A fabrication method for a water-absorbent filter includes obtaining a homogenized tragacanth suspension by dissolving tragacanth in a solvent, where the solvent may include distilled water, ethyl acetate, acetic acid, and formic acid, obtaining a support layer by coating a stainless steel mesh with a thin layer of a hydrophobic polymer, coating a stainless steel mesh with the thin layer of the hydrophobic polymer comprising electrospinning a hydrophobic polymer solution onto the stainless steel mesh, forming a tragacanth nanofibrous web on the support layer by electrospinning the homogenized tragacanth suspension onto the support layer, and cross-linking the tragacanth nanofibrous web by exposing the tragacanth nanofibrous web to a saturated vapor of a cross-linking agent.

Disclosed is a non-flammable thermal insulating composite substrate for motor vehicles including: a textile component constituted by a layer of needle-sewn non-woven fabric composed of a percentage of pre-oxidized polyacrylonitrile fiber included between 40% and 70%, preferably 58% and of the remaining percentage of polyethylene glycol-terephthalate fiber, the textile component having weight preferably 400 gr/m.sup.2; and a barrier fixed to the textile component using a spreading process, constituted by a thermoplastic resin based on low density polyethylene added with non-halogen flame retardants, the barrier having weight preferably 100 gr/m.sup.2. The composite substrate has the following features: a thickness included between 2 mm and 5 mm, preferably 3.8 mm; a weight included between 300 gr/m.sup.2 and 700 gr/m.sup.2, preferably 500 gr/m.sup.2; odorless; no emission of fumes; dimensionally stable, even at heatstroke, with a maximum variation of 1%; and non-flammability.

Disclosed is a non-flammable thermal insulating composite substrate for motor vehicles including: a textile component constituted by a layer of needle-sewn non-woven fabric composed of a percentage of pre-oxidized polyacrylonitrile fiber included between 40% and 70%, preferably 58% and of the remaining percentage of polyethylene glycol-terephthalate fiber, the textile component having weight preferably 400 gr/m.sup.2; and a barrier fixed to the textile component using a spreading process, constituted by a thermoplastic resin based on low density polyethylene added with non-halogen flame retardants, the barrier having weight preferably 100 gr/m.sup.2. The composite substrate has the following features: a thickness included between 2 mm and 5 mm, preferably 3.8 mm; a weight included between 300 gr/m.sup.2 and 700 gr/m.sup.2, preferably 500 gr/m.sup.2; odorless; no emission of fumes; dimensionally stable, even at heatstroke, with a maximum variation of 1%; and non-flammability.

A thermal insulation and fire protection felt product is provided. The felt product includes a first layer including a first plurality of nonwoven mechanically entangled oxidized polyacrylonitrile (PAN) precursor fibers bonded together by a first plurality of melted thermoplastic polyphenylene sulfide (PPS) fibers homogeneously mixed with the first plurality of mechanically entangled PAN precursor fibers. The first plurality of melted thermoplastic PPS fibers form a matrix of bond points between individual fibers of the first plurality of mechanically entangled PAN fibers. A second layer includes a second plurality of nonwoven mechanically entangled oxidized PAN precursor fibers bonded together by a second plurality of melted thermoplastic PPS fibers homogeneously mixed with the second plurality of mechanically entangled PAN precursor fibers. The second plurality of melted thermoplastic PPS fibers form a matrix of bond points between individual fibers of the second plurality of mechanically entangled PAN fibers.

A method of making a carbonized preform for a carbon-carbon composite brake disk may comprise: stacking a plurality of textile fabric layers, each textile fabric layer in the plurality of textile fabric layers including oxidized polyacrylonitrile (PAN) fibers, each textile fabric layer in the plurality of textile fabric layers being more uniform than a typical fabric layer formed from cross-lapping; each fabric layer being thinner than a typical fabric layer from cross-lapping, needling the plurality of textile fabric layers to form a needled non-woven board; cutting a fibrous preform from the needled non-woven board; and carbonizing the fibrous preform. The resultant non-woven carbonized preform maintains a higher fiber volume and more consistent properties throughout than what would otherwise be achieved using a typical fabric layer from cross-lapping.

Systems and methods are provided that entail polymeric fibers produced via an electrospinning process, and metallic nanostructures adhered to surfaces of the polymeric fibers via an electroless deposition process. Suitable materials for the polymeric fibers and metallic nanostructures include polyacrylonitrile (PAN) fibers and copper nanostructures, respectively.

Systems and methods are provided that entail polymeric fibers produced via an electrospinning process, and metallic nanostructures adhered to surfaces of the polymeric fibers via an electroless deposition process. Suitable materials for the polymeric fibers and metallic nanostructures include polyacrylonitrile (PAN) fibers and copper nanostructures, respectively.

A nonwoven fiber assembly. The nonwoven fiber assembly includes a nonwoven fibrous web including a plurality of discontinuous fibers; and a nonwoven fabric at least partially surrounding the nonwoven fibrous web; the nonwoven fabric including a plurality of randomly-oriented fibers, the plurality of randomly-oriented fibers comprising: at least 60 wt % of oxidized polyacrylonitrile fibers; and from 0 to less than 40 wt % of reinforcing fibers having an outer surface comprised of a (co)polymer with a melting temperature of from 100° C. to 450° C.; and a fluoropolymer binder on the plurality of randomly-oriented fibers.

A nonwoven fiber assembly. The nonwoven fiber assembly includes a nonwoven fibrous web including a plurality of discontinuous fibers; and a nonwoven fabric at least partially surrounding the nonwoven fibrous web; the nonwoven fabric including a plurality of randomly-oriented fibers, the plurality of randomly-oriented fibers comprising: at least 60 wt % of oxidized polyacrylonitrile fibers; and from 0 to less than 40 wt % of reinforcing fibers having an outer surface comprised of a (co)polymer with a melting temperature of from 100° C. to 450° C.; and a fluoropolymer binder on the plurality of randomly-oriented fibers.

Composites comprising polymeric nanofibers, metal oxide nanoparticles, and optional surface-segregating surfactants and precursor compositions are disclosed. Also disclosed are nonwoven mats formed from the composites and methods of making and using the composites. The composites enable the deployment of nanostructured materials for water treatment within a self-contained membrane with high water fluxes, as well as a number uses.