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Synthesis and viscoelastic properties of new thermosetting resins having isocyanurate and oxazolidone rings in their molecular structures
Author(s) -
Kinjo Noriyuki,
Numata ShunIchi,
Koyama Toru,
Narahara Toshikazu
Publication year - 1983
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1983.070280516
Subject(s) - thermosetting polymer , isocyanate , materials science , epoxy , curing (chemistry) , viscoelasticity , composite material , polymer , glass transition , polymer chemistry , polymer science , polyurethane
Abstract A new type of thermosetting resin can be obtained from solventless varnishes composed of polyfunctional isocyanates and epoxides. The IR spectra show that the cured resins have isocyanurate and oxazolidone rings in their chemical structure, hence their name, isocyanurate–oxazolidone resins. The viscoelastic behavior of the cured resins can be varied considerably by selecting an appropriate reactant species and changing the equivalent ratio of the isocyanate and epoxy groups in the varnishes. Three relaxations, labeled α, β, and γ, characterize their dynamic mechanical spectra. The α‐dispersion is due to the glass transition, the β‐dispersion, to local mode motions of the backbone chains of resins, and the γ‐dispersion, to the molecular motions of long alkyl chains. If certain additives are mixed into the varnishes before curing, microphase separation takes place during the reactions. The resins finally obtained have a peculiar physical structure in which rubber particles are dispersed throughout a matrix phase as confirmed by scanning electron‐microscopic analysis and viscoelastic behavior.