Breaking the theoretical boundaries between material stiffness and damping performance is the core driving force for advancing advanced structural vibration reduction technologies. However, existing multiscale design paradigms for extreme performance are constrained by the rigid theoretical assumption of “no internal material activity,” prohibitive computational resource overhead, and trial-and-error iterations that depend on experience. To address these challenges, this study constructs a design framework integrating an internal chemical damping source with a multiscale hierarchical structure-coupled deformation excitation mechanism, proposing an efficient extreme performance design method that enables intelligent micro-configuration design without pre-setting theoretical assumptions. Specifically, this study introduces a dual dynamic covalent bond network composed of disulfide and imine bonds as the damping sources. Secondly, a dimensionless damping excitation criterion is established as a static proxy metric, transforming the computationally expensive dynamic analysis problem into an efficient static solution process. Finally, through the screening of a multiscale microstructure library, the coupled design of chemical activity and structural deformation is realized. Experimental results demonstrate that the intense local strain concentration induced by the rigid body-centered cubic skeleton can alter the potential energy dissipation characteristics of the vitrimer, exciting physical chain segment mobility and chemical exchange reactions. The fabricated multiscale metamaterial achieves a peak loss modulus of 1044 MPa over a broad temperature range, transcending the empirical performance boundaries of conventional engineering materials.
Re-milling between storage and vulcanization is a routine step in silica-reinforced rubber compounding, yet how it alters the structures developed during storage remains underexamined. Herein, we identify re-milling before vulcanization as an effective post-storage processing strategy that reorganizes storage-induced filler networks and rubber-silica interfaces, thereby establishing a direct link between storage history, structural evolution, and the final performance of SSBR/SiO2 compounds. It has been shown that re-milling disrupts filler agglomerates, promotes structural reorganization, and strengthens interfacial bonding. This interfacial strengthening was evidenced by the higher bound-rubber contents of the re-milled samples, which increased by 25%, 15%, and 20% relative to the non-re-milled counterparts after 1, 2, and 4 days of storage. These structural and interfacial modifications translated into a rebalanced property profile, with pronounced benefits in fatigue and abrasion resistance obtained at the expense of part of the wet-grip-related response. Fatigue lifetime increased by 170%, 87%, and 36% for the 1, 2, and 4 day conditions, respectively, and a split-plot analysis of variance confirms that the magnitude of this gain depends significantly on the preceding storage time. DIN abrasion volume was significantly reduced by re-milling. This trade-off is reflected in tan δ at 0 °C, the corresponding material indicator, which was significantly lower after re-milling. After 4 days of storage, the formation of large, stable filler aggregates prevented re-milling from fully reversing the storage-induced structural evolution, thereby weakening its regulation of the structure-property balance. This reduced structural reversibility indicates that re-milling should be conducted before the filler network becomes highly stabilized.
The transition from a linear to a circular plastics economy depends on credible verification of recycled content claims. However, regulatory thresholds emerging under the EU Packaging and Packaging Waste Regulation, the UK Plastic Packaging Tax, and the Australian Consumer Law have exceeded the current analytical capability required to substantiate them. This challenge is most acute for mechanically recycled polyolefins, which dominate plastic packaging by volume yet remain chemically indistinguishable from virgin material and carry processing history confounds that single technique measurements cannot resolve. This review examines analytical barriers to recycled-content verification and distinguishes polymer blend quantification from the more difficult task of verifying recycled provenance. Spectroscopic, thermal, rheological, molecular, chromatographic, and fractionation techniques are evaluated as descriptor-generating tools, with emphasis on their limitations under realistic industrial variability. The review then explains a three-layer verification methodology comprising calibration with representative virgin and recyclate standards, predictive modelling with data fusion, and confidence-bounded reporting. Based on this methodology, six analysis-assisted deployment workflows are proposed, with emphasis on their maturity, validation requirements, limitations, and implementation barriers. Finally, this review introduces roadmaps and future directions for moving toward regulator-grade recycled-content verification frameworks that integrate analytical descriptors with sampling, uncertainty reporting, and chain-of-custody evidence.
