Extraction and Silylation of Cellulose Nanofibers from Agricultural Bamboo Leaf Waste for Hydrophobic Coating on Paper

Bamboo leaves are a resource of cellulose fibers that can be further developed into value-added products. In this research, cellulose nanofibers were obtained from Tinwa bamboo leaves, and then chemically modified with (i) hexadecyltrimethoxysilane (HDTMS) and (ii) perfluorooctyltriethoxysilane (POTS). The modified nanofibers were then used as a hydrophobic biopolymer coating on paper, as an alternative to commonly used fossil-based coatings. Hydrophobicity in terms of surface and bulk properties of the coated paperboards was investigated. The results showed that the hydrophobic coatings obtained provided a high contact angle up to 141° and a decrease of water penetration speed during immersion up to 94% when using ultrasonic technique. The coated paperboards exhibited color difference values compared with an uncoated paperboard in the range of 0.4 to <2 which is hardly distinguishable from the human eye. These results suggest that a biopolymer obtained from modified bamboo leaves does in fact provide a suitable replacement for hydrophobic coating on paper.

竹叶是纤维素纤维的天然来源，可进一步开发为高附加值产品。本研究从Tinwa竹叶中提取得到纤维素纳米纤维，随后分别采用(i)十六烷基三甲氧基硅烷（HDTMS）、(ii)全氟辛基三乙氧基硅烷（POTS）对其进行化学改性。将改性后的纤维素纳米纤维用作纸张用疏水型生物聚合物涂层，以替代当前广泛使用的化石基涂层。本研究对涂布纸板的表面与本体疏水性能展开了系统探究。结果表明，所制备的疏水涂层可实现最高141°的接触角；采用超声测试时，浸泡过程中的水渗透速率可降低高达94%。与未涂布纸板相比，涂布纸板的色差范围为0.4至小于2，该色差几乎无法通过人眼分辨。上述结果证实，由改性竹叶制备的生物聚合物确实可作为纸张疏水涂层的理想替代方案。