炭含量对竹炭/高密度聚乙烯复合材料电磁屏蔽和力学性能的影响

Effect of carbon content on shielding and mechanical properties of bamboo charcoal/HDPE composites

为了探究竹炭含量对竹炭基复合材料性能的影响,以竹炭(BC)和高密度聚乙烯(HDPE)为原料,采用“熔融挤出-模压”成型工艺制备竹炭/高密度聚乙烯(BC/HDPE)复合材料,通过对不同竹炭含量的BC/HDPE复合材料进行测试,研究炭含量对复合材料力学性能、热性能、电磁屏蔽性能以及微观结构的影响。结果表明,竹炭对BC/HDPE复合材料的力学性能具有增强作用,复合材料的储能模量、抗弯强度随竹炭含量的增加逐渐提高,竹炭含量为70%时BC/HDPE复合材料的弯曲强度达到51.76 MPa。竹炭含量对复合材料的电导率、屏蔽性能影响显著,竹炭含量50%时电导率达到逾渗阈值,竹炭含量为60%时电导率达到19.37 S/m,此时复合材料的屏蔽效能达到27.56 dB,其可应用在电磁屏蔽领域中。通过扫描电镜观察发现,BC与HDPE基体始终紧密地结合在一起,HDPE将不同的竹炭颗粒紧密黏结到一起,使界面处没有明显间隙,形成了一种竹炭颗粒均匀分散且结构致密的界面,导致该复合材料电学、力学性能优异。

As one of the natural raw materials,bamboo charcoal(BC)has the merits of developed pore structure and large specific surface area.Therefore,it has a strong adsorption capacity and is widely used in the field of the environmental improvement.In addition,bamboo charcoal has good electrical conductivity,thermal stability,electromagnetic shielding,and far infrared radiation,thus having great application prospects.At present,there are limited studies on the preparation of bamboo charcoal-based composites with high filling capacity and electromagnetic shielding performance.Therefore,in order to explore the influence of bamboo charcoal content on the properties of bamboo charcoal based composites,the BC/HDPE(High Density Poly Ethylene)composites with different bamboo charcoal contents were tested by the universal mechanical testing machine,dynamic thermomechanical analyzer,differential scanning calorimetry,scanning electron microscope,vector network analyzer and other instruments,composite material mechanics performance,thermal performance,electromagnetic shielding performance,and the influence of the microstructure were characterized with different contents of bamboo charcoal in this work.Then the results showed that the bamboo charcoal can enhance the mechanical properties of BC/HDPE composites.This strengthening effect was shown in the storage modulus and bending strength of BC/HDPE composites,which gradually increased with the increase of bamboo charcoal content.When bamboo charcoal content was 70%,the bending strength of BC/HDPE composites reached 51.76 MPa.Bamboo charcoal content also had a significant effect on the conductivity and shielding performance of the composites.When bamboo charcoal content was 50%,the conductivity reached the percolation threshold,and when the bamboo charcoal content was 60%,the conductivity reached 19.37 S/m,and the shielding performance of the composites reached 27.56 dB,which can be used in the field of electromagnetic shielding.The scanning electron microscopy(SEM)showed that the BC and HDPE matrix were always closely bound together,HDPE bonded different bamboo charcoal particles together,so that there was no obvious gap at the interface,forming a compact interface with bamboo charcoal particles homogeneously dispersed,leading to the excellent electrical and mechanical properties of the composite material.Through this work,the electromagnetic shielding mechanism of bamboo charcoal-based composites is clarified,which will provide basic data and reference significance for bamboo charcoal products with high added values.