Study On Processability And Thermal Oxidative Aging Properties Of High Hardness Epdm

In this paper,we discussed how to improve the processability of high filled EPDM rubber and further study its rheological properties based on low Mooney oil-free EPDM Keltan 2450.The effects of plasticizing system,reinforcing resin and nano filler on Mooney viscosity,vulcanization characteristics,mechanical properties,heat and oxygen aging properties and dynamic properties of peroxide curing EPDM were investigated.Firstly,three different kinds of plasticizers were studied.Liquid plasticizers will significantly improve the processability of the compound due to its plasticizing and softening effect,but also lead to the significant decline of the static mechanical properties of the vulcanizate.On the contrary,PE wax as the solid particle did little of the processing performance of the compound,but which can better maintain the static mechanical properties of the vulcanizate.It is further confirmed by RPA test that the increase of the amounts of liquid plasticizers will lead to the rapid decline of modulus and the decrease of filler network structure,which is very important to the properties of filled rubber.In order to improve the hardness of high filled EPDM vulcanizate,the effect of hardening resin HS with different styrene content on the properties of EPDM vulcanizate was studied in this paper.HS can better enhance the static mechanical properties of vulcanizate.Through RPA test and Mooney viscosity at different temperatures,it shows that the influence of HS on the processability of compound at different temperatures is different.Different RPA test procedures are designed to further explore the influence of HS on the filler network structure that HS can increase the degree of the structure of filler network.Furthermore,in order to explore the role of nano filler in EPDM system,SWCNT was added in unfilled and highly filled systems respectively.The enhancement of static mechanical properties of vulcanizate by SWCNT is particularly obvious in unfilled systems,and it will also form a destructible network structure;In the filled system,the increase of the amount of SWCNT will also mean the increasing of the PO which has obvious effect on the dispersion of filler.And further considering the filler network and the dispersion of SWCNT,the situation is more complex.Finally,the effects of the above variables on the mechanical properties and crosslinking density of EPDM vulcanizate after thermal oxidative aging were also discussed.PO,PE wax,liquid butadiene and HS can react with the free radical of peroxide thermal decomposition to a certain extent,so that the crosslinking density further decreases after aging,but it will maintain the mechanical properties of the aged vulcanizate.The effect of the increase of SWCNT on the aging properties of EPDM vulcanizate is more reflected in the effect of PO.