Y. Imai et al., Effect of blending tricalcium phosphate on hydrolytic degradation of a block polyester containing poly(L-lactic acid) segment, J BIOM SC P, 10(7), 1999, pp. 773-786
The effect of blending tricalcium phosphate (TCP) on hydrolytic degradation
of a new type of poly(L-lactic acid)/poly(ethylene;hexamethylene / sebacat
e) block polyester (60:40 wt%) was studied. 100- and 250-mu m film specimen
s blended with 0, 10, and 30 wt% TCP were immersed in phosphate buffered sa
line (pH 7.4) at 37 degrees C for up to 80-104 weeks. At appropriate interv
als, water absorption, dry and wet tensile strength, molecular weight, and
thermal properties of the specimens were measured by weighing, tensile stre
ngth testing, size exclusion chromatography, and differential scanning calo
rimetry, respectively. Some samples were characterized by H-1 NMR spectrosc
opy. Blending of TCP with the block polyester was effective in retarding de
gradation. The blended TCP was thought to retard degradation for the most p
art by neutralizing the lactic acid oligomers produced by hydrolysis of the
poly(lactic acid) part during the initial stage of degradation.