基于功能化黄腐植酸的聚乳酸结晶调控及聚乳酸材料的高性能化

Fulvic acid (FA) is prepared with the high quality local weathered coal resources from Xinjiang, and functionalizational fulvic acid with high efficient nucleating properties is prepared by introduction of amide groups onto the surface of humic acid via molecular design, moreover, poly (lactic acid) (PLA) materials are prepared with functionalizational fulvic acid (FFA) as the high efficient nucleating agent. The heterogeneous nucleation behavior of FFA on PLA crystal, the self-assembly behavior of FFA in PLA melt, the generation mechanism and influence factors of nucleation shish-like bril and nucleation of FFA are investigated, which reveals the dependence regulartity of the crystallization rate and crystal morphology of PLA on the FFA concentration, and puts forward the mechanism model of the crystal morphological evolution of PLA induced by FFA. Furthermore, the effects of the controlling crystallization of PLA on the mechanical properties, heat resistance,toughness, hydrolysising resistance and biodegradability of PLA materials are studied. The crystallization properties of PLA are effectively controlled by FFA, which will enrich the crystal morphology and structure of PLA and dramatically improve the crystallization properties. Therefore, the high performances of PLA materials are also achieved, which will solve the bottleneck problem of PLA material development and application, and provide new ideas, new methods and new technology for high performance of PLA products processed by practical injection molding. The project will be significant for the treatment of serious "white pollution" from Xinjiang, and the improvement of new materials development and talent cultivation of Xinjiang as well as high value-added development of weathered coal resources and featured resources transformation from Xinjiang.

依托新疆优质风化煤资源制备黄腐植酸(FA)，基于FA的结构特点通过分子设计制备功能化黄腐植酸(FFA)，实现其高效成核性，并以FFA为高效成核剂制备聚乳酸(PLA)材料。通过研究FFA在PLA熔体中的自组装行为、FFA成核微纤产生及成核机制、FFA诱导PLA结晶形态演变影响因素，揭示PLA结晶速率及结晶形态对FFA浓度的依赖性规律，提出PLA结晶形态演变机理模型，考察结晶调控对PLA材料的力学性能、耐热性、韧性、耐水解性及生物降解性的影响。通过FFA对PLA结晶性能的有效调控丰富PLA结晶形态与结构、提高PLA结晶速率，实现PLA材料的高性能化，解决PLA材料开发与应用的瓶颈问题，为采用普通注射成型方法制备高性能化PLA制品提供新思路、新方法和新工艺。项目的开展对于治理新疆严重的“白色污染“、推进新材料产业发展和人才培养及新疆地产风化煤资源的高附加值开发和特色资源转化具有重要的意义。

依托新疆优质风化煤资源制备了改性腐植酸(AHA)及功能化黄腐酸(FFA)，以其为高效成核剂对聚乳酸(PLA)材料进行结晶改性。通过研究AHA、FFA在PLA熔体中的结晶成核机制、诱导PLA结晶形态演变影响因素，揭示PLA结晶速率、结晶形态的变化规律，考察结晶调控对PLA材料的力学性能、耐热性、多重熔融行为、流变行为及降解性的影响，建立构效关系，获得PLA的酶解动力学机理，同时分析和比较了AHA的抑菌性。通过丙交酯开环聚合、ATRP及RAFT等方法，对FA进行表面功能化改性，研究其对PLA材料的增韧、热稳定性、结晶动力学及流变行为的影响机制。主要内容如下：.（1）对FA进行酰胺化改性，制备了FA-BH和FAA。FA-BH(0.1wt％)和FAA(0.3wt%)使得PLA的冲击强度分别提高了74.56％、104.94％，实现了PLA的结晶改性和增韧效应。.（2）分别以三氯化磷、羰基二咪唑为原料制备AHA-A、AHA-D。结果表明AHA-A、AHA-D均能显著提高PLA的结晶速率，因此对PLA具有显著增韧作用。AHA-A、AHA-D的酰胺基团发挥抑菌性作用，其中AHA-D对四种菌株的抑制作用要强于AHA-A。.（3）采用对苯二胺制备MFA。MFA(0.5wt%)使PLA材料冲击强度提高了97.2％。FTIR表征表明PLA和MFA之间形成了氢键作用，强化了PLA的异相成核作用。MFA提高PLA的酶解表观活化能，减弱了蛋白酶K与PLA的亲和力，对其酶解性略有抑制。.（4）PLA-FA作为助剂对PLA产生塑化作用，改善了PLA加工流变性能。PLA-FA使得PLA的球晶生长速率从7.67μm/min下降至5.74μm/min，成核密度增加，半结晶时间缩短，结晶速率大幅提高，PLA的冲击强度提高了191.93%，热稳定性提高。.（5）以FA为原料合成FA-α-N。在剪切作用和FA-α-N的协同作用下，PLA成核位点繁多，PLA晶体形貌从球晶演变为点晶，FA-α-N在PLA分子的结晶过程中起到较强的异相成核作用，使PLA结晶周期缩短，正常发育的晶胞数目增多，结晶度增大进而实现PLA的结晶改性。.（6）表面改性FA具有较强的疏水性，与PLA熔体产生强相互作用，界面相容性增强，因此对PLA产生明显的异相成核作用，有效消除PLA的冷结晶峰，对PLA具有显著的增韧效应，并提高其热稳定性。