Effect of hybrid filler (HNTs‐phthalocyanine) on the thermal properties and flammability of diene rubber

Rubber is an essential polymer widely used in the auto-industry. We report a method for the synthesis of zinc phtalocyanine (ZP), chloroalumino phthalocyanine (CP), and their hybrid fillers obtained by the synthesis of the two phtalocyanines in the presence of halloysite nanotubes (HNTs). The hybrid fillers were characterized by means of microscopic, thermal, and particle size measurement analysis. The effect of these fillers on the properties of diene rubbers were assessed in comparison with a physical mixture of halloysite and ZP or CP pigment. The dispersion degree of hybrid fillers inside an elastomeric matrix (rubber) was assessed with the atomic force microscopy. The influence of the hybrid fillers on the thermal and mechanical properties and flammability of butadiene-acrylonitrile (NBR) and butadiene-styrene (SBR) rubbers was assessed by analyzing the measurement results obtained by means of thermogravimetric analysis, differential scanning calorimetry, Zwick Tensile testing, FAA micro-calorimeter, and oxygen index determination. We found that regardless of the spatial network structure of NBR and SBR rubbers, the incorporation of hybrid fillers into the matrix of the elastomers showed an improvement in their thermal and mechanical properties as well as a significant reduction in flammability. The improvement is attributed to the smaller size and much better dispersion of HZ and HC in relation to the particles of phthalocyanine. The colored composites of NBR rubber, containing hybrid filler (HZ or HC), showed an increase in the heat capacity compared to the uncolored samples, which can increase safety by facilitating the processes of self-extinguishing. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42593.