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A definition of the concepts “gelation temperature” and “gelation curve” by means of relaxation time spectra
Author(s) -
Visscher K.,
Mijnlieff P. F.
Publication year - 1990
Publication title -
makromolekulare chemie. macromolecular symposia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.257
H-Index - 76
eISSN - 1521-3900
pISSN - 0258-0322
DOI - 10.1002/masy.19900390109
Subject(s) - relaxation (psychology) , superposition principle , infinitesimal , spectrum (functional analysis) , flow (mathematics) , thermodynamics , cole–cole equation , basis (linear algebra) , statistical physics , mathematics , physics , mathematical analysis , quantum mechanics , mechanics , dielectric , psychology , social psychology , geometry
With the aid of the Boltzmann superposition principle, the infinitesimal flow behaviour of a substance can be described in terms of a memory integral. The memory function in this integral can be expanded in a set of relaxation times and relaxation strengths: the relaxation spectrum. On basis of a specific form of the fluctuation‐dissipation theorem, a physical meaning is proposed for the relaxation spectrum. The theory of complex functions enables one to show that the relaxation spectrum, determined from dynamic mechanical measurements, has a unique meaning. The infinitesimal flow behaviour, expressed in terms of the relaxation spectrum, is used to develop a general description of the phenomenon of thermoreversible gelation. This description method was applied to a styrene‐isoprene‐styrene triblock copolymer solution.