Papers Having Low Density and High Average Specific Modulus

A process for making a paper, comprising the steps of

• a) forming an aqueous slurry comprising polymeric fibers comprising a first polymer and polymeric binder comprising a second polymer,
• wherein the first polymer is a copolymer having a structure derived from the reaction of para-oriented aromatic diamine monomer and benzimidazole monomer with a para-oriented aromatic diacid monomer, and the polymeric fibers have a 2 theta (2θ) x-ray diffraction angle peak of 20.2 (+/−0.5) degrees, and
• wherein the second polymer is a copolymer having a structure derived from the reaction of para-oriented aromatic diamine monomer and benzimidazole monomer with a para-oriented aromatic diacid monomer;
• b) removing water from the slurry on a paper machine to form a wet paper composition;
• c) drying the wet paper composition to form a dried sheet;
• and
• d) thermally consolidating the dried sheet in one or more steps between nipped rolls heated to a surface temperature of 260° C. or more, using a nip pressure of 700 to 5000 lbs./inch (268 to 894 kg/cm);
• to form a paper having an average specific modulus of 8500 Pa-m3/g or higher and a density of 0.50 grams per cubic centimeter or less.