The diffusion coefficient of naphthalene in supercritical ethanol was measured at 519—534 K and 6.5—16.2 MPa by using the Taylor dispersion technique.The association factor of ethanol molecules was estimated according to the measured experimental data and the infinite diffusion coefficients of naphthalene in high-pressure ethanol published previously.It was shown that the association factor was only a function of temperature varying between 1.8 and 2.8 for liquid and supercritical ethanol.However, the association factor remarkably changed with pressure at the near-critical region of ethanol,reaching a maximum up to 14.

In order to upgrade the performance of poly(p-phenylenebenzobisoxazole) (PBO) materials and to promote its commercialization,a novel method for preparing PBO resin as developed by the homo-
polycondensation of a new AB-PBO monomer, 2-(4-methoxycarbonylphenyl)-5-amino-6-hydroxybenzoxazole (MAB), which was innovatively synthesized by the selective reduction of 4,6-dinitroresorcinol (DNR), then condensation-cyclization with 4-methoxycarbonylbenzoyl chloride and finaly catalytic-hydrogenation.The results showed that: (1) The intrinsic viscosity of PBO resin prepared from 98.2％ purity MAB was more than 10 dl/g in glassware,the total yield (based on DNR) was more than 64 %, polymerization time was shortened to 15 h and the operation was convenient; (2) MAB was exactly identified by ¹H-NMR, ¹³C-NMR, FT-IR and easily prepared at a total yield of 66%.The process has advantages of simple raw materials preparation, controllable selective reduction, one-pot condensation-cyclization, mild hydrogenation condition, and good economics.The selective reduction product: 4-Amino-6-nitroresorcinol hydrochloride (ANR•HCl) could be used as a key intermediate in the improvement of PBO performance; (3) The novel synthesis route could be developed into a new technique for commercialization.The new AB-PBO monomer, has outstanding stability (purity decreases only 0.12% after 270 days in the presence of air).There is no need for antioxidant agent in storage and polycondensation.MAB has equi-molar polycondensing group.The novel synthesis route is better than the AA-type 4,6-diamino resorcinol dihydrochloride plus BB-type terephthalic acid monomers co-polycondensation route.

Bismuth-doped tin dioxide (BTO) nanometer powders were prepared by the wet chemical method using tin tetrachloride (SnCl₄), bismuth nitrate ［Bi(NO₃)₃］ and ammonia as raw materials. Non-bridge hydroxides and capillary force between particles were found to be key factors causing hard aggregation of BTO through analyzing the formation mechanism of hard aggregation. The hard aggregation of BTO was eliminated effectively when the Bi-Sn precursor (BSP) was treated with post processing including dispersing with ultrasonic wave, refluxing and distilling with addition of n-butanol and benzene (DRD) and drying by microwave. Characterized with X-ray diffraction (XRD) and transmission electron microscopy (TEM), BTO spherical particles with tetragonal phase structure are well crystallized, dispersed easily and the average size was less than 10 nm.