聚乙烯醇性質對聚醋酸乙烯乳膠樹脂性能之影響

Effects of Properties of Polyvinyl Alcohol on the Performance of Polyvinyl Acetate Emulsion Resin

本研究以兩種皂化度及兩種聚合度之聚乙烯醇（PVA）做為保護膠體合成聚醋酸乙烯（PVAc）樹脂乳液，探討不同種類PVA對所合成PVAc樹脂乳液性質之影響，試驗過程以乾燥樹脂薄膜之浸水試驗分析其耐水性，以FTIR分析其分子結構，以DSC分析其熱性質，並以木條膠合進行其膠合強度試驗。由試驗結果得知，以部分皂化型PVA或聚合度較大之PVA為保護膠體所合成之PVAc樹脂乳液有較高之黏度；PVA分子將留存於乾燥PVAc薄膜中，以完全皂化型PVA為保護膠體之PVAc樹脂薄膜之耐水性質較佳；DSC分析顯示PVA本身之熱熔融及熱裂解溫度受其皂化度所影響，然所合成PVAc之熱性質則與PVA之性質無明顯關係；不同種類PVAc應用於木材膠合時，合成時採用分子量較大之PVA為保護膠體者，其膠合強度較佳，皂化度之影響則較不明顯。 In this study, polyvinyl alcohols (PVA) with two different degrees of saponification and two different degrees of polymerization were used as the protective colloid in the synthesis of polyvinyl acetate (PVAc) emulsion resins. The effects of various kinds of PVA on the performances of PVAc emulsion resin were investigated. Furthermore, the dried films of PVAc were soaked in water to estimate their water resistance. The FTIR was used to analyze the molecular structure. The DSC was used to analyze the thermal properties. The bonding strength was evaluated with wood specimens. The results showed that PVAc emulsion resins prepared with PVA of partially saponified or higher degree of polymerization as the protective colloid had the higher viscosity. The PVA used would retain in the dried films of PVAc. The films prepared from the PVAc that synthesized with the full saponified PVA as protective colloid had better water resistance. DSC analysis showed that the thermal melting and thermal degradation temperature of PVA would be influenced by the degree of saponification of PVA. But the thermal performance of PVAc was independent with the properties of PVA. As the various kinds of PVAc were used in wood gluing, the PVAc emulsion resins synthesized with higher molecular weight PVA as the protective colloid had better bonding strength. But the influence of degree of saponification was not obvious.

In this study, polyvinyl alcohols (PVA) with two different degrees of saponification and two different degrees of polymerization were used as the protective colloid in the synthesis of polyvinyl acetate (PVAc) emulsion resins. The effects of various kinds of PVA on the performances of PVAc emulsion resin were investigated. Furthermore, the dried films of PVAc were soaked in water to estimate their water resistance. The FTIR was used to analyze the molecular structure. The DSC was used to analyze the thermal properties. The bonding strength was evaluated with wood specimens. The results showed that PVAc emulsion resins prepared with PVA of partially saponified or higher degree of polymerization as the protective colloid had the higher viscosity. The PVA used would retain in the dried films of PVAc. The films prepared from the PVAc that synthesized with the full saponified PVA as protective colloid had better water resistance. DSC analysis showed that the thermal melting and thermal degradation temperature of PVA would be influenced by the degree of saponification of PVA. But the thermal performance of PVAc was independent with the properties of PVA. As the various kinds of PVAc were used in wood gluing, the PVAc emulsion resins synthesized with higher molecular weight PVA as the protective colloid had better bonding strength. But the influence of degree of saponification was not obvious.