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Title: Graphene-based thermosetting polymer nanocomposites : unsaturated polyester and hyperbranched polyester
Author: Wen, Yahui
ISNI:       0000 0004 7428 1685
Awarding Body: University of Sheffield
Current Institution: University of Sheffield
Date of Award: 2018
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Graphene has attracted tremendous interests from scientists and researchers due to its excellent physical such as strong mechanical properties, excellent thermal and electrical conductivity, and low cost. In this work, graphene oxide (GO) was synthesized by Hummers method. Graphene based unsaturated polyester (UPR) nanocomposites were prepared by simple mixing method with and without organic solvent. Tensile test, 3-point bending test, Dynamic mechanical analysis (DMA), Thermogravimetric analysis (TGA) were carried out to study the effect of GO on mechanical properties, glass transition temperature, and thermal stability of UPR. Scanning electron microscope (SEM) and Fourier-transform infrared spectroscopy (FTIR) were employed to investigate the fracture surface of composites and the chemical structure of composites, respectively. In addition, the influence of GO on the crosslinking density of UPR was studied as well. L-ascorbic acid (vitamin C) is a non-toxic reductant for reducing of GO, which exhibit similar electrical conductivity as rGO reduced by Hydrazine hydrate. To enable the insulating UPR to be electrical conductive, UPR/rGO composites were synthesized in two method: 1) the reduction of GO was carried out prior to the synthesis of UPR composites. 2) The reduction of GO was carried out during the synthesis of UPR composites. Electrical conductivity, thermal conductivity, thermal stability, glass transition temperature and mechanical properties were investigated. A 100% eco-friendly and toxic free method was employed for bio-based hyperbranched polyester (HBPE) with water resistance, partially automatically self-healing properties. Stable GO/ethanol dispersion was achieved by modification of GO by Paraphenylenediamine (PPD), which can last for few months without precipitation. A series of HBPE/P-rGO nanocomposites were synthesized by using in situ polymerization. Nuclear Magnetic Resonance (1H NMR, 13C NMR), titration were performed to characterize neat HBPE. DMA was used to investigate the glass transmission temperature (Tg) of HBPE in nanocomposites. TGA was employed to study the thermal properties. Tensile tests were carried out for the investigation of hysteresis properties, mechanical properties, and self-healing behavior.
Supervisor: Foreman, Joel ; Hayes, Simon Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available