Development of Nylon based Polymer Nanocomposites Reinforced with Pristine and Functionalized Multi-Walled Carbon Nanotubes (MWCNTs)

Abstract

Composites are a type of materials which are produced through reinforcement of a matrix phase with suitable filler in particle, whisker, or fiber form. Nanocomposites are a subgroup of composite materials that have reinforcing material in nanostructured form. Carbon nanotubes have been a material of great interest ever since there discovery in 1991. These have exceptional strength, electrical conductivity, thermal properties and chemical characteristics and are used for various applications all over the globe. Multi-walled carbon nanotubes MWCNTs were synthesized using chemical vapor deposition method (CVD) over nickel ferrite (NiFe2O3) catalyst nanoparticles by co-precipitation method. Acetylene (C2H2) as carbon precursor source and argon (Ar) as diluent were used for synthesis of MWCNTs. MWCNTs was characterized to assess their purity, and size distribution (diameter and length). After purification, different functional groups such as hydroxyl –OH, carboxylic –COOH, acyl chloride –COCl and amine –NH2 were attached via chemical treatment to enhance the chemical bonding affinity of these CNTs with polymeric matrix and improve their alignment and dispersion. Thermoplastics Nylon was used as matrix material with different loadings of pristine and functionalized MWCNTs as reinforcements. Nanocomposites were fabricated by solution mixing and melt mixing techniques. Both methods have their own advantages and disadvantages; while solution mixing results in good dispersion of MWCNTs, produce voids, thus adversely affecting the properties of polymer matrix. Melt method on the other hand, save from voids which was caused by solvent but has low dispersion of MWCNTs. Extruder, hot press and injection moulding machine were used to fabricate the nanocomposites through both methods. Strength, ductility, stiffness, hardness, fracture toughness, crystallinity, bonding analysis and micro structure (before and after fracture) were studied. Thermal stability was investigated for polymer reinforced nanocomposites with pristine and functionalized MWCNTs. Nanoparticles, MWCNTs, functionalization of MWCNTs and nanocomposites were characterized by various tools as TEM, SEM, EDX, XRD, Raman, FTIR, TGA, DTA, DSC, TMA, DMA and mechanical testing.