- 期刊
不同種類PVA對溶膠－凝膠法製備PVA/Silica混成材料性質之影響
Effects of Various Kinds of PVA on the Properties of PVA/Silica Hybrid Made by Sol-Gel Process
摘要
本研究在酸性催化劑之條件下進行四乙基矽氧烷(Tetraethoxysilane, TEOS)之溶膠－凝膠反應，並使其與不同皂化度及聚合度之PVA混成製備PVA/Silica混成材料，以探討不同性質PVA對所製備混成材料之耐水性、機械性質及熱性質之影響。由實驗結果得知，4種PVA所製備PVA/Silica混成材料均呈透明狀，顯示有機相與無機相間相容性良好，無巨觀相分離產生。各PVA/Silica混成材料之耐水性較純PVA者明顯提升，且隨TEOS添加比例及酸催化劑添加量增加而提高，以高聚合度PVA為原料者之浸水重量保留率大於低聚合度者，而部分皂化型PVA為原料者之浸水膨潤性大於完全皂化型。由拉伸性質顯示PVA/Silica混成材料之強度較純PVA者明顯提升，且受PVA聚合度的影響較皂化度明顯。由TGA及DTG分析結果可知，PVA/Silica混成材料於高溫加熱後之重量保留率比純PVA高，顯示無機相可增加PVA之熱安定性。隨酸催化劑添加量提高，其PVA/Silica混成材料之重量保留率隨之增加，且其熱降解溫度向高溫偏移。在HCl/TEOS=0.05(mol ratio)時，完全皂化型PVA所製備之混成材料其熱解ONSET溫度較部分皂化型高，然隨酸催化劑添加量增加至HCl/TEOS=0.2(mol ratio)時其熱解性質差異減少，顯示隨酸催化劑添加量之增加其無機相的網狀結構更為完整，使PVA性質對混成材料耐熱性之影響明顯降低。
並列摘要
In this study, the inorganic silica was introduced into the polyvinyl alcohol (PVA) by the sol-gel reaction of tetraethoxysilane (TEOS) under acid condition to form the PVA/Silica hybrid. Effects of the degree of polymerization and saponification of PVA on the water resistance, tensile properties and thermal stability of PVA/Silica hybrid were investigated. The appearance of PVA/Silica hybrid films prepared in this study showed well transparency, indicating the good compatibility between organic phase and inorganic phase in the hybrids. The water resistance of PVA/Silica hybrid was better than pure PVA, and the more TEOS content and acid catalyst added, the higher water resistance would be. The weight retention of PVA/Silica hybrid after water soaked was larger for PVA with higher degree of polymerization than with lower degree of polymerization. The swelling coefficient of PVA/Silica hybrid was higher for partially saponifiation PVA than fully saponifiation PVA. The tensile strength of PVA/Silica hybrid was higher than pure PVA, and dependent significantly on the degree of polymerization of PVA. From the results of TG and DTG analysis, the weight retention of PVA/Silica hybrid after high temperature heated was higher than pure PVA indicating that the inorganic phase could improve the thermal stability of PVA. With increasing the content of acid catalysis, the weight retention of hybrid would be raised and the thermal degradation would be shifted to higher temperature. PVA/Silica hybrid was prepared with fully saponification PVA had the ONSET temperature of thermal degradation higher obviously than partially saponification at HCl/TEOS=0.05 (mol ratio), but the differences of thermal properties of PVA/Silica hybrid with various PVA were decreased at HCl/TEOS=0.2 (mol ratio). The structure of inorganic became more complete with higher acid catalyst content, the influence of property of PVA on the hybrids would be reduces.