Impact fracture behaviour of silane-treated halloysite nanotubes-reinforced unsaturated polyester

• The micromechanism of plastic deformation under impact loading was investigated.
• The impact fracture properties were characterised at different testing temperatures.
• Silane coupling agent was used to improve the dispersion.
• Good interfacial adhesion and uniform structures of HNT in polyester resin was observed.
• SEM examinations revealed a change in fracture mechanism with the addition of nanoparticles.

This work investigates the effects of untreated and silane-treated halloysite nanotube (HNT) particles on the micromechanism of plastic deformation of unsaturated polyester (UP) nanocomposites under impact loading conditions. The impact fracture properties of the prepared materials were characterised based on the temperature range of −20 to +60 °C using falling weight impact tester. The chemically-modified halloysite with silane coupling agent (s-HNT) showed less hydrophilic towards the polyester matrix, thereby a good interfacial adhesion and uniform structures of HNT in the matrix are obtained compared to the untreated. The incorporation of both unmodified and modified HNT particles up to 5 wt.% into the UP revealed a modest increase in the impact strength and total energy of nanocomposites, since the well dispersed particles in the matrix hindered the crack propagation under the impact loading. SEM examinations revealed that the fracture mode on UP surface was a smooth fast brittle while, the nanocomposite surfaces showed a sign of plastic deformation.