Morphological and mechanical behavior of polyurethane/epoxy interpenetrating polymers and its flax fiber‐reinforced composites.

The application of plant fiber‐reinforced epoxy plastic is severely limited by its relatively low mechanical properties, especially for its brittleness and weak interlaminar properties. The physical and mechanical properties in both nano‐ and macro‐scales of polyurethane/epoxy interpenetration networks were deeply investigated through dynamic mechanical analysis, atomic force microscope and the tensile tests. The atomic force microscope analysis shows that proper amount of polyurethane and evenly distribution could improve the mechanical properties of the resin cast due to the polyurethane/epoxy interpenetrating networks fix the phase zone and increases the strength and stiffness of the system and this was proven with macroscale tensile tests. Moreover, it is impressive to notice that with addition of 15 wt% of polyurethane into epoxy, the initial fracture toughness of its corresponding composite exhibits 48% enhancement. The results in this study indicate that polyurethane/epoxy interpenetration networks show positive effect on improving the interfacial and interlaminar properties of plant fiber reinforced composites. [ABSTRACT FROM AUTHOR]