Preparation and properties of PLA/long alkyl chain modified multi-walled carbon nanotubes nanocomposites

Abstract

In this investigation, poly(lactic) acid (PLA)/multi-walled carbon nanotubes (CNTs) hybrids were prepared using a melt blending process. To increase the compatibility between CNTs and PLA, the surfaces of the CNTs were firstly pretreated in acid solution (HNO₃) to functionalize them with carboxylic groups (-COOH). Then, stearyl alcohol was grafted onto carboxylic groups using a dehydrating agent, N,N′-dicyclohexylcarbodiimide. Chemically modified CNTs (CNT-C18) were thus obtained. Therefore, modified carbon nanotubes (CNT-C18) dispersed excellently in organic solvents. PLA/CNTs nanocomposites were prepared by the melt-blending method. Experimental results reveal that the PLA/CNT-C18 nanocomposites that consisted of well-dispersed nanotubes exhibited enhanced thermal and mechanical properties. Adding 4 wt% CNT-C18 to a nanocomposite increased the storage modulus (E′) at 40°C by 17.8%, and the loss modulus (E″) at the glass transition temperature (T_g) by 15.1%. Adding 3 wt% CNT-C18 also reduced the surface resistivity of the PLA nanocomposites from >10¹⁶ Ω/cm²to 10⁴ Ω/cm². Such PLA/CNT-C18 nanocomposites are highly efficient in anti-static agents and can be exploited in the outer coverings of electronic devices.