摘要
对纳米纤维素(cellulose nanocryslal,CNC)进行羧甲基化改性,以提高其再分散性。以取代度(degree substitution,DS)为响应值,利用响应面法(response surface methodology,RSM)优化羧甲基纳米纤维素(N-CMC)的制备工艺,并运用透射电镜(TEM)对改性前后的CNC进行形貌表征,研究羧甲基改性对纳米纤维素结构的影响。结果表明:对N-CMC取代度有显著影响的4个因素为,Na OH/CNC质量比、Na OH/一氯乙酸(MCA)摩尔比、醚化Ⅰ段温度和醚化Ⅰ段时间;中心组合设计结合RSM分析确定主要影响因素的最佳水平组合为,Na OH/CNC质量比1.44、Na OH/MCA摩尔比2.40、醚化I段温度50℃、醚化I段时间50 min,此条件下N-CMC取代度的平均值为1.343±0.015,与理论预测值1.364相符。TEM分析显示,改性后的CNC仍保持了球形的结晶结构,只是粒径略有增大,且表面结构更加疏松。羧甲基取代纳米纤维素表面的部分羟基,并未显著影响其结晶结构,且有利于其在极性介质中的再分散。
In this study,cellulose nanocrystal（ CNC） was modified by carboxymethylation to improve their redispersion. Specifically,the response surface methodology（ RSM） was applied to optimize the preparation conditions of carboxymethylated cellulose nanocrystal（ N-CMC） to obtain the maximum substitution degree（ DS） of CNC. Compared with the original morphology of CNCs,modified CNC was characterized by transmission electron microscopy（ TEM） to study the effect of carboxymethylation on the crystalline structure of CNC. The results showed that the DS of N-CMC was significantly influenced by Na OH/CNC mass ratio,Na OH/monochloracetic acid（ MCA） mole ratio,first-stage etherification temperature and time. RSM analysis based on Central Composite Design was applied to assess the optimal values of the selected factors,and the optimal conditions were： Na OH/CNC mass ratio 1. 44,Na OH/MCA mole ratio 2. 40,first-stage etherification temperature 50 ℃,for 50 min. Under the optimum conditions,the experimental value of DS of 1. 343 ± 0. 015 was well consistent with the predicted value of 1. 364. Furthermore,morphology characterization confirmed that the modified CNC was still spherical nano particles,only the particle size slightly increased,and the microstructure became looser. Therefore,Carboxymethylation did not significantly change CNC＇s crystal structure,but improved its re-dispersion in the polar medium.
出处
《食品与发酵工业》
CAS
CSCD
北大核心
2016年第3期142-149,共8页
Food and Fermentation Industries
基金
重庆市科委民生专项一般项目(cstc2015shmszx0367)2015--甘薯渣纤维高值化利用关键技术研究
重庆市科委集成示范项目(cstc2012jcsf-jfzh0033)--重庆特色农产品产业协同创新与关键技术攻关
社会事业与民生保障科技创新专项--薯类食品安全加工技术研究与应用(cstc2015shms-ztzx0113)
关键词
纳米纤维素
羧甲基改性
响应面分析
形貌表征
cellulose nanocrystals
carboxymethylation
response surface analysis
morphology characterization
