Effect Of Different Experimental Conditions On Morphology And Dispersibility Of Calcium Silicate Hydrate

Calcium silicate?CaSiO₃?materials have been more and more widely used because of their excellent performance.Besides its application in traditional industry,calcium silicate has aroused great interest from everyone in the fields of life sciences and aerospace electronics,such as drug transportation,medical plastic surgery,bone tissue engineering and so on,because of its good biological activity.It is also more widely used.Hollow nano-spheres have gained much attention owing to their large surface area?large surface permeability and low density.Now the most commonly used method for preparing nanomaterials is the soft template method.The most representative of soft template is the micelle.In this paper,we studied the preparation of hydrated calcium silicate with different morphology,integrity and dispersion by adjusting various experimental conditions,and the detailed experimental process and results are as follows:The reaction of reactants sodium silicate and calcium nitrate were carried out,and SDBS was added to the container as a template of the reaction.Different experimental conditions were set up to adjust the formation of dispersion and integrity and the ideal morphology of the CSH by changing the morphology and dispersion performance of the template.Through different testing methods to characterize and analyze the sample,the experimental results show that the concentration of SDBS,the concentration of calcium and silicon source,stirring,reaction time and other experimental conditions directly or indirectly affect the dispersion and morphology of the hydrated calcium silicate to a certain extent.XRD spectra showed that when the concentration of Ca?NO₃?₂·4H₂O and SDBS solution remained constant,the smaller the concentration of Na₂SiO₃·9H₂O,the thinner the wall of the spherical shell CSH,the lower the crystallinity and the weaker the intensity of the diffraction peak.When the concentration of Ca?NO₃?₂·4H₂O and Na₂SiO₃·9H₂O was kept constant,the greater the concentration of SDBS,the more the number of CSH micelles,the more the number of CSH formed spherical shell,and the thinner the wall of spherical shell.That is,when SDBS reaches a certain concentration,the concentration of Ca and Si does not change,the number of spherical shell-shaped CSH does not change,and the amount of XRD is not changed.The intensity of diffraction peak also did not change much when the concentration of SDBS was high.With the increase of reaction time from 1 day to 20 days,the diffraction peaks become stronger and stronger,indicating that the ordered crystallization growth of CaSiO₃ will continue to occur on the surface of spherical shell CaSiO₃ with the prolongation of reaction time.Stirring or not has little effect on the growth mode of CSH,which indicates that agitation can only make the mixture between solutions more uniform and the contact between reactants fuller,but it has little effect on the crystallinity of the product CSH.The polymerization degree of Si-O of[SiO₄]^4-tetrahedron in CSH was qualitatively and quantitatively studied by FT-IR technology.It was found that the[SiO₄]^4-tetrahedron structure of CSH exists in the form of Q².The increase of Na₂SiO₃·9H₂O concentration,the increase of SDBS concentration,the increase of reaction time and the stopping of agitation all caused the vibration peak at 977cm^-11 to shift to the direction of low wavenumber,and the peak intensity became stronger.The results show that the polymerization degree of CSH increases and the relative content of Q² structure increases under these reaction conditions.The concentration of Na₂SiO₃·9H₂O and SDBS was the main control factor.SEM images showed that when the concentration of SDBS was low,the number of micelles formed and CSH dispersed well,and when the concentration of SDBS was higher,the number of micelles formed was more,the CSH was not well dispersed,the aggregation was serious,and the damaged part was incomplete,the growth rate of spherical CSH is slower,the shell wall is thinner and be vulnerable to breakage.When the concentration of Ca?NO₃?₂·4H₂O is small and the concentration of Na₂SiO₃·9H₂O is high,the wall thickness and morphology of CSH are complete.The suitable ratio of SDBS and Na₂SiO₃·9H₂O is the main control factor to promote the growth of spherical shell CSH.The increase of reaction time will cause the micelle aggregation seriously,and agitation will affect the integrity of micelle to a certain extent.By adjusting the concentration of reactants,the CSH with different morphologies of spherical shell,rod shape and layered layer can be obtained.According to the results of the characterization and the experience of the predecessors,the formation mechanism of spherical shell and rodlike shape of calcium silicate hydrate was analyzed and summarized.