No abstract

No abstract

The modified asphalt binders with hindered phenolic antioxidant (Irganox 1010) were prepared by melt blending, and the effects of Irganox 1010 on physical and rheological properties of base asphalt were investigated by means of conventional physical properties tests and dynamic shear rheometer (DSR) tests. The short-term and long-term thermo-oxidative aging properties of asphalts with Irganox 1010 were studied by thin-film oven test (TFOT) and pressure aging vessel (PAV) test. The influence of Irganox 1010 on the chemical structure and compositions of asphalt before and after the aging test were evaluated using Fourier transform infrared spectroscopy (FTIR) analysis and thin-layer chromatography with flame ionization detection (TLC-FID) analysis, respectively. The results show that the penetration and ductility are increased, whereas the viscosity and softening point are decreased, with the addition of Irganox 1010, and Irganox 1010 also decreases the complex modulus and increases the phase angle of asphalt binder. The antioxidant-treated binders exhibit excellent resistance to thermo-oxidative aging. Furthermore, Irganox 1010 inhibits the carbonyl (at 1,700 cm−1) index and sulfoxide (at 1,035 cm−1) index increment by oxidation of phenolic hydroxyl and degradation of ester group, and changes of chemical compositions of asphalt show that Irganox 1010 peptizes the asphaltenes and exhibits effective inhibition of gelatinization of asphalt binder during the process of thermal oxidation aging.

No abstract

No abstract

No abstract

No abstract

In the present study, a new procedure, arc-melting followed by spark plasma sintering, was employed to prepare BaTi 2 O 5 ceramics with high relative density and large dimension. Single-phased BaTi 2 O 5 powders were synthesized from BaCO 3 and TiO 2 powders by arc-melting, and then the BaTi 2 O 5 powders were densified by spark plasma sintering at different temperatures (1273-1473 K) and pressures (20-50 MPa). Single-phased BaTi 2 O 5 ceramic was obtained at and below 1423 K, however, it tended to decompose at elevated temperatures. Considering the upperbound decomposing temperature, we further enhanced the densification of BaTi 2 O 5 ceramics by increasing the sintering pressure, and a high relative density of 92.1 % was achieved at 50 MPa. The permittivity of the BaTi 2 O 5 ceramics was 28.7 at 1 MHz, and increased with the measuring temperature, reaching a maximum value of 191 at the Curie temperature of~740 K.