Evaluation of microstructure of natural rubber/nano-calcium carbonate nanocomposites by solvent transport properties

Abstract

The research on rubber reinforcement is a traditional but vitally essential topic. However, many issues in this aspect are presently still not well understood and explained. Moreover, when rubber reinforcement is obtained by using nanoparticles, it is even more difficult to clearly understand the relationship between the microstructure and properties. The special character of rubber, being a multicomponent system (rubber, vulcanising agent, accelerants, reinforcements, etc.), complicates even more the analysis of the parameters affecting the rubber/nanoparticle composite formation. Therefore, we believe the results obtained by means of transport experiments represent a good approach for understanding the reinforcing capability of nanofillers. The reinforcing capability of nano-CaCO3 in natural rubber (NR) was characterised by means of transport properties such as diffusion, sorption and permeability coefficients, swelling ratio, enthalpy, entropy and activation energy. Concentration of nano-CaCo3 in NR was varied from 0 to 20 parts per one hundred parts of rubber by weight (phr). Transport process of toluene by use of equilibrium weight swelling of the NR and nanofilled composites have been studied in details. The effects of nanofiller concentration and temperature on transport of toluene through nano-CaCO3 filled NR vulcanisates were studied. The microstructure of the nanocomposites was investigated by scanning electron microscopy. The diffusivity data of the systems have shown the dependence on the temperature and microstructure of nanocomposite. Generally, the concentration of nano-CaCO3 plays an important role in transport process.