Rheological Characterization Of Cellulose Nanocrystal And Its Application In Liquid Silicon Rubber

The aspect ratio of cellulose nanocrystal(CNC)is a key parameter in its practical applications.Therefore,accurately characterizing the aspect ratio of the CNC is very important.At present,the microscopic observation method is widely used,which can reflect the morphology of CNC intuitively.However,there are some inadequacies: the long statistical period and small statistical weight.This paper,according to the Bachelor equation,rheological method was used to study the aspect ratio of CNC by Ubbelohde viscometer,and the optimum experimental conditions for measurement was obtained.This research mainly divided into three parts:(1)exploring the effect of surface charge density on the rheological characteristics of the aspect ratio of the CNC;(2)exploring the effects of external salt on the rheological properties of the CNC for the aspect ratio;(3)Explore the effect of CNC' poly-dispersity coefficient on rheological determination.Results show that the dispersion of the aspect ratio have no effect on rheological determination of the aspect ratio of the CNC,but the presence of the surface charge affects the measurement results.The presence of additional ions can reduce the influence of surface charge on the aspect ratio of rheological measurements.According to Debye-Hükel theory,the additive salt concentration when ?-1 = d(the Debye length is equal to the diameter of the CNC)is the best additive salt concentration,The diameter of the CNC is mostly around 5-15 nm,so the addition of 1-3 m M Na Cl is optional for rheology measurement in characterize the aspect ratio of the CNC;CaCl2 can also effectively shield the CNC surface charge,but the addition amount was not easy to control;As for AlCl3,because of its own flocculation,it can not be used for CNC surface charge shielding.In addition,on the basis of the study of CNC morphology,cellulose nanocrystal and Liquid silicon rubber(LSR)composites were prepared.APTES was used to modify the CNC,and then the surface-modified CNC was compounded with silicone rubber.The mechanical properties,optical properties,thermodynamic properties and curing kinetics were characterized.The results showed CNC had a better enhancement than the same amount of SiO2.However,due to the existence of amino groups in the APTES,the addition amount of the CNC was limited.