CF unsizing and oxidation process is similar to a previous report [5]. The CNTs just
need to be treated to attach carboxylic groups as usual [5]. The
oxidized CFs with the carboxyl groups are put into the methanol
solution of PAMAM at 22±2 °C for 12 h. The functionalized fibers
are then rinsed with methanol and dried in vacuum at 50 °C for 1 h.
As a result, a nano-patterned dendrimer layer is adsorbed onto the
CF surface and a large amount of amino groups covers the CF
surface. In order to get different adsorption densities, the feeding
ratios by weight of CF:PAMAM can change from 1:0.2×10−4 to
1:5×10−4. Subsequently, 1 mg of the treated CNTs is dispersed in a
50 ml acetone solvent with an ultrasound bath at 50 °C for 1 h. A
5 mg amino-functionalized CF is dipped into the CNTs suspension
for 12 h, followed by a heat treatment at 100 °C. After acetonewashing
in an ultrasound bath, the CNT/CF multi-scale reinforcement
(MSR) is finalized.