The combustion performance of adding different metal hydroxide flame retardants in asphalt was investigated by the limit oxygen index test, and the flame retardant process of hydroxide flame retardant was studied by thermogravimetric analysis. The results showed that calcium hydroxide, magnesium hydroxide, aluminum hydroxide all play positive roles on flame retardancy of asphalt. Aluminum hydroxide has the best effect on flame retardation; calcium hydroxide and magnesium hydroxide show similar flame retardation. The temperature range of the decomposition of different metal hydroxide was different. Aluminum hydroxide has the lowest decomposition temperature, while calcium hydroxide has the highest decomposition temperature. Barrier layer composed of metal oxides is formed after the decomposition of flame retardant , which can prevent the further burning of asphalt.
Speed control of longitudinal ventilation systems in road tunnels is being combined with typical model predictive control (MPC) strategies which may bring huge energy saving potential to the system. Theoretical analysis of the inertia effect is presented based on the energy equation of one dimensional incompressible unsteady flow, step response model is chosen to describe the dynamic behaviors of the system. The results show that the effect of jet speed change on CO concentration is nonlinear within fan’s economical working range and the settling time of CO level has similar change trend with that of the flow field but is a little longer. The system settling time is longer when jet speed decreases than it increases and is related to the change extent of jet speed. The effect of traffic intensity on CO concentration can be regarded as linear disturbance to the system output. These results may provide useful indexes to control the tunnel ventilation system more economically and lay foundation for the application of predictive control strategy in the system.
Liquid crystal polyurethane (LCPBI) containing biphenylnate and imide units was synthesized and characterized and used to modify the conventional epoxy resin (E-51). Experimental results revealed that the impact strength of the epoxy resin modified with LCPBI was 2.5 times higher than that of unmodified epoxy resin, and the tensile strength as well as the bending strength was also improved. The thermal decomposition temperature of modified systems was also 15-20oC higher than that of the unmodified system, and the fracture structures of the blends was investigated by SEM.
A series of novel liquid crystal polyurethanes containing biphenylnate and imide units were synthesized through the polyaddition reaction of 4,4′-Bis-(2-hydroxyhexoxy)biphenyl (BP2), 2,4-toluenediisocyanate (2,4-TDI) with N,N′-bis(2-hydroxyhexyl)-dicarboxyimide (BHDI) by altering the molar ratio of BP2 and BHDI. The effects of structure difference molar ratio between BP2 and BHDI on the liquid crystalline behavior and thermal stability were studied. Results showed that all of the polyurethane polymers exhibited thermotropic nematic liquid crystalline textures in the range of 160~190°C. The melting temperatures (Tm) and the thermal stability increased with increasing BHDI content.
An unanticipated sideeffect of China’s developing economy was the increase in heavy road trafficvehicles utilizing high pressure tires on both new and old infrastructure.Today the extent of rutting has become one of the main forms of asphalt road surfacebreakage. To improve the robustness and high temperature properties of roadsurfacing asphalt, a new high-modulus material has been developed and used tomodify normal road petroleum asphalt. The results from laboratory experimentsconducted at the Jiangsu Baoli Asphalt Co., LTD and real road trials inPeople's Democratic Republic of Algeria, Shanghai, Shanxi and Jiangsu provincein China, indicate that the high-modulus asphalt performed significantly betterat higher-temperatures when compared to samples of more commonly used asphaltmixtures. The high-modulus additive (No. ZQ-1) was prepared in Jiangsu BaoliAsphalt Co. LTD, and the basic production process, the basic properties as wellas the effection to base bitumen was analysed in the paper. And the DynamicStability was evaluated using an automated rut-depth measuring system. Thewater stability and low temperature properties were also discussed. Themodified asphalt material has comparable storage and usage costs to existingutilized asphalts though with enhanced high-temperature properties.
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