| 摘要: | 本研究中製備聚乙烯醇(PVA)與氫氧基磷灰石(HA)水凝膠複合材料，先將聚乙烯醇與氫氧基磷灰石混合加熱使聚乙烯醇完全溶於去離子水中，將其PVA/HA水溶液放入-20 ℃低溫冷藏箱中12小時，再移出室溫下解凍2小時，反覆此動作1~7次，得到PVA/HA水凝膠，實驗中探討當冷凍解凍次數不同與氫氧基磷灰石含量不同兩種系統做探討。
經由熱重分析儀(TGA)顯示，當冷凍解凍次數提高時，熱性質有上升的趨勢；而當添加氫氧基磷灰石含量增加時，此現象依然存在。由高性能動態流變儀(AR)測試得知，當冷凍次數提高時，因PVA/HA複合水凝膠物理交聯提高，儲存模數(G’)亦有上升的趨勢產生。經XRD測試得到，當PVA/HA複合水凝膠結晶度提高，其繞射峰有明顯提高的現象。SEM圖中顯示出，隨著冷凍解凍次數增加時，PVA與HA顆粒的包覆效果更好，分子鏈間的結合更緊密。拉力測試中，當物理交聯程度提高時，PVA/HA複合水凝膠的抗張強度與楊氏系數亦會提高。而相同的冷凍解凍次數下，由於加入9 %的HA後產生分散不均勻的現象，故抗張強度有下降的現象。而利用抗張測試中利用Mooney–Rivlin equation看出PVA/HA複合水凝膠在微觀的結晶中，當冷凍解凍次數提高時，曲線有越早上揚的趨勢，而在冷凍解凍次數達到七次時，HA含量對於抗張數值有明顯的影響及變化。由應變回歸實驗得知，當冷凍解凍次數提高時，應變回復值越接近原點，表示隨著物理交聯程度提高時，分子間作用力越大，使得PVA/HA複合水凝膠彈性越好，故在線性範圍內做回復實驗時，越接近完全回復的彈性體。
In this paper, we present the polyvinyl alcohol(PVA)/hydroxyapatite(HA) hydrogel nanocomposite. First, we mix PVA and HA in the hot DI-water solution. Second, we put the solution in the -20 ℃ refrigerator for 12 hours, then take it out at room temperature to thaw for two hours. And hydrogel was obtained by repeating second step 1 to 7 times. The PVA/HA hydrogel that we get was divided into two systems, different times of freezing and thawing cycle and different contents of HA, to discuss.
The TGA testing revealed when increasing the freezing and thawing cycles, the thermal properties would increase, too; the thermal properties still increased when increasing the contents of HA. In Advanced Rheometer testing, the PVA/HA hydrogel’s physical crosslinking is enhanced by increasing freezeing and thawing cycles, and the storage modulus is enhanced, too. In XRD testing, the characteristic peak of diffraction would obviously raise when the crystallinity of PVA/HA increases. The SEM figure shows the more times of freezing and thawing cycles we increased, the stronger bonding of molecule we had. In tensile testing, if the physical crosslinking enhanced, the tensile strength、Young’s modulus would be enhanced, too. Under the same freeze and thaw cycles, the tensile strength of 9% HA addition decreased because of dispersion was not uniform. In tensile testing, using Mooney–Rivlin equation to prove the micro structure of PVA/HA hydrogel, the curves will show early upturn by increasing the times of freeze and thaw cycles. When freezing and thawing cycles arrived 7 cycles, the contents of HA will obviously affect the tensile strength. In the strain recovery testing, we can conclude that, as the times of freezing and thawing cycles increase, the strain recovery will become more close to the origin. This outcome reveals that as the physical crosslinking rises, the attractive power of molecule will become more strong, and thus making the elasticity of PVA/HA hydrogel well. In conclusion, within the linear elactic range, PVA/HA hydrogel will be more close to fully recovered elastomer. |
