The Modification On Poly Aryl Ether Functional Composite Materials By Ferriferrous Oxide Nanoparticles With Different Morphologies

Poly(aryl ether nitrile)s belong to the class of structured polymer materials. Due to its excellent over-all properties such as thermostability, radiation resistance, mechanical strength and machinability, etc, they have been applied widely in special areas such as aerospace, military electronics, communication and so forth.PEN has many cyano groups in structure which can improve its adhesive properties. Besides, it has good processability. Thus, it can be used as an excellent matrix of the preparation of advanced functional materials.However, as the application conditions are becoming increasingly demanding, materials with higher performance are required. Therefore, the disadvantages of traditional magnetic materials, such as oxidation in high temperature, poor processability and particles aggregation, are showing up.This thesis takes PEN, which has thermostability, radiation resistance and high modulus, as the matrix resin with Fe3O4 nanoparticles dispersed in it, so that a type of pen composite materials can be produced. They not only possess better mechanical property and good thermostability, but also excellent magnetic performance and better processability.We also studied the effect of shape and content difference of Fe3O4 nanoparticles on the electromagnetic properties of composite materials, in hopes to develop a magnetic PEN composite material with good interface compatibility and excellent performance. In summary, this is composed of four parts as follows:Firstly, a series of Fe3O4 nanospheres with different morphology and crystallinity were synthesized through solvent-thermal route. These results indicated that the size, magnetic and microwave electromagnetic performance of Fe3O4 nanospheres can be adjusted through changing the synthesis process conditions. Results showed that the Fe3O4 with diameter about 65 nm possesses outstanding electromagnetic properties because of its excellent surface structure and dispersity.Secondly, we used Fe3O4 nanoparticles as fillers, and PEN as the matrix resin to prepare PEN/ Fe3O4 composites with different content of Fe3O4 nanoparticles.The results showed that Fe3O4 nanoparticles had no significant impact on the thermal stability of PEN. Besides, the mechanical property of the composites can be enhanced manifestly by controlling the content of Fe3O4. However, the tensile strength of PEN/Fe3O4 composite films reached their highest values with 80.64 MPa when the Fe3O4 particles content is 1 wt%. The VSM indicated that the Ms of the composite films increased with the increasing Fe3O4 particles loading. The rheological properties of magnetic composites showed that Fe3O4 particles presented better dispersibility when the content of Fe3O4 particles is less 3wt%.Thirdly, we studied the effect of Fe3O4 nanoparticles with different diameter on PEN/Fe3O4 composites. The results showed that Fe3O4 nanoparticles had no significant effect on the thermal characteristics of the PEN substrate, but improved the thermal stability of the matrix resin slightly.The particle size of Fe3O4 nanoparticles has a greater impact on the mechanical properties. The tensile strength of the composites had a tendency to increase first and then decrease. The particle size of Fe3O4 nanoparticles has manifest impact on the dielectric constant of PEN/Fe3O4 composites.With the decreasing of particle size for Fe3O4 nanoparticles, the dielectric constant of PEN/Fe3O4 composite increase to the peak then decrease down. And when the particle size of the microspheres Fe3O4 is decreased to ~65nm, the composite materials have good compatibility.Finally, we studied the effects of Fe3O4 nanocrystals with special octahedral morphology and structure on the properties of PEN/Fe3O4 composite materials.The results showed that small amount of Fe3O4 octahedral nanocrystals had no significant effect on the thermal properties of PEN. However, by controlling the amount of Fe3O4 octahedral nanocrystals, the mechanical properties of the composites can be enhanced greatly.When the content of Fe3O4 octahedral nanocrystals was about 2%, the composite materials have better dielectric properties. The research of the dynamic rheological behavior of composites showed that when the content of Fe3O4 octahedral nanocrystals was about 1 % and the composite materials have well compatibility.