Influence of glass composition on the properties of glass polyalkenoate cements. Part IV: influence of fluorine content

The influence of fluorine content of the glass in a series of glasses based on: 4.5SiO(2)-3.0Al(2)O(3)-1.5P(2)O(5)-(5.0-X)CaO-XCaF2 was investigated o n their cement formation with poly(acrylic acid). Increasing the fluorine c ontent of the glass was found to reduce the glass transition temperature, a s a result of fluorine replacing bridging oxygens by non-bridging fluorines . Working and setting times of the cement pastes reduced with increasing fl uorine content of the glass. Compressive strength and Young's moduli increa sed with fluorine content initially and then remained approximately constan t. Fracture toughness, toughness and un-notched fracture strength were not significantly influenced by fluorine content. The results are consistent wi th fluorine simultaneously disrupting the glass network and reducing the ba sicity of the glass. (C) 2000 Elsevier Science Ltd. All rights reserved.