Design of the ultimate behavior of tetrafunctional epoxies modified with polysulfone by controlling microstructure development

Citation
Pa. Oyanguren et al., Design of the ultimate behavior of tetrafunctional epoxies modified with polysulfone by controlling microstructure development, J POL SC PP, 37(19), 1999, pp. 2711-2725
Citations number
37
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Organic Chemistry/Polymer Science
Journal title
JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS
ISSN journal
0887-6266 → ACNP
Volume
37
Issue
19
Year of publication
1999
Pages
2711 - 2725
Database
ISI
SICI code
0887-6266(19991001)37:19<2711:DOTUBO>2.0.ZU;2-V
Abstract
The reaction-induced phase separation in a tetrafunctional epoxy-cyclic anh ydride system modified with polysulfone (PSF) was followed by optical micro scopy (OM), light scattering (LS), and scanning electron microscopy (SEM). The selected system was N,N,N',N'-tetraglycidyl-4,4'-diamino diphenylmethan e cured with methyl tetrahydrophthalic anhydride, in the presence of variab le PSF concentrations. The different experimental techniques allow us to es tablish the phase separation mechanism. For modifier concentrations close t o the critical point, 10 and 15 wt% PSF, phase separation proceeded by spin odal demixing (SD). For a modifier concentration much lower than the critic al point, 5 wt% PSF, phase separation occurred via the nucleation and growt h (NG) mode. For 7.5 wt% PSF, depending on the cure temperature, SD or NG w as observed. Dynamic mechanical behavior of the resulting materials had bee n discussed based on fractionation of different species during the phase se paration process. The fracture toughness increased significantly when bicon tinuous (10 wt% PSF) or phase-inverted (15 wt% PSF) structures were generat ed. For mixtures containing 15 wt% PSF, the dependence of fracture toughnes s on the stoichiometric ratio (anhydride groups/epoxy groups) was analyzed. (C ) 1999 John Wiley & Sons, Inc.