Papers by Author: Qiu Ju Sun

Abstract: Diatomite was treated by titanate coupling agent and blended with low-density polyethylene (LDPE) by the method of melt-mixing blend. The performance of the blends, such as thermal behavior, mechanical property and microstructure, were analyzed with differential scanning calorimetry, thermo-gravimetric analysis, tensile strength testing and scanning electron microscopy. The results showed that influenced the crystalline behavior of LDPE phase in the blends and made the crystallization rate of LDPE phase decreased. Moreover, the thermo-decomposing temperature of the blends increased with increasing the diatomite content, diatomite significantly improved the thermal stability of the blends. Tensile strengths of the blends firstly decreased and then increased. When the diatomite content was 30%wt, the tensile strength of the blend reached to 14.6MPa. SEM photographs showed the good dispersion and interaction.

Abstract: A GC/MS method was established for the determination of phthalates plasticizers in bottled beverages. The calibration curves are all linear in the range of 0.01 to 5μg/L with correlation coefficients greater than 0.997. The recoveries are in the range between 97.27% and 105.05% under two levels. The testing data of the samples showed that the five bottled beverages all contained DBP, DIBP and DEHP plasticizers, and DIBP content was obviously higher than the other two.

Abstract: CaCO3 whiskers were treated by stearic acid and the surface property of the treated whisker were evaluated by activation index. When the mass fraction of stearic acid was 4.0%, activation exponential increased to 80.0% almost from zero. The composites were prepared by blending with polypropylene and the treated whiskers. The performance of the composites, such as thermal behavior, mechanical properties and microstructure, were analyzed with differential scanning calorimetry, scanning electron microscopy and tensile testing. The results showed that CaCO3 whisker played heterogeneous nucleation to induce crystalline behavior of PP phase in the blends and the crystallization rate of PP phase also increased because of CaCO3 whiskers intervening. Moreover thermo-decomposing temperature and tensile strengths of the blends all increased with increasing whisker content, except a little less than that of pure PP as filling 3.22% CaCO3 whiskers, but the elongation at break increased with increasing whisker content.

Abstract: Calcium carbonate (CaCO₃) whiskers were firstly treated by sodium stearate, and then blended with polypropylene (PP) to prepare the composites by a closely intermeshing co-rotating twin-screw extruder at 200°C. The performance of the composites, such as thermal behavior, microstructure and mechanical properties, were analyzed with differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM) and mechanical testing. The results showed that CaCO₃ whisker influenced the crystalline behavior of PP phase in the blends because of its intervening. Moreover, thermo-decomposing temperature, tensile and bending strengths of the blends all increased with increasing whisker content. CaCO₃ whiskers had good reinforcing and toughening effects on PP.