| 摘要: | 石化燃料常被用作能源資源和生產各種塑膠材料，像是塑膠、聚氨酯泡棉等，其生產過程會排放大量的二氧化碳。為了解決全球氣候變遷、石化燃料逐漸枯竭等嚴重的環境議題，國際上轉而研究生物基材料，其中聚乳酸(polylactic acid, PLA)，由於具有良好的物理性能以及可被生物分解等特點，逐漸被廣為使用以取代部分的傳統石化塑膠。但根據現有文獻顯示，目前聚乳酸塑膠的回收方法並無ㄧ特定的方式與標準，由於當PLA受到高溫的加工環境下容易裂解，因此在回收、清洗、再造粒等傳統回收方式上相當不利。再者，目前生產聚氨酯硬質泡沫體(rigid polyurethane foam, RPUF)，需要倚賴大量石化燃料，對環境較不友善。為符合國際潮流、循環經濟以及資源最大化的趨勢，本研究將聚乳酸塑膠進行化學回收，利用醇解反應使聚乳酸降解成的產物，作為聚氨酯硬質泡沫體的前驅原料，製成聚氨酯硬質泡沫材料，既能達到回收聚乳酸的目的，還可以生產聚氨酯硬質泡沫體，以減少石化燃料耗竭的問題。
本研究有二個重點，一為探討以醇解法進行化學回收生物可分解塑膠聚乳酸，形成聚酯多元醇，並進行聚氨酯硬質發泡的可行性評估；二為探討其聚氨酯硬質泡沫產品的物理及化學性質與市面上販售之聚氨酯硬質泡沫的差異。在進行PLA醇解選用2-甲基-1,3-丙二醇(2-Methyl-1,3-propanediol, MPO)及甘油二種醇類，利用甘油以增加聚酯多元醇的官能度，以提升聚氨酯硬質泡沫體的物理、化學性能，採用聚乳酸/醇類在100/70以及100/60的比例下進行實驗，其中醇類比例再細分為MPO/甘油(%/%)為100/0、97/3、95/5、90/10、85/15、80/20共12組的比例，實驗結果得到聚乳酸/醇類比例在100/70的情況下，且MPO/甘油在90/10的條件下，有最佳的物理、化學性能。;Fossil fuels are widely used as energy resources and sources of plastic materials production, such as plastics, polyurethane foam, and so on. Fossil fuels is the main sources of carbon dioxide emissions in greenhouse gases. To solve this problem, bio-based materials have been developed worldwide. Among them, polylactic acid (PLA), due to its good physical properties and biodegradability, has gradually been widely used to replace traditional petrochemical plastics. However, there is no specific method and standard to recycle waste polylactic acid plastic at present. PLA is easy to degrade under high temperature environment, so it is quite vulnerable in traditional recycling methods such as cleaning and re-granulation. In addition, the current production of rigid polyurethane foam (RPUF), relying on considerable usage of fossil fuels, is unfriendly to the environment. In order to reach circular economy and decrease the use of fossil fuels, this research aims to chemically recycle waste polylactic acid plastics, and conduct alcoholysis to degrade polylactic acid into precursors for the following polyurethane rigid foams process. It can not only achieve the purpose of recycling polylactic acid, but also produce rigid polyurethane foam to reduce the depletion of fossil fuels.
In this study, two alcohols, 2-Methyl-1,3-propanediol (MPO) and glycerol, were selected, and glycerol was used to increase the functionality of polyester polyol to improve the physical and chemical properties of polyurethane rigid foam produced. The experiments were carried out in which the ratios of PLA to alcohols were 100/70 and 100/60, respectively. Furthermore, the alcohols were subdivided into MPO and glycerol, and the ration of MPO/glycerol (%/%) were 100/0, 97/3, 95/5, 90/10, 85/15, and 80/20, respectively. It is obtained that under the condition of polylactic acid 100/70, MPO/glycerol has the best physical and chemical properties under the condition of 90/10. |
