Feasibility study to investigate caking in washing powder formulations using a Freeman FT4 powder rheometer

ABSTRACT

Because of legislation and environmental concerns, washing powder manufacturers have phased out phosphate builders in favor of substitutes such as sodium carbonate. This has meant that the new formulations have a greater tendency toward unwanted agglomeration (caking), based on moisture uptake and migration. This study examines the feasibility of using a Freeman FT4 powder rheometer to examine the effect of moisture migration, using the basic flow energy value to compare formulations of sodium carbonate content 27–37% and sodium sulfate content 10–20% by mass after 7 d exposure to 80% relative humidity at 20°C. The results showed that 31 and 33% sodium carbonate formulations were the most resistant to caking, with 27 and 37% being the most susceptible under the test conditions. Using the method of Brockbank et al. (2015 Brockbank, K., B. Armstrong, Y. Chandorkar, and T. Freeman. 2015. Understanding powder caking as a consequence of a range of mechanisms by means of powder rheometry. Particulate Science and Technology 33:102–08.[Taylor & Francis Online], [Web of Science ®] , [Google Scholar]), the FT4 was also used to detect the presence of a hard crust; under the test conditions, no hard crust was found. However, the presence of soft caking was detected in the force–height profile, showing a less abrupt transition.     

医用金属材料表面含磁粉的TiO2薄膜的制备及其血液相容性

用溶胶-凝胶法在316L不锈钢及镍钛合金基片上制备含SrFe12O19磁性粉末的TiO2薄膜,分析了膜基的结合强度,并用X射线衍射仪(XRD)、扫描电镜(SEM)等对磁性粉末的表S面结构及形貌进行了分析.动态凝血时间和溶血率的测定结果表明用含磁粉的TiO2薄膜进行表面改性的316L不锈钢和NiTi合金动态凝血时间延长,溶血率下降,证明含磁粉的TiO2薄膜有很好的血液相溶性.