Two methods have been developed for the preparation of biaxially oriented poly(phenylene vinylene) from its poly(sulfonium salt) precursor. A two‐stage stretching process permits non‐equibiaxial stretching over a wide range of deformation ratios and a bubble expansion technique allows equibiaxial planar extension. The resulting films were examined using X‐ray diffraction prior to chemical doping with SbF5 vapor. Biaxial orientation was shown to exert considerable influence over the attainable electrical conductivity.

Burnett Associates, Inc. (BAI), under contract to the U.S. Bureau of Mines, has developed a reliable and cost effective method of remote placement of point support columns in abandoned mines through boreholes to provide local support, especially under surface structures in subsidence prone areas. The development of the system to remotely build a concrete support cylinder in an abandoned mine required the coordination of mechanical system and concrete design. The mechanical system was designed to remotely place concrete in a cylindrical shape. The concrete was designed to meet the requirements of low slump with high enough strength to resist the forces applied by the ground above the mine. The support cylinder is fabricated through an 8-inch borehole by pumping concrete through a second 4-in pipe inside the borehole. The 4-in pipe has a flexible trunk on the lower end that is bent from the surface when it is inside the mine void. When pumping starts, the 4-in pipe is rotated and a spiral of concrete is placed on the mine floor. Operation continues until the concrete seals at the roof. A normal weight concrete as recommended by ACI 211 having a maximum slump of 1-2 in, a maximum coarse aggregate size of 1/2 in, and a minimum compressive strength of 5,000 psi was used. Cylinders have been fabricated to roof heights of 6 ft. There does not appear to be a technical height limitation. The concrete cylinder can support up to 40 x 10 6 lbs when fully cured and filled with gravel, depending on cylinder diameter.