Phase changing stearate ions as active fillers in multifunctional carboxylated acrylonitrile–butadiene composite: Exploring the role of zinc stearate.

A suitable polar additive‐like zinc stearate (ZnSt) was incorporated in varied amounts to the mixture of carboxylated acrylonitrile–butadiene rubber and zinc oxide in the pursuit to introduce smart traits in the composites. Zinc stearate is not reported to effectively crosslink carboxylated nitrile rubber as compared to ZnO but, by the virtue of its strong crystalline nature (solid particles), it enhances the mechanical properties like stress–strain, tear strength, hardness, and so forth of the rubber composites. Moreover, due to the melting nature of the ZnSt at a relatively higher temperature, an alteration of the mechanical behavior of the composite is observed. In addition to the mechanical adaptability, the sample is also found to offer shape memory properties. Initially, the specimens were deformed above the melting temperature (Tm) of ZnSt (∼121 °C) to create a temporary shape, and then they were fixed into that shape by quenching the material to a temperature much below Tm, keeping the stress constant. The permanent form was recovered when the specimens were reheated above Tm without applying any stress. The efficiency of shape fixing was used as the determinant of the shape memory behavior, and up to 90% efficiencies were achieved. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48271. [ABSTRACT FROM AUTHOR]