Victoria University

Inorganic Polymers (Geopolymers) as Potential Bioactive Materials

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dc.contributor.advisor MacKenzie, Kenneth Rahner, Nils 2009-07-12T22:26:14Z 2009-07-12T22:26:14Z 2009 2009
dc.description.abstract The primary aim of this project was to synthesise potassium activated geopolymer composites with bioactivity, and this was realised by adding 10wt% of calcium hydroxide, nano-structured calcium silicate or calcium phosphate to the geopolymer matrix. The synthesised samples were cured at 40'C then heated to 550'C and 600'C to reduce their alkalinity. Tensile strength was measured by diametral compression. The effect of exposure to simulated body fluid (SBF) was determined by x-ray diffractometry (XRD), 27Al, 29Si and 43Ca nuclear magnetic resonance spectroscopy with magic angle spinning (MAS NMR), pH measurements, inductively coupled plasma (ICP), scanning electron microscopy (SEM) and energy dispersive x-ray analysis (EDS). XRD, 27Al and 29Si MAS NMR confirmed that all the samples retained their structural characteristics of a true aluminosilicate geopolymer, even after heating and exposure to SBF. EDS examination of the calcium-containing geopolymer composites showed that the calcium distribution was generally homogeneous. Exposure of the geopolymer composites to SBF at body temperature, was used to simulate the behaviour of the geopolymer composites in blood plasma. XRD and SEM/ EDS analysis showed that the geopolymers containing calcium hydroxide and calcium silicate formed hydroxyl apatite (HA) and carbonate hydroxyl apatite (HCA) after their exposure to SBF, indicating a degree of bioactivity. The absorption of calcium and phosphorus from the SBF and the observation of nano crystals rich in these elements provide some evidence of bioactive phases in the composite containing calcium phosphate and the reference geopolymer. The reference and the calcium phosphate geopolymer (both heated to 600XC) produced the lowest pH (ca.8) in the SBF. ICP analysis of the SBF after exposure shows that most of the aluminium remains in the geopolymer structure. The greatest release of aluminium (< 2.7 ppm after 168 hours) was found for the calcium hydroxide geopolymer (heated to 600'C). Diametral compression testing showed that the strength of the calcium phosphate-containing geopolymer heated to 550'C (4.17 MPa) is comparable with that of Bioglass(R)(5.56 MPa), currently used as a bio-material. Although none of the composites are ideal in all respects, they show sufficient promise to suggest that with further refinement, geopolymer materials may well be become candidates as bioactive ceramics. en_NZ
dc.language.iso en_NZ
dc.publisher Victoria University of Wellington en_NZ
dc.subject Calcium en_NZ
dc.subject Aluminium en_NZ
dc.subject Biomaterials en_NZ
dc.title Inorganic Polymers (Geopolymers) as Potential Bioactive Materials en_NZ
dc.type Text en_NZ
vuwschema.contributor.unit School of Chemical and Physical Sciences en_NZ
vuwschema.subject.marsden 250204 Bioinorganic Chemistry en_NZ
vuwschema.type.vuw Awarded Research Masters Thesis en_NZ Chemistry en_NZ Victoria University of Wellington en_NZ Master's en_NZ Master of Science en_NZ
vuwschema.subject.anzsrcfor 039999 Chemical Sciences not elsewhere classified en_NZ

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