Nanowebs

A nonwoven nanoweb that is formed by a process comprising calendering a polymeric nanoweb between a nip between a first roll and a second roll and applying a pressure to the web across the thickness of the web, in which one of the first roll and the second roll is a hard roll, the other roll being a soft roll having a hardness less than Rockwell b 50, and heating the web to a temperature between the Tg of the nanoweb polymer and its Tom, wherein the calendered nanoweb has less than about 15% by area in the plane of the web comprising melted regions.

A process for stabilizing the surface of a polymeric nanoweb comprising calendering the nanoweb through a nip between a first roll and a second roll and applying pressure to the web across the thickness of the web, wherein one of the first roll and the second roll is a hard roll, the other roll being a soft roll having a hardness less than Rockwell B 50, and heating the web to a temperature between the Tg of the nanoweb polymer and its Tom.

A nonwoven nanoweb comprising polymer nanofibers having a solidity of at least about 20%, a basis weight of at least about 1 gsm, a thickness of between about 1 μm and 400 μm and a maximum pore size of about 15 micrometers, wherein the nanoweb has less than about 15% by area in the plane of the web comprising melted regions.

A nonwoven nanoweb comprising polymer nanofibers having a solidity of at least about 20%, a basis weight of at least about 1 gsm, a thickness of between about 1 μm and 400 μm and a tensile strength at break in the machine direction of at least about 4.1 MPa, wherein the nanoweb has less than about 15% by area in the plane of the web comprising melted regions.