Paste-processed ultra high molecular weight polyethylene expanded into dense articles

A method of forming a dense UHMWPE film comprising:

• forming a dry, porous UHMWPE tape from a UHMWPE polymer having a molecular weight of at least 2,000,000 g/mol and a melt enthalpy of at least 190 J/g;
• and
• compressing the dry, porous UHMWPE tape below the melting temperature of the UHMWPE polymer;
• and
• stretching the UHMWPE tape in at least two directions at a temperature above the melt temperature of the UHMWPE polymer to form the dense UHMWPE film, wherein the dense UHMWPE film comprises:
• a first detectable endotherm from about 135° C. to about 143° C.;
• and
• a second detectable endotherm from about 145° C. to about 155° C.

A method of forming a dense UHMWPE film, comprising:

• forming a dry, porous UHMWPE tape from a UHMWPE polymer having a molecular weight of at least 2,000,000 g/mol and a melt enthalpy of at least 190 J/g;
• and
• stretching the dry, porous UHMWPE tape in at least two directions at a temperature above the melt temperature of the UHMWPE polymer to form the dense UHMWPE film, wherein the dense UHMWPE film comprises:
• a first detectable endotherm from about 135° C. to about 143° C.;
• and
• a second detectable endotherm from about 145° C. to about 155° C.

A method of forming a dense UHMWPE film, comprising:

• (a) forming a porous UHMWPE tape from a UHMWPE polymer having a molecular weight of at least 2,000,000 g/mol and a melt enthalpy of at least 190 J/g;
• (b) expanding the porous UHMWPE tape below the melt temperature of the porous UHMWPE tape to form a porous membrane;
• and
• (c) compressing the porous UHMWPE membrane at a pressure of at least 1 MPa thereby forming the dense UHMWPE film, comprising:
• a first endotherm from about 135° C. to about 143° C.;
• a second detectable endotherm from about 145° C. to about 155° C.