| Insoluble sulfur(short for IS) is prepared by molten method using saturated aqueous solution of ammonium persulfate as initiator, carbon tetrachloride saturated with iodine as stabilizing agent, optimized design is conducted toward the influencing factors of content and stability of IS: the amount of initiator and stabilizing agent, constant temperature and reaction time. The results show that the optimum production conditions are as follows: using 0.05% carbon tetrachloride saturated with iodine (weight by iodine)as stabilizing agent, constant temperature is 220℃, and reaction time is 20min; composite initiator carbon tetrachloride solution of SBS (Styrene-butadiene-styrene block polymer, in the shape of linear and star) can improve content of IS prominently, 2%～3% higher when initiated by the one with linear SBS; unitary linear regression models are established separately basing on the effects of quenching temperature on content and stability of IS. The results show that content and stability of IS increase with the decrease of quenching temperature, and a negative linear correlation is displayed between quenching temperature and content of IS, as well as between quenching temperature and stability of IS. Heat stability of IS is determined by differential scanning calorimetry (DSC) and X-ray diffraction(XRD), which further approve the high temperature stability of IS hereof.In the asphalt modification process, considering modified asphalt intenerate point as experimental parameter, univariate analysis and orthogonal design methods are conducted toward influencing factors: amount of IS, blending temperature, reaction time and amount of phosphoric acid, the optimal combination is as follows: blending temperature is 170℃, reaction time is 20min with 2.0mL phosphoric acid per 100g asphalt and 6% IS. The study on existent forms and blending mechanism of IS in asphalt are carried out by scanning electronic microscope(SEM), infrared spectrometry(IR) and differential scanning calorimetry(DSC), and considers that irregular shape particles of IS in asphalt present a homogeneous and steady blending system, as well as form chemical crosslink with base asphalt, hence the modified asphalt heat resistent temperature rise obviously. Compatibilty of IS with asphalt is enhanced since the adding of phosphoric acid. |
