Study On PP/Carbon/Sisal Fiber And Electromagnetic Shielding Performance Of Its Composite Material

Electromagnetic waves shielding also become a hot research. In order to achieve bettershielding effect, many countries have done a lot of research in the theory of theelectromagnetic shielding and the development of new shielding materials. Amongst thevarious methods of electromagnetic shielding, filler type electromagnetic shielding materialsbecomes one of the important areas of research because of its characteristics that can be madeinto complex products, processes simple, without special equipment, low cost, wideapplication. Our country get behind other countries in this field, the majority of this kind ofmaterials depends on imports. Therefore, the researches on the electromagnetic shieldingcomposite materials are necessary.Common shielding composition blending with carbon particles has many shortcomings.Such as great filling amount, difficult dispersion and low shielding efficiency. In this paper,we derived PP/sisal fiber shielding composition by blending PP with chemical treated sisalfiber that as a carrier to adsorb electric carbo n particles. Effect of the number of steamexplosion and addition of carbon particles such as carbon black and GB on shieldingefficiency and mechanical properties of shielding composition in400MHz to18GHz rangehad been studied based on the theory presented by material science and electromagnetism.Results showed that shielding efficiency was increased with the increase of SF-G(sisalfiber and graphite after steam explosion) from0to50%in sisal fiber/GB/PP composite.Shielding efficiency reached to maximum when the concentration of sisal fiber/carbon blackwas50wt%. The maximum of shielding efficiency was25.1dB in the frequency from400MHz to1GHz and33.4dB in the frequency from1GHz to18GHz.In this case, thepercolation threshold of the blends is below30%(equivalent to15%of GB). The results showthat the steam explosion can effectively solve the shortcomings of GB. The steam explosiongreatly reduces the percolation of the composite. The result of CB/sisal fiber/PP compositeshowed that shielding efficiency was not increased with the increase of SF-C(sisal fiber andcarbon black after steam explosion) from0to40%in the frequency from400MHz to1GHz.But the shielding efficiency was increased obviously with the increase of SF-C from0to40% in the frequency from1GHz to18GHz. The maximum of shielding efficiency was41.2dB inthe frequency from1GHz to18GHz. In this case, the percolation threshold of the blends isbelow20%(equivalent to10%of CB). The results showed that the sisal fibe r had noshielding efficiency; the shielding efficiency of composite with steam explosion was muchhigher than composite without steam explosion. Meanwhile, tensile stress of the compositiondecreased slowly as the addition of sisal fiber/carbon black grew.