Isothermal crystallization behavior and unique banded spherulites of hydroxyapatite/poly(L-lactide) nanocomposites

Hydroxyapatite/poly(L-lactide) (HA/PLLA) nanocomposites were prepared by the solvent mixing method. The isothermal crystallization behavior was studied by differential scanning calorimetry (DSC) and polarized optical microscopy (POM). The results show that the crystallization behavior of HA/PLLA composites was strongly affected by the content of HA and crystallization temperature, and the addition of HA could promote nucleation and enhance the crystallization rate. When isothermal crystallization was carried out at 110℃, the HA/PLLA nanocomposite with 1% HA content crystallized most rapidly among all the composites and the half crystallization time was only 1.0 min. Banded spherulites were observed for the HA/PLLA composites, but no banded spherulites were seen in the crystals of PLLA under the same condition.