Effect of polymeric additions on the properties of calcium salt cements

Abstract

RecentlY, great attention has been paid to calcium salts cements, beca use oftheir advantages in comparison with conventional calcium phosphate biocerarnics employed for bone repairing, regarding in situ handling, and shaping abilities. Nevertheless, the strength of calciurn salts cements is relatively low; especially during the early stages of irnplantation, and their setting times are often too short or too long for clinical application. The airn of this work was the improvement of the properties of three calciurn salts cements. The effect of the addition of sodium alginate (SA) and polyacrylic acid (PAA) to the above formulations of calcium salt cements was studied. Both SA and PAA content pendan! carboxylic groups able to interact with Ca², Mg²⁺, and H⁺ ions thus reinforcing the cement mass. Initial pH, setting time, compressive strength, phase composition and rnicrostructure of cements with and without additives were determined. The presence of 4.8 wt-% SA in the cement Fl decreased its setting time from 14 to 12 min. and increased its initial compressive strength from 4.9 to 7.2 MPa. Flrrthennore, theaddition of SAdirninished the decayin compressive strength ofthis cement after 1-week immersion in sirnulated body fluid. A possible explanation for the reinforcing effect of SA in Fl cement is the formation of fibrous alginic acid, which would act as a reinforcing fiber in the inorganic cement matrix. Fbr the rest of combinations of cements and additives studied, a deleterious effect on their properties was always found.