Investigation of the rigid amorphous fraction in Nylon-6

H. Chen; Peggy Cebe

doi:10.1007/s10973-007-8215-4

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Journal of Thermal Analysis and Calorimetry

Volume/Issue:: Volume 89: Issue 2

Investigation of the rigid amorphous fraction in Nylon-6

Authors:

H. Chen

H. Chen Tufts University Department of Physics and Astronomy Medford MA 02155 USA

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Peggy Cebe

Peggy Cebe Tufts University Department of Physics and Astronomy Medford MA 02155 USA

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Pages:: 417–425

Online Publication Date:: 19 Jul 2007

Publication Date:: 01 Aug 2007

Article Category:: Research Article

DOI:: https://doi.org/10.1007/s10973-007-8215-4

Keywords:: Nylon-6; rigid amorphous fraction (RAF); TMDSC

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Abstract

A three-phase model, comprising crystalline, mobile amorphous, and rigid amorphous fractions (χ_c, χ_MA, χ_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 LN₂-cooled glass beads, the glass transition temperature and χ_RA decrease substantially, χ_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 χ_RA to increase, and χ_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 (ξ_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_g.

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Journal of Thermal Analysis and Calorimetry

Print ISSN:: 1388-6150

Online ISSN:: 1572-8943

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Journal of Thermal Analysis and Calorimetry
Language	English
Size	A4
Year of Foundation	1969
Volumes per Year	1
Issues per Year	24
Founder	Akadémiai Kiadó
Founder's Address	H-1117 Budapest, Hungary 1516 Budapest, PO Box 245.
Publisher	Akadémiai Kiadó Springer Nature Switzerland AG
Publisher's Address	H-1117 Budapest, Hungary 1516 Budapest, PO Box 245. CH-6330 Cham, Switzerland Gewerbestrasse 11.
Responsible Publisher	Chief Executive Officer, Akadémiai Kiadó
ISSN	1388-6150 (Print)
ISSN	1588-2926 (Online)