Influence of the addition of microcrystalline cellulose (Mcc) on structural properties of cellulose nanofibrils (NFC) suspensions and films

ABSTRACT Background: In the study of biologically-based materials, nanocelluloses have been showing great prominence and positioned themselves as promising alternatives for the production of different industrialized materials. This polymer has received significant attention recently because it is produced from renewable sources and has unique properties offered by its organic nature and semi-crystalline structure. This work aimed to study the structural properties of suspensions and films by increasing MCC concentration in the form of powder with variations of 5 % (m/m) from 5 % to 30 %. Results: As expected, incorporating MCC increased the Segal index. The morphological analysis showed an increase in the diameters of the structures (NFC / MCC) in the suspensions when the presence of MCC was more significant, and films with cluster formations were observed. The films showed air permeability. Due to the MCC increase, the surface charge had results close to electrostatically stabilized nanosuspensions. An increase in the resistance to thermal degradation of the films was also observed Conclusion: NFC has promising properties for different applications; it provides a film with a stable structure and is resistant to oxygen and tensile stresses. In addition, MCC has excellent potential due to its high crystallinity, structural characteristics, and nature. The increase of the MCC content altered the properties of the suspensions and films produced with NFC, forming a cohesive and resistant film, and influencing the performance of the different properties of the materials evaluated in this study, like air permeability, suspension stability, and thermal resistance.

摘要
研究背景：在生物基材料研究领域，纳米纤维素（nanocellulose）一直展现出极高的关注度，并已成为制备各类工业化材料的极具潜力的替代原料。该聚合物近年来受到广泛关注，因其源自可再生资源，且凭借其有机本质与半结晶结构赋予了独特的性能。本研究旨在通过调整粉末状微晶纤维素（MCC，microcrystalline cellulose）的添加浓度，以5%（质量比，m/m）为梯度设置浓度范围为5%至30%，探究其对悬浮液与薄膜结构性能的影响。
研究结果：正如预期，添加MCC可提升西格尔指数（Segal index）。形貌分析结果显示，当悬浮液中MCC占比提升时，悬浮液内的纳米原纤化纤维素（NFC，nanofibrillated cellulose）/微晶纤维素（MCC）复合结构的直径随之增大，且观测到薄膜出现团簇状结构。所制备的薄膜具备透气性能。随着MCC添加量提升，薄膜表面电荷的检测结果接近静电稳定型纳米悬浮液的电荷水平。同时观测到薄膜的抗热降解性能得到提升。
研究结论：纳米原纤化纤维素（NFC）在各类应用场景中具备可观的应用潜力：其制备的薄膜结构稳定，且具备良好的抗氧性与抗拉伸应力性能。此外，微晶纤维素（MCC）凭借其高结晶度、独特的结构特性与天然属性，同样具备极佳的应用潜力。MCC添加量的提升会改变以NFC为基材制备的悬浮液与薄膜的各项性能：可形成内聚性优异的稳定薄膜，并对本研究中评估的材料多项性能产生影响，包括透气性能、悬浮液稳定性与热抗性。