Ethyl cellulose was grafted with ionic liquids in optimal yields (62.5–64.1%) and grafting degrees (5.93–7.90%) by the esterification of the hydroxyl groups in ethyl cellulose with the carboxyl groups in ionic liquids. In IR spectra of the ethyl cellulose derivatives exhibited C=O bond stretching vibration peaks at 1760 or 1740 cm⁻¹, confirming the formation of the ester groups and furnishing the evidence of the successful grafting of ethyl cellulose with ionic liquids. The ethyl cellulose grafted with ionic liquids could be formed into membranes by using the casting solution method. The resulting membranes exhibited good membrane forming ability and mechanical properties. The EC grafted with ionic liquids-based membranes demonstrated PCO₂/PCH₄ separation factors of up to 18.8, whereas the PCO₂/PCH₄ separation factor of 9.0 was obtained for pure EC membrane (both for CO₂/CH₄ mixture gas). The membranes also demonstrated an excellent gas permeability coefficient PCO₂, up to 199 Barrer, which was higher than pure EC (PCO₂ = 46.8 Barrer). Therefore, it can be concluded that the ionic liquids with imidazole groups are immensely useful for improving the gas separation performances of EC membranes.

Polyurethane cement (PUC) is a kind of high-strength composite bending and strengthening material that is made by adding an appropriate amount of super fine aggregate, such as cement, into the polyurethane matrix. Carbon nanofiber polyurethane cement (CNFPUC) prepared by adding an appropriate amount of carbon nanofiber (CNF) can significantly reduce the resistivity of PUC. In order to reveal the change regulation of electrical resistivity of CNFPUC under fatigue load, the four-point bending fatigue life test of CNFPUC under different temperatures and stress levels was conducted by using a multifunction test device on a mixture of UTM-30 asphalt. The results showed that the resistivity increased slightly with the increase of bending strain in the process of the CNFPUC bending test, which presented a two-stage trend of a small increase and a sharp increase, and the maximum bending tensile stress was up to 26.65 MPa. Under periodic load, the resistivity increased with the increase of stress level and cycle times. When the damage amount reached 90%, the fatigue resistivity increased sharply, and with the increase of stress level, the effect of temperature on resistivity decreased gradually. This study may provide a theoretical basis for practical engineering applications.

The sensitivity of carbon nanofiber polyurethane cement (CNFPUC) was evaluated to determine whether the cement can act as an intelligent reinforcement material. The percolation thresholds at different polymer-to-cement ratios were determined through experimentation. Taking a specific carbon nanofiber (CNF) content of the percolation zone, several CNFPUC mixtures with different poly-ash ratios and silica fume contents were made. They were then sampled from the mixture and poured into a hexahedron CNFPUC test block; the coefficient of variation of resistance and the piezoresistive characteristics under axial load were examined and the blocks were examined by scanning electron microscope. The sensitivity of the CNFPUC mixture was evaluated via the resistance variation coefficient of a sample hexahedron. For different CNF dosages, the critical value of the variation coefficient was used to assess the sensitivity characteristic by fitting the conic curve. These findings may provide a novel and simple method for determining the sensitivity of CNFPUC mixtures.

To examine the intelligent sensing properties of polyurethane cement mixed with carbon nanofiber and used as beam reinforcement material, 7 reinforced concrete T‐beams were made and reinforced with carbon nanofiber polyurethane cement material (CPUC). Four‐point bending tests were conducted. Reinforcing concrete beams with CPUC material might increase the yield load and ultimate load of beams significantly. The overall stiffness of the reinforced beam was enhanced. CPUC played a significant inhibitory role in the formation and development of beam cracks. A sudden change in the rate of CPUC resistance can be used to monitor the yield of a steel bar, and then, a safety warning for the components can be launched. By establishing a model of the relationship between the resistance change rate and the external load, the bearing capacity of the beam is evaluated in real time, and the dual effects of reinforcement and health monitoring of the beam are realized simultaneously.