Effects of modified nano HA on crystallization and rheological properties of PLA PBAT blends

The modified nano hydroxyapatite (HA)/polylactic acid(PLA)-poly (butylenes adipate-co-terephthalate)(PBAT) blends were prepared by melting co-extrusion. The crystallinity, rheological behavior, mechanical impact properties and surface structure of the modified nano HA/PLA-PBAT were studied respectively with differential scanning calorimetry (DSC), rheometer, material testing machine and scanning electron microscope (SEM). The DSC results show that the glass transition temperature of HA/PLA-PBAT blends rise first and decline finally as the modified nano HA content increases. The cold crystallization temperature decreases gradually and it reduces by 13℃. The crystallization ability of HA/PLA-PBAT is improved by increasing the crystallinity from 24.33% to 33.47%. The viscosity of HA /PLA-PBAT blends which is a non-Newtonian decrease when the shear rate rises. When the mass ratio of the modified nano HA increases, the storage modulus and the loss modulus of HA/PLA-PBAT blends gradually decrease; the yield strength, the notched impact strength and the tensile strength increase first then decrease, reaching the mass ratio of modified nano HA that is added to 2%(80/20/2). The SEM results show that a little modified nano HA could be dispersed evenly in the blends, and it could enhance the toughness of the blend system significantly.