Novel ester group functionalized cyclic olefin polymers (COPs) with high glass transition temperature, high transparency, good mechanical performance and excellent film forming ability have been achieved in this work via efficient ring-opening metathesis copolymerization of exo 4,4a,9,9a,10(1′, and comonomers (5-norbornene-2-yl methylacetate (NMA), 5-norbornene-2-yl methyl 2-ethylhexanoate (NME) or 5-norbornene-2-yl methyldodecanoate (NMD)) utilizing the Grubbs first generation catalyst, Ru(CHPh)(Cl)2(PCy3)2 (Cy = cyclohexyl, G1), followed by hydrogenation of double bonds in the main chain. The fully hydrogenated copolymers were characterized by nuclear magnetic resonance, FT-IR spectroscopy analysis, gel permeation chromatography, and thermo gravimetric analysis. Differential scanning calorimetry curves showed that the glass transition temperatures (Tg) linearly decreased with the increasing of comonomers content, which was easily controlled by changing feed ratios of HBM and comonomers. Static water contact angles tests indicate that hydrophilicity of copolymers can also be modulated by changing the comonomers incorporation. Additionally, the mechanical performances of copolymers were also investigated.
In contrast to conventional heat treatment processes, electropulsing not only heats an alloy, but also exerts some other positive effects during the heating process. In this paper, the microstructural evolution and mechanical properties of a deformed Zr40Ti5Al4V alloy after electropulsing treatment were investigated. The results showed that when the charging voltage was 2 kV, there was a slight decrease in dislocation density due to the electron wind which softened the alloy even though the highest temperature of the specimen during the treatment was only 86 °C. Increasing the charging voltage to 6 kV not only further increased the heating temperature, but accelerated the phase transformation process of α″ → β → α. The presence of the α phase strengthened the alloy but notably deteriorated its ductility. A full and refined β phase microstructure could be obtained when the charging voltage was increased to 8 kV. This simultaneously increased the strength and ductility of the alloy.
Onion-like carbon (OLC) was fabricated by annealing nanodiamond at temperatures ranging from 500°C to 1400°C. At 800°C, nanodiamond was completely transformed into amorphous carbon. At 900°C, OLC began appearing. As the annealing temperature increased from 1000°C to 1200°C, OLC particles size became larger and larger and the amorphous carbon coexisted in the center of the OLC particle became less and less. At 1400°C, all the amorphous carbon was transformed into the OLC.
A flash butt welding model of a high manganese steel crossing was established using the thermal coupled finite element method (FEM). The model considers comprehensively the physical parameters of materials, which change with temperature, as well as the burning material caused by the splutter during welding process. The temperature field of the flash butt welding joint and the cooling curves of the high manganese steel crossing at various locations near the welding seam were simulated. Comparisons with actual welding specimens of high manganese steel crossing indicated that flash butt welding model of the high manganese steel crossing is reasonable, and the temperature field distribution near the welding seam after flash butt welding can thus be appropriately evaluated by the simulation results.
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