Process for the preparation of carbon fiber-carbon nanotubes reinforced hybrid polymer composites for high strength structural applications

A process for the preparation of carbon fiber carbon nanotubes (CNTs) reinforced polymer composites wherein the steps comprising:

• a) mixing 0.1 to 0.5% (w/w) of multi walled carbon nanotubes (MWCNTs) having a diameter in the range of 20 to 100 nm and a length in the range of 20 to 200 microns with 45 to 55 g of epoxy polymer pre heated at a temperature ranging from 40 to 60 degree C. and homogenizing for 5 to 30 min to obtain a mixture;
• b) adding a hardener at 23% by weight of epoxy to the mixture obtained in step [a] followed by stirring for 2 to 10 min using a magnetic stirrer;
• c) cutting six layers of Carbon fiber cloth (CF) of dimension 14 cm×17 cm each from a carbon fiber cloth sheet;
• d) dispersing the MWCNTs having the diameter in the range of 20 to 100 nm and the length in the range of 20 to 200 microns in a solvent with a high energy homogenizer for 10 to 15 min;
• e) sonicating the MWCNTs obtained in step [d] for a period of 20 to 40 min and again homogenizing for 5 to 10 min to obtain homogenized MWCNTs;
• f) fabricating five MWCNT papers having a dimension of 20 cm×20 cm using the homogenized MWCNTs obtained in step [e] by vacuum filtration;
• g) cutting the MWCNT papers obtained in step [f] to a dimension of 14 cm×17 cm length;
• and
• h) applying the mixture obtained in step [b] on both sides of the six layers of the CF as obtained in step [c] and the MWCNT papers as obtained in step [g] and stacking them alternately and sandwiched between die steel plates, followed by pressing at 100 to 150 kg/cm2 first at a temperature ranging from 70 to 90 degree C. for a period of 1.5 to 2.5 h and then at a temperature ranging from 140 to 160 degree C. for a period of 3.5 to 4.5 h, followed by cooling at room temperature to obtain the desired CNTs reinforced polymer composites.