Flash spun plexifilamentary strands and sheets
View Patent ↗A flash-spun plexifilamentary fiber strand having a BET surface area of less than 12 m 2 /g, a crush value of at least 0.9 mm/g wherein said fiber strand comprises predominantly fibers formed from polyethylene, said fibers having a total crystallinity index of less than 55%, and sheets made thereof.
1. A thermally or mechanically consolidated sheet comprising a flash-spun plexifilamentary fiber strand comprising fibers having a total crystallinity index of less than or equal to 55%, the flash-spun plexifilamentary fiber strand having a BET surface area of less than or equal to 12 m 2 /g and a crush value of greater than or equal to 0.9 mm/g,
wherein said fiber strand comprises predominantly said fibers, and said fibers are formed from homopolymers of ethylene and have a monoclinic and orthorhombic structure as determined by X-ray characterization and a crystallinity index of the monoclinic structures is higher than 1%;
the sheet resulting from a flash spinning process utilizing a spin agent medium comprising a mixture of i) and ii), wherein
i) is dichloromethane or trans-1,2-dichloroethylene; and
ii) is 2,3-dihydrodecafluoropentane, 1,1,1,2,2,3,3,4,4,5,5,6,6-tridecafluorohexane, 1,1,2,2,3,3,4,4,5,5,6,6-dodecafluorohexane, or a hydrofluoroether.
2. The sheet of claim 1 wherein said fibers have a total crystallinity index of less than or equal to 52%.
3. A multilayer structure comprising a multiplicity of two or more sheets wherein at least one sheet is a sheet according to claim 1 .