Novel composite microcapsule for Karstedt catalyst: a latent green one based on organic gum for curing silicone rubber at medium temperature

Abstract

In response to issues such as high curing temperatures (100–200°C), degradation of product color, and insufficient process controllability in traditional addition-curing silicone rubber systems caused by catalyst inhibitors, this study proposed a novel green modification strategy based on microcapsule technology. Through the use of a composite aggregation technique, an innovative microcapsule system was successfully developed, utilizing gelatin (GE)/octenyl succinic anhydride-modified gum arabic (OSA-GA) as the shell and Karstedt catalyst as the core. The composition of the wall provided dual advantages: effectively preventing the pre-reaction between the catalyst and the matrix, which would significantly extend the storage time at room temperature from 40 min to 20 h, and enable a significant reduction in curing temperature based on the specific softening temperature of the wall (at 60°C). The research methodically examined the impact of process parameters on the morphology and functionality of the microcapsules, and verified via Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA) that the microcapsules featured consistent core-shell structure and superior thermal response properties. The microencapsulated system could reduce the curing temperature to 60°C while maintaining the mechanical properties of silicone rubber, without introducing toxic substances. The study provided a valid strategy for developing environmentally friendly, room-temperature-stable silicone rubber systems and hold significant application values.