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Reactivity of epoxy resin in dispersed dicyandiamide system and dynamic viscoelasticity of the resulting product
Author(s) -
Muroi Souichi,
Ishimura Hidekazu,
Outsuka Masahiko
Publication year - 1986
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.1986.070320528
Subject(s) - curing (chemistry) , viscoelasticity , epoxy , bisphenol a , materials science , chemistry , diglycidyl ether , dimethylamine , activation energy , polymer chemistry , composite material , organic chemistry
A study was made on the curing reaction, leading to a cross‐linked network, of bisphenol A diglycidyl either in a dispersed dicyandiamide (DICY) system containing benzyl dimethylamine accelerator and on the dynamic viscoelasticity of the resulting product as related to the DICY particle size (Ds), and compared with a dissolved DICY system. The curing reaction rate varied inversely with logarithmic Ds and directly with the total surface area of the DICY particles, and the finally attainable extent of reaction of the epoxide group decreased with increasing Ds. Activation energy ranged from 14 to 17 kcal/mole depending slightly on Ds. The dynamic viscoelasticity of the cured product was also affected greatly by Ds. Cured product from the system with a 3 μm DICY displayed only a primary transition peak around 180°C in plots of viscoelastic decrement as a function of temperature. With DICY of larger than 10 μm Ds, the number of transition peaks increased to two or three, with a primary peak, a secondary peak around 140μC, and a tertiary peak around 90μC. The relative height of the secondary or tertiary peak increased with increasing Ds. The reaction of the dissolved DICY system proceeded at much the same rate as the 25 μm Ds system, but yielded a cured product with viscoelasticity similar to that of the 3 μm Ds system.