Influence of functionalization on properties of MWCNT–epoxy nanocomposites

The effects of various functionalized multi-walled carbon nanotubes (MWCNTs) on morphological, thermal, and mechanical properties of an epoxy based nanocomposite system were investigated. Chemical functionalization of MWCNT by oxidation (MWCNT-COOH) and direct-fluorination (MWCNT-F) were confirmed by FTIR, Raman spectroscopy, and TGA. Utilizing in situ polymerization, 1 wt% loading of MWCNT was used to prepare epoxy-based nanocomposites. Compared to the neat epoxy system, nanocomposites prepared with MWCNT-COOH showed 25.5% increase in ultimate flexural strength and 54.8% increase in flexural modulus. A decrease in strength was observed for the MWCNT-F nanocomposites. The premature degradation was attributed to a presumable catalyzation by hydrofluoric acid, HF, which evolved from the MWCNT-F during the curing process. However, only the MWCNT-F nanocomposites showed 22% increase in thermal properties (Tg). All nanophased systems showed increase in storage modulus.