The yield was then washed by methanol and distilled water, and then dried under the vacuum at room temperature.
3.2.Curing process and sample preparation
EP (100 phr) with varying contents of LNR (5-20 phr) were first mixed together and heated for 20 min, at 60 °C in a water bath with stirring. When the mixture had cool down to 40°C, the 60 phr curing agent (isophorone diamine) was added and the mixing was continued for an about 2 min. The mixture was then poured into a mould and left in vacuum for 5-10 min at room temperature (26°C) to remove any air bubbles. The mixture was then cured for 1 h at 100°C. The sample was then postcured at 110°C for 2 h in an air oven. At this stage the cured specimen was allowed to cool slowly at room temperature in the mould.