Effect of carbonization on mechanical properties of halloysite nanotube-FRP nanocomposites with different morphological structures

In this study, halloysite nanotubes (HNTs), an environmentally friendly inorganic nanomaterial, was added to epoxy matrix glass and basalt fiber reinforced plastics (GFRP and BFRP) by heat treatment of HNTs with crystalline and amorphous structure at $700^{\circ }\mathrm{\text{C}}$ and $1000^{\circ }\mathrm{\text{C}}$. Their interfacial bonding strength and effect of HNTs before and after carbonization by flame were analyzed. We found that the HNT/epoxy formed a physical barrier on the surface because of the char generated by carbonization. The barrier showed excellent thermal stability and limiting oxygen index in BFRP. The flexural strength after carbonization was low in the amorphous 1000HTHNT-BFRP with strong interfacial bonding. In other words, the morphological structure of the HNTs helped the improvement of the interfacial bonding strength; hence, the reinforcing effect of the HNTs on the thermal stability and mechanical strength before and after carbonization can be controlled.