Study On Polyimine Magnetorheological Thermoplastic Elastomer

Magnetorheological elastomers(MREs)is a kind of composite material with solid matrix encapsulating micron-sized magnetic particles.The properties of polymer matrix and the types of magnetic particles are important factors affecting Magnetorheological effect(ME).Dynamic polymer(Dynamer)is a rapidly developing research field in recent years.By introducing dynamic bonds into the polymer chain,the materials have the dynamic characteristics such as environmental responsiveness,viscoelasticity and self-repairing.Dynamers derived from various dynamic bonds have attracted wide attention in the fields of smart materials,liquid crystals,bioactive materials,photoelectric materials and so on.Imine bond is a typical dynamic bond formed by dehydration condensation of carbonyl compounds and amine derivatives.Polyimine(PIm)based on the imine bond is of both thermoplastic and self-healable materials.However,there are less study on PIm as a matrix material to prepare MREs and exploration of PIm's impact on the performance of MREs.It is a worthy field to study on MREs based on polyimine and inorganic particles with rheological effect,high mechanical properties and damping properties.Therefore,in this thesis PIm MREs with the dynamic viscoelastic and the thermoplastic properties were studied.The main research work is as follows:Four kinds of PIms were prepared from monomers with different side groups,polar its groups and chain length by reaction of diethylenetriamine,P(hexamethylene)triamine,3,3'-diamino-N-methyldipropylamine and polyether amine(n=2-3)with p-phthalaldehyde,respectively.Then the PIms were characterized by infrared spectroscopy and X-ray diffraction was carried out.Dynamic and static mechanical properties test and thermogravimetric analysis.The results show that there are two kinds of PIms which can be elastomeric state at room temperature respectively synthesized by thereaction of terephthalaldehyde(PIm2)reacted with 3,3'-diamino-N-methyldip-ropylamine and polyether amine(n=2-3)(PIm3).The thermal stability of PIm2 is higher than that of PIm3.Finally,the pyrolysis process of four kinds of PIms was analyzed by real-time infrared spectroscopy.At the gel points of polymerization,carbonyl iron(CI)as function filling phase was dispersed uniformly into cross-linked PIm2(LPIm2)and cross-linked PIm3(LPIm3)as substrate.The dynamic viscoelasticity of MREs were tested.The effects of crosslinking degree and magnetic particle content on the magnetorh-eological properties of composites were systematically studied.The results show that the storage modulus of MREs based on LPIm2 is the highest when the crosslinking degree is 2.1%.The storage modulus of MREs filled with different volume fractions of CI increases at first content,and then decreases with the increase of applied magnetic field.The optimal rheological properties are obtained at 30 vol%content.MREs with 30 vol%CI-2.1%LPIm2 had the highest loss modulus,while MREs with 10 vol%CI-6.5%LPIm2 had the lowest loss modulus.The maximum storage modulus and relative magnetorheological effect of LPIm3 MREs are obtained at the 4.3%crosslinking degree.When the volume fraction of ME was 30 vol%,the optimal value was obtained.The damping performance of 30voI%CI-LPIm3 decreases first and then increases with the increase of crosslinking degree.It is concluded that the relative MR effect of 30volCI-2.1%LPIm2 MREs are the highest,with a value of 29.89%.30 vol%CI-4.3%LPIm3 MRE obtained the highest storage modulus and relative ME,with a value of 281.33%.The dynamic viscoelasticity of MREs with LPIm2 and LPIm3 as matrix under magnetic field was compared.The relative ME,magnetic saturation modulus and loss modulus of LPIm3 MREs are higher than those of LPIm2 MREs.The loss factor of 30 vol%-4.3%LPIm3 MREs is higher than that of 30 vol%-2.1%LPIm2 MREs at the magnetic field intensity of 0-800mT.When the magnetic field intensity is at arrange of 800-1200mT,the arrange particle hinders the movement of CI particles,resulting in the decrease of loss modulus.The loss factor of 30 vol%-4.3%LPIm3 MREs is lower than that of 30 vol%-2.1%LPIm2 MREs.The self-heal performance of LPIm2 MRE and LPIm3 MRE decreased due to the addition of CI particles.