MSE Seminar - Dr. Piet J. Lemstra (PLEM) - Plem/Polco BV Veldhoven, Netherlands
Dr. Piet J. Lemstra (PLEM)
Wednesday, December 9, 2015
10:00 a.m. MRDC 2505
“Processing of High-Performance Polyethylene Fibers and Tapes”
Polyethylene fibers possessing excellent tensile properties, notably in terms of specific strength and E-moduli, can be produced via the so-called solution(gel)-spinning process, developed at DSM in the 1980s. In this process dilute solutions of ultra-high-molecular-weight (UHMW-PE) polyethylene are spun and the as-spun fibers are quenched in a non-solvent, usually water. During dissolution the long-chain molecules become disentangled in the spinning dope and, upon quenching the as-spun fibers, the disentangled state is preserved, due to crystallization. These so-called gel precursor fibers can be easily drawn to high-draw ratios in a T-range close to the melting temperature to generate chain alignment in the fiber direction.The ultra-drawability of the as-spun (gel)fibers was explained in terms of a reduced number of entanglements[i]. Based on this entanglement model the more dilute the solutions the better the drawability of the quenched fibers and hence fiber properties.In practice, however, solutions of about 10% are used to compromise on economics but still a commercial PE fiber plant is more or less a solvent recycling plant (90% of the solvent has to be recovered!!). Very recently Smith et al[ii]. showed that high-performance PE fibers could be spun from more concentrated solutions, appr. 25%, violating the classical entanglement model to some extent. They employed environmentally benign solvents like vegetable oils which open the route to fully ‘green’ PE fibers. Another approach, currently employed by Teijin, is to generate disentangled UHMW-PE directly in the reactor and consolidate the reactor powder into films which can be drawn into high-performance tapes.[iii] In this route no solvent is used at all. These recent and other developments will be presented and discussed with the focus on feasibility and impact on processing the intractable polymer UHMW-PE into high-performance fibers/tapes.
[i] Smith,P.;Lemstra,P.J.;Booy, H.C. J. Polym.Sci. 1981, 19(5), 877-888
[ii] C&EN Volume 93 Issue 47 | p. 5 | News of The Week Issue Date: November 30, 2015
[iii] Teijin Endumax® , you tube “Endumax; Teijin Aramid; agentschap.nl”
Piet J. Lemstra (PLEM) received his PhD from the University of Groningen in 1975. He then was post-doctoral fellow at the University of Bristol (UK) under supervision of the late prof. Andrew Keller. From 1976, he worked at DSM Research, where together with Paul Smith he developed the super strong Dyneema® fiber. In 1985 he became professor of Polymer Technology at the Eindhoven University of Technology . From 1994-1997 he has been director of the graduate school (PTN) and in 1997 he founded together with Professor Leen Struik the Dutch Polymer Institute (DPI), where he worked until 2004 as scientific director. In 2004 he founded the Polymer Technology Group Eindhoven BV. He retired from TU/e in 2011 and is now working for PlemPolco BV focused on high-performance fibers.