Fast solvent removal by mechanical twisting for gel spinning of ultrastrong fibers



A new method for fast solvent removal in gel spinning was investigated. Instead of solvent evaporation or coagulation as conventionally used, the new method involves mechanically twisting the gel-fiber along the fiber axis. By removing the majority of solvent in the gel-fiber by mechanical twisting not only the emission of solvent vapor and the production of waste solvent mixture or coagulation byproducts are minimized but also the fiber production rate is significantly increased. The new solvent removal method was demonstrated through gel spinning of high-strength ultrahigh-molecular-weight polyethylene fibers using both volatile and nonvolatile spin solvents. Approximately 90% of the spin solvent was removed by a single-step twisting process and the resulting fiber retained the high mechanical properties conventionally obtained. A mechanistic model was developed for estimating the solvent removal as a function of twisting. With respect to the gel spinning industry, the new solvent removal method holds a promise of simplifying the solvent removal and recovery steps and improving the production rate, leading to more efficient and effective gel spinning processes. POLYM. ENG. SCI., 55:745–752, 2015. © 2014 Society of Plastics Engineers