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

Abstract

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

Direct drawing of gel fibers enabled by twist‐gel spinning process

“…The effect of increasing TPmm on the tensile properties of gel-spun UHMWPE fibers was reported in a previous publication [6]. With decahydronaphthalene as a spin solvent, no significant change in the tensile properties of the hot drawn fibers was observed with increasing TPmm; however, a maximum TPmm was also observed above which the fiber becomes nonuniformly deformed and frequently breaks [6]. SEM images of the fibers after mechanical spin-solvent removal are shown in Fig.…”

“…Further increase in TPmm does not significantly increase solvent removal; however, excessive deformation of the gel fiber occurs at higher TPmm leading to instability of the process, and reduced tensile properties in the final hot drawn fiber. The effect of increasing TPmm on the tensile properties of gel‐spun UHMWPE fibers was reported in a previous publication . With decahydronaphthalene as a spin solvent, no significant change in the tensile properties of the hot drawn fibers was observed with increasing TPmm; however, a maximum TPmm was also observed above which the fiber becomes nonuniformly deformed and frequently breaks .…”

Gel spinning of UHMWPE fibers with polybutene as a new spin solvent

“…The fiber properties and the corresponding gel properties depend on factors such as the solvents used, the polymer concentration, and the processing temperatures . Various solvents have been attempted to form gels with polyethylene to obtain high strength fibers . Dodecane, naphthalene, p‐xylene, 1,2,4‐trichlorobenzene, kerosene and camphene have been used to dissolve UHMWPE .…”

Two‐stage drawing process to prepare high‐strength and porous ultrahigh‐molecular‐weight polyethylene fibers: Cold drawing and hot drawing

“…Ultrahigh‐molecular‐weight polyethylene (UHMWPE) fibers have been widely applied in industrial, civil, sports, medical, military, and other fields because of its outstanding mechanical strength, impact resistance, abrasion resistance, self‐lubrication, biocompatibility, and low‐temperature resistance . Recently, numerous innovative applications have surged out for UHMWPE fibers ranging from gas venting and air filtration to specialized separation and adsorption in harsh or corrosive environments .…”

“…Ultrahigh-molecular-weight polyethylene (UHMWPE) fibers have been widely applied in industrial, civil, sports, medical, military, and other fields because of its outstanding mechanical strength, impact resistance, abrasion resistance, self-lubrication, biocompatibility, and low-temperature resistance. [1][2][3][4] Recently, numerous innovative applications have surged out for UHMWPE fibers ranging from gas venting and air filtration to specialized separation and adsorption in harsh or corrosive environments. [5][6][7] These novel applications unanimously require a porous structure while retaining the high strength of the UHMWPE fibers to offer sufficient microchannels for mass transfer or large surface areas for adsorption.…”