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A platform for research: civil engineering, architecture and urbanism
Polyelectrolyte cements
Aluminosilicate glasses of certain compositions react with acidic polyelectrolytes to form rapidly setting cements which are strong, translucent, adhesive and bland. The ion-leachable glass systems used to form cements include: SiO2-Al2O3-CaO, SiO2-Al2O3-CaF2, SiO2-Al2O3-CaO-CaF2, SiO2-Al2O3-CaF2-AlPO4 and SiO2-Al2O3-CaF2-AlPO4-Na3AlF6. On mixing glass powder and polyacid solution into a paste, metal ions are extracted from the powder and migrate into the liquid phase where they combine with the polyanion to form a cement hydrogel composed of calcium and aluminium salts. The partially-reacted glass particles are incorporated into the cement hydrogel to form a strong, translucent cement. The chemical composition of the glasses significantly changes the properties of the resultant cements. The vulnerability of the glass network to acid attack increases with the alumina content leading to reduced setting times. The presence of fluoride in the glass improves the working properties of the cement paste since fluoride acts as a complexing agent which accelerates the extraction of ions from the glass, but simultaneously withholds them temporarily from the polyanion chain. For cements formed from glasses containing low amounts of fluoride tartaric acid is used as an alternative complexing agent. Polyelectrolyte cements find uses in dentistry since they are translucent, non-irritant and adhere to enamel and dentine. The cements are also used for surgical splint bandages.
Polyelectrolyte cements
Aluminosilicate glasses of certain compositions react with acidic polyelectrolytes to form rapidly setting cements which are strong, translucent, adhesive and bland. The ion-leachable glass systems used to form cements include: SiO2-Al2O3-CaO, SiO2-Al2O3-CaF2, SiO2-Al2O3-CaO-CaF2, SiO2-Al2O3-CaF2-AlPO4 and SiO2-Al2O3-CaF2-AlPO4-Na3AlF6. On mixing glass powder and polyacid solution into a paste, metal ions are extracted from the powder and migrate into the liquid phase where they combine with the polyanion to form a cement hydrogel composed of calcium and aluminium salts. The partially-reacted glass particles are incorporated into the cement hydrogel to form a strong, translucent cement. The chemical composition of the glasses significantly changes the properties of the resultant cements. The vulnerability of the glass network to acid attack increases with the alumina content leading to reduced setting times. The presence of fluoride in the glass improves the working properties of the cement paste since fluoride acts as a complexing agent which accelerates the extraction of ions from the glass, but simultaneously withholds them temporarily from the polyanion chain. For cements formed from glasses containing low amounts of fluoride tartaric acid is used as an alternative complexing agent. Polyelectrolyte cements find uses in dentistry since they are translucent, non-irritant and adhere to enamel and dentine. The cements are also used for surgical splint bandages.
Polyelectrolyte cements
Polyelektrolyt-Zemente
Wilson, A.D. (author) / Prosser, H.J. (author)
1981
12 Seiten
Conference paper
English
CHEMIE , ZEMENT , GLAS , MINERALOGIE , DRUCKFESTIGKEIT , POLYELEKTROLYT , PHASENSYSTEM , MISCHUNGSVERHAELTNIS , MESSEN , TECHNOLOGIE , MOLEKUEL , POLYMERISATION
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