Abstract
The influence of thermal treatment on the performance of polymers as dispersants for calcium hydropxyapatite, HAP, was investigated in an aqueous system. The polymeric additives tested include: homo-polymers of acrylic acid (AA) and maleic acid (MA); co-polymer of AA:SA (2-acrylamido-2-methylpropane sulfonic acid) and ter-polymers of AA:SA:t-bAM (tertiary butyl acrylamide) and AA:SA:SS (sulfonated styrene). It was found that polymers containing SA upon exposure to heat treatment (i.e., 150° to 200°C, 1 hr to 20 hr) undergo degradation. The extent of degradation as investigated by NMR and FT-IR techniques indicates that at higher temperature and longer exposure time, SA is essentially degraded to acrylic acid. Among the ter-polymers tested, SS containing polymer exhibits more stability to thermaI treatment than the t-BuAm containing polymer. In addition, it has been found that polymer architecture strongly influences the performance of polymer as HAP dispersant.
