Abstract
An ionomeric, leathery thermoplastic with high mechanical strength is prepared by a new thermal processing method from a soft, melt‐processable rubber. Compositions made by incorporation of equal‐mass lignin, a renewable oligomeric feedstock, in an acrylonitrile‐butadiene rubber often yield weak rubbers with large lignin domains (1–2 µm). The addition of zinc chloride (ZnCl2) in such a composition based on sinapyl alcohol‐rich lignin during a solvent‐free synthesis induces a strong interfacial crosslinking between lignin and rubber phases. This compositional modification results in finely interspersed lignin domains (<100 nm) that essentially reinforce the rubbery matrix with a 10–22 °C rise in the glassy‐to‐rubbery transition temperature. The ion‐modified polymer blends also show improved materials properties, like a 100% increase in ultimate tensile strength and an order of magnitude rise in Young's modulus. Coarse‐grained molecular dynamics (MD) simulations verify the morphology and dynamics of the ionomeric material. The computed result also confirms that the ionomers have glassy characteristics.
