【摘要】： 木質(zhì)素是植物纖維原料主要成分之一,在自然界中蘊藏量僅次于纖維素。目前人類對木質(zhì)素的利用還很不充分。由于木質(zhì)素中含碳量較高(一般在55%～66%之間),因此可作為碳纖維原料進行利用。 本文以乙酸木質(zhì)素及堿木質(zhì)素為原料制備納米碳纖維。首先采用靜電紡絲法制備乙酸木質(zhì)素納米纖維,然后通過預(yù)氧化以及碳化處理得到木質(zhì)素納米碳纖維。采用THF, DMF,乙酸三種不同的溶劑對乙酸木質(zhì)素進行靜電紡絲。結(jié)果表明以乙酸為溶劑可以得到AAL納米纖維,以THF以及DMF為溶劑不能電紡成纖。為了在碳化過程中保留纖維形態(tài),需要對原纖維進行預(yù)氧化處理。結(jié)果發(fā)現(xiàn),AAL納米纖維的預(yù)氧化處理需要在空氣氛圍中在低于1℃/min的升溫速率下進行。對AAL纖維的碳化處理在升溫速率100℃/h的條件下,碳化溫度需要低于700℃。對700℃碳化的纖維的結(jié)晶形態(tài)以及表面元素含量進行了分析。結(jié)果表明碳為無定形碳,碳含量86.7%,碳化不完全。 采用靜電紡絲法制備了堿木質(zhì)素納米纖維,并討論了電導(dǎo)率,溶液濃度,電壓,極距,推速對堿木質(zhì)素靜電紡絲的影響。結(jié)果表明隨著溶液質(zhì)量分數(shù)的增加,纖維的直徑顯著增大。當溶液質(zhì)量分數(shù)為40%以及45%時,隨電壓升高,纖維直徑先增大后減小,在60kv時最小。推速增大,纖維直徑顯著增大。極距對纖維形貌沒有影響,對纖維直徑影響也不大。隨極距增大,纖維直徑先減小后增大。對堿木質(zhì)素納米纖維分別在500℃,600℃,700℃進行了碳化處理。分析了熱處理過程中纖維直徑的變化,發(fā)現(xiàn)纖維直徑減小說明纖維在熱處理過程中發(fā)生收縮。并對不同溫度下碳化的纖維的結(jié)晶形態(tài)以及石墨化程度進行了分析。發(fā)現(xiàn)碳纖維均為無定形碳。隨著碳化溫度的升高,石墨化程度增加。
[Abstract]:Lignin is one of the main ingredients of plant fiber, which is second only to cellulose in nature. At present, human use of lignin is still very inadequate. Lignin can be used as carbon fiber because of its high carbon content (usually between 55% and 66%). Carbon nanofibers were prepared from lignin acetate and alkali lignin. Firstly, lignin nanofibers were prepared by electrospinning, and then lignin nanofibers were prepared by preoxidation and carbonization. The lignin of acetic acid was electrospun with three different solvents of THF, DMF, acetic acid. The results showed that AAL nanofibers could be obtained with acetic acid as solvent, while THF and DMF could not be electrospun into fibers. In order to preserve the fiber morphology during carbonization, preoxidation of the original fiber is needed. The results show that the preoxidation of AAL nanofibers needs to be carried out at a heating rate of less than 1 鈩，

本文編號：2326797