Effect Of Different Particle Sizes Of Microspheres On Pore Structure Of Calcium Phosphate Cement

Objective: To explore the effect of microsphere porogen on the pore connectivity and porosity of calcium phosphate cement (CPC), and to provide reference for the addition of microsphere porogen.Methods: 1.Constructing mathematical model: Four kinds of mathematical models of two kinds of sphere packing with different particle sizes are constructed, and calculated the sphere packing density and the index of sphere connectivity.2. According to the result of mathematical modeling, the introduction of poly (methyl methacrylate) (PMMA) microspheres as research tools, set up three experimental groups :① 15μm/100μm PMMA microspheres and CPC composite ; ② 50μm/100μm PMMA microspheres and CPC composite; ③15μm/20μm PMMA microspheres and CPC composite ; ④ 100μmPMMA microspheres and CPC composite. The volume ratios of the three groups were 55.9%. Scanning electron microscopy was used to observe the accumulation of PMMA microspheres, and the connectivity index of the microspheres was calculated.3. the use of four kinds of PMMA microspheres (15μm, 20μm, 50μm and 100 μm) and CPC compound, each kind of microspheres accounted for complex volume ratio respectively 20%, 40% and 60%, respectively, marshalling group A1, A2 and A3 group; group B1, B2 and B3 group; group C1, C2 and C3 group;group D1, D2 and D3 groups and simple CPC group (Group E). The internal porosity of the composite was observed after calcination, and the porosity was calculated by the density method. Data results using SPSS 16.0 statistical software to statistical.Result: 1. Mathematical model calculation results: the four mathematical models of particle diameter ratio are 0.15:1, 0.41:1, 0.7:1 and 1:1; the sphere packing density are 60.8%, 55.9%, 55.9% and 60.4% ; the index of sphere connectivity are 1.60, 1.67, 1.50, 1.71, respectively.2. Sphere connectivity index results: 15μm /100μm PMMA microspheres,50μm/100μm PMMA microspheres, 15 μm/20μm and 100μm PMMA microspheres with CPC composite sphere connectivity index were0. 18 ±0. 07,0.21 ± 0.46, 0.041± 0.09 and 0.451± 0.09.3. Scanning electron microscopy (SEM) found that PMMA microspheres /CPC complexes have more pores than CPC control group, with the PMMA microspheres particle size increased, the pore diameter increased; with increase of the PMMA microspheres volume ratio, the pore number increased.Conclusion: 1. We introduce a quantitative index of pore connectivity, the higher the pore connectivity index is, the better the connectivity of the pores is2. Two microspheres with different particle sizes, the particle size ratio is greater than 0.7, the sphere connectivity index is higher.3. The microspheres and CPC were compounded with the increase of the pore volume ratio and the porosity of the composites increased, but the increase of the porosity was not related to the particle size.