Electrically conductive thermoplastic vulcanizates (TPV) based on polypropylene (PP)/nitrile rubber (NBR) blends loaded with multiwalled carbon nanotube (CNT) were prepared by dynamic vulcanization. CNT was incorporated into the system using two different mixing sequences: (i) one‐step method, by adding CNT after the PP and NBR and (ii) two‐steps method involving a previous PP/CNT master batch. Scanning electron microscopy and transmission electron microscopy were used to analyze the morphology of the nanocomposites. Dynamic‐mechanical analysis and rheological properties were also used for characterizing the TPV and TPE samples. Both mixing strategies favored the location of the CNT inside the PP phase. The one‐step approach resulted in a percolation threshold as low as 0.19 vol% with conductivity value of 0.04 S m−1 for the system loaded with only 0.50 vol% of CNT. The electromagnetic interference shielding effectiveness and microwave absorbing properties were evaluated in the X‐band frequency range. The TPV samples prepared by both methods displayed an overall electromagnetic attenuation of around 70%.

Carbon black and high performance silica have been widely employed as binary system filler in tire tread formulations. This study evaluated the total and partial substitution of silica by metakaolin (MK) on the properties of tread rubber composites. Dynamic mechanical thermal analysis and abrasion tests were conducted as typical assessments of tire tread performance: rolling resistance (fuel consumption), wet traction (safety), and abrasion (durability). Further the energy spent by the equipment during the processing of formulations was also analyzed, as well as rheological and mechanical properties. A significant reduction of rolling resistance was obtained with 75% and 100% of silica substitution by MK, which could lead to lower heat buildup in tire tread applications, without showing negative effects on wet traction, although abrasion showed undesired results. The substitution of silica by MK also lowered energy demanded for processing. No major changes were observed in vulcanization parameters and mechanical properties, which is interesting considering the fact that MK is nonreinforce filler.

This study aimed at evaluating the coupling effect of silane Si69 bis(triethoxysilylpropyl)tetrasulfide in metakaolin (MK) in automobile tire tread compounds based on a styrene–butadiene rubber/butadiene rubber blend. A reference compound of a typical tread recipe, filled with silica and carbon black, was used as a reference due to the acknowledged effect of TESPT in silica incorporation in elastomers. A silica sample without silane was also prepared. Silica was then completely substituted by MK, producing two samples, with and without silane. The samples were tested for crosslink density, rheometry, and morphology, and the vulcanization reaction parameters were determined and evaluated. Silane improved the interaction between MK and the polymer matrix, evidenced by the increase in crosslink density and vulcanization reaction rate, the same effect silane causes on silica-filled composites. Morphology also revealed that silane increased MK dispersion and adhesion to rubber. On the other hand, MK seems not to be as reinforcing as silica, considering that maximum torque is related to the stiffness of the material, with MK exhibiting lower values for this parameter.

The present paper evaluates a thermoplastic vulcanizate (TPV) of polypropylene (PP) and nitrile rubber (NBR), with and without carbon nanotube (CNT), with a potential application in structures that protect radar antennas, radomes. Morphological analysis, izod impact test, electromagnetic properties measurement and S-parameters were performed in order to verify its operational functioning. The presence of CNT affected the morphology of TPV, reducing the size of NBR particles. This enhanced impact strength results, besides the already known reinforcing effect of CNT on polymeric matrices. Electromagnetic parameters showed that both filled and unfilled TPV are low-loss materials. However, better impact result makes the filled TPV the most indicated material for radome application.

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