Gadkari Siddharth
Department of Mechanical and Aerospace Engineering, Monash University, Clayton 3168, Australia.
Department of Chemical Engineering, Indian Institute of Technology⁻Bombay, Mumbai 400076, India.
Polymers (Basel). 2017 Oct 12;9(10):501. doi: 10.3390/polym9100501.
"Electrospinnability", or the ease with which a solution can be used to obtain bead-free uniform fibers, depends on a large number of parameters, including solution properties, process parameters and ambient conditions. In this study, the effect of the polymer relaxation time on electrospinning of dilute polymer solutions is investigated numerically. It is shown that elastic stresses (ES) increase exponentially with the Deborah number ( D e ). For each polymer concentration there exists a critical D e below which the ES are insufficient to overcome capillary stresses (CS) and lead to the formation of beaded fibers. However, above the critical D e , there is a higher probability of the ES overcoming the CS and leading to the formation of uniform fibers. This analysis suggests the possibility of improved electrospinnability even with dilute polymer solutions, provided the relaxation time is sufficiently large. It is also found that changes in the drag coefficient due to change in the polymer conformation and self-concentration of polymer molecules would become significant for the electrospinning of polymer solutions with a longer relaxation time and high conductivity.
“电纺可纺性”，即一种溶液用于获得无珠均匀纤维的难易程度，取决于大量参数，包括溶液性质、工艺参数和环境条件。在本研究中，对聚合物松弛时间对稀聚合物溶液电纺的影响进行了数值研究。结果表明，弹性应力（ES）随德博拉数（De）呈指数增加。对于每种聚合物浓度，都存在一个临界De，低于该值时，弹性应力不足以克服毛细应力（CS）并导致形成珠状纤维。然而，高于临界De时，弹性应力克服毛细应力并导致形成均匀纤维的可能性更高。该分析表明，即使是稀聚合物溶液，只要松弛时间足够长，也有可能改善电纺可纺性。还发现，对于具有较长松弛时间和高电导率的聚合物溶液电纺，由于聚合物构象变化和聚合物分子自浓度变化引起的阻力系数变化将变得显著。
