In this research, we have developed a novel and environmentally friendly process for the preparation of porous UHMWPE thin films. This process utilizes a combination of "swell-drawing" and "nascent powder sintering" technology and a non-toxic solvent, mineral oil, to produce films of high porosity and high mechanical performance. One attractive feature of our process is the ease of solvent removal whereby nearly 99.8% of solvent can be readily removed by compression and acetone washing....[ Read more ]

In this research, we have developed a novel and environmentally friendly process for the preparation of porous UHMWPE thin films. This process utilizes a combination of "swell-drawing" and "nascent powder sintering" technology and a non-toxic solvent, mineral oil, to produce films of high porosity and high mechanical performance. One attractive feature of our process is the ease of solvent removal whereby nearly 99.8% of solvent can be readily removed by compression and acetone washing.

Nascent powders were compacted into coherent slabs and they were swollen inside mineral oil within mechanical integrity to gel-crystallized state for further compression at elevated temperature to a porous thin film. It was found that the compaction temperature determined the morphologies of the films. TEM analysis shows that only the films prepared from the slab compacted at temperature below the melt transition temperature, T_m, of the nascent powder are highly porous. They exhibit an openly porous network wherein the inner surfaces are interconnected by crystal bridges, which are stacking of lamellae with thickness of ~6-8 nm. They also show very high ductility and could be drawn readily to a draw ratio above 12 giving a Young’s modulus and a tensile strength of 52 GPa and 1.32 GPa, respectively. The DSC analyses on the as compacted slabs shows that the samples prepared at compaction temperature above T_m have lower melt transition temperature and they underwent significant dissolution during swelling process. Thus, our process route has to be started with slabs prepared from low temperature compaction.