木質素磺酸鹽碳化製備木質素基碳纖維生產之研究

The Production of Lignin-based Carbon Fibers from Carbonization of Lignosulfonate

顏詩軒(Shih-Hsuan Yen)

指導教授 ： 張豐丞

國立臺灣大學/生物資源暨農學院/森林環境暨資源學研究所/碩士(2015年)

https://doi.org/10.6342/NTU.2015.10186

摘要

本試驗以木質素磺酸鹽作為前驅物研發木質素基碳纖維，透過靜電紡絲法製作纖維並加以碳化，找尋其最適的碳化製程參數，並測試木質素基碳纖維之性質。結果顯示，預氧化製程以1°C/min升溫至250°C最佳，能改善纖維試片完整性並提高纖維含碳比例。碳化製程以兩階段升溫進行效果較好，其碳纖維產率提升且維持纖維試片之完整性。碳化的製程以第一階段升溫速率為關鍵，須以較慢的升溫速率進行，試驗結果顯示以1°C/min升溫速率最為合適，若高於此速率時，纖維易破損。第一階段碳化溫度則以400°C較佳，且碳纖維產率較高。而碳化第二階段試驗結果顯示，隨碳化最終溫度上升，碳纖維產率減少且纖維含碳比例則隨之增加，而電傳導率跟拉伸強度亦隨之增加。碳化第二階段之持溫時間延長會使碳纖維產率下降及纖維含碳比例上升，其中纖維含碳比例可達86.01%，電傳導率可達1388 cm/Ω。再將最佳碳化製程用於製備活性碳纖維，以CO2作為活化劑，並將製程分為一階段活化及兩階段活化。試驗結果顯示，燒失率及比表面積隨活化持溫時間延長而增加。而碳化階段及預碳化溫度為700°C時，活性碳纖維有較佳表現，其燒失率較低且比表面積較高。將兩種活化法相比，則發現兩段式活化較一段式活化效果佳，可降低燒失率且所得之比表面積明顯較高，可達643.89 m2/g。綜合以上結果所示，碳纖維製備之升溫速率為決定纖維型態及性質之關鍵。而木質素磺酸鹽經碳化及活化後，可得到良好的電傳導率及比表面積，顯示木質素基碳纖維相當值得後續的研究及開發應用。

關鍵字

木質素磺酸鹽 ； 碳化 ； 碳纖維 ； 活性碳纖維 ； 靜電紡絲法

並列摘要

This study aimed to use lignosulfonate as a precursor to develop lignin-based carbon fibrous materials and investigate producing lignin-based carbon fibers through electrospinning and subsequent carbonization. In addition, this study attempted to optimize the fiber production process and examined the properties of such carbon fibers. The results revealed that producing the fibers in a pre-oxidation process with a heating rate of 1°C/min and target temperature of 250°C can generate a favorable outcome. Specifically, the pre-oxidation enhanced the integrity and carbon content of fiber mats. Moreover, in contrast to one-phase carbonization, the two-phase carbonization process is favorable to increase fiber production and improve fiber mat integrity. According to the results, the heating rate at the first carbonization phase was crucial, and the rate of 1°C/min facilitated achieving an optimal fiber production. The produced fibers were prone to rupture at heating rates over 1°C/min. Concurrently, the target temperature of the first carbonization phase was also important; namely, 400°C rather than 300°C can assist in improving the fiber mat integrity and fiber production. In the second carbonization phase, when the final temperature was increased, the fiber production and diameter decreased, and the fiber carbon content, electric conductivity, and tensile strength increased. Moreover, an increase in the carbonization time can decrease the overall fiber production and increase fiber carbon content; consequently, the carbon content and electric conductivity could increase to 86.01% and 1388 cm/Ω, respectively. To produce activated carbon fibers, the proposed optimal carbonization process was applied using CO2 as the activation agent, and one-step and two-step activation processes were also conducted. According to the experimental study, when the activation time was prolonged, the burn-off rate and specific surface area increased; moreover, the ideal pre-carbonization temperature was 700°C. The results also suggested that two-step activation was superior to one-step activation in decreasing the burn-off and increasing the specific surface area (the maximal area was 643.89 m2/g). In summary, the proposed lignin-based carbon fibrous material can be used as a potential electronic conductor or adsorbent and is worth exploring and developing for future applications.

並列關鍵字

Lignosulfonate ； Carbonization ； Carbon fibers ； Activated carbon fibers ； Electrospinning

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