, mobile amorphous, and rigid amorphous fractions (X{sub c}, X{sub MA}, X{sub rA}, respectively) has been applied in the study of semicrystalline Nylon-6. The samples studied were Nylon-6 alpha phase prepared by subsequent annealing of a parent sample slowly cooled from the melt. The treated samples were annealed at 110 C, then briefly heated to 136 C, then re-annealed at 110 C. Temperature-modulated differential scanning calorimetry (TMDSC) measurements allow the devitrification of the rigid amorphous fraction to be examined. We observe a lower endotherm, termed the 'annealing' peak in the non-reversing heat flow after annealing at 110 C. By brief heating above this lower endotherm and immediately quenching in LN{sub 2}-cooled glass beads, the glass transition temperature and X{sub RA} decrease substantially, X{sub MA} increases, and the annealing peak disappears. The annealing peak corresponds to the point at which partial de-vitrification of the rigid amorphous fraction (RAF) occurs. Re-annealing at 110 C causes the glass transition and X{sub RA} to increase, and X{sub MA} to decrease. None of these treatments affected the measured degree of crystallinity, but it cannot be excluded that crystal reorganization or recrystallization may also occur at the annealing peak, contributing to themore » de-vitrification of the rigid amorphous fraction. Using a combined approach of thermal analysis with wide and small angle X-ray scattering, we analyze the location of the rigid amorphous and mobile amorphous fractions within the context of the Heterogeneous and Homogeneous Stack Models. Results show the homogeneous stack model is the correct one for Nylon-6. The cooperativity length ({var_epsilon}{sub A}) increases with a decrease of rigid amorphous fraction, or, increase of the mobile amorphous fraction. Devitrification of some of the RAF leads to the broadening of the glass transition region and shift of T{sub g}.« less

Authors:
;
Publication Date:
Research Org.:
Brookhaven National Laboratory (BNL) National Synchrotron Light Source
Sponsoring Org.:
Doe - Office Of Science
OSTI Identifier:
929990
Report Number(s):
BNL-80599-2008-JA
Journal ID: ISSN 1418-2874; TRN: US200822%%954
DOE Contract Number:
DE-AC02-98CH10886
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Thermal Analysis and Calorimetry; Journal Volume: 89; Journal Issue: 2
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; NYLON; AMORPHOUS STATE; PHASE STUDIES; ANNEALING; RECRYSTALLIZATION; THERMAL ANALYSIS; TRANSITION TEMPERATURE; X-RAY DIFFRACTION; national synchrotron light source

