An in situ surface modification method of ultra-high molecular weight polyethylene fiber on the basis of dry gel-spinning technique

A novel in situ surface modification strategy of ultra-high molecular weight polyethylene (UHMWPE) fiber is proposed, which is related to the dry gel-spinning technique and the directional entrapping modification. The surface modification, with poly (ethylene oxide) monooleate (OEO) as the modifier, applied a short entrapping time combined with a long storage period to match the high-speed spinning process. Swelling treatment, contact angle and XRD results show that the swollen fibers with swelling degrees between 6.4 and 9.6 wt% are suitable for the surface modification, via which modifier molecules can be facilely embedded into the amorphous regions of swollen surfaces. The modified surface acquires high polarity with a contact angle of 57.2° under conditions of the entrapping time of 60 s and storage period of 12 h. Large micelles of the OEO modifier, induced by great modifier concentrations and high storage temperatures, are proved to be helpful for the surface modification. The introduction of vinyl group in the modifier (oleate of OEO) together with the utilization of benzoyl peroxide (BPO) in the surface modification greatly reinforces the modifier fixation in modified surfaces. The modified fibers give rise to 43.5% elevation of the impact strength of epoxy resin composite relative to unmodified fibers, because of the polar acquirement on fiber surfaces.