聚氨酯弹性体被称为“划时代的新型高分子材料”，是当前世界六大具有发展前途的合成材料之一。由于聚氨酯弹性体的原料来源广泛，聚氨酯的分子结构可设计性强，具有高强度、高模量、高弹性、耐摩擦、耐高温及简便的成型工艺等特点，被广泛应用于汽车、航空航天、电器和电子等领域。目前聚氨酯原料大多过度依赖于石油资源，开发和寻找新的原料来代替来自石油资源的大分子二元醇至关重要。木质素来源于植物纤维的细胞壁，其成本低廉、来源广泛且绿色可再生。木质素中含有大量的刚性基团和活性基团羟基，为其带来了良好的反应性，若能用木质素部分代替来自石油资源的大分子二元醇，不仅能减少聚氨酯合成的成本，也可以提升聚氨酯材料的性能。

本文采用物理和化学改性的手段，将木质素引入到聚氨酯弹性体体系中，在提高木质素分散性和相容性的基础上，系统的探究了木质素改性聚氨酯弹性体的拉伸性能、耐水解性能及热稳定性能。具体研究结论总结如下：

（1）确定了原料种类，并合成一系列木质素为5%，不同异氰酸根指数（R）的聚氨酯弹性体。通过对其拉伸性能的测试，当R=1.5所合成的聚氨酯弹性体拉伸性能最优。

（2）以R=1.5，合成一系列不同木质素含量的聚氨酯弹性体。并采用红外光谱对其结构进行表征，结果表明木质素基聚氨酯弹性体的成功合成，当R=1.5，木质素含量为5%，聚氨酯弹性体的拉伸性能最优，其断裂强度为31.83 MPa，断裂伸长率为1544.10%，硬度为78 A，接触角为77.6°，初始分解温度为256.83 ℃。

（3）使用十八烷基二异氰酸酯对木质素进行改性，成功得到改性的木质素，并将其引入到聚氨酯弹性体中，制备了一系列单异氰酸酯改性木质素基聚氨酯弹性体。结果表明，当R=1.5，改性木质素含量为10%，聚氨酯弹性体的断裂强度为24.72 MPa，断裂伸长率为859.50%，硬度为74 A，接触角为60.9°，初始分解温度为248.5 ℃，其综合性能最优，可满足高强度聚氨酯弹性体的使用要求。

（4）通过KH550对木质素进行改性，得到胺硅烷化木质素，将其作为扩链剂，合成不同预聚体链长聚氨酯弹性体。结果表明，当MDI:PCDL=0.15，预聚体反应5 h，KH550与木质素的质量比为2:1时，聚氨酯弹性体的断裂强度为46.41MPa，断裂伸长率为670.82%，硬度为74 A，接触角为101°，初始分解温度为308.83 ℃，其综合性能最优，可满足高强度聚氨酯弹性体的使用要求。

Polyurethane elastomers are known as "epoch-making new polymer materials", and currently one of the six promising synthetic materials in the world. Due to the wide range of raw material sources of polyurethane elastomers, the molecular structure of polyurethane is highly designable, and has the characteristics of high strength, high modulus, high elasticity, friction resistance, high temperature resistance and simple molding process. It is widely used in automobiles, aerospace and aerospace, electrical and electronic fields. At present, most polyurethane raw materials are overly dependent on petroleum resources. It is very important to develop and find new raw materials to replace macromolecular diols from petroleum resources. Lignin is derived from the cell wall of plant fibers, which is inexpensive, widely available, and green and renewable. Lignin contains a large number of rigid groups and active hydroxyl groups, which brings good reactivity to it. If lignin can partially replace macromolecular diols from petroleum resources, it will not only reduce the cost of polyurethane synthesis, but also it can also improve the performance of polyurethane materials.

In this paper, the method of physical and chemical modification was used to introduce lignin into the polyurethane elastomer system. On the basis of improving the dispersibility and compatibility of lignin, hydrolysis resistance, thermal stability and the tensile properties of lignin-modified polyurethane elastomer were systematically explored. The specific research conclusions are summarized as follows:

(1) The kinds of raw materials were determined, and a series of polyurethane elastomers with 5% lignin and different isocyanate index (R) were synthesized. Through the test of its tensile properties, the tensile properties of the polyurethane elastomer synthesized when R=1.5 are the best.

(2) A series of polyurethane elastomers with different lignin contents were synthesized with R=1.5. Its structure was characterized by infrared spectroscopy. The results showed that the lignin-based polyurethane elastomer was successfully synthesized. When R=1.5 and the lignin content was 5%, the tensile property of the polyurethane elastomer was the best, and its breaking strength was 31.83 MPa, the elongation at break was 1544.10%, the hardness was 78 A, the contact angle was 77.6°, and the initial decomposition temperature was 256.83 °C.

(3) Using octadecyl diisocyanate to modify lignin, the modified lignin was successfully obtained, and it was introduced into polyurethane elastomers to prepare a series of monoisocyanate modified lignin-based polyurethane elastomers. The results showed that when R=1.5, the modified lignin content was 10%, the breaking strength of the polyurethane elastomer was 24.72 MPa, the breaking elongation was 859.50%, the hardness was 74 A, the contact angle was 60.9°, and the initial decomposition temperature was 248.5 °C, its comprehensive performance was optimal, and it can meet the use requirements of high-strength polyurethane elastomers.

(4) Lignin was modified by KH550 to obtain amine silanized lignin, which was used as chain extender to synthesize polyurethane elastomers with different prepolymer chain lengths. The results showed that when MDI:PCDL=0.15, the prepolymer reaction was 5 h, and the ratio of KH550 to lignin was 2:1, the breaking strength of the polyurethane elastomer was 46.41 MPa, the elongation at break was 670.82%, the hardness was 74 A, and the contact angle was 101° and the initial decomposition temperature was 308.83 °C. Its comprehensive performance was the best, which can meet the use requirements of high-strength polyurethane elastomers.