熔体静电纺丝中的震荡拔河效应

As a solvent-free approach, melt electrospinning is thought more environmentally benign, less cost, higher efficiency than solution electrospinning. It attracts more and more attention from scientific and industrial community. However the bigger fiber diameter of this method brings bottleneck constraints to its further development. To solve the problem, we made a lot of attempts such as rising the temperature, adding hyper branched polymer or using plasticizer to reduce viscosity. But very few fibers in a batch were thinner than 200nm. Most are thicker than 1μm. The primary cause for this issue is that the polymer coils in the melt have serious entanglement and are difficult to become disentanglement. The viscosity is very high and polymer chains cannot slide over each other easily because there are more interactions between the chains. Oscillation has been successfully utilized in plastic processing to reduce the viscosity. So this proposal will introduce oscillating electric field in melt electrospinning, and arrange plenty of experiments and mesoscale simulations to study the Oscillating Tag-of-war Effect, which means the rule of the frequency, the amplitude, the wave shape of the oscillation and the jet charge features impact on the fiber diameter, disentanglement of polymer coil, orientation of polymer chains and fiber move trail. The research will make important contribution to the understanding of fundamental physical phenomena in melt electrospinning such as motion of polymer chains. It will also be likely to get the preparation method of massive high performance nanoscale fibers. Then it will make a big promotion to the large scale applications of nanofibers.

熔体静电纺丝不需要溶剂，比溶液静电纺丝环境友好、成本低、效率高，越来越受到国际科学界和工业界的重视，但是其纤维直径偏大，成了制约其发展的瓶颈。申请者曾分别尝试了升高温度、添加超支化高分子降粘剂、添加增塑剂等多种方法来降低熔体粘度，以获得小直径纤维，但除了少量纤维直径能小于200纳米外，多数还是微米级。造成纤维直径偏大的主要原因是熔体内高分子线团缠结程度大且解缠困难，熔体的粘度大，高分子链不易滑移出来而成纤。借鉴工业上已成功的振动力场降低粘度的方法，本课题拟引入震荡电场力，通过大量实验和介观模拟深入考察熔体静电纺丝过程中的震荡拔河效应－电场力的震荡幅度、频率、波形以及射流上电荷性质对纤维直径、高分子线团解缠、分子链取向及运动轨迹的影响规律。研究结果将对深刻理解静电纺丝过程中的分子链运动规律等基础物理现象、获得大批量高性能的纳米级纤维制备方法、开创纳米纤维大规模应用的新时代具有十分重要的意义。

本项目通过引入介观模拟方法和系列深入实验，研究了不同形式的震荡电场下熔体静电纺丝过程中分子链的受力、拉伸、解缠、纤维结晶度和分子链取向等进行了深入研究。深入开展了震荡电场对熔体静电纺丝过程影响的实验研究，发现震荡电场可以在一定的条件下减小熔体静电纺丝纤维直径，揭示了震荡电场对熔体静电纺丝过程中分子链解缠结的有益作用，不仅降低了纤维直径，还促进了纤维结晶度的提高，为熔体静电纺丝的工业化奠定了重要基础。研究了重力-电场力不同角度耦合情况下分子链的动力学变化过程的不同，发现了离心力对纺丝过程影响明显，并进行了重点研究，发展了很有工业化应用前景的离心熔体静电纺丝方法。开展了电场诱导相分离静电纺丝体系的DPD模拟及实验研究。截止到目前，在项目支持下，共发表标注的文章29篇，其中SCI文章14篇；申请专利19项，其中9项已获得授权；参加国内外学术会议18人次，有力宣传了项目取得的科研结果。在项目研究期间，项目负责人与国内外科学家进行了学术交流与合作，先后组织了4次全国级别的学术沙龙和一次全国静电纺丝大会，为我国静电纺丝领域的学术交流和合作发展贡献了自己的力量。该项目的研究，对推动离心熔体静电纺丝这种非常有工业化前景的新型纺丝方法制备出高性能的纳米纤维，进而推动科技进步和造福人民群众发挥积极作用。