http://hdl.handle.net/10204/3839 2013-05-18T11:52:39Z http://hdl.handle.net/10204/6711 Title: Solar absorption and thermal emission properties of multiwall carbon nanotube/nickel oxide nanocomposite thin films synthesized by sol-gel process Authors: Roro, KT; Tile, N; Mwakikunga, B; Yalisi, B; Forbes, A Abstract: Multiwall carbon nanotubes (MWCNTs)/nickel oxide (NiO) nanocomposites were successfully prepared by a sol–gel process and coated on an aluminium substrate. The MWCNTs were chemically functionalized and then added into NiO alcogels, and magnetic stirred for homogeneous dispersion into the NiO matrix solution. The morphology of the resulting nanocomposite thin films showed that the MWCNTs were embedded in the NiO nano-particle matrix, while HRTEM confirmed that the MWCNTs were surrounded by the NiO nano-particles. Raman spectra for functionalized MWCNTs displayed a red shift from the pristine MWCNTs suggesting successful purification/functionalization. The spectrum for the MWCNTs/NiO nanocomposite indicated the presence of both the TO and LO phonons of NiO, and the D and G bands of the MWCNTs. Red and blue shifts of the NiO phonons and the MWCNT phonons suggested that the vibrational properties of both materials were changed to form new nanocomposite vibrational properties. Despite unoptimized layer thickness and composition, the solar absorptance of the functionalized MWCNTs/NiO nanocomposite films was 0.84 (for a single layer). The thermal emittance at 100 °C was approximately 0.2. These results suggest that MWCNTs/NiO nanocomposite materials are suitable for solar thermal applications. Description: Copyright: 2012 Elsevier. This is an ABSTRACT ONLY. The definitive version is published in Materials Science and Engineering: B, vol. 177(8), pp 581–587 2012-05-01T00:00:00Z http://hdl.handle.net/10204/6677 Title: Development of thermoresponsive poly(propylene-g-N-isopropylacrylamide) non-woven 3D scaffold for smart cell culture using oxyfluorination-assisted graft polymerisation Authors: Chetty, AS; Vargha, V; Maity, A; Moolman, FS; Rossouw, C; Anandjiwala, R; Boguslavsky, L; Mancama, D; Focke, WW Abstract: Growing cells on 3D scaffolds is far superior to the conventional 2D monolayer culture method. In this study, a novel 3D thermoresponsive poly(propylene-g-N-isopropylacrylamide) (PP-g-PNIPAAm) nonwoven fabric (gNWF) was developed for cell culture using oxyfluorination-assisted graft polymerisation (OAGP). New polar functional groups were detected on the oNWF, and PNIPAAm was confirmed in the gNWF by attentuated total-reflectance Fourier transform infrared (ATR-FTIR) and scanning X-ray photoelectron spectroscopy (S-XPS). Scanning electron microscopy (SEM) revealed a rough surface morphology and confinement of the PNIPAAm graft layer to the surface of the fibres in the gNWF. The OAGP method did not affect the crystalline phase of bulk PP, however, twin-melting thermal peaks were detected for the oNWF and gNWF indicating crystal defects. Contact angle studies showed that the surface of the gNWF exhibited a thermoresponsive behaviour. Hepatocyte cells attached onto gNWF disks in a bioreactor at 37 C and remained viable for 10 days in culture. Upon cooling the cell culture media to 20 C, cells were spontaneously released as 3D multi-cellular constructs without requiring destructive enzymes. The development of 3D thermoresponsive scaffolds capable of non-invasive 3D cell culture could provide a more reliable in vitro model for cells. Description: Copyright: 2013 Elsevier. This is an ABSTRACT ONLY. The definitive version is published in Colloids and Surfaces A: Physicochemical and Engineering Aspects, vol. 419, pp 37-45 2013-02-01T00:00:00Z http://hdl.handle.net/10204/6673 Title: Fabrication and properties of polylactic acid fabric based sandwich panels with arylated soy protein isolate as the binder Authors: Kumar, R; Moyo, D Abstract: PLA fabrics were coated with arylated soy protein isolate (ASPI) dispersions at different levels of 2,2-diphenyl-2-hydroxy ethanoic acid (DPHEAc) (1 to 10 wt.% wrt SPI). In order to optimize the level of DPHEAc in ASPI, the fabricated ASPI coated PLA fabric were subjected to mechanical, thermal, thermomechanical and water uptake studies. Interfacial interactions between ASPI and PLA were assessed by fracture morphology. Finally, ASPI coated PLA fabrics at the 5 wt.% of DPHEAc were successfully used to prepare sandwich panels with the ASPI coated PLA fabric skins for a Nomex based honeycomb core. The ultimate bending and peeling load of the sandwich panels with one layer of ASPI coated PLA fabric were determined. A few remnants of the honeycomb core attached to the PLA fabrics after peeling load tests visually suggested the presence of strong adhesive bond between honeycomb core and PLA fabric skins. Description: Copyright: 2012 American Scientific Publishers. This is an ABSTRACT ONLY. The definitive version is published in Journal of Biobased Materials and Bioenergy, vol. 6(5), pp 521-530 2012-10-01T00:00:00Z http://hdl.handle.net/10204/6667 Title: Plasticisation and complexation of certain polymers in supercritical CO2 Authors: Labuschagne, P Abstract: A polymer system (polyvinylpyrrolidone + polyvinyl acetate-co-crotonic acid) was successfully identified for use as encapsulation material for sensitive actives using supercritical CO2 as plasticisation medium, having the following properties: 1. Ability to plasticise sufficiently in supercritical CO2, 2. Ability to form an inter-polymer complex in supercritical CO2, 3. Ability to swell in aqueous medium in order to release actives, and 4. FDA-approved. Description: A thesis submitted to Faculty of engineering Department of polymer technology, Tshwane University of Technology, in fulfillment of the requirements for Master of Technology. 2004-09-01T00:00:00Z