Experimental investigation of mechanical properties of nano-particulate polymer composite filaments

Abstract

The excellent properties of carbon nanotubes (CNTs) make them one of the filler materials of choice for composite reinforcement. CNTs reinforced nanocomposites have shown their potential applications in many areas, such as aerospace, automotive and smart textile. This project focuses on multi-walled carbon nanotubes (MWCNTs) filled polypropylene (PP) nanocomposite systems. The objective is to better understand the relationships between dispersion state of the CNTs and the properties of melt spun filaments. The properties of bulk composites made through compression moulding are also tested to help understand the PP/CNT composite filament systems. In this thesis, the background of reinforcement mechanism, raw materials (PP, and CNTs), CNTs filled nanocomposites, percolation threshold and melt-spinning process are reviewed. The raw materials, processing conditions/parameters, and characterisation techniques are introduced in the experimental methodology section, and the results are discussed in the following chapter. The addition of CNTs had an increase on the Young’s modulus and tensile strength of compression-moulded (CM) samples and made them brittle. The Young’s modulus and tensile strength had a linear relationship with CNTs concentration at low CNTs volume fraction. However, the tensile properties of the nanocomposites determined when the CNTs concentration further increased, which is attributed to the formation of CNT agglomerates. The electrical conductivity increased by seven orders of magnitude after reaching percolation threshold. The sample at 1 K/min cooling rate had a lower concentration percolation threshold than that at 23 K/min, which is allowed the better CNTs dispersion. For melt-spinning fibres, drawing the fibre had the same effect on tensile properties as the addition of CNTs. However, this had an opposite effect on the electrical conductivity of the fibres, due to the change in orientation state of CNTs during the drawing process, which was 12 characterized by Raman spectroscopy. The orientation of matrix chain and crystal was characterized by XRD.

Date of Award	1 Aug 2022
Original language	English
Awarding Institution	The University of Manchester
Supervisor	William Sampson (Supervisor) & Arthur Wilkinson (Supervisor)