Premium
Combined small‐ and wide‐angle X‐ray scattering study of early stages of polymer crystallization
Author(s) -
Panine P.,
Urban V.,
Boesecke P.,
Narayanan T.
Publication year - 2003
Publication title -
journal of applied crystallography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.429
H-Index - 162
ISSN - 1600-5767
DOI - 10.1107/s0021889803008513
Subject(s) - small angle x ray scattering , materials science , crystallinity , scattering , spinodal decomposition , crystallization , small angle scattering , optics , crystallography , chemical physics , phase (matter) , physics , thermodynamics , chemistry , composite material , quantum mechanics
The early stage of melt crystallization in low‐density polyethylene was investigated by simultaneous time‐resolved small‐angle and wide‐angle X‐ray scattering (SAXS/WAXS) techniques. The high detectivity of the two‐dimensional detectors together with the large photon flux of an undulator source permitted the collection of SAXS and WAXS patterns with nearly single‐photon sensitivity and sub‐second time resolution. As a result, the crystalline fraction well below 0.001 can be reliably detected and the apparent induction time is considerably reduced (<10 s). The time evolution of both the SAXS invariant and the degree of crystallinity follow the well established Avrami‐type growth law. Despite the orders of magnitude improvement in sensitivity, the difference in the onset time of SAXS and WAXS signals is not significant. The behaviour of the SAXS data in the very early stages is not consistent with spinodal decomposition mechanism as described by the linearized Cahn–Hilliard theory.