Improvement of the properties of rubber nanocomposites is a challenge for the rubber industry because of the need for higher performance materials. Addition of a nanometer‐sized filler such as silicon carbide (SiC) to enhance the mechanical properties of rubber nanocomposites has rarely been attempted. The main problem associated with using SiC nanoparticles as a reinforcing natural rubber (NR) filler compound is poor dispersion of SiC in the NR matrix because of their incompatibility. To solve this problem, rubber nanocomposites were prepared with SiC that had undergone surface modification with azobisisobutyronitrile (AIBN) and used as a filler in blends of epoxidized natural rubber (ENR) and natural rubber. The effect of surface modification and ENR content on the curing characteristics, dynamic mechanical properties, morphology and heat buildup of the blends were investigated. The results showed that modification of SiC with AIBN resulted in successful bonding to the surface of SiC. It was found that modified SiC nanoparticles were well dispersed in the ENR/NR matrix, leading to good filler‐rubber interaction and improved compatibility between the rubber and filler in comparison with unmodified SiC. The mechanical properties and heat buildup when modified SiC was used as filled in ENR/NR blends were improved. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45289.

Highlights Ultrasonication is incorporated with the Dunlop method as a novel alternative technique for producing natural rubber latex foam. Ultrasonic irradiation effects on the properties of flexible elastomeric foam formed via liquid–solid state transformation in an aqueous media are first reported. The introduced ultrasonic process causes no delays or interruptions in the production of natural rubber latex foam. An optimal ultrasonication period promotes homogeneous nucleation and endothermic dissipation processes, which improved the foam's morphology and physico-mechanical properties.

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A low-emission catalyst for the preparation of flexible polyurethane (FPUR) foams was developed. Copper-amine complex solutions in ethylene glycol (EG), namely, Cu(OAc) 2 (en) 2 -EG and Cu(OAc) 2 (trien)-EG (en, ethylenediamine; trien, triethylenetetramine), were synthesized and used as catalysts for the preparation of FPUR foams. The synthesis of Cu(OAc) 2 (en) 2 -EG and Cu(OAc) 2 (trien)-EG is convenient because the synthesis of copper-amine complexes can be done in situ using ethylene glycol as a solvent and no purification step is needed. It was found that Cu(OAc) 2 (en) 2 -EG was a suitable catalyst for FPUR foam preparation. In comparison to Dabco EG (or triethylenediamine), which is a commercial catalyst for FPUR foam preparation, Cu(OAc) 2 (en) 2 -EG had a comparable catalytic activity in gelling reaction and a higher catalytic activity in blowing reaction. The FPUR foam prepared from Cu(OAc) 2 (en) 2 -EG had a lower density than that prepared from Dabco EG.

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