length, but contain imperfections that limit the value of the bulk conductivity. The value of 1950 S cm ±1 should be taken as an upper limit to the conductivity of these fibers at this time. A detailed study of the temperature dependence of the electrical conductivity of films of PANi/AMPSA may be found in the literature. [17] Tensile measurements of the fiber were undertaken using an Instron stretch rig set up for room temperature singlefiber testing. The Young's modulus of the ªas-spunº fibers before ªneckingº occurred was found to be between 40 and 60 MPa for all the fibers spun into the aforementioned three coagulants. The tensile strengths at breaking were between 20 and 60 MPa. For example, a fiber spun into butyl acetate had a Young's modulus of 40 ± 10 MPa and a tensile strength at breaking of 50 ± 10 MPa. This is of the same order of magnitude as undrawn nylon 12. Although variations between the fibers showed no coagulant to be clearly favorable above another in terms of fiber properties, we tend to favor butyl acetate due to its low cost, relatively high flash point (22 C), and high boiling point (125 C).We have spun fibers from dope solutions with a lower solids content of PANi/AMPSA (0.6) in DCA. These fibers spin at a lower pressure (<100 psi) and formed smoothly cylindrical fibers in the three aforementioned coagulants. The fibers are electrically conductive and cold draw. We have been unable to study such fibers in more detail because our small-scale coagulation bath did not allow the fiber to form without adhering to itself.These first results show that it is possible to wet spin fibers of PANi/AMPSA in dichloroacetic acid into various coagulation solvents. The fibers spun into selected coagulants are electrically conductive and can be cold drawn to extensions of >500 % with a concomitant rise in electrical conductivity of~1500 %. The fibers appear void free and, when drawn, the strain-hardened fibers show final breaking strains of the order of 50 MPa. These fibers are stable in air and could be produced cheaply on an industrial scale. A more comprehensive wet spinning rig is presently under development to improve the fiber spinning and post-processing conditions; therefore fiber performance should rise accordingly. We intend to study the mass balance, momentum, and energy transfers in this fiber-spinning process for later publication.

No abstract

A series of tetrapodal derivatives of tetraphenylmethane were synthesized and characterized. Crystals obtained from tetrakis(4-acetamidophenyl)methane (lc) and from tetrakis[4-(4-aminobenzamido)phenyl]methane (2b) were analyzed by X-ray diffraction. The analyses pointed to the crystal packing problems faced by molecules of this kind by showing that the crystals, with composition lc'2DMF'2H20 and 2b'2DMSO, respectively, contained cocrystallized solvent molecules. The solvent molecules were found in both cases to be held in place by H bonds; in the case of 2b.2DMSO they occupied channels running along the b axis. Tetrakis(4-aminophenyl)methane (lb) was used in polycondensation reactions with terephthalic acid, under modified Yamazaki conditions, to produce rigid aromatic polyamide networks. The networks were obtained as gels encompassing the whole volume of the reaction mixture. The volume of the gels did not vary noticeably upon changing the solvent (1-methyl-2-pyrrolidone) with less polar solvents, but the gels collapsed upon drying. No crystallinity was observed.

SUMMARY Thin films of methacrylic polymers, obtained by copolymerization of perfluorodecyl-and 2-ethylhexyl methacrylate, were prepared by spin coating or by the Langmuir-Blodgett (LB) technique. The permeability to water of these materials was studied by means of the attenuated total reflection (ATR) technique, revealing the strong dependence of the swelling phenomenon on the films' surface composition and structural order. The presence of polar groups on the fildair interface facilitates the wetting of the thin films.