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Nano-porous carbon (NPC) composites derived from metal-organic frameworks (MOFs) possess effective microwave absorption (MA) properties. However, the fabrication of MOF-derived NPC composites with full-band MA performance is challenging. In this work, the effect of the bandgap on the microwave dielectric behavior of Mn-MOF derivatives was investigated. The results demonstrated that a narrower MnO2 bandgap resulted in higher conductivity and a larger dielectric constant of the corresponding materials. The three-dimensional (3D) MnO@NPC composites achieved excellent low-frequency MA ability. The maximum reflection loss (RL) of MnO@NPC carbonized at 800 °C reached −54.38 dB at 5.12 GHz. The 1D-3D mixed-dimensional MnO2@NPC composites with the ultra-strong MA response in the full band were obtained by oxidizing MnO@NPC to MnO2@NPC. MnO2@NPC-800 showed superior MA capacity with the maximum RL value equal to −63.21 dB at 12.48 GHz and 2.05 mm thickness. The maximum RL values in S, C, X, Ku bands also exceeded −50 dB. Such an outstanding MA performance of MnO2@NPC-800 composite was attributed to the MnO2 presence and its multi-dimensional structure. This work provides the foundation for the fabrication of MOF-derived materials capable of full-band MA.

Blocked mercaptosilane possessing two functionally active end groups can chemically react with both silica and rubber leading to significant improvement in silica-filled vulcanizate products. The effect of the novel blocked mercaptosilane (3-propionylthio-1-propyltrimethoxylsilane) (called hereafter PXT) on the structure, mechanical, and dynamic mechanical properties of NR/silica composite were studied. Equilibrium swelling test and scanning electron microscope (SEM) indicate that PXT is able to enhance the crosslinking density of natural rubber (NR)/silica composites and the dispersion of silica in matrix. Mechanical measurement of properties show that PXT can strengthen the reinforcement of silica for NR vulcanizate. In the presence of PXT, the resistance to flex cracking, abrasion and dynamic compression fatigue, and heat build-up of NR/silica composites can be improved substantially. For the application of automotive tire, it also obtains high-skid resistance and low-rolling resistance simultaneously at 2 phr of the PXT concentration. POLYM. COMPOS., 2009. © 2009 Society of Plastics Engineers

A novel block mercaptosilane (3-benzothiazolthio-1-propyltriethoxylsilane) (Silane-M) was synthesized and characterized by Fourier transform infrared spectra, 1H nuclear magnetic resonance, and elemental analysis. Styrene–butadiene rubber (SBR)/silica composites were prepared with Silane-M, and its effect on the properties of materials was studied. Results show that Silane-M can substantially improve the dispersion of silica and strengthen the reinforcement of silica for SBR vulcanizates like anchors of silica to rubber matrix. As expected, it enhances the tensile, tear strength, dynamic compression property, and resistance to abrasion of SBR/silica composites. By adding Silane-M into the system, SBR/silica composites get superior skid resistance and high glass transition temperature (Tg). © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009