Synthesis of silane-grafted ethylene vinyl acetate copolymer and its application to compatibilize the blend of ethylene-propylene-diene copolymer and silicone rubber

Fluorination Modification of Methyl Vinyl Silicone Rubber and Its Compatibilization Effect on Fluorine/Silicone Rubber Composites

Among numerous rubbers, high-performance rubber composites can be obtained by mixing fluororubber (FKM) with excellent oil resistance and silicone rubber (SiR) with excellent low-temperature resistance. While the difference in polarity between these two kinds of rubbers leads to a reduction in the properties of the composites. To solve the compatibility problem between the two-phase interfaces in FKM/SiR composites, in this research, fluorinated silicone rubbers (MVQ-g-PFDT) of methyl vinyl silicone rubber (MVQ) grafted with 1H,1H,2H,2H-perfluorodecanethiol (PFDT) were prepared via a facile and efficient thiol-ene click reaction, which was then added into FKM/SiR composites. The results showed that the fluorine-containing side chains could effectively inhibit the low-temperature crystallization phenomenon of silicone rubber and further broaden its application ranges in low-temperature environments. The properties of FKM/SiR composites with the addition of MVQ-g-PFDT were significantly improved, with the highest tensile strength of 14.1 MPa and the lowest mass change rate of 6.71% after 48h immersion at 200 °C in IRM903 oil. Additionally, the hydroxyl groups between the fluorine-containing side chains of MVQ-g-PFDT and the surface of silica facilitate the enhancement of the uniform dispersion of fillers. Atomic force microscopy (AFM) characterization results showed a distinct enhancement of the compatibility between the two phases of FKM and SiR. This work would provide further insight into efforts to improve compatibility between rubbers with widely different polarities.

EVA and SEBS-MA copolymers incorporated silicone rubber/SEBS blends: improvement of mechanical and thermal properties

Enhancing the mechanical and thermal properties of Silicone rubber (SR)/SEBS blends using various compatibilizers opens the opportunity for such new blends to meet the market desire. For this purpose, blends with a 1:1 ratio of SR and SEBS are prepared with different amounts of EVA or SEBS-MA copolymers as compatibilizer. Mechanical properties of the blend are enhanced by adding EVA and SEBS-MA. Addition of 6 phr EVA profoundly improves the tensile strength from 7.70 to 10.06 MPa. Thermogravimetric analysis reveals that the presence of compatibilizer can improve the thermal stability of the blend, especially its initial degradation temperature (T5%). T5% of the blend increases from 376 to 390 °C when comprising 6 phr SEBS-MA. Morphology of the blends is investigated using SEM and AFM. Results of the relaxation modulus curves obtained by rubber process analyzer (RPA) demonstrate that the amount of relaxation in the uncured blends is higher than the cured ones. A comparison of the relaxation of the blends indicates that the relaxation modulus of the SEBS-MA compatibilized blends is enhanced more than other blends after curing. Further investigations indicate that the compatibilized blends exhibit higher tear energy and lower compression set.