Solid-state Nuclear Magnetic Resonance Study On The Structure And Molecular Dynamics In Cellulose Gel/Poly (?-caprolactone) Composites

Natural polymer composites have broad application prospects in many fields.However,for many composites with good performances,the interaction between each component and the aggregation structure is not very clear,thus the relationship between the structure and performance of materials is unclear.Increasing the research in this respect will be helpful to understand the properties of composites deeply and guide the design of the relevant materials.Cellulose Gel/Poly??-Caprolactone?composites is a kind of these materials.In this paper,solid state nuclear magnetic resonance?NMR?method is used to study the molecular dynamics properties of Cellulose Gel/Poly??-Caprolactone?composites in the process of melting in order to explain the enhancement effect of cellulose on poly??-Caprolactone?.The specific work is as follows:1.CelluloseGelispreparedbyusingLi OH/urea.Cellulose/Poly??-Caprolactone?composites and pure poly??-Caprolactone?is prepared by in situ ring-opening polymerization.Solid ¹³C NMR is used to obtain the mass ratio of cellulose and poly??-Caprolactone?and the solid¹H NMR is used to gain the average degree of polymerization of poly??-Caprolactone?in the composites.Wide Angle X-ray Diffraction is used to obtain the crystallinity of composites and DSC is used to measure the melting point of materials.2.Solid ¹³C NMR and solid ¹H NMR is used to the the relationship between the spectra and the structure in the process of heating of Cellulose Gel/Poly??-Caprolactone?composites,pure poly??-Caprolactone?and Cellulose Gel.¹H-¹H NOESY is used to study the distance between two protons in the process of melting.It is found that the changing trend of distance is different for each proton-proton pair.The spin-spin relaxation time T₂,spin-lattice relaxation time T_1?in the rotating coordinates,spin-lattice relaxation time T₁ in the laboratory coordinates is used to study the molecular dynamics properties of Cellulose Gel/Poly??-Caprolactone?composites,pure poly??-Caprolactone?and Cellulose Gel at different frequency during the process of heating in order to illuminate the relationship between the molecular dynamics and material structure.