PDF(Pubmed)
Abstract：
Porous β-tricalcium phosphate (Ca3(PO4)2; β-TCP) was prepared via freeze-drying and the effects of this process on pore shapes and sizes were investigated. Various samples were prepared by freezing β-TCP slurries above a liquid nitrogen surface at -180 °C with subsequent immersion in liquid nitrogen at -196 °C. These materials were then dried under reduced pressure in a freeze-dryer, after which they were sintered with heating. Compared with conventional heat-based drying, the resulting pores were more spherical, which increased both the mechanical strength and porosity of the β-TCP. These materials had a wide range of pore sizes from 50 to 200 µm, with the mean and median values both approximately 100 µm regardless of the freeze-drying conditions. Mercury porosimetry data showed that the samples contained small, interconnected pores with sizes of 1.24 ± 0.25 µm and macroscopic, interconnected pores of 25.8 ± 4.7 µm in size. The effects of nonionic surfactants having different hydrophilic/lipophilic balance (HLB) values on foaming and pore size were also investigated. Materials made with surfactants having lower HLB values exhibited smaller pores and lower porosity, whereas higher HLB surfactants gave higher porosity and slightly larger macropores. Even so, the pore diameter could not be readily controlled solely by adjusting the HLB value. The findings of this work indicated that high porosity (>75%) and good compressive strength (>2 MPa) can both be obtained in the same porous material and that foaming agents with HLB values between 12.0 and 13.5 were optimal.
摘要：
通过冷冻干燥制备多孔β-磷酸三钙（Ca3（PO4）2；β-TCP），并研究了该过程对孔形状和尺寸的影响。通过在-180°C下将β-TCP浆料冷冻在液氮表面上方,随后在-196°C下浸入液氮中来制备各种样品。然后将这些材料在冷冻干燥机中减压干燥，然后加热烧结。与传统的基于热的干燥相比，由此产生的毛孔更呈球形，这增加了β-TCP的机械强度和孔隙率。这些材料的孔径范围从50到200微米，无论冷冻干燥条件如何，平均值和中值都约为100µm。汞孔隙率测定数据显示，样品中含有少量，互连孔，尺寸为1.24±0.25µm，宏观，互连孔尺寸为25.8±4.7µm。还研究了具有不同亲水/亲油平衡（HLB）值的非离子表面活性剂对起泡和孔径的影响。用具有较低HLB值的表面活性剂制成的材料表现出较小的孔和较低的孔隙率，而较高的HLB表面活性剂给出较高的孔隙率和稍大的大孔。即便如此,仅通过调节HLB值不能容易地控制孔径。这项工作的结果表明，高孔隙率（>75％）和良好的抗压强度（>2MPa）都可以在相同的多孔材料和发泡剂的HLB值在12.0和13.5之间是最佳的。
