机械处理对花生壳纤维素纳米纤丝的性能影响

Influence of Mechanical Treatments on Properties of Cellulose Nanofiber from Peanut Shell

利用不同机械力对花生壳纯化纤维素进行逐级开纤处理,研究了不同尺度纤维素纳米纤丝(CNF)的微观形貌,采用抽滤法将CNF制备成膜,对比分析了不同样品的断面特征、力学性能、光学性能以及热性能。结果表明,研磨可从花生壳纯化纤维素中剥离出直径约200nm的CNF,纤丝制备成膜后结构较为疏松,层间距大,再经高压均质和超声连续处理可制备出高长径比花生壳CNF,纤丝直径分布在15nm左右,成膜后在膜断面形成了紧密连续结构。经研磨-均质-超声逐级细化后的CNF膜的透光率可达66.7%,相比研磨膜提高了近40%,同时表现出极佳的力学性能,拉伸强度和杨氏模量分别为181MPa和7.1GPa,较研磨膜分别提高了99%和22%,断裂伸长率亦提升至7.3%。此外,该薄膜的热膨胀系数低至12.2ppm/K,具有优异的热稳定性。

Purified cellulose from peanut shell was gradually defibrillated by different mechanical methods to obtain cellulose nanofibers.The morphologies of the cellulose nanofiber(CNF)with different diameters were observed through SEM.The morphology of cross sections,mechanical properties,optical properties and thermal properties of different CNF sheets were compared.The results show that grinding can fibrillated the cellulose fiber to CNF with the diameter about 200 nm.This kind of CNF film has a large distance between layers and loose structure.Followed by high pressure homogenization and ultrasonication,high aspect ratio CNF with diameters about 15 nm were successfully prepared.This CNFs film has a dense structure in cross section.The regular transmittance of the film with the diameter of 15 nm was 66.7%,which is 40%higher than the CNF film just by grinding.Meanwhile,this kind of film also shows the excellent mechanical properties.It has a tensile strength of 181 MPa and Young's modulus of 7.1 GPa.Meanwhile,the elongation at break of the film is improved to 7.3%.Moreover,the film exhibited favorable thermal stability with the CTE value as low as 12.2 ppm/K.