Properties of Cross-Linked Phenolic Resins

Posted by dhio
courtesy ofFig1.modeling of molecules by using J-OCTA (left=EP, right=ethylenediamine)
Structure–property relationships of cross-linked phenolic resins have been studied by using atomistic molecular dynamics simulations.  The cross-linked structures were prepared by cross-linking reactions of linear phenolic resin oligomers (9-mer).  In this study, three cross-linked structures with degrees of cross-linking (D) of 70%, 82%, and 92% were investigated.

Fig.1 Cross-linking reaction model of phenolic resins.



Fig.2 Structure of a cross-linked phenolic resin.


In order to evaluate the effect of D on glass transition temperature (Tg ), specific volume was calculated as a function of temperature.  As shown in Fig.3, an increase in D accompanies an increase in Tg.  This indicates that segmental motions were suppressed by the cross-links.In addition, to estimate mechanical properties in a glassy state of the cross-linked structures, uniaxial elongations were performed at 300 K.  Fig.4 shows the calculated stress-strain curves, which indicates a clear dependence of the curve on D.

The details of this study are also described in ref.1.


Fig.3  Change in specific volume: red, D = 70%; blue, D = 82%; green, D = 92%.  The glass transition temperature of each structure was determined from the change in the slope.



Fig.4 Stress–Strain Curves: red, D = 70%; blue, D = 82%; green, D = 92%.


[1] A. Izumi, T. Nakao and M. Shibayama, Soft Matter, 2012, 8, 5283–5292.