Poly (vinylidene fluoride)/fluororubber/silicone rubber thermoplastic vulcanizates prepared through core-shell dynamic vulcanization: Formation of different rubber/plastic interfaces via controlling the core from “soft” to “hard”

- We explore regulating the core-shell structure in PVDF/FKM/SR TPV.
- Core-shell structure was formed via a controlled dynamic vulcanization.
- Mechanical properties increase with increasing levels of crosslinking in SR.
- Structure and properties are determined by different rates of FKM/SR crosslink.

In the previous report, we proposed a novel core-shell dynamic vulcanization technique to prepare a fluorosilicone thermoplastic vulcanizate (TPV) based on poly (vinylidene fluoride) (PVDF), fluororubber (FKM) and silicone rubber (SR). However, we did not discuss the relationship between the structure and properties of the TPV from the viewpoint of core-shell structure. For example, why the mechanical properties of a shell-crosslinked TPV were inferior to that of a core-crosslinked TPV? In this paper, we have valuable insights on this issue and provide guide for regulating core-shell structure in polymer blends. We found that SR molecule chains were possibly forced to migrate to the interface between PVDF and FKM under strong shearing during dynamic vulcanization. When DCP content <0.4 wt%, some of the soft SR formed films, and most of it formed “soft” particles. When DCP content ≥0.4 wt%, all of SR formed “hard” particles, and thus a perfect core-shell structure was formed after the crosslinking of FKM. The mechanical properties of the TPVs were also largely improved with increasing levels of crosslinking in SR.

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