Halloysite nanotubes immobilized by copper itaconic acid complexes as smoke suppressant for soft polyvinyl chloride

Abstract

AbstractCurrently, there are few reports of core–shell‐structured smoke suppressants that can provide a growth substrate and stabilize the char layer. In response to this problem, core–shell nanoparticles of halloysite nanotubes (HNTs) coated with copper itaconate complex were prepared by layer‐by‐layer assembly method. The electrostatic forces between HNTs and copper ions and the coordination between the itaconic acid and copper ions contributed this synthesis. The micromorphology, chemical composition, and structure of HNT@CuC5H4O4 were characterized, and its effects on the flame‐retardant and smoke‐inhibition properties, mechanical properties, and thermal stability of the soft polyvinyl chloride (PVC) were investigated. The results showed that the core–shell structure of HNT@CuC5H4O4 contributed to its homogeneous dispersion in PVC and the formation of interlocking mesh structure. Thus, the incorporation of HNT@CuC5H4O4 enhanced the strength and stiffness of soft PVC without sacrificing its ductility. Besides, copper ions on HNT@CuC5H4O4 could promote the cross‐linking carbonization of the PVC at high temperature. The formed char layer catalyzed by CuC5H4O4, together with its attached three‐dimensional network structure of HNT constituted a compact and continuous char layer with high thermal stability, which effectively prevented the release of combustible volatiles and toxic gases as well as heat transfer.