Mechanical properties improvement of montmorillonite‐filled isotactic polypropylene nanocomposites by β‐modification

To investigate the effect of β‐crystallization on mechanical properties of isotactic polypropylene (iPP) nanocomposites, montmorillonite (MMT)‐filled α‐iPP and β‐iPP nanocomposites were prepared by MMT with α‐ and β‐nucleating surface, respectively. The polymorphic composition, mechanical properties and fracture morphologies of α‐MMT and β‐MMT filled iPP nanocomposites were compared and the exfoliation of MMT in the iPP matrix were investigated. It is found that the tensile modulus, yield strength, and flexural properties of β‐MMT filled iPP nanocomposites are higher than those of β‐iPP and the impact strength of β‐MMT filled iPP nanocomposites is higher than those of both β‐iPP and α‐iPP nanocomposites. The impact strength increases with increasing of the β‐crystal content. However, the β‐crystal content has little influence on the tensile and flexural properties of β‐MMT filled iPP nanocomposites. Compared with α‐MMT, the exfoliation of β‐MMT in iPP as well as interfacial adhesion between MMT and iPP are improved. POLYM. COMPOS., 38:E412–E420, 2017. © 2016 Society of Plastics Engineers