A comparison of the hot-compaction behavior of oriented, high-modulus, polyethylene fibers and tapes

The purpose of this article is twofold. First, there is an account of the h ot-compaction behavior of a new, Highly oriented, high-modulus polyethylene (PE) tape with the trade name of Tensylon(R) (manufactured by Synthetic In dustries, USA). This tape, produced by a melt spinning route, has mechanica l properties comparable to those of commercially available gel-spun fibers. Unidirectional samples were produced for a range of compaction temperature s to determine the optimum compaction conditions to obtain the best mechani cal properties of the resulting compacted sheets. Second, the mechanical pr operties of the best Tensylon sample, manufactured at a compaction temperat ure of 153 degreesC, was compared with three other hot-compacted, highly or iented PE materials, based on Certran(R), Dyneema(R), and Spectra(R) commer cial PE fibers. The results showed that the optimum compaction temperature was in most cases about 1 degreesC below the point at which substantial cry stalline melting occurred. At this optimum temperature, differential scanni ng calorimetry (DSC) melting studies showed that approximately 30% of the o riginal oriented phase had been lost to bond the structure together. In the case of Dyneema, the properties of the fiber were not translated into the properties of a compacted sheet, and morphological studies showed that this was because melting did not occur on the fiber surfaces, but rather in the interior of the fiber due to a skin structure. The properties of the compa cted Tensylon tapes were found to be exceptional, combining very high modul us and strength with interlayer bonding and good creep resistance. Moreover , the optimum temperature appeared to be about 2 degreesC below the point a t which complete melting occurred, giving a wider processing window for thi s material.