The present disclosure relates to a polymer foam and a preparation method thereof. The polymer foam is obtained by physically foaming a thermoplastic elastomer or a polyolefin material, and has an apparent density of 0.30 g/cm.sup.3 or less and a rebound degree of 50% or more as measured according to ASTM D2632.

The present disclosure relates to a method for physically foaming a polymer material and a foamed article. The method for physically foaming a polymer material comprises: (1) making a thermoplastic elastomer or a polyolefin material into a blank with an injector, an extruder, or a molding press; (2) subjecting the polyolefin blank to a crosslinking reaction to obtain a crosslinked polyolefin blank; (3) subjecting the thermoplastic elastomer blank or the crosslinked polyolefin blank to a high pressure impregnation with a supercritical fluid in an autoclave, then releasing the pressure to a normal pressure to obtain a supercritical fluid-impregnated blank; and (4) placing the supercritical fluid-impregnated blank into an end-product mold to perform an 1:1 in-mold foaming to obtain a finished foam article.

The instant application discloses, among other things, ways to manufacture reduced density thermoplastics. A rapid foaming process which may create a polymer product by saturating thermoplastic sheet or preforms, heating, and then forming into final shape, is described. The polymer product may include an integral solid skin. This method may be utilized with any thermoplastic. The material handling, saturation methods, and end products are also described.

Aspects hereof provide methods for molding a single-phase solution comprised of a polymer composition and a gas. The polymer composition and the gas are maintained under pressure during the molding operation to prevent a cellular structure from being formed by the dissolved gas in the polymer composition coming out of solution. The mold cavity in which the single-phase solution is introduced for molding purposes is pressurized to a mold pressure that is sufficient to maintain the single-phase solution as a single-phase solution as the mold cavity is filled. Subsequent to filling the mold cavity with the single-phase solution under pressure, the resulting article may be exposed to a reduction in pressure causing the entrapped gas to form a cellular structure.

A staple cartridge assembly for use with a surgical stapling instrument includes a staple cartridge including a plurality of staples and a cartridge deck. The staple cartridge assembly also includes a compressible adjunct positionable against the cartridge deck, wherein the staples are deployable into tissue captured against the compressible adjunct, and wherein the compressible adjunct comprises a first biocompatible layer comprising a first portion, a second biocompatible layer comprising a second portion, and crossed spacer fibers extending between the first portion and the second portion.

A staple cartridge assembly for use with a surgical stapling instrument includes a staple cartridge including a plurality of staples and a cartridge deck. The staple cartridge assembly also includes a compressible adjunct positionable against the cartridge deck, wherein the staples are deployable into tissue captured against the compressible adjunct, and wherein the compressible adjunct comprises a first biocompatible layer comprising a first portion, a second biocompatible layer comprising a second portion, and crossed spacer fibers extending between the first portion and the second portion.

A staple cartridge assembly for use with a surgical stapling instrument includes a staple cartridge including a plurality of staples and a cartridge deck. The staple cartridge assembly also includes a compressible adjunct positionable against the cartridge deck, wherein the staples are deployable into tissue captured against the compressible adjunct, and wherein the compressible adjunct comprises a first biocompatible layer comprising a first portion, a second biocompatible layer comprising a second portion, and crossed spacer fibers extending between the first portion and the second portion.

A foamed article is made by infusing the article of thermoplastic elastomer with a supercritical fluid, then removing the article from the supercritical fluid and either (i) immersing the article in a heated fluid or (ii) irradiating the article with infrared or microwave radiation.

A method for saturating a thermoplastic polymer material includes continuously moving the polymer material through a pressurized pressure vessel. To do this, the method includes sealing the pressure vessel with a series of dynamic seals that allows the polymer material to continuously move through the pressure vessel while maintaining the pressure inside the pressure vessel.

A staple cartridge assembly is disclosed which comprises a cartridge body and an implantable layer. The implantable layer includes fibers comprised of a first material and a second material. The first material and the second material have different glass transition temperatures. After the fibers comprised of the first material and the second material have been intermixed or interwoven, the layer is exposed to a temperature which exceeds the lower of the two glass transition temperatures. This heating process causes the layer to constrict and increase in thickness. The layer, when implanted, can compensate for variations in tissue thickness within the staples.