Tailored‐Structure Zinc Oxide as an Effective Vulcanization Activator: A Sustainable Approach to Enhanced Performance in Natural Rubber Compounds

Journal of Applied Polymer Science, no.e71302, 2026 (Peer-Reviewed Journal)

ABSTRACT

Growing environmental concerns have increased the need to reduce zinc oxide (ZnO) in sulfur vulcanization without compro-

mising rubber performance. This study investigates MICro- naNO structured ZnO (MicNo- ZnO), a hierarchically structured

zinc oxide consisting of micrometer- sized platelets built from ZnO nanoparticles, as an alternative activator for natural rubber.

MicNo- ZnO loadings between 5 and 0.5 phr were compared with a conventional 5 phr ZnO formulation. Rheometric analysis

showed higher cure extent and effective crosslink density even at significantly reduced ZnO levels. Despite up to 90% ZnO re-

duction, MicNo- ZnO compounds exhibited comparable scorch safety, high cure extent, and retained mechanical performance

along with improved resistance against thermal aging. Cyclic compression tests confirmed lower hysteresis and reduced stress

softening under limited cyclic loading. SEM–EDX mapping indicated a more homogeneous spatial distribution of zinc- and

sulfur- containing regions in the MicNo- ZnO compounds than in the conventional ZnO formulation. XRD results confirmed the

presence of crystalline ZnO domains, with decreasing peak intensity as the ZnO loading was reduced. This work presents the in-

vestigation of MicNo- ZnO, a hierarchically structured zinc oxide consisting of micron- sized platelets assembled from chemically

bonded nanoparticles, as a vulcanization activator for natural rubber compounds.