The present disclosure is directed to a physically crosslinked, closed cell continuous multilayer foam structure comprising at least one foam polypropylene/polyethylene layer with a KEE cap layer. The multilayer foam structure can be obtained by coextruding a multilayer structure comprising at least one foam layer composition layer with at least one cap layer composition layer, irradiating the coextruded structure with ionizing radiation, and continuously foaming the irradiated structure.

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 present disclosure is directed to a physically crosslinked, closed cell continuous multilayer foam structure comprising at least one foam polypropylene/polyethylene layer with a recycled polyolefin material layer. The multilayer foam structure can be obtained by coextruding a multilayer structure comprising at least one nonrecycled foam composition layer with at least one recycled foam composition layer, irradiating the coextruded structure with ionizing radiation, and continuously foaming the irradiated structure.

Provided for example is a method for producing a resin foam product with an internal cavity, the method including: preparing a composition including a curable material and a foaming agent; forming a resin structure with an internal cavity communicating with an outer space by curing the composition; blowing a fluid to the resin structure; and fabricating the resin foam product by foaming the resin structure with the fluid blown thereto.

A method of microcellular foam molding an article is provided with filling a mold with a polyolefin compound; forming crosslinks in the mold to obtain a crosslinked mold; dissolving a supercritical fluid into the crosslinked mold under a predetermined pressure and at a predetermined temperature for a predetermined period of time to obtain a second mold configured to allow the supercritical fluid to effuse through; and heating the second mold at a second predetermine temperature for a predetermined foaming time until a foamed article is finished in the second mold. A second embodiment involves using elastomers as foaming materials is also provided.

The present disclosure is directed to a physically crosslinked, closed cell continuous multilayer foam structure comprising at least one foam polypropylene/polyethylene layer with a recycled polyolefin material layer. The multilayer foam structure can be obtained by coextruding a multilayer structure comprising at least one nonrecycled foam composition layer with at least one recycled foam composition layer, irradiating the coextruded structure with ionizing radiation, and continuously foaming the irradiated structure.

There is provided a polyolefin resin foam sheet formed by foaming a polyolefin resin, wherein the expansion ratio of the foam sheet is 1.5 to 20 cm.sup.3/g, the average cell sizes in the MD direction and the TD direction of the foam sheet are 130 m or less, and the following formulas (1) and (2) are satisfied:

T.sub.M/D6(1); and

T.sub.T/D5(2), where T.sub.M denotes the tensile strength at 90 C. in the MD direction, T.sub.T denotes the tensile strength at 90 C. in the TD direction, and D denotes the density (g/cm.sup.3) of the foam sheet.

Described herein are methods and processes of manufacturing irradiation crosslinked polypropylene foam. In some embodiments, this includes extrusion of all material components, including a liquid crosslinking agent, to manufacture extruded structures for production of irradiation crosslinked polypropylene foam.

Described herein are methods and processes of manufacturing irradiation crosslinked polypropylene foam. In some embodiments, this includes extrusion of all material components, including a liquid crosslinking agent, to manufacture extruded structures for production of irradiation crosslinked polypropylene foam.