Preparation And In Vitro Degradation Of Poly(propylene Fumarate)/(calcium Polyphosphate/calcium Sulphate) Composites

In this study, a two-part bone tissue engineering scaffold which consists of solidpoly（propylene fumarate）（PPF） matrix and calcium polyphosphate/calcium sulphate（CPP/CaSO₄） filler was investigated. This new material can form pores in situ, andkeep enough compressive strength in a certain time after the pores formed.Poly（propylene fumarate）（PPF） was synthesized by a two-step method, andcharacterized with1H-NMR and GPC. We fabricated calcium polyphosphate powder,and then we investigated on the preparation of porous spherical CPP/CaSO₄granules.PPF/CPP/CaSO₄composites were formed by using N-vinyl pyrrolidinone （NVP） as acrosslinking monomer, benzoyl peroxide （BPO） as a radical polymerization initiator,N, N-dimethyl-p-toluidine （DMPT） as an accelerator, and CPP/CaSO₄granules asfiller. The phase composition of CPP/CaSO₄granules sintered at differenttemperatures and degradation product was analyzed by X-ray powder diffraction（XRD）; the degradation behavior of composites were investigated by weight loss,water absorption and swelling degree; the morphology change was observed by scanelectron microscope （SEM）.The phase composition of CPP/CaSO₄granules was effected by sinteringtemperature and CPP/CaSO₄ratio. All the armorphous CPP crystallized to β-CPP inthe CPP/CaSO₄granules sintered at580℃. Yet, for the CPP/CaSO₄granules sinteredat560℃, the more CaSO₄content, the less β-CPP crystallization. Thus it can beconcluded that the addition of CaSO₄could inhibit the devitrification of CPP.The in vitro biodegradation property of PPF/CPP/CaSO₄composites wasexamined by using cylindrical specimens with length of5mm and diameter of6mm.The composite degradated faster with a higher CaSO₄content or a higher NVP/PPFratio. The compressive strength decreased with the decrease of NVP/PPF ratio and theincrease of the CaSO₄content.