| Soon after the discovery of graphene, graphene-like single-layered molydenum disulfide(Mo S2), a new two-dimensional(2D) layered material with unique “sandwich†structure has attracted considerable attention. Due to the unusual chemical and physical properties, Mo S2 has been widely used in the fields of catalyst, battery, photoelectronic device and composites.In the present study, we used Li-intercalated molydenum disulfide as raw material to prepare natural rubber(NR)/Mo S2 or styrene-butadiene rubber(SBR)/Mo S2 compound via latex co-coagulation technique. Then, the obtained compounds were compounded with silica or carbon black. Furthermore, we prepared Mo S2/polyethylene glycol(PEG) mixture through lyophilization method, the resulted Mo S2-PEG was able to mix with rubber and other fillers in a two-roll mill directly, making it possible for Mo S2 to be used in pratical application. The aim of this thesis is to provide new insights into improved filler dispersion in rubber by Mo S2 and the main contents include the following three aspects.(1) NR/Mo S2 compound was prepared through latex co-coagulation technique, following by compounded with silica in a Haake internal mixer. Lastly, the mixtures of NR/Si O2/Mo S2 were compounded with sulfur by two-roll milling. It was found that a small amount of Mo S2 nanoplatelets significantly improved the silica dispersion. With the addition of only 3 phr Mo S2, the tensile modulus(stress at 300% strain) and tensile strength of the composite filled with 30 phr silica were improved by over 70% and 60%, respectively. In addition, heat build-up was substantially decreased by 17 °C. The charge repulsion, difference in surface energies between silica and Mo S2 and the increase in distance of silica particle were responsible for the largely improved dispersion of silica.(2) SBR/Mo S2 compound was prepared via latex co-coagulation technique and then mixed with carbon black by two-roll milling. The static and dynamic mechanical properties of the composites were greatly enhanced. For example, the substitution of carbon black with only 3 phr of Mo S2 led to the increment in tensile modulus(stress at 300% strain) by over 50%. With the substitution content of 2 phr, the loss factor at 60 °C(tan δ measured at 5% of strain) was decreased by 17% and Akron volume loss was decreased by 90%. In addition, With the substitution content of 1 phr, heat build-up was substantially decreased by 10 °C compared with a control sample of SBR/carbon black composite. It was proposed that the surface carbide was formed by the reaction between Mo S2 active edges and carbon black, which leads to decreased microcrystalline size of carbon black, increased disordering degree of the microcrystalline. Consequently, the three-dimensional filler network was more developed and stablized.(3) We utilized PEG to modified Mo S2 via lyophilization. Benefited from the hindrance effect of PEG, Mo S2 remained single layered in the mixture, as evidenced by SEM and XRD results. Then, we added the obtained Mo S2-PEG to tire tread compound through a two-roll mill. The results showed that the substitution of carbon black with Mo S2-PEG significantly improved the dynamic propertities without deteriorating the static properties of composites. With 2 phr of Mo S2-PEG mixture(weight ratio 1:1) was used to substitute carbon black, the loss factor at 60 °C(tan δ measured at 5 % of strain) and heat build-up were decreased by 8% and 18%, respectively. In addition, Akron volume loss decreased by 26%. Such amazing improvements in dynamic properties were mainly ascribed to the filler dispersion improvement induced by the incorporation of Mo S2-PEG. |
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