No abstract

The starch xanthate/natural rubber (SX/NR) composite was prepared by directly mixing and co-coagulating NR latex and the modified starch paste with carbon bisulfide. The vulcanization kinetics of NR and SX/NR composite were investigated by using a rubber process analysis (RPA). The mechanism of SX/NR composite vulcanization was similar to that of pure NR. The values t0and tdisof XS/NR composite were shorter than that of NR, and the activation energy E1for the induction period was smaller. The activation energies E2and E3for the curing period were smaller than that of NR.

In this paper, Bacterial oxidation-cyanide leaching experiments were carried out and the carbonaceous substances composition of carbonaceous gold concentrate was been studied. The elemental composition was 9.73 % iron, 9.66 % sulfur, 4.84 % arsenic and 13.23 % carbon which element carbon and organic carbon was 12.11wt.% and 0.06 wt.% respectively. The main carbonaceous substances were elemental carbon which the morphology was dense and similar to graphite. The removal rates of iron, arsenic and sulfur were achieved to 93.78%, 97.02% and 95.54% respectively by bioleaching, and the gold recovery of oxidation residue reached 92.34% by carbon inhibited cyanide leaching process. The sulfide minerals packing problem could be effectively solved by bacterial oxidation process and greatly increased the gold recovery. So the bacteria oxidation and carbon inhibited leaching process is applicable to the carbonaceous gold ore.

The influence of microstructures on wettability on stainless steel was investigated. Two kinds of different microstructures were manufactured by a laser processing method with micro parallel grating and square pillars array. The experimental and theoretical values of contact angle (CA) were obtained. Furthermore, within the groove spacing processing size range in micron scale, the experimental results agreed with the theoretical predictions based on the Wenzel. By the influence of machining and measuring conditions, the experimental values of CA were smaller than the predicted theoretical values. A linear relationship between the CA and the micro-scale structures was obtained, which showed the CA was increased with an increase of groove spacing. With the same structural parameters, the CA of square pillars array microstructures was larger than parallel grating microstructures.

The characterization of the aging behavior of raw natural rubber (NR) coagulated by microorganisms (NR-m) was performed on a rubber processing analyzer (RPA) by tests of frequency sweep, strain sweep and stress relaxation, respectively. With the prolongation of the aging time, the storage modulus (G'), storage torque (S'), complex viscosity (η*) and stress relaxation time of raw NR-m decreased while the damping factor (tanδ) were increased. As the oscillation frequency was increasing, the G' rose gradually but the tanδ decreased. The η*diminished over the whole range of frequency shear rate (γƒ) values. Its change remained all almost the same at low strain shear rate (γs) but began to decrease sharply when the rate reached a higher value. The S' soared up in the region of less than 10°, but began to slow down after that point.