Objectives

To compare the effects of replacing reinforcing barium glass particles by DCPD (dicalcium phosphate dihydrate), as opposed to simply reducing glass filler content, on composite flexural properties and degree of conversion (DC). On a second set of experiments, composites with different “DCPD: glass” ratios were exposed to prolonged water immersion to verify if the presence of DCPD particles increased hydrolytic degradation. Methods: Two series of composites were prepared: 1) composites with total inorganic content of 50 vol% and “DCPD: glass” ratios ranging from zero (glass only) to 1.0 (DCPD only), in 0.25 increments, and 2) composites containing only silanized glass (from zero to 50 vol%). Disk-shaped specimens were fractured under biaxial flexural loading after 24 h in water. Another set of specimens of composites with different “DCPD: glass” ratios was stored in water for 24 h, 30, 60, 90 and 120 days and tested in flexure. DC was determined using FTIR spectroscopy. Data were analyzed using Kruskal-Wallis/Dunn test (flexural properties) or ANOVA/Tukey test (DC, alpha: 0.05). Results: For glass-only composites, reducing inorganic content caused a linear decrease in strength. The presence of DCPD did not affect composite strength up until a “DCPD: glass” ratio of 0.5. On the other hand, materials with 0.75 and 1.0 DCPD showed significantly lower strength than the glass-only composite with 12.5 vol% filler and the unfilled resin, respectively (p < 0.001). Except for the 0.25 DCPD composite, the presence of DCPD did not contribute to increase flexural modulus. After water storage, composites containing DCPD showed higher percent reductions in properties than the control, but only in a few cases the effect was statistically significant (strength: 0.5 DCPD, modulus: 0.25 and 1.0 DCPD). DC was only marginally affected by DCPD fraction. Significance: For composites with “DCPD: glass” of 0.25 and 0.5, reductions in strength were related to the lower glass content, and not due to the presence of DCPD. Flexural modulus was primarily defined by glass content. Overall, composites containing DCPD particles presented higher reductions in properties after water storage, but it remained within limits reported for commercial materials.

中文翻译：

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正磷酸钙的作用：增强玻璃比和延长的储水量对再矿化复合材料的弯曲性能。

目标

为了比较用DCPD（磷酸二钙二水合物）代替增强钡玻璃颗粒（而不是简单地减少玻璃填料含量）对复合材料弯曲性能和转化率（DC）的影响。在第二组实验中，将具有不同“ DCPD：玻璃”比率的复合材料暴露于长时间的水浸中，以验证DCPD颗粒的存在是否增加了水解降解。方法：制备了两种系列的复合材料：1）无机总含量为50 vol％的复合材料，“ DCPD：玻璃”比率从0.25（仅玻璃）到1.0（仅DCPD），以0.25的增量变化，以及2）仅包含硅烷化玻璃（从零到50体积％）。圆盘状试样在水中24小时后在双轴弯曲载荷作用下断裂。将另一组具有不同“ DCPD：玻璃”比率的复合材料样品在水中储存24小时，30、60、90和120天，并进行挠曲测试。使用FTIR光谱法测定DC。使用Kruskal-Wallis / Dunn检验（弯曲特性）或ANOVA / Tukey检验（DC，α：0.05）分析数据。结果：对于仅玻璃的复合材料，减少无机含量会导致强度线性下降。直到“ DCPD：玻璃”比为0.5时，DCPD的存在才影响复合强度。另一方面，具有0.75和1.0 DCPD的材料分别显示出比分别具有12.5体积％填料和未填充树脂的纯玻璃复合材料低得多的强度（p <0.001）。除0.25 DCPD复合材料外，DCPD的存在无助于提高挠曲模量。储水后，含有DCPD的复合材料的性能下降幅度要比对比例高，但只有少数情况下效果具有统计学意义（强度：0.5 DCPD，模量：0.25和1.0 DCPD）。DC仅受DCPD分数的影响很小。意义：对于“ DCPD：玻璃”为0.25和0.5的复合材料，强度降低与较低的玻璃含量有关，而不是由于DCPD的存在。弯曲模量主要由玻璃含量定义。总体而言，含有DCPD颗粒的复合材料在储水后性能下降幅度更大，但仍处于商业材料报道的极限范围内。