Studies On The Preparation And Properties Of EPDM/POE Dynamic Thermoplastic Vulcanizates

EPDM/POE dynamic thermoplastic vulcanizates (TPV) were prepared via dynamic vulcanization technology in Haake plasticorder in this paper. Polyolefin elastomer (POE) was used to substitute thermoplastic resin of Polypropylene (PP) as one of the primary materials, and the hardness of the prepared EPDM/POE TPV decreased while the elasticity was improved compared with EPDM/PP TPV. Some advanced instruments such as the Scanning Electron Microscopy(SEM), Capillary Rheometer, Rubber Process Analyzer (RPA) and Dynamic Mechanical Thermal Spectrometer (DMTS) were used and the effect of process parameters, curing systems, filler systems and softening systems on the curing properties, mechanical properties, morphologies, aging properties, rheological properties and dynamic mechanical properties were investigated. According to the theory that all properties were determined by structure, a new view of"the effect mechanism of all factors on the properties can be researched by the curing properties"was raised. Research results showed that the effects of blending temperature, EPDM/POE ratio, rotation speed, blending time and process method on the curing properties were significant. Curing extent increased firstly then decreased with the improvement of blending temperature and EPDM/POE ratio while decreased gradually with the raise of rotation speed. Curing rate increased with the change of abovementioned factors. Considering the factors of process and property comprehensively, the process parameters of 150℃, 40 r·min-1, 40/60 (EPDM/POE) and blending one more minute after the biggest torque were determined.The effects of sulfur curing system, peroxide curing system and phenolic curing system on the properties were studied. Results showed that the crosslink density increased with the increment of curing agent concentration and the curing extent of sulfur curing system was the highest at the same content. Optimal properties were obtained when the dicumyl peroxide (DCP) and sulfur content was 0.5phr, respectively, and phenolic resin amount was 1.0phr. The tensile strength reached 11.0MPa when 0.5phr sulfur was added. The curing extent of the EPDM/POE system can be calculated directly from the curves of Haake plasticorder."Sea-island"two phase morphology was observed from SEM photographs in the TPV materials. SEM images illustrated that the EPDM cured particles preferred to be elliptic shape while spherical forms as 1.0phr sulfur was added. Thermal experiments showed that dynamic vulcanization made the glass transition temperature (Tg) and melting temperature (Tm) moved to the high temperature.The influences of filler system on the properties of EPDM/POE TPVs were discussed and the results indicated that CaCO3 retarded the curing process while carbon black can accelerate the sulfur cure system. Compared with the light CaCO3, nano-CaCO3 had better reinforcement effect on the TPV composites, and N220 provided more obvious effect on the TPV than N550. Conclusively, optimal comprehensive properties were obtained when the carbon black content was 20phr. RPA experiments showed that there was a progressive nonlinear behavior which was more and more clearly with the increment of carbon black content. But TPVs filled with more carbon black exhibited the fastest drop of G' with increasing strain amplitude. The order of tanδat different carbon black content was tanδ(10phr) < tanδ(0phr) < tanδ(30phr) < tanδ(50phr) at lower strain amplitude. Additionally, the G' and G'' of TPVs with N220 were higher than that with N550, while the tanδwas opposite. To illuminate the effect of carbon black, curometer curves and carbon black dispersion pictures were also used in this paper.Researches about the effect of softening system on the properties showed that paraffin oil and naphthenic oil both can increase the curing extent of the relevant system. The curing extent increased first then decreased with the increment of paraffin oil and the decrease was dramatic at 20phr. Rheometer experiments showed that EPDM/POE TPVs was sensitive to shear rate and slightly affected by the change of temperature. Paraffin oil can improve the flow property when the shear rate reached a value. From the aging test, the results were concluded that dynamic vulcanization can improve the aging resistance and the prepared TPV material can be processed and used three more times with a small change in mechanical properties. Being considerated comprehensively, paraffin oil was perfect to the EPDM/POE system. The Shore hardness can reach 65A when the paraffin oil content was 40phr. Dynamic mechanical thermal spectrometer results showed that EPDM/POE TPVs was a kind of material with damping properties. The temperature range of tanδ>0.3 was about 57℃and the biggest value of tanδwas 0.53.