Differences in curing behavior of cocured and IPN materials

Autor: Chun-Chen Chiu, Mu-Shih Lin
Rok vydání: 2001
Předmět:
Zdroj: Journal of Applied Polymer Science. 80:963-969
ISSN: 1097-4628
0021-8995
DOI: 10.1002/app.1177
Popis: This study addressed the blending and cocuring of resole and epoxy, using NaOH and 4,4′-diaminodiphenylmethane as curing agents. IR band shifts regarding the molecular interactions were investigated with FTIR. Exothermic peak shifts during cocuring reactions were studied with dynamic DSC. Viscosity increases were measured with a Brookfield LVT viscometer at 100°C. The dynamic mechanical properties of the cocured samples were investigated using rheometric dynamic spectroscopy (RDS). Experimental results revealed that the molecular interactions between resole and epoxy resulted in good compatibility as shown by the single damping peak in the RDS curve and the single glass transition for each cocured sample. Also apparent were accelerated curing rates, leading to shifts of the exothermic peaks to lower temperature and faster viscosity increases. Nevertheless, enhanced gel fractions and increased glass-transition temperatures (Tg) of the samples were generally observed for this cocured system. The average molecular weight between crosslinked points calculated for the cocured materials also showed much less than the two components. These curing behaviors were quite different from those of the Interpenetrating Polymer Network (IPN) materials, which usually indicated lowered gel fractions, decreased Tg, and higher average molecular weight between crosslinkings than for components. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 963–969, 2001
Databáze: OpenAIRE
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