Fabrication and characterisation of polymeric nano-composites

Abstract

In this study, graphitised multi-walled carbon nanotubes (GMWCNT) are used to reinforce high impact polystyrene (HIPS) as base material for fabricating nanoparticle reinforced composites with improved material properties "" GMWCNTHIPS. For two phases composite, three weight percentages of nanoparticles in the devised nanocomposites - 1wt%, 3wt% and 5wt% are selected and 2wt% of three phase composite, 1wt% of GMWCNT and 1wt% of graphitized carbon nanofibers (GCNF), to investigate its weight fraction's influence on material properties and mechanical behaviours. The nano-composites are fabricated using moulding injection in lab as standard ASTM samples. These samples are then employed for mechanical tests including uniaxial tension test and four-point bending test. A microstructural analysis of the samples is conducted to determine the microstructure of GMWCNT-HIPS nano-composites, in particular for the interfacial zone of nanotube and base material. Meanwhile a finite element analysis is developed and applied for modelling the uniaxial tension and four-point bending and conducting a parametric study to guide the adjustment of main control parameters of moulding injection process as a material design tool. The obtained results show that the mechanical properties of final-product materials are influenced by manufacturing processes and controlled by main factors that affect that processes. Also, 3D printing, also referred to additive manufacturing (AM), has been developed as a revolutionary manufacturing process, becoming a potential process to replace conventional manufacturing processes. 3D printing process "" Fused Deposition Modelling/Fused Filament Fabrication (FDM/FFF) has been developed to rapidly print thermoplastic products while the traditional manufacturing process "" injection moulding has been well developed for making thermoplastic products with a long history. In this research, a comparative study is experimentally conducted to investigate material properties and mechanical behaviours of two commonly-used 3D printing thermoplastic materials "" Acrylonitrile Butadiene Styrene (ABS) and Polylactic Acid (PLA) via uniaxial tension and three point bending tests according to ASTM standard. The mechanical properties of final product materials are influenced by manufacturing processes and controlled by main factors that affect that processes. In order to optimise the 3D printing process using available 3D printers at lab, correlations between main control parameters and material properties of ABS and PLA are extracted based on the experimental results obtained considering the mould injection as a benchmarking process. A series of finite element analyses are developed and applied for conducting a parametric study to guide the adjustment of main control parameters of layer-by-layer 3D printing process as a material design tool.

Date of Award	2019
Original language	English