Study On Preparation,Structure And Properties Of Soft Magnetic Elastomer

Magnetic elastomers based on rubber and Fe₃O₄ powders are recieving more and more attentions in electronic communication products,automotive parts and other fileds due to their light density,good processability and the varied rubber matrix.However,in order to meet requirements of applications,sometimes,high level amount of Fe₃O₄ powders needed to be added into elastomer matrix.The compatibility between unmodified Fe₃O₄ powders and elastomeric polymer deteriorated the mechanical properties and processabilities of magnetic elastomers sharply.In this paper,.zinc dimethacrylate?ZDMA?was used as in-situ compatibilizer and reinforcing agent to solve the above problem.We prepared the NBR/Fe₃O₄/ZDMA composites and PP/EPDM/Fe₃O₄/ZDMA TPV,and their structures and properties were studied.?1?We selected the polar nitrile butadiene rubber?NBR?as rubber matrix and the Fe₃O₄were composited with NBR by using ZDMA as in-situ compatibilizer and reinforcing agent.ZDMA polymerization and NBR crosslinking were induced by peroxide.The effects of ZDMA on the morphology,magnetic properties,mechanical properties,curing characteristics,processabilities,thermal properties of NBR/Fe₃O₄/ZDMA composites were investigated.The results of XRD and vibrating sample magnetometer?VSM?showed that the ZDMA did not affect the magnetic properties of NBR/Fe₃O₄/ZDMA composites,and the magnetic properties were depended on the content of Fe₃O₄ in composites when the particle size of Fe₃O₄ was constant.The results of SEM showed that the ZDMA not only enhanced the interfacial compatibility between Fe₃O₄ and NBR matrix,but also improved the dispersion of Fe₃O₄ in NBR matrix.Tensile strength of the NBR/Fe₃O₄ composites could be increased from 2.5MPa to 6.8¹3.1MPa with addition of 5¹5 phr ZDMA.The results of TG,mooney viscosity and curing curves showed that the ZDMA improved the thermal stability,processability and vulcanization efficiency of the composites.?2?In order to meet the requirements of application in high temperature,the thermal oxygen agings of NBR/Fe₃O₄/ZDMA?100/70/10?composites with different types of antiagers?HS-911,BY,RD,ODA,and DAPD?were investigated.The effects of antiagers on the curing characteristics,processabilities,mechanical properties and crosslinking density of NBR/Fe₃O₄/ZDMA composites were also studied.The results showed that the antiager delayed the curing time and reduced mooney viscosity,crosslinking density of NBR/Fe₃O₄/ZDMA composites.The mechanical properties of NBR/Fe₃O₄/ZDMA composites were affected by antiager.The anti-aging agent DAPD significantly improved the elongation at break and tensile strength of NBR/Fe₃O₄/ZDMA composites.Hot oxygen aging results showed that the antiager DAPD of PPD class had the best hot oxygen aging protection effect for NBR/Fe₃O₄/ZDMA composites after aging at 100^oC.Antiager HS-911,ODA of DPA class had the best hot oxygen aging protection effect for NBR/Fe₃O₄/ZDMA composites after aging at 120 or 135^oC.?3?Moreover,we selected the nonpolar polypropylene?PP?,ethylene-propylene-diene?EPDM?as elastomeric polymer matrix and prepared PP/EPDM/Fe₃O₄/ZDMA TPV via dynamic vulcanization.The effects of ZDMA on the properties and structure of PP/EPDM/Fe₃O₄/ZDMA TPV were investigated.The results showed that the crystal form of Fe₃O₄ was not changed during dynamic vulcanization in the presence of ZDMA.The magnetic properties of PP/EPDM/Fe₃O₄/ZDMA TPV were mainly depended on its content in the system.Addition of ZDMA not only improved the interfacial compatibility between PP continuous phase and EPDM dispersive phase,but also increased the interfacial compatibility between Fe₃O₄ particles and TPV matrix.Furthermore,it improved the dispersion of Fe₃O₄ in TPV matrix,which resulted in the improvement of mechanical properties of TPV.Meanwhlie,most Fe₃O₄ powders were located in EPDM phase.ZDMA limited the migration of Fe₃O₄powders from EPDM to PP phase during dynamic vulcanization,which was possibly due to the effective control of Fe₃O₄ migration by PZDMA,PP-graft-PZDMA and EPDM-graft-PZDMA.With the increase of ZDMA dosage,the inhibition of Fe₃O₄ migration was also enhanced.