Investigation on Brill transition of nylons 6/16, 4/16 and 2/16 by variable‐temperature WAXD and FTIR

Abstract

Brill transition behaviour of nylons 6/16, 4/16 and 2/16 has been studied systematically by variable‐temperature wide‐angle X‐ray diffraction (WAXD) and real‐time FTIR. It is shown that all nylons investigated undergo Brill transitions before melting on heating. Brill temperatures detected by real‐time FTIR are consistent with the results of variable‐temperature WAXD measurements. In addition, Brill bands were identified based on real‐time IR spectra and further consideration of —NH— groups provided additional information for discussing the mechanism of the crystalline transition. Copyright © 2003 Society of Chemical Industry

Amorphous and crystalline phase interaction during the Brill transition in nylon 66

“…At the transition point the two diffraction maxima are replaced by one with a spacing of 0.42 nm [6][7][8]. Over the years since its discovery, the Brill transition has been studied for various types of even-even and odd-even polyamides [9][10][11][12][13] and for different crystallization conditions [10]. In a recent study on the Brill transition in transcrystalline nylon 66 we pointed out that the explanation for the effect of the crystalline structure on this first order transition must be based on the existence of reciprocal interactions between the crystalline and amorphous phases [14], which corresponded to the finding that structural changes within the crystalline domains in the lamellae (as in the Brill transition) are accompanied by changes in the packing of the amorphous chain segments outside the lamellae [15].…”

A study of the crystalline transitions of polyamides X 18

“…The number‐average molecular weights of the prepared polyamides15 were in the range of 1.4 × 10 3 to 2.1 × 10 4 g mol −1 . The melt‐crystallized samples were prepared by pressing above the melting temperatures ( T m ) of the polyamides, while the solution‐crystallized ones were obtained by hot‐filtering the solutions of crystal suspensions, as discussed in previous studies 2, 3…”

“…This phenomenon was first found in nylon 66 by Brill in 1942 1. In recent years, the Brill transition of many even‐even polyamides and even polyamides has been investigated 2–4. The Brill transition is usually easily observed using variable‐temperature wide‐angle X‐ray diffraction (WAXD).…”

Phase Evolution of Polyamide 6 (PA6)‐Based Thermoplastic Elastomers during Heating and Cooling Investigated by Moving‐Window 2D Correlation Infrared Spectroscopy

“…[ 10 ] Other polyamides, e.g., PA66, PA6/16, PA4/16, display a similar Brill transition as observed by many researchers. [ 11–13 ] In the case of PA6, a transition of the monoclinic structure at room temperature (PA6‐α crystalline phase) to the high‐temperature monoclinic structure (PA6‐α ′ crystalline phase) was also observed despite the controversy surrounding the existence of Brill transition in them. [ 10,14 ] The morphological transitions of TPAEs at elevated temperatures become particularly complex in contrast with polyamides with the incorporation of soft segments.…”