Synthesis And Characterization Of Cellulose-based Magnetic Composite With Fe₃O₄as A Novel Absorbing Materials

With the development of science and technology, electromagnetic pollution was more serious, harmful for health. Therefore, study on preparation of microwave absorbing materials became an issue for novel functional materials. Considering the defects of ferrite as microwave absorbing material, composite technology could combine the advantages of organics and inorganics, possesses well magnetic properties of inorganics and low density, high intensity of organics.In this study, cellulose and Fe3O4nanoparticles were used to prepare two kinds of composites by different methods, liquid homogeneous process and solid reaction process. The article investigated the preparation of Fe3O4, cellulose nanoparticles and composites, discussed the reaction mechanism through the analysis of characterizations.(1) Fe3O4nanoparticle has been synthesized by a co-precipitation process with oleic acid used as surface dispersant. Both synthesized Fe3O4nanoparticle before and afer suface modification have typical inverse spinel structure, and show spherical distribution. The film formed by oleic acid on the surface of Fe3O4nanoparticles could restrain the agglomeration; improve the dispersity and particle size distribution. When the addition of oleic acid was4wt%, the saturation magnetization (Ms) value of Fe3O4nanoparticle was confirmed to be82.066emu/g.(2) Cellulose nanoparticles were extracted from bagasse by high press homogenization technology. Through the properties comparison of regenerated cellulose nanoparticle, spray drying method was fixed to be the optimal drying treatment. The Ms value of cellulose nanoparticle was only0.0124emu/g due to its weak magnetic.(3) The Fe3O4/cellulose composite powders have been prepared by a liquid homogeneous process. Fe3O4nanoparticles have been distributed among the cellulose matrix under interaction of electrostatic attraction and Van der Waals force. The thermal stability of reacted cellulose has been improved, and decomposition temperature increased to680℃. The composite prepared by Fe3O4nanoparticles with surface modificated by4wt%oleic acid shown Ms value of11.376emu/g, higher than original composite. The sample with4wt%initiator possessed the optimal microwave absorbing properties of-13dB.(4) The Fe3O4/cellulose composite in sheet form has been prepared by a solid reaction process. Fe3O4nanoparticle was distributed on the surface of cellulose through Van der Waals force. The thermal stability of cellulose has been also improved, and the reaction ratio of cellulose was about28.8%, higher than liquid homogeneous process. The microwave reflection of the sample with50wt%cellulose has shown high microwave absorbing characterization of-28dB.