发泡剂插层剥离型水滑石/聚合物发泡材料的研究

It should be noted that layered double hydroxides (LDHs) would be significantly improved foaming ability of polymer resins. They normally contribute nanofillers’ effects to the enhancement of cell nucleation and suppression of cell coalescence. Design of polymeric microcellular foams for high performance will be obtained by studying key effects of foaming, which are explored through combining foaming process with different dispersed phase of characteristic and distribution. Unfortunately, the foaming process is very complicated, the dynamic variation of dispersed phase is based on delamination of LDH monolayers in resin matrix, and the available equipment can not reach the actual case, as a consequence, researchers don’t know the exactly mechanism behind the phenomenon. In this project, the specific layered material—delaminated foaming agent intercalated LDHs are synthesized to be fabricated polymeric foaming system. The delamination effect of LDH leads to the layered material with secondary dispersion that induced by a bubble growth. Therefrom a dispersed phase system and phase interface characteristic can be controlled. These results caused us to investigate the effect of it on cell nucleation, cell growth, and gas diffusion rate. The mechanism of polymer nanocomposites foaming will be deeply understood by combining the foaming process with dispersed phase size and phase interface area. Based on those results, we are going to acquire a mechanism of composite reinforcement, and focus on designing a more reasonable polymer nanocomposite foaming system with the aim to support the commercial application of layered material-LDHs.

水滑石材料显著改善聚合物的发泡行为，其作用主要是加强泡孔成核和抑制泡孔聚并。聚合物极性分子链插层水滑石后引起层板剥离，改变复合材料中分散相特性，而其动态作用于聚合物发泡过程的本质并不清晰，探明多相发泡体系中分散相特征影响发泡行为的关键因素，有助于设计高性能聚合物微发泡材料。本项目制备发泡剂插层剥离型水滑石搭建聚合物多相发泡体系，探究发泡过程中水滑石层间气泡长大诱使层板剥离发生的二次分散过程。通过控制多相体系中分散相状态和相界面特性，研究剥离型水滑石在聚合物发泡过程中对气泡成核、气体扩散、生长和泡孔定型等过程的影响机制，分析水滑石作用于聚合物发泡过程的本质，实现聚合物材料发泡质量的可控，推动水滑石材料作为可调变分散体系应用于聚合物发泡材料。

纳米材料显著改善聚合物的发泡行为，其作用经研究发现主要归因于影响聚合物熔体特性和结晶过程。研究实现了水滑石(LDH)层间结构的可控插层，以硝酸根型LDH为插层前体，在水溶液中合成4,4'-偶氮(4-氰基戊酸)（ACVA）羧酸根阴离子柱撑水滑石。发现柱撑LDH-ACVA的插层量与受插层客体ACVA特性的影响，在酸性条件下，当增加ACVA的量有利于插层量提升。在聚丙烯中添加柱撑LDH样品，有效提高了复合材料的结晶成核能力，有利于泡孔结构的稳定。LDH的加入可以有效改善PP复合材料的发泡行为，这归因于LDH的成核能力、在基体中的分散效果及复合材料流变性能的综合结果。通过焙烧改性水滑石，控制变量法考察温度和时间对水滑石层间结构的影响。将十二烷基苯磺酸钠(SDBS)成功插层到LDHs中，将水滑石添加到复合材料中，PP-g-MAH的相畴减小，呈现明显的海岛相。流变行为表明焙烧改性后的水滑石作为异相成核剂来有效改善聚乳酸的流变性能，并使得PLA的玻璃化转变升高和冷结晶温度降低。通过固相发泡法制备了结构可控的生物降解开孔聚丁二酸丁二醇酯（PBS）/甲壳素纳米晶（ChNCs）复合泡沫材料。研究发现，ChNCs的添加能够改善PBS/ChNCs复合材料的黏弹性和结晶行为。随着ChNCs含量增加，PBS/ChNCs开孔发泡材料的泡孔壁厚度增加，泡孔尺寸变小。综上，将功能性无机及有机阴离子引入制备出功能性的纳米填料，在复合材料中实现纳米材料分散尺度的控制，赋予材料各种性能，对拓展纳米填料功能化复合材料的应用领域具有重要的理论及实际意义。