Preparation of cyclic oligomeric alkylene phthalates via pseudo-high dilution condensation of alkylene diols with iso- and terephthaloyl chlorides and conversion to high molecular weight polyesters via ring-opening polymerization is described. Sterically unhindered amines such as quinuclidine or 1,4-diazabicyclo[2.2.2]octane (DABCO) catalyze the condensation significantly faster than other tertiary amines and are useful for carrying out this conversion in high yield, in the first direct reaction of diol and diacid chloride to form cyclic polyesters. The mixtures of oligomeric cyclics melt at 150-200 degrees C, providing liquids of low viscosity. Ring-opening polymerization using tin or titanate catalysts affords high molecular weight polymers within minutes. Complete polymerization of PBT oligomeric cyclics can be achieved at 180-200 degreesC, significantly below the polymer's melting point of 225 degreesC, and with molecular weights as high as 445 x 10(3). Polymers formed via such a process are more crystalline than conventionally prepared polyesters.
Direct electrophilic substitution of the cyclopentadienyl ring of cymantrene has been used to prepare five cymantrenyl‐monomers with unsaturated sidechains. Direct substitution of cymantrene with acryloyl‐ and methacryloyl chloride under Friedel‐Crafts conditions has led to acryloyl‐ and methacryloylcymantrene. The complexes have been characterized using 1H and 13C NMR, IR and elemental analysis. Both complexes polymerize under treatment with AIBN at 60–70°C. The chelated complex [n5‐C5H4(CH2CH=CH2)]‐Co[(NH)2C6H4], was prepared from the treatment of [n5‐C5H4(CH2CH=CH2)]Co(CO)2 with I2 followed by (NH)2C6H4 and base. The complex was characterized with 1H NMR and IR but failed to undergo free‐radical polymerization. The strategies used to prepare organometallic polymers are discussed.
Carbon deposit tests using No. 2 distillate fuel were performed in a flowing fuel/flowing atmosphere chamber utilizing a heated vertical test plate which simulates the interactions of fuel spray with combustor surfaces in a gas turbine downstream of the fuel nozzle. This type of interaction can occur in the premixing region of a low-NOx combustor operating on No. 2 fuel and can impact performance and reliability.
Deposit formation was studied as a function of surface temperature, surface composition, duration of exposure, atmospheric composition, and fuel type. Surface temperature and oxygen content in the atmosphere appear to have the greatest effect upon deposition: whereas the surface composition and exposure duration have a negligible effect. Conversion of fuel to deposits decreases somewhat as fuel flaw rate increases. A peak conversion to deposits of 0.1 grams per kg of fuel (0.01% conversion) occurred at a surface temperature of 345 C (653 F). The conversion fraction dropped to less than 1% of [he peak conversion below 225 C (437 F) and above 410 C (777 F). A comparison with published data from horizontal plate tests show different rates at specific temperatures which can be attributed to the test geometry, flow rate and residence time.
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