不同超声时间对竹材薄壁细胞基纳米纤维素薄膜性能的影响

Effect of Ultrasonication Time on the Properties of Nanocellulose Film Made from Bamboo Parenchyma Cells

为了高效利用竹材中的薄壁细胞,提高其附加值。首先采用物理法高效分离毛竹材中薄壁细胞和纤维。然后,采用不同时间的高强度超声处理与化学预处理制备了纳米纤维素(NCF)薄膜。结果表明,不同超声处理时间对NCF薄膜的结构和微观形貌影响较大。延长超声处理时间,可使得薄膜的微观结构变得更加完善,即表面更加光滑且截面更加致密;同时可以轻微地提高NCF薄膜的结晶度和NCF上纤维素分子间的氢键作用。另外,随着超声处理时间的增加,NCF薄膜的拉伸性能显著提高,溶胀度和水蒸气透过系数则显著降低。其中,与未处理样品相比较,超声处理50 min制得NCF薄膜的拉伸强度提高了355.4%,溶胀度和水蒸气透过系数分别降低了40.0%和81.1%。但是保水性基本保持不变。

In order to utilize the bamboo parenchyma cells efficiently and thus improve their added value. They were separated from bamboo fiber through a mechanical method. Subsequently, nanocellulose fibrils (NCFs), isolated from bamboo parenchymal cells via a combined process of high intensity ultrasonication with different times and chemical pretreatment, were used to prepare the NCF films. Results showed that ultrasonication had a considerable effect on the structure of NCF films. With the increasing in ultrasonication time, the microstructure of the film became more perfect, i.e. the surface was smoother and the cross section was denser. Meanwhile, the crystallinity of the NCF films and the hydrogen bonding between the cellulose molecules on the NCF was also slightly improved. The tensile properties of the NCF film were remarkably improved with an increment of ultrasonication time, while valves of the swelling ratio and water vapor permeability were signi ficantly decreased. Interestingly, compared with the untreated sample, the tensile strength of the NCF film with ultrasonication time at 50 min was increased by 355.4%, and the corresponding values of swelling ratio and water vapor permeability were declined by 40.0% and 81.1%, respectively. However, the water retention was basically unchanged.