Melt-crystallized films of three kinds of ultrahigh molecular weight polyethylenes (UHMW-PE's) having
Mv‘s of 1.0-6.0 × 10
6 were tensile-drawn in the temperature range of
Td = 140-160°C, slightly above their static melting temperatures (133-135°C). The effects of
Mv on the melt-draw behavior and the tensile properties of the resultant drawn products were studied. The deformation of the entanglement networks in molten UHMW-PE, which occurred during the melt-drawing, induced the chain extension, orientation and crystallization depending on the drawing variables. For a given
Mv, the ductility increased with increasing the
Td, reaching a maximum at a specific
Td, which increased with the sample
Mv. At yet higher
Td's, the ductility decreased rapidly with the
Td. The optimum
Td, as defined by the
Td where the highest tensile properties were achieved, increased with
Mv from 140°C for the lowest
Mv to 155°C for the highest
Mv. Although the tensile properties for a given
Mv increased with the draw ratio (DR) at a given
Td, those at a given DR decreased with increasing the
Td. As a result of the specific effect for each of these drawing variables on the ductility and tensile properties, the highest tensile modulus of 88 GPa and strength of 1.3 GPa were obtained for the UHMW-PE with the highest
Mv. These values are among the highest ever reported for the melt-drawing of UHMW-PE.
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