Coated Nano-Sized CaCO3 Reinforced Semi-Crystalline EPDM

Nano-sized calcium carbonate (CaCO 3 ) was used to reinforce a semi-crystalline ethylene-propylene-diene monomer rubber (EPDM). For comparison, micron-sized CaCO 3 was also studied. It was found that both nano-sized CaCO 3 and micron-sized CaCO 3 improved the mechanical properties of the EPDM vulcanizates, and nano-sized CaCO 3 exhibited better reinforcement effect than micron-sized CaCO 3 . The difference in reinforcement effects of nano-sized CaCO 3 and micron-sized CaCO 3 was explained in terms of the filler particle size and the crosslink density of the vulcanizates. The nano-sized CaCO 3 was also modified by titanate, borate, and aluminate-titanate complex coupling agents and used to reinforce EPDM vulcanizates. The results showed that titanate coupling agent coated nano-sized CaCO 3 exhibited the best reinforcement ability. FE-SEM micrographs showed that stearic acid, titanate, and aluminate-titanate complex coupling agents could improve the dispersion of the CaCO 3 in the rubber matrix remarkably, whereas borate coupling agent could not. The effect of modified nano-sized CaCO 3 on the dynamical mechanical properties was also studied. Incorporation of CaCO 3 reduced the glass transition temperature (Tg) of the vulcanizates. In comparison with nano-sized CaCO 3 , micron-sized CaCO 3 depressed the Tg more remarkably.