Abstract

The effect of cellulose nanofibers (CNFs) on the mechanical and structural properties of poly (vinyl alcohol) (PVA) hydrogels cross-linked dually by a freezing/thawing method and a cross-linker (borax) was investigated using tensile tests, FT-IR measurements and synchrotron simultaneous small-angle/wide-angle X-ray scattering (SAXS/WAXS). The cross-linking with borax and addition of CNF greatly improved the tensile performance of the PVA hydrogels prepared in the freezing/thawing method, e.g., the dual cross-linking resulted in remarkable increase in the fracture strain, the Young’s modulus and the tensile strength. The fiber length effect on the mechanical properties of the CNF/PVA/borax hydrogels was examined, so that addition of CNF with longer fiber length increased the tensile modulus, whereas addition of CNF with shorter length caused extensibility higher than 1000% even at high CNF concentrations. SAXS/WAXS and FT-IR measurements have revealed that PVA was crystallized due to the freezing/thawing process, and both of PVA and CNF were cross-linked with borax, and hydrogen bonds between hydroxy groups of PVA (or/and CNF) were formed, indicating that the multiple cross-linking is effective for improvement of the tensile performance. In addition, the CNF/PVA/borax gel with the multi-physical cross-linking was found to possess the ability of the self-healing.

中文翻译：

---

冻融法与硼砂交联的纤维素纳米纤维/聚乙烯醇水凝胶的机械和结构性能

摘要

使用拉伸测试，FT-FT法研究了纤维素纳米纤维（CNFs）对通过冷冻/解冻方法和交联剂（硼砂）双重交联的聚乙烯醇（PVA）水凝胶的机械和结构性能的影响。红外测量和同步加速器同时进行小角度/广角X射线散射（SAXS / WAXS）。与硼砂的交联和CNF的添加大大提高了冷冻/解冻方法制备的PVA水凝胶的拉伸性能，例如，双重交联导致断裂应变，杨氏模量和拉伸强度显着增加。研究了纤维长度对CNF / PVA /硼砂水凝胶力学性能的影响，因此添加具有更长纤维长度的CNF可以提高拉伸模量，而添加较短长度的CNF，即使在较高的CNF浓度下，也导致可扩展性高于1000％。SAXS / WAXS和FT-IR测量表明，PVA由于冷冻/解冻过程而结晶，并且PVA和CNF均与硼砂交联，PVA（或CNF）的羟基之间的氢键为氢键。这表明多重交联对于改善拉伸性能是有效的。另外，发现具有多物理交联的CNF / PVA /硼砂凝胶具有自我修复的能力。在PVA（或/和CNF）的羟基之间形成氢键，表明多重交联对于改善拉伸性能是有效的。另外，发现具有多物理交联的CNF / PVA /硼砂凝胶具有自我修复的能力。在PVA（或/和CNF）的羟基之间形成氢键，表明多重交联对于改善拉伸性能是有效的。另外，发现具有多物理交联的CNF / PVA /硼砂凝胶具有自我修复的能力。