Fibers, yarns, woven fabric including the yarns and fibers, and methods of manufacturing the same are disclosed. Fibers can include base material staple fibers and dissolvable or water-soluble fibers that are mixed together to define an ultra-homogenous yarn comprising base material and dissolvable material, which is provided in at least the warp direction to form a woven fabric having a 7-end, 8-end or 10-end sateen weave. A processing step provides for the removal of the dissolvable fibers to produce a yarn defining a plurality of pores that are uniformly distributed throughout the structure of the yarn. The woven fabric has a thread count between 450-1200. The woven fabric is thermally-insulative, breathable and moisture-wicking.

A flash-spun plexifilamentary fiber strand having a BET surface area of less than 12 m.sup.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%, said fiber strand having an elongation at break greater than 55% and sheets made thereof.

A flash-spun plexifilamentary fiber strand having a BET surface area of less than 12 m.sup.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%, said fiber strand having an elongation at break greater than 55% and sheets made thereof.

A flash-spun plexifilamentary fiber strand having a BET surface area of less than 12 m.sup.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.

A flash-spun plexifilamentary fiber strand having a BET surface area of less than 12 m.sup.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.

A process for the preparation of plexifilamentary film-fibril strands of polymer. The process includes the steps of generating a spin fluid containing (a) 5 to 30 wt. % containing one or more polymer types, (b) a primary spin agent selected from the group consisting of dichloromethane, cis-1,2-dichloroethylene and trans-1,2-dichloroethylene, and (c) a co-spin agent comprising 1H,6H-perfluorohexane or 1H-perfluorohexane or 1H-perfluoroheptane. The spin fluid is flash-spun at a pressure that is greater than the autogenous pressure of the spin fluid into a region of lower pressure to form plexifilamentary film-fibril strands of the polymer. The co-spin agent is present in the spin fluid in an amount sufficient to form an azeotrope-like composition with the primary spin agent in the presence of the one or more polymer types. The polymer may be selected from the group consisting of high density polyethylene, polypropylene, polybutene-1, polymethylpentene, polyvinylidene fluoride, poly (ethylene tetrafluoroethylene), and blends of the foregoing.

A process for the preparation of plexifilamentary film-fibril strands of polymer. The process includes the steps of generating a spin fluid containing (a) 5 to 30 wt. % containing one or more polymer types, (b) a primary spin agent selected from the group consisting of dichloromethane, cis-1,2-dichloroethylene and trans-1,2-dichloroethylene, and (c) a co-spin agent comprising 1H,6H-perfluorohexane or 1H-perfluorohexane or 1H-perfluoroheptane. The spin fluid is flash-spun at a pressure that is greater than the autogenous pressure of the spin fluid into a region of lower pressure to form plexifilamentary film-fibril strands of the polymer. The co-spin agent is present in the spin fluid in an amount sufficient to form an azeotrope-like composition with the primary spin agent in the presence of the one or more polymer types. The polymer may be selected from the group consisting of high density polyethylene, polypropylene, polybutene-1, polymethylpentene, polyvinylidene fluoride, poly (ethylene tetrafluoroethylene), and blends of the foregoing.

An easy-print packaging sheet and a manufacturing method therefor. Raw materials of the easy-print packaging sheet contain polyethylene; the smoothness of the packaging sheet is 70-250 seconds; the drape coefficient of the packaging sheet is 78-92%; the burst index of the packaging sheet is 8-15 kPa.Math.m.sup.2/g; and the light shielding rate of the packaging sheet is 85-95%. The packaging sheet having good comprehensive performance is prepared by means of a flash spinning process and the improvement of raw materials and a spinning process.

A flash spinning method for preparing non-woven fabrics based on microwave thermal fusion, a microwave thermal fusion device, and a non-woven fabric preparation device are provided. The flash spinning method includes: step S1, collecting filament bundles to form a non-woven fabric precursor, adding a microwave heating liquid to the non-woven fabric precursor; the microwave heating liquid being configured to absorb microwave energy and convert the microwave energy into thermal energy; and step S2, performing microwave heating on the non-woven fabric precursor containing the microwave heating liquid obtained in the step S1 to obtain a heated non-woven fabric, and performing a hot press forming treatment on the heated non-woven fabric to obtain a finished non-woven fabric. There is no temperature gradient in layers of the non-woven fabric precursor, thereby significantly improving the peeling strength of the finished non-woven fabric.

A fiber manufacturing method includes the following steps of: dissolving a polymer in a solvent to obtain a polymer solution; spraying the polymer solution into a liquid heated to a boiling point of the solvent or higher, and evaporating the solvent to precipitate a fibrous polymer in a sealed precipitation tank, the liquid being immiscible with the polymer and the solvent; conveying the precipitated fibrous polymer in a liquid from the precipitation tank; water-rinsing the fibrous polymer conveyed in the liquid in the conveying step in a sealed water-rinsing tank; conveying the water-rinsed fibrous polymer in a liquid from the water-rinsing tank; and cooling and condensing solvent gas that is generated in the spraying step and the water-rinsing step.