棉浆不同预处理方法制备纤维素纳晶的研究

Preparation of Cellulose Nanocrystal from Cotton Pulp with Different Pretreatments

关键词:  棉浆  酸水解  纤维素纳晶  表征

Key Words:cotton pulp  acid hydrolysis  cellulose nanocrystal  characterization

摘要:分别以未经任何预处理棉浆、PFI磨磨浆预处理棉浆、二甲基亚砜（DMSO）预处理棉浆和质量分数为4% NaOH预处理棉浆为原料，采用酸水解法制备纤维素钠晶（Cellulose Nanocrystal, CNC），并采用扫描电镜（SEM）、X射线衍射图谱（XRD）、红外光谱分析（FTIR）及热重分析(TG)等方法对CNC的性能进行表征和分析。SEM分析表明,前3种方法制备的CNC为棒状粒子，长度为200~400 nm、直径为几十纳米；但NaOH预处理制备的CNC为直径在100 nm左右的球状粒子，且有明显的絮聚现象。XRD分析表明,CNC和棉浆属同一晶型，但CNC结晶度提高。FTIR分析表明，采用以上4种方法制备的CNC和棉浆具有相同官能团。TG分析表明,制备的CNC热稳定性低于棉浆，这一点在采用NaOH预处理制备的CNC上表现更明显，且该方法制备的CNC在600℃时，残留率最大（约40%），具体原因还有待进一步研究。

Abstract:The cotton pulps pretreated with PFI refining, dimethyl sulfoxide(DMSO), 4% sodium hydroxide respectively and without any pretreatment were used as raw material to prepare the cellulose nanocrystals(CNCs) by acid hydrolysis. The properties of the CNCs were characterized by scanning electronic microscope(SEM), X-ray diffraction(XRD), infrared spectrum(IR) and thermogravimetric analysis (TG). The observation of SEM indicated that the CNCs prepared with by the first 3 pretreated cotton pulps had rod-like shape, the length was 200～400 nanometers and the diameter was about dozens of nanometers. But the CNCs prepared with NaOH pretreated cotton pulp had spherical shape and remarkable flocculation, the diameter was about 100 nanometers. XRD results indicated that the CNCs had the same crystal type as cotton pulp and the crystallinity of CNCs was improved. IR spectroscopic analysis demonstrated that the CNCs had the same functional groups as cotton pulp. TG analysis of the CNCs showed that the thermal stability of CNCs was worse than that of cotton pulp. But surprisingly the CNCs using NaOH pretreated cotton pulp as raw material had the largest residual quantity up to 40% at 600℃, the reason of this unordinary result remains to be explained in further study.