| 摘要: | 傳統塑膠包裝價格低廉、使用方便、易加工，多年來被廣泛使用於民生用途，惟其不易分解之特性，對環境造成巨大衝擊，近幾年受到環保法規及國際環保思潮之影響，已發展出環境污染較低之替代性材料，以取代塑膠袋、塑膠容器。本研究將生物可分解性(biodegradable)極高之澱粉(starch)及聚乙烯醇(polyvinyl alcohol, PVA)進行摻合，並以甘油作為增塑劑對澱粉及聚乙烯醇進行塑化，進而探討其對有機溶劑之抗化學浸透性(permeation)。
本研究首先開發一新型浸透測試腔，其結合固相微萃取(solid-phase microextraction, SPME) 技術以減少採集介質化學品之用量，並可降低對浸透化學物之偵測極限。本研究利用新型浸透測試腔，探討二氯甲烷、二氯乙烷及苯對於高密度聚乙烯(high density polyethylene，HDPE)地工止水膜(geomembrane)之浸透性，並比較其與ASTM F739標準測試方法之差異；結果顯示兩種測試腔所得到之浸透係數(permeability coefficient)有顯著相關性(r=0.96)，因此新型SPME測試腔將可用於測試高分子薄膜之抗浸透性。
隨後利用新型浸透測試腔探討摻合不同比例(0%、10%、20%及30%)改質澱粉之聚乙烯醇，對於二氯甲烷、1,2-二氯乙烷、三氯乙烯與四氯化碳之抗浸透性。研究結果發現隨著改質澱粉含量的增加，有機溶劑之浸透性會增加，其浸透性分別為二氯甲烷>1,2-二氯乙烷>三氯乙烯>四氯化碳。最後利用Fick’s Law及質傳模式，得到測試有機溶劑在澱粉/PVA薄膜之擴散係數(diffusion coefficient)及溶解度(solubility)；結果發現在PVA薄膜中，受測有機溶劑之擴散係數及溶解度均與其分子量、莫耳體積和辛醇-水分配係數(Log Kow)有統計上顯著相關。但是當改質澱粉與PVA摻合後，有機溶劑在薄膜之擴散係數與其分子量、莫耳體積和辛醇-水分配係數未達統計上顯著相關，此結果顯示甘油及澱粉可能影響有機溶劑分子在PVA薄膜之擴散作用。本研究結果將可用以評估使用澱粉/PVA材料時，有機溶劑之化學浸透潛勢。
By environmental law and international environmental impact of the propaganda, we have to look for what will not pollute the environment and find out alternative materials to replace plastic bags, plastic containers and plastic device. Therefore, it is a hot topic of biodegradable plastics of chemical and material science. In this study, the starch and polyvinyl alcohol (PVA) were mixed with spin starch/PVA blend fiber. Apart to this, Starch and PVA were plasticized by glycerin.
In this study, a stainless steel cell with a one-inch diameter was proposed to investigate the permeation of dichloromethane, 1,2-dichloroethane, and benzene through high-density polyethylene in a closed-loop test system. Because of in-cell SPME sampling, the new test cell used a smaller volume of collection medium and showed a more sensitive means to monitor the permeant in the collection medium. Compared with the ASTM F739 cell, the standardized breakthrough times were shorter, and the permeability coefficients were greater for the new cell. Although the optimum SPME sampling parameters should be obtained in advance, the in-cell SPME method can be an appropriate approach in determining the chemical resistance of polymeric membranes to permeation by organic solvents.
Afterward the permeation experiments were conducted using the in-cell SPME method to investigate the permeability of dichloromethane, 1,2-dichloroethane, trichloroethylene, and carbon tetrachloride through modify starch/PVA films. The permeation coefficients of organic solvents in the starch/PVA film were dichloromethane> 1,2-dichloroethane> trichloroethylene> carbon tetrachloride, and found to be increased with the starch contents.
Simultaneously, a mass transfer model was established using Fick’s Law to obtain the diffusion coefficient and solubility of organic solvents in the modify starch/PVA films. It was found that the diffusion coefficients and solubilities of organic solvents in PVA films were significantly correlated well with their molecular weights, molar volume and Log Kow, respectively. However, it is doubtful that the diffusion of organic solvents in the starch/PVA was affected by the plasticizer blended in the polymer film. |
