Structure characteristics contributing to flame retardancy in diazo modified novolac resins

Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/28338

Title:	Structure characteristics contributing to flame retardancy in diazo modified novolac resins
Authors:	Wu,HH;Chu,PR
Contributors:	中央大學
Keywords:	THERMAL-CHARACTERISTICS;FUNCTIONAL NOVOLAC;PHENOLIC RESINS;EPOXY-RESINS;MECHANISMS;POLYMERS;POLYMERIZATION;DEGRADATION
Date:	2009
Issue Date:	2010-06-29 19:46:26 (UTC+8)
Publisher:	化學研究所
Abstract:	The physical characteristics of two modified novolac resins (carbonyl phenyl azo novolac resin; CPAN and 4-(4-hydroxyphenyl azo) benzyl ester novolac resin; HPDEN) bearing nitrogen and aromatic functional groups by diazo-coupling or esterification in the branch structure of phenol novolac resin were examined. Presence of the modifiers raised the phenolic decomposition temperature (5% weight loss) from 300 degrees C (pure Phenolic) to 330 degrees C and 380 degrees C, while the char residue increased from 45% to 56% and 68%, respectively. The kinetics for thermal degradation energies (E.) also rose from 151 kJ/mol K to 254 kJ/mol K (CPAN) and 273 kJ/mol K (HPDEN). The retarded decomposition kinetics is attributed both to the increase of crosslink densities and high aromatic content in the derivative resins. On the other hand, the diazo-coupling or phenyl diazenyl ester produces non-combustible gases (N-2, CO2 and CO) during formation of aromatic char which dilute the ambient oxygen gas. Both the production of gases and the retarded kinetics due to cross-linking are definitive for the improved flame resistance. (C) 2009 Elsevier Ltd. All rights reserved.
Relation:	POLYMER DEGRADATION AND STABILITY
Appears in Collections:	[Graduate Institute of Chemistry] journal & Dissertation

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