Cellulose nanocrystals(CNC)were a natural polymer nucleating agent,but their poor dispersion in hydrophobic polyester limits their potential applications.In this study,two different molecular weight polyethyleneimine(PEI)were used to modify the surface of TEMPO oxidized CNC(TONC),with zeta potential and Fourier infrared tests indicating the attachment of a large number of amino groups via both non-covalent and covalent bonding.The resulting nanocellulose was blended with polycaprolactone using a melt extrusion method,and XRD,POM and DSC tests showed that the nanocellulose improved the nucleation efficiency and crystallization properties of the polyester matrix.The Tc was increased from 26.8 ℃ to 32.5 and 31.8 ℃,while the Tm was increased from 57.5 ℃ to 63.1 and 60.1 ℃.The tensile strength of the resulting composites increased by 35.78％and 24.90％,and Young's modulus increased by 23.15％and 20.16％,respectively.PEI was found to reduce the hydrogen bond density between TONC molecules,thereby reducing TONC agglomeration in the matrix and increasing the nucleation rate of nanocellulose in the polyester matrix,effectively improving the mechanical properties of the resulting nanocomposite.
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