Recently, cellulose nanofibers (CNF) have gained significant attention as renewable and high-value nano-biomaterial that has the potential to regulate microstructures and enhance the strength properties of paper products. However, the distribution of CNF in paper sheets may impact the physical properties differently, requiring further understanding. In this study, the effects of different CNF distributions on pore sizes and strength properties in paper sheets were investigated. The hypothesis is that the different distributions of CNF within paper sheets can exhibit different functions in improving the physical properties of paper sheets. Three types of paper sheets containing CNF were respectively prepared by mixing with pulp (CNF (mixture)), distribution on the surface of paper sheets (CNF (surface)) and adding in the middle of paper sheets (CNF (middle)). Results show that CNF can narrow the pore size distribution of paper sheets, particularly in samples with CNF (surface) and CNF (middle) that form dense CNF layers. The highest mechanical strength improvement was observed with mixed CNF. X-ray photoelectron spectroscopy (XPS) analysis revealed that this is due to the strong hydrogen bonding between CNF and pulp fibers, resulting from a large bonding area and effective contact with pulp fibers. This study provides a new perspective on CNF distribution within paper sheets for improving wet web strength properties.

最近，纤维素纳米纤维 (CNF) 作为可再生和高价值的纳米生物材料受到了广泛关注，它具有调节微观结构和增强纸制品强度性能的潜力。然而，CNF 在纸张中的分布可能会不同地影响物理特性，需要进一步了解。在本研究中，研究了不同 CNF 分布对纸张孔径和强度性能的影响。假设是 CNF 在纸张中的不同分布可以在改善纸张的物理特性方面表现出不同的功能。通过与纸浆（CNF（混合物））混合，分别制备了三种含有 CNF 的纸张，分布在纸张表面 (CNF (surface)) 和添加在纸张中间 (CNF (middle))。结果表明，CNF 可以缩小纸张的孔径分布，特别是在具有 CNF（表面）和 CNF（中间）形成致密 CNF 层的样品中。使用混合 CNF 观察到最高的机械强度改进。X射线光电子能谱（XPS）分析表明，这是由于CNF与纸浆纤维之​​间的强氢键结合，结合面积大，与纸浆纤维有效接触所致。本研究为改善湿纸幅强度性能的纸张内 CNF 分布提供了新的视角。特别是在具有 CNF（表面）和 CNF（中间）形成致密 CNF 层的样品中。使用混合 CNF 观察到最高的机械强度改进。X射线光电子能谱（XPS）分析表明，这是由于CNF与纸浆纤维之​​间的强氢键结合，结合面积大，与纸浆纤维有效接触所致。本研究为改善湿纸幅强度性能的纸张内 CNF 分布提供了新的视角。特别是在具有 CNF（表面）和 CNF（中间）形成致密 CNF 层的样品中。使用混合 CNF 观察到最高的机械强度改进。X射线光电子能谱（XPS）分析表明，这是由于CNF与纸浆纤维之​​间的强氢键结合，结合面积大，与纸浆纤维有效接触所致。本研究为改善湿纸幅强度性能的纸张内 CNF 分布提供了新的视角。