| Core-shell structured wood plastic composites is a new environmental composites combined several different material performance. The excellent performance or functional composites can be got by reasonable designing different core, shell materials. Based on the above research ideas, core-shell structured bamboo plastic composites were prepared using of bamboo residue and white mud in the process of bamboo pulp making by co-extruded technology. This paper firstly studied the major components of leftovers and properties of high-density polyethylene(HDPE), and then investigated the manufacture and properties of core-shell structured bamboo plastic composites, meanwhile, discussed the shell materials on properties of core-shell structured bamboo plastic composites. The main content of this paper are shown as follows.The research related to leftovers and HDPE composites. The morphology and main component analysis, HDPE composites were used HDPE as matrix and bamboo pulp fiber, white mud and nano calcium carbonate as infill, disscussed the performance of HDPE composites. The results showed that the main components of white mud is calcium carbonate and its particle size distribution between 700 nm and 50 microns, bamboo fiber length to diameter is small, its particle size in 25-75 microns and greater than 75 microns; the flexural properties of HDPE composites increased as the addtion of fillers, but decreased the impact strength. 10wt% nano calcium carbonate in HDPE composites could improve synthesized characteristic. Dynamic thermomechanical analysis(DMA) analysis showed that the addition of white mud, nano calciμm carbonate and bamboo pulp fiber in composites increased rigid significantly, The increased storage modulus and reduced loss factor reflected the three kinds of raw materials for composite toughening effect weaken.The physical mechanical and thermal stability properties of core-shell structured bamboo plastic composites. With bamboo residue/HDPE as the core layer, HDPE composites for shell material, core-shell structured bamboo plastic composites were prepared by co-extruded process, the effect of the mass fraction of nano calcium carbonate, bamboo pulp fiber and white mud in the shell on the physical mechanical and thermal stability properties of composites. The study found that compared with the extruded composites, with consistent density, flexural, tensile and impact properties of core-shell structured bamboo plastic composites improved significantly; long-term immersion test showed that the core shell structured bamboo plastic composites has excellent water resistance; TG analysis showed that the initial decomposition temperature of the core-shell structured bamboo plastic composites decreased, but the peak temperature almost unchanged, this indicated that the shell layer has less effect on the thermal stability of core-shell structured bamboo plastic composites. Pyrolysis kinetics of core-shell structured bamboo plastic composites results showed the bamboo pulp fiber and nano calciμm carbonate were 10% and 15% respectively, the average apparent activation energy of composites reached the maximμm, the addition white mud in the shell slightly lower, but the extent of the average activation energy was not significant under the experimental condition.The research related to microstructure of core-shell structured bamboo plastic composites. The mechanical properties of composites were tested using nano indentation, the microstructure characteristic parameters of particle distribution index A, particle average size D and standard deviationSD were extracted based on image processing technology, the fractal dimension D was used to study the microstructure and impact properties of composites. The study found that the shell materials have significantly effect on the elastic modulus and hardness of core-shell structured bamboo plastic composites, and the plastic deformation capacity of the composites was also different; when the content of nano calcium carbonate and white mud was 5% and 15% respectively, the particle dispersion and distribution were better. The fractal dimensions of the fracture surface were within the range of from 2.1610 to 2.2204 by pixel-covering method, this indicated that impact fracture surface of the composites had significant fractal characteristics. And the relationship between impact strength and fracture surface fractal dimension of the composites obeyed exponential function roughly, the surface fractal dimension of the fracture can effectively reflect the macro mechanical properties of the core-shell structured bamboo plastic composites.The research related to dynamic mechanical properties of core-shell structured bamboo plastic composites. The interface compatibility was charactered using the contact Angle and the DMA. The results showed that the content of nano calcium carbonate was 5%, bamboo pulp fiber and white mud was 20%, surface free energy of shell materials was similar the core layer, this is indicated that the interface is better between the core and shell material, Under 1 Hz frequency the spectrum showed that during the-20 to 50℃, when the bamboo pulp fiber and white mud added up to 15%, the storage modulus of core-shell structured bamboo plastic composites is higher, but decreased with the adding of the nano calcium carbonate. when the white mud and nano calciμm carbonate added up to 15%, the interface of the composites interaction parameter B value was significantly increased. Different shell materials had effect on glass transition temperature and loss factor; Under the condition of multiple frequency measured spectrum showed that the 45℃(glass state), the storage modulus of composites showed significant dependence on frequency presented increase firstly and decrease then with the increased filler in the shell layers. In the rubbery state, the storage modulus dependent on frequency has no obvious regularity; The proportion of bamboo pulp fiber in the shell has effect on the glass transition apparent activation energy(Ea). the variations of Ea as the bamboo pulp fiber and white mud added in the shell was greater than the nano calcium carbonate in shell, through calculate A values quantitative characterization the variation of interface bonding state between core layer and shell layer according to the loss factor laws of the hybrid composite materials.Wear resistance and aging properties of core-shell structured bamboo plastic composites. Analysis the wear resistance and aging resistance of surlyn base and HDPE base core-shell structured bamboo plastic composites. The study found that, compared with pure HDPE, the wear rate of the composites fell by nearly 1/4 after joining 10% nano calcium carbonate and 20% white mud particles, when the shell is surlyn, the wear-resisting performance of the composites had not significantly improved; after 7 cycles,-22-23℃ and-22-52℃ freeze and thaw cycle, the color and weight of the two kinds of composites changes smaller; xenon accelerated aging faded badly and surface roughness increased of the extruded composites at first 800 h, and the brightness and color difference were increased, while the core-shell structured bamboo plastic composites increases more slowly; FTIR test results showed that the chemical change in surface after 1050 h of the accelerated ageing. |
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