Study On The Properties And Mechanism Of Bagasse Modified By Inorganic Salt And The Preparation And Performance Of Composite Materials

This dissertation firstly selected five inorganic salts of sodium chloride,magnesium chloride,calcium chloride,zinc chloride and aluminum chloride as the modifier of bagasse(BFS),a series of BFS-PVA/ST composites were prepared by extrusion-injection molding method.The structure and morphology of bagasse,the interface performance,mechanical properties and thermal properties of modified bagasse-reinforced PVA/ST composites were characterized by infrared spectroscopy(FT-IR),X-ray photoelectron spectroscopy(XPS),X-ray diffraction(XRD),scanning electron microscopy(SEM),differential scanning calorimetry(DSC),dynamic thermomechanical analysis(DMA)and electronic universal testing machine.The results showed that inorganic salts can effectively weakened the hydrogen bonds in BFS,enhanced the interface properties of composite materials,improved the mechanical properties and thermal properties of composite materials.The modification effect order is Al Cl₃>Mg Cl₂>Zn Cl₂>Ca Cl₂>Na Cl.FT-IR results showed that the O-H stretching vibration peak at 3381 cm^-1 became stronger and narrower,inorganic salt modification weakened the hydrogen bonding between BFS molecules and molecules;XPS results showed that the inorganic salt changed the atomic composition of BFS surface,destroyed the BFS covered structure and exposing more cellulose;XRD results showed that the coordination reaction of metal ions and hydroxyl groups reduced the crystallinity of BFS.DSC results proved that the melting temperature of the modified BFS reinforced composite increased;DMA results showed that the storage modulus of the modified BFS reinforced composite increased,the damping modulus decreased,the glass transition temperature decreased,the interface adhesion of the composites increased,both the tensile strength and elongation at break of the composites increased significantly,from 8.3 MPa and 33%to 12.3 MPa and 46%respectively,increased48%and 37%compared with raw BFS reinforced composite.The SEM results were consistent with the above conclusion.The inorganic salt makes the surface of the BFS rough and can be evenly dispersed in the composite matrix.BFS and the matrix have good interface compatibility.The single factor method combined with infrared absorption spectroscopy and tensile property test were used to study the influence of inorganic salt metal ion radius,valence state,inorganic salt processing concentration,time and temperature on the relative hydrogen bond strength of BFS and the tensile strength of composite.Infrared absorption spectrum results showed that the relative hydrogen bond strength of BFS increased with the increase of the radius of the inorganic salt metal ion,and decreased with the increase of the ion valence state,processing concentration,time and temperature.The tensile property test results showed that the tensile strength of the composite material decreased with the increase of the radius of the metal ion,and increased with the increase of the valence state of the metal ion.While the ion was the aluminum ion with the smallest radius and the highest valence state,the tensile strength reached the highest 16.9 MPa,an increase of 159.4%compared to raw BFS reinforced composite.The tensile strength increased firstly and then decreased with the increase of the processing concentration.At a concentration of 2.0%,the tensile strength reached a maximum of 18.2 MPa,which was increased by 179.4%compared with raw BFS reinforced composite.The tensile strength increased with the increase of the processing time,but the performance no longer improved significantly after 1.5 h,the tensile strength was 19.2 MPa,which was 194.9%higher than raw BFS reinforced composite.The tensile strength increased with the increase of the processing temperature,and the tensile strength reached a maximum of 17.2 MPa at 50?,which is 163.9%higher than raw BFS reinforced composite.Based on the single-factor test,response surface methodology was applied to design the experiment and investigate the effects of the inorganic salt cation radius,inorganic salt processing concentration and time on the relative hydrogen bonding strength of BFS and the tensile properties of the composite.The results showed that the best conditions for the response value of BFS relative hydrogen bond strength were the processing time of 1.4 h,the processing concentration of 2.1%,and the inorganic salt cation radius of 72.0 pm.The polynomial equation calculated using the tensile strength of the composite as the response value under the conditions of a processing time of 1.5h,a processing concentration of 1.6%,and a cation radius of 72.0 pm,the predicted value was not much different from the actual value,and had practical value.