Citation Formats

Chen,H., and Cebe, P.. Investigation of the Rigid Amorphous Fraction in Nylon-6. United States: N. p., 2007. Web. doi:10.1007/s10973-007-8215-4.
Chen,H., & Cebe, P.. Investigation of the Rigid Amorphous Fraction in Nylon-6. United States. doi:10.1007/s10973-007-8215-4.
Chen,H., and Cebe, P.. Mon . "Investigation of the Rigid Amorphous Fraction in Nylon-6". United States. doi:10.1007/s10973-007-8215-4.
@article{osti_929990,
title = {Investigation of the Rigid Amorphous Fraction in Nylon-6},
author = {Chen,H. and Cebe, P.},
abstractNote = {A three-phase model, comprising crystalline, mobile amorphous, and rigid amorphous fractions (X{sub c}, X{sub MA}, X{sub rA}, respectively) has been applied in the study of semicrystalline Nylon-6. The samples studied were Nylon-6 alpha phase prepared by subsequent annealing of a parent sample slowly cooled from the melt. The treated samples were annealed at 110 C, then briefly heated to 136 C, then re-annealed at 110 C. Temperature-modulated differential scanning calorimetry (TMDSC) measurements allow the devitrification of the rigid amorphous fraction to be examined. We observe a lower endotherm, termed the 'annealing' peak in the non-reversing heat flow after annealing at 110 C. By brief heating above this lower endotherm and immediately quenching in LN{sub 2}-cooled glass beads, the glass transition temperature and X{sub RA} decrease substantially, X{sub MA} increases, and the annealing peak disappears. The annealing peak corresponds to the point at which partial de-vitrification of the rigid amorphous fraction (RAF) occurs. Re-annealing at 110 C causes the glass transition and X{sub RA} to increase, and X{sub MA} to decrease. None of these treatments affected the measured degree of crystallinity, but it cannot be excluded that crystal reorganization or recrystallization may also occur at the annealing peak, contributing to the de-vitrification of the rigid amorphous fraction. Using a combined approach of thermal analysis with wide and small angle X-ray scattering, we analyze the location of the rigid amorphous and mobile amorphous fractions within the context of the Heterogeneous and Homogeneous Stack Models. Results show the homogeneous stack model is the correct one for Nylon-6. The cooperativity length ({var_epsilon}{sub A}) increases with a decrease of rigid amorphous fraction, or, increase of the mobile amorphous fraction. Devitrification of some of the RAF leads to the broadening of the glass transition region and shift of T{sub g}.},
doi = {10.1007/s10973-007-8215-4},
journal = {Journal of Thermal Analysis and Calorimetry},
number = 2,
volume = 89,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}
  • In this study, the flexible nylon-6 was reinforced by the semi-rigid aromatic polyamide, poly (p-diphenyl oxide terephthalamide) (POA), through physical polybending and chemical copolymerization using p-aminophenylacetic acid (P-APA) as a coupling agent. From the DSC measurements, it was shown that Tg of the polyblends was increased with the increase of POA content. The Tg and Tm of multiblock copolyamides were found to be higher than those of polyblends and triblock copolyamides. From the Rheovibron measurements, it was shown that the POA with nylon-6 poy-blends exhibited higher E{prime} and Tg value than that of nylon-6, which increased with the increase ofmore » POA content. The Tg and E{prime} values of multiblock copolyamides were higher than those of polyblends triblock copolyamides. Scanning electron microscopy revealed that the polyblends were a dispersed phase structure, although the multiblock copolyamides exhibited a homogeneous texture rather than an aggregated one. From the wide-angle x-ray diffraction pattern, the triblock copolyamides and polyblends had two diffraction peaks, i.e., 2 {theta} = 20.5{degrees} and 24{degrees}. However, the multiblock had only one at 2 {theta} = 20{degrees}, which indicates that a different crystal structure of multiblock copolyamides. For the mechanical properties, it was found that the multiblock copolyamides had a more significant reinforcing effect than those of polyblends and triblock copolyamides. 21 refs., 11 figs., 5 tabs.« less
  • The nanoscale phase behavior of a semicrystalline polymer is important for mechanical, thermal, optical and other macroscopic properties and can be analyzed well by thermal methods. Using quasi-isothermal (QI) heat capacity measurements, we investigate the formation behavior of the crystalline, mobile amorphous, and rigid amorphous fractions in poly(trimethylene terephthalate), PTT. The crystal and rigid amorphous phases comprise the total solid fraction in PTT at temperatures above T{sub g}, the glass transition temperature of the mobile amorphous fraction. PTT was quasi-isothermally cooled step-wise from the melt which causes its crystalline fraction to be fixed below 451 K. Between the high temperaturemore » fulfillment of the T{sub g} step and 451 K, the temperature dependent rigid amorphous fraction (RAF) is completely determined. For PTT, most of the RAF vitrifies between 451 K and T{sub g} step by step during QI cooling after the crystals have formed. The constraints imposed by the crystal surfaces reduce the mobility of the highly entangled polymer chains. We suggest the vitrification of RAF proceeds outward away from the lamellar surfaces in a step by step manner during QI cooling. Upon reheating, devitrification of RAF occurs at a temperature above its previous vitrification temperature, due to the effects of densification brought by physical aging during the long period of quasi-isothermal treatment. Finally, we consider recent concepts related to jamming, which have been suggested to apply to filled polymer systems, and may also be applicable in describing constraints exerted by crystal lamellae upon the RAF.« less
  • No abstract prepared.