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Industries have been utilizing amphiphobicity of durable water repellents (DWRs) to make textiles for decades for both water repellency and stain resistance. However, polymeric per- and polyfluoroalkyl substances (PFASs) were used the most often until today since fluorinated chemicals own super low surface energies and amphiphobic fluorinated moieties. As environmental issues and health concerns have been raised, researchers started investigating environmentally friendly non-fluorinated DWRs. This review paper aims to explore typical works mainly consisting of long-chain PFASs based, short-chain PFASs based, silicones-based, and hydrocarbonsbased DWRs, to exhibit the principles behind their amphiphobicity, and to compare and discuss their water repellency, oil repellency, and durability. In general, neither silicones nor hydrocarbons possess satisfying stain resistance and durability as fluorinated materials, even if the hydrophobicity can reach a similarly high value. In this work, the major purpose is to point out the advantages and corresponding limitations of different types of DWRs for industries and suggest potential improvements that other researchers can make in the future.

To realize continuous real-time monitoring of the large-scale internal strain field of coal and rock mass, a bidirectional strain sensor based on FBGs encapsulated using a hollow cylindrical steel tube was designed. The sensor’s structural parameters were optimized through unidirectional loading, and the strain change laws of the sensor were analyzed under unidirectional and bidirectional loading conditions, in which the stress-strain fitting curves of the sensor and the relationships of the strain in the vertical and horizontal directions were obtained under different lateral pressure loading conditions. A similar theoretical model was established to verify the accuracy of the linear relationship between the surrounding rock stress and the strain measured by the sensor system.

Unsaturated polyester resins (UPRs) are expansively used in different applications and recycling the significant amounts of UPR waste is still a universal problem. Vitrimerization is a feasible, environmental-friendly, cost effective, and operative method, which can be used for recycling the crosslinked UPRs. In this method, the thermoset permanent network is changed into a dynamic network similar to the vitrimer-type polymers. The results show that the existence of a transesterification catalyst in the system significantly enhances the efficiency of vitrimerization. The vitrimerized UPR thermosets can be reprocessed three times with mechanical properties comparable to the initial UPR. The results show that the excess of external hydroxyl groups in the system can prevent the formation of zinc ligand complexes in the network and consequently reduce the crosslinked density and mechanical properties of vitrimerized samples. The vitrimerized thermoset powder can be reprocessed through injection molding, extrusion, and compression molding which are conventional thermoplastic processing techniques. The unrecyclable UPR thermoset wastes can be recycled and reused through vitrimerization with the least loss in mechanical properties.