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.
Ultra-high molecular weight polyethylene (UHMWPE) can be used as the candidate material for mixed transmission pipelines due to its fabulous wear durability, corrosion resistance, and self-lubricating qualities. Nonetheless, the connection between its microstructures and tribological performance is still unclear, and hence it is difficult to elucidate the mechanism of its wear resistance. Four types of UHMWPE samples (GUR 400Fine, GUR 4012, GUR 4130, and GUR 4150) were chosen for this study, and their tribological properties were tested. The results show that the coefficient of friction (COF) and wear rate (WR) of GUR 4130 decrease as the temperature increases, but its crystallinity would not be changed while its entanglement density increases and they were confirmed by dynamic mechanical analysis. Additionally, GUR 400Fine and GUR 4012 have similar molecular weight, GUR 400Fine's COF and WR are 1.12 and 1.37 times higher than those of GUR 4012 due to its lower entanglement density. Additionally, higher molecular weight causes higher entanglement density and better tribological performance. In conclusion, we have prepared UHMWPE with better wear resistance through a simple processing method.
Polylactic acid (PLA) is a kind of polyester from biomass. To increase the ductility of PLA, melt blending was used to prepare the polylactic acid/poly(butylene diglycolate) blends in this study. The effect of poly(butylene diglycolate) (PBD) on the thermal, crystallization, tensile, and dynamic mechanical properties of PLA was investigated. The blend containing 30 wt% PBD has a substantially improved elongation at break (79%) due to the lower glass transition temperature of PBD compared to PLA. The results indicated that PLA and PBD exhibited partial compatibility, which was confirmed by dynamic mechanical analysis (DMA) and scanning electron microscope (SEM). Fourier transform infrared spectroscopy (FTIR) analysis showed there is the interaction between PLA and PBD. In summary, the incorporation of PBD resulted in improved mechanical properties, indicating potential for applications requiring enhanced ductility.
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