Natural rubber (NR) composites highly filled with nano-α-alumina (nano-α-Al₂O₃) modified in situ by the silane coupling agent bis-(3-triethoxysilylpropyl)-tetrasulfide (Si69) were prepared. The effects of various modification conditions and filler loading on the properties of the nano-α-Al₂O₃/NR composites were investigated. The results indicated that the preparation conditions for optimum mechanical (both static and dynamic) properties and thermal conductivity were as follows: 100 phr of nano-α-Al₂O₃, 6 phr of Si69, heat-treatment time of 5 min at 150°C. Furthermore, two other types of fillers were also investigated as thermally conductive reinforcing fillers for the NR systems: (1) hybrid fillers composed of 100 phr of nano-α-Al₂O₃ and various amounts of the carbon black (CB) N330 and (2) nano-γ-Al₂O₃, the particles of which are smaller than those of nano-α-Al₂O₃. The hybrid fillers had better mechanical properties and dynamic performance with higher thermal conductivity, which means that it can be expected to endow the rubber products serving under dynamic conditions with much longer service life. The smaller sized nano-γ-Al₂O₃ particles performed better than the larger-sized nano-α-Al₂O₃ particles in reinforcing NR. However, the composites filled with nano-γ-Al₂O₃ had lower thermal conductivity than those filled with nano-α-Al₂O₃ and badly deteriorated dynamic properties at loadings higher than 50 phr, both indicating that nano-γ-Al₂O₃ is not a good candidate for novel thermally conductive reinforcing filler. POLYM. COMPOS., 37:771–781, 2016. © 2014 Society of Plastics Engineers

Nitrile-butadiene rubber (NBR) compounds were prepared with different amounts of hydrogenated transgenic soybean oil (HTSO) as renewable plasticizers. For comparison, similar compounds were prepared with petroleum-based dioctyl-phthalate (DOP), one of the most common plasticizers for NBR. Four HTSOs with different degree of hydrogenation were used, of which three HTSOs are prepared by hydrogenation reaction at different reaction conditions and one is commercial available. The plasticization effects of HTSO and of DOP were studied by Mooney viscometry, capillary rheometry, differential scanning calorimetry (DSC), and rubber processing analysis (RPA). The results showed that all the HTSOs had better plasticization effect than DOP on NBR. The swelling index result showed that the highly-hydrogenated-HTSO plasticized NBR vulcanizate have higher crosslinking density than the low-hydrogenated ones. It is worthy to mention that, the introduction of high-hydrogenated-HTSO greatly improved both the processability of the NBR compounds and the mechanical performance of the final products, which is hard to achieve for most of the plasticizers. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40643.

The flame-retardant properties of asphalt for some building applications are very important. In this study, we mainly focused on the influence of organically modified montmorillonite (OMMT) on the flame-retardant and other properties of asphalt in a large content range and explored suitable contents of OMMT for modified asphalts. Modified asphalts with different contents of OMMT from 2 to 15 wt % were prepared by melt blending. The X-ray diffraction results revealed that the intercalated structure was formed in the OMMT-modified asphalt. Rubber processing analysis results indicated the formation of a filler–network structure in the OMMT-modified asphalt. The limiting oxygen index and cone calorimetry results suggested that OMMT could be used as efficient and ideal flame retardants of asphalt. The results also reveal that excess OMMT contents (i.e., >10 wt %) depredated the flame-retardant performance of the modified asphalt. We analyzed the mechanism by taking into account of the features of the modified agent for OMMT. The experimental data showed that the viscosity, softening point, and penetration index of the OMMT-modified asphalt increased with increasing OMMT content, but the ductility decreased slightly when the OMMT content was not beyond 7 wt %. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 10.1002/app.40972.