On the Preparation of Ultrafine Calcium Sulfate Whiskers with Hydrothermal Method and Application Research in Polypropylene

摘要

Hydrothermal method was applied in the preparation of calcium sulfate whiskers in airtight reactor using gypsum as primary materials.The optimum conditions of preparation are as follows: pH value 9.8～10.1,concentration 5%,material size 18.1 μm,which were determined by the analysis of the diameter of CaSO4 whiskers through SEM.On these conditions a product of ultrafine CaSO4 whiskers with diameter of 0.19μm and aspect ratio of 98 is obtained.Ultrafine CaSO4 whiskers with different concentrations,modified by titanate NDZ-401,were added into polypropylene as intensifier and composites of Ultrafine CaSO4 whiskers/polypropylene were prepared by melting-extruding method.Mechanical performance of the composites was tested and surface morphology of the composites was observed by SEM.The results indicated that impact notched izod of the composites was enhanced by 49.5% compared with pure polypropylene when 10.0% Ultrafine CaSO4 whiskers were added into polypropylene and toughening effect was very remarkable.Dispersion behaviour and interface phenomenon of Ultrafine CaSO4 whiskers in polypropylene matrix were investigated by SEM.The results indicated that Dispersion performance of Ultrafine CaSO4 whiskers modified by titanate NDZ-401 in polypropylene matrix is good,which improved mechanical performance of composites to some extent.