Interfacial Bonding Mechanism And Rheological Behavior Of Nano Particles Treated Bamboo Fiber Reinforced Polymer Composites At Different Processes

The objective of this study was to understand the mechanism of the interfacial properties of nano-CaCO3 reinforced bamboo-plastic composites and the effect of the relative motion of the composite components on the interface under different forming pressures.Nano-CaCO3 impregnation modification(IM)and blending modification(BM)techniques were used,the bamboo-plastic composite materials were processed by hot press molding(3.42 MPa),extrusion molding(20±5 MPa),injection molding(106.67 MPa)and FDM(0 MPa).The mechanical,thermal,combustion,interfacial and rheological properties of the composites were investigated.The main findings are as follows:(1)IM made CaCO3 adhere to the surface of bamboo pulp fiber,with a loading amount of 15 wt%,forming micro-nano particles and reducing the "void" effect.Considering the flexural,impact and tensile properties of the composites produced from the three processing methods comprehensively,when the fiber content was at a 30 wt%,the comprehensive mechanical properties(flexural,impact and tensile properties)of composites were relatively superior.Nano-CaCO3 modification technique was more suitable for extrusion molding process,and the reinforcing effect of IM was better than BM.(2)CaCO3 modification technology changed the molecular orientation of the fiber surface,which induced the crystallization of the matrix polymer,thus improving the crystallinity(CrI),apparent activation energy(Ea),residual amount and affected the combustion performance of the composites.The composites prepared by extrusion molding process had the highest heat distortion temperature,storage modulus(E'),CrI and Ea.The composites prepared by injection molding process had the shortest ignition time,the largest heat release rate,and the highest fire risk.The composites prepared by hot press molding were easiest to burn.The nano-reinforced composites were harder to ignite than the control.(3)The surface free energy of the composite prepared by extrusion molding process was between 40-50 mJ/m2,which indicated that it was hydrophilic.The composites treated by IM were better than those that underwent BM and the control,due to the CaCO3 that had filled the holes on the surface of bamboo pulp fiber to form hydrogen bond and improved the interfacial properties of the composite based on the interfacial mechanical interlocking mechanism.A distinct fractal characteristic was observed in the curved fracture morphology of the composites prepared by extrusion molding process.At 30 wt%,the fractal dimension D of the composite was the largest.The flexural strength was exponentially related to D,it is verified experimentally that this error was<10%.(4)The composites prepared by three processing methods were considered mesoporous materials.The adsorption-desorption was not completely reversible.The closed isotherm of adsorption-desorption indicated that the holes had uniform shape and size,which was an indication of no crack hole and good interface combination.The impact strength of composites prepared by the three processing methods had a significant difference,which is indicated by the R2 was 0.4563.The composite manufactured by extrusion molding process had the best interfacial performance with its Ea being the lowest,namely,124.88 kJ/mol(control sample)and 115.99 kJ/mol(the composites treated by IM).The lower the Ea,the less potential energy was needed to change the structure of the composites.The interfacial performance of the composites manufactured by hot press molding process was the worst,and the Ea was 174.18 kJ/mol(control sample)and 143.28 kJ/mol(the composites treated by IM).(5)The antioxidant KY1010 increased the oxidation induction time and temperature,thus improved the antioxidant performance of the filaments.When FDM was used to prepare the composites,the filaments were accumulated with zero pressure and the interfacial bonding was worse than the other three processing methods.The effect of CaCO3 with a micro-nano scale on the tensile strength of filaments was better than the particles with a nano scale or a micro scale.(6)Compared with the control sample,nano-CaCO3 impregnation and blending modification technology reduced the total energy of the composite by 5.92%and 2.65%,respectively,which in turn,reduced the agglomeration of the bamboo fiber within the composite.The well dispersion of the micro-nanoparticles helped to decrease the number of voids,and made the interfacial hydrogen bond of composite stronger.The above results effectively confirmed the macroscopic and interfacial microcosmic properties.