Research On Properties Of Kaolinite Supported Rare Earth Compound And Its Filled Rubber Composites

In this paper,a series of La（OH）₃ with different morphologies were prepared by precipitation method,and the influence of temperature and time on the morphologies of La（OH）₃ was investigated.On this basis,the kaolinite from the Qingshuihe area of Inner Mongolia was used as the raw material,and the kaolinite particle size was refined by the wet ball milling process;the La（OH）₃/Kaolinite composite was prepared by the precipitation method.Then the La（OH）₃/Kaolinite composite was filled into natural rubber（NR）and styrene butadiene rubber（SBR）matrix by emulsion blending method to prepare La（OH）₃/Kaolinite/Rubber composites.The effect of La（OH）₃ on the surface of kaolinite was studied and then investigated the effects of the loading amount of La（OH）₃on the surface of kaolinite（expressed by the value of La/Kaol）,the filling amount of La（OH）₃/Kaolinite composites and kaolinite particle size on the processing vulcanization performance,mechanical properties and thermal stability of La（OH）₃/Kaolinite/Rubber composites.On this basis,the reinforcement mechanism of La（OH）₃/Kaolinite composites were explored.（1）La（NO）₃·6H₂O was used as the raw material and ammonia water was used as the precipitant to prepare La（OH）₃ powders with different morphologies.XRD results shows that at the same reaction temperature,the diffraction peaks of La（OH）₃ powder gradually increase with the increase of reaction time.The results of SEM and TEM shows that at the same reaction temperature,with the increase of reaction time,La（OH）₃ changed from flake to rod shape.The analysis of XRD and TG-DTG results shows that at 730℃,La（OH）₃ converted into La₂O₃ completely,and La₂O₃ continued the morphological characteristics of La（OH）₃.（2）La（OH）₃ was loaded on the surface of kaolinite by precipitation method to prepare a series of La（OH）₃/Kaolinite composites.The results of XRD shows that after La（OH）₃ was loaded on the surface of kaolinite,the La（OH）₃/Kaolinite composite has new characteristic peaks at 2θ=15.7°,28.1°,40.1°,47.0°,55.3°and 64°.And with the increase of the loading of La（OH）₃ on the surface of kaolinite,the two diffraction peaks of kaolinite at 0.715nm and 0.375nm gradually decreases.FT-IR results shows that after kaolinite was loaded with lanthanum hydroxide,its absorption peaks at 3694.1cm^-1,3619.6cm^-1,1035.0cm^-1,914.7cm^-1,541.4cm^-1 and 472.5cm^-1.The absorption peak of kaolinite gradually weakens with the increase of La/Kaolinite value.This may be due to the existence of La（OH）₃ on the surface of kaolinite affects the absorption of infrared light by kaolinite.SEM-TEM results shows that after loading La（OH）₃,flaky material appears on the surface of kaolinite,and the originally smooth surface becomes rough.There is a La peak in the total EDS spectrum of La（OH）₃/Kaolinite composites.Therefore,the appearance of La can also indicate that La（OH）₃ was successfully loaded on the surface of kaolinite.（3）La（OH）₃/Kaolinite/NR and La（OH）₃/Kaolinite/SBR composites were prepared by the emulsion blending method.The effects of the loading amount of La（OH）₃ on the surface of kaolinite（expressed by the value of La/Kaol）,the filling amount of La（OH）₃/Kaolinite composites and the particle size of kaolinite on the mechanical properties and thermal stability of the composites were investigated.The results shows that with the increase of La/Kaolinite value,the mechanical properties of the two composites increase at first and then decrease.Compared with pure NR,the tearing strength increased from 37.25KN/m to 56.38KN/m;while compared with pure SBR,the tensile strength and tear strength of La（OH）₃/Kaolinite/SBR composites were greatly improved.The maximum tensile strength and maximum tear strength were 11.90MPa and36.78KN/m.With the increase of filling amount of La（OH）₃/Kaolinite composites,the tensile strength and tear strength of the composite reached the maximum value,and the maximum values were 16.95MPa and 57.35KN/m.At the same time,when the filling amount of La（OH）₃/Kaolinite composite is 50phr,the tensile strength of La（OH）₃/Kaolinite/SBR composites reached the maximum,and its value was 11.90 MPa,an increase of 648.43%compared with pure SBR.In this experiment,we only studied the effect of the particle size of kaolinite on the mechanical properties of La（OH）₃/Kaolinite/NR composites.The tensile strength,tear strength and 500%elongation stress of the composites increases with the decrease of kaolinite particle size,and the maximum values were 20.04MPa,57.35KN/m,and 4.03MPa.With the increase of La/Kaol value,the increase of the filling amount of La（OH）₃/Kaolinite composites and the decrease of Kaolinite particle size,the thermal stability of composites were improved to varying degrees.