Novel application of Zn‐containing Zeolitic Imidazolate Frameworks in promoting the vulcanization and mechanical properties of natural rubber composites

Abstract

Three kinds of Zn-containing Zeolitic Imidazolate Frameworks (Zn-ZIFs, including ZIF-8, ZIF-11 and ZIF-14) based on the zinc ions coordinating with different imidazolate ligands were added into the natural rubber (NR) using the DM and TMTD binary accelerators system, respectively. The influences of Zn-ZIFs on the sulfur vulcanization behaviors and mechanical properties of NR matrix were evaluated. The results indicated that the addition of ZIF-8 or ZIF-14 could realize the fast vulcanization of NR at 130 C (the ordinary vulcanization temperature of NR is above 150 C), while ZIF-11 did not show the obvious accelerating performance. Amongst the three Zn-ZIFs, ZIF-8 benefited NR matrix for the acquirement of the highest tensile strength and the largest crosslinking density. As an optimal additive, ZIF-8 with 0.6 phr distinctly improved the physical-mechanical, thermo-oxidative aging resistance and dynamic mechanical properties of NR composites. It proved that Zn atom and its coordination porous network in Zn-ZIFs played synergistic effects in accelerating vulcanization and enhancing mechanical properties of NR matrix besides its role of reinforcement filler. Then the above ZIF-8/DM/TMTD vulcanization system was used to prepare the UHMWPE fibers/NR composites. The mechanical properties of the UHMWPE/NR composites were significantly improved in contrast to the pure NR matrix.

Use of ZIF‐8 as vulcanization additive to optimize natural rubber composites to lower the amount of ZnO

“…Zhiqiang Lei et al explored the in situ growth of ZnO nanoparticles onto MOF‐Zn and improved the agglomeration behavior of ZnO nanoparticles and facilitated the dispersion of ZnO in rubber through the interaction between MOF‐Zn and ZnO nanoparticles 25 . Xing Tian applied different kinds of ZIF materials in the vulcanization of natural rubber, and speculated that ZIF materials have the synergistic effect of accelerating the vulcanization and improving the mechanical properties of the NR matrix in addition to their role as reinforcing fillers 26 . However, the mechanism of MOF materials in promoting rubber vulcanization has not been thoroughly investigated and still needs further investigation and discussion.…”

Metal Organic Frameworks: Current State and Analysis of Their Use as Modifiers of the Vulcanization Process and Properties of Rubber

“…It should be noted, however, that the amount of zinc present in the entire mixture was summed to be higher than in the reference sample, which contained only zinc oxide [103]. The addition of three different zeolitic imidazolate frameworks to natural rubber-based blends as a functional additive allowed, with a suitable accelerator system, a reduction in the vulcanization temperature while maintaining or improving its mechanical properties and increasing its crosslinking density [104]. These relationships resulted from the higher Zn content in the blends.…”