FTIR Spectroscopy for Gypsum after Treatment withSteam Pressure

A. Al-Jobouri, H.

	FTIR Spectroscopy for Gypsum after Treatment withSteam Pressure
Journal of Al-Nahrain University - Science
Article 1, Volume 14, Issue 2, 2011, Pages 123-130
Author
H. A. Al-Jobouri
Abstract
The effect of 2 bar steam pressure was studied on the Mm and Ms mineral sources of calciumsulphate dihydrate CaSO4.2H2O with and without milling respectively, which is than comparedwith autoclave calcium sulphate hemihydrate Mα ; α-hemihydrate, and CaSO4.2H2O annular; Maby using FTIR spectroscopy technique at a wave number range 500-4000 Cm-1. The transmittanceratio; {T-ratio = [ (T660/T1620) x 100] } for Mα, Ma, and Mm, was 96.96 %, 95.26% and 72.47%respectively compared with 82.70% at Mm which is treated with 2 bar steam pressure; MP2. Thetransmittance ratio; [T-ratio] decreased in Ms after the steam pressure (1-6 bar) treatment. Theeffect of time 0.5 to 2.5 h on passing under 6 bar steam pressure onMm displays the wave numbersat the range 2000 - 2500 Cm-1 which nearly reaching the same to spectrum of Mα. FTIR– spectrumat the range 500-1500 Cm-1 for AL-ahliyah gypsum ( gypsum-Iraqi plaster ); Mh which is calciumsulphate dihydrate heated in open vessel and Mm on treatment by 6 bar steam pressure for 2.5 h;MP6 was studies the destruction of this spectrum range comparing with Mα. The disadvantage ofsteam pressure on gypsum was observed by stretching of OH-group at the rang 3000-4000 Cm-1 inMm, where the increasing of steam pressure in MP2 and MP6 caused in disappearing the wavenumbers of 3609 and 3553 Cm-1 compared with the wave numbers appearing in Mα and Mh. Thisstudy showed the steam pressure may be used as a good parameter to change Mm to Mα whichequivalent to the physical properties of dental material.

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