Curing and pyrolysis of cresol novolac epoxy resins containing [2-(6-oxido-6H-dibenz(c,e)(1,2)oxaphosphorin-6-yl)-1,4-naphthalenediol].: An article from: Polymer Engineering and Science

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From the author: This study investigates the curing kinetics, thermal properties and decomposition kinetics of cresol novolac epoxy (CNE) with two curing agents. 2-(6-oxido-6H-dibenz(c,e)(1,2)oxaphosphorin-6-yl)-1,4-benzenediol (ODOPN), and phenol novolac (PN). In comparison with the conventional PN system, introducing ODOPN, a phosphorus-containing bulky pendant group, into CNE increases [T.sub.g] by 33[degrees]C, char yield from 30% to 38%, and LOI from 22 to 31. The DSC curing study reveals that the [E.sub.a] of the CNE/ODOPN epoxy can be obtained by Kissinger's method. The resulting [E.sub.a] values indicate that the catalytic effect of EMI is insignificant on CNE/ODOPN but is marked on CNE/PN, whose [E.sub.a] was reduced from 131.5 to 75.6 KJ/mole. This result may be caused by the fact that the symmetric diol attached to the 1 and 4 positions of the naphthalene ring in ODOPN sets up a steadily resonating structure and inhibits the catalytic action. Further investigating the conversion ratio with curing temperature yielded experimental data that agreed closely with Kaiser's model. The orders of the autocatalyzed reaction. m, and the crosslinking reaction. n, are close to 0.5 and 1.0, respectively, independently of the scan rate. Finally, the TGA decomposition study by Ozawa's method demonstrates that the mean [E.sub.a] declines with the phosphorus content, because the easy decomposition of the phosphorus compound in the initiation stage facilitates the formation of an insulating layer. However, results in this study further reveal an increasing tendency for [E.sub.a] with decomposition conversion for an ODOPN/PN mixture with the ODOPN content of over 50%, probably because of the retardation of gas diffusion by the insulating layer of phosphorus compound.

Citation Details
Title: Curing and pyrolysis of cresol novolac epoxy resins containing [2-(6-oxido-6H-dibenz(c,e)(1,2)oxaphosphorin-6-yl)-1,4-naphthalenediol].
Author: S.-P. Rwei
Publication:Polymer Engineering and Science (Refereed)
Date: February 1, 2004
Publisher: Society of Plastics Engineers, Inc.
Volume: 44 Issue: 2 Page: 376(12)

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