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Natural rubber (NR) demonstrates excellent mechanical strength and tensile elasticity after vulcanization. However, the sulfur curing system will generate many problems, including the usage of toxic accelerators, blooming, and unrecyclable products. Therefore, it is a big challenge to prepare high-performance elastomers without sulfur vulcanization in the natural rubber (NR) industry. Here, a small amount of graphene oxide (GO)/zwitterionic chitin nanocrystals (NC) hybrids (GC) are first introduced in NR latex to reinforce unvulcanized NR. The NR/GC nanocomposite exhibits a high tensile strength of 19.2 MPa and a large breaking elongation of 825.9%, rivaling that of sulfur-vulcanized rubber. NC with amino and carboxyl groups can act as a macromolecular bridge and enhance the interfacial interaction between GO sheets and NR particles due to its strong attraction to both of them. Moreover, the dispersion of GO in NR is dramatically improved after adding NC due to the hybrid-synergetic effect. Thus, the formed uniform hybrid nanofiller networks strongly absorbed on NR macromolecules can significantly enhance the mechanical properties of nanocomposites. As a concept of proof, the medical gloves prepared by NR/GC latex show better performances than those of the vulcanizates, including good recycle ability, higher water vapor permeability, and good biocompatibility.

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Our previous work demonstrated that the toughness of PLLA could be improved dramatically by dynamic vulcanizing blends of PLLA/NBR with dicumyl peroxide (DCP) as a cross-link agent. Herein, to reveal the toughening mechanism of DCP on the PLLA/NBR thermoplastic vulcanizates (TPVs), the distribution of DCP in the PLLA matrix and NBR phase was modulated by changing feeding procedures. The cross-link density of NBR, phase morphology, and mechanical properties of PLLA/NBR−TPVs were investigated thoroughly. It was found that impact toughness of the blends is dependent on the distribution of DCP, while the tensile properties almost keep unchanged with alteration of the feeding procedure. PLLA/NBR−TPV prepared by premixing DCP with PLLA and NBR separately had the highest toughness and comparable tensile properties. This was attributed to the synergistic effect between the improved PLLA molecular chain entanglement due to the DCP initiated branch reaction of PLLA and improvement of the compatibility between two phases.