Wei-Wen Li,Wei-Ming Ji,Yi Liu,Feng Xing,Yu-Kai Liu
This study aimed to explore the damping property of a cement-based material with carbon nanotube (CNT). In the study, the cement composites with different contents of CNT (0 wt%, 0.033 wt%, 0.066 wt%, and 0.1 wt%) were investigated. Logarithmic Decrement method and Dynamic Mechanical Analysis (DMA) method were utilized to study the damping property of CNT/cement composite. The influences of CNT on pore size distribution and microstructure of composite were analyzed by Mercury Intrusion Porosimetry (MIP) and Scanning Electron Microscopy (SEM), respectively. The experimental results showed that CNT/cement composite presented higher flexural strength index than that of a pure cement paste. Additional CNT could improve the vibration-reduction capacity of cement paste. Furthermore, the experiments proved that CNT could bridge adjacent hydration products and support load transfer within cement matrix, which contributed to the energy dissipation during the loading process.
A series of novel polyurethane (PU)/epoxy resin (EP) graft interpenetrating polymer network (IPN) composites with graded length side chains were prepared from toluene diisocyanate (TDI), polytetrahydrofuran glycol (PTMG), EP, trimethylolpropane (TMP), and diol chain extenders. The effects of the side chain lengths, content, and groups on the damping properties and mechanical properties were investigated. Two damping peaks were observed in the PU/EP IPN system, indicating that the peak damping factor (tan δ ) increased with increased side chain length at low temperatures. The introduction of an apolar side chain slightly narrowed the damping range. However, the side chain carrying polar groups broadened the damping temperature range. The strong H-bond interaction between the ester group of side chain and the N H of hard segments in PU was believed to favor microphase separation to form a larger-sized domain and induce the appearance of the relaxation peak at high temperatures. Consequently, the effective damping temperature range was broadened. The side chain content tethered in the hard segment remarkably influenced the damping properties of PU/EP IPNs both at low and high temperatures. The width and intensity of the tan δ peaks of PU/EP IPNs increased with increased side chain content. The mechanical properties (tensile strength and elongation at break) were significantly affected by the side chain content. Thus, an important method of improving the mechanical damping of elastomers by controlling the side chain molecular structure was established.
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