Construction Of Composite Material Based On Cellulose And Properties Investigation

Cellulose and polylactic acid?PLA?are difficult to dissolve in the same solvent.When they are precipitated out of the solvent,phase separation can be easily generated.The above problems restrict the homogeneous preparation of composites based on cellulose in high performance.Herein,this study designed a series of highly efficient solvents that can both dissolve hydrophilic cellulose and hydrophobic PLA by precisely designing the molecular structure of the ionic liquids and controlling the mass ratio of ionic liquids and co-solvent.Furthermore,we also explored the dissolving mechanism of cellulose and PLA in these solvent systems,trying to solve the scientific problems that cellulose and PLA were difficult to be co-dissolved in the same solvent because of the hydrophilicity of cellulose and hydrophobicity of PLA.By adopting the technology of precipitate out step by step,cellulose and PLA can be precipitated from solvents at the same time,generating no phase separation.The homogeneous composites of high properties can be achieved by combining cellulose and PLA together from molecule level.Furthermore,we investigated the distribution and interaction mechanism of cellulose and PLA in the composite materials and their effect on the macroscopic properties of the composites.This study also revealed the affection of component mass ratio on the properties of the composites.The main contents are listed as follows:?1?According to the structure and unique properties of ionic liquids,we designed a series of ionic liquid solvent systems which were screened for the dissolution of cellulose and poly acid ester by studying the dissolving rule and mechanism of cellulose and poly acid ester in these solvents,providing a scientific evidence for the design of solvent systems of ionic liquids?both cellulose and poly acid ester were dissolved?.?2?Cellulose and various kinds of poly acid ester have significant differences of hydrophilicity.When cellulose and poly acid ester are precipitated from solvent systems,the common precipitating agents lead to phase separation in the process of precipitation,resulting in some problems such as material shrinks,crimp and uncontrollable morphology,etc.Therefore,the effects of the type,the composition and the order of the precipitating agents on the precipitating speed and behavior of the composites were systematically studied.It is expected that this study provides a scientific evidence for the controllable preparation of hydrophilic/hydrophobic homogeneous composites with specific functions.?3?Cellulose/poly acid ester homogeneous composites were characterized by SEM,XRD,IR,TGA and ¹³C MAS NMR and so on.The mechanical properties of dry samples were also measured by universal mechanical tester.What's more,the influence of the ratio of components,the type of precipitant and drying condition on the structure and morphology,thermal properties and mechanical properties of composites were also investigated.Furthermore,the distribution of cellulose and biodegradable polymers in composite materials were also investigated.This study provides an evidence for the controllable preparation of functional materials with the required mechanical properties.?4?The weight loss percentage of samples was measured by means of soil burial.The effects of buried time and proportion of material component in composites on the morphology,thermal properties and the degradation rate constant of this composites were also systematically investigated.?5?The survival rate of EC109 cells on the composite films was determined.The influences on cell adhesion,growth and proliferation by the composite material component proportion were investigated,providing scientific knowledge for the controllable preparation of biological macromolecular composite materials with biocompatible properties.