Study on Properties and Low Temperature Thermal Expansion Rate of Environmentally Friendly Polyurethane Foam
|Course||Agricultural Mechanization Engineering|
|Keywords||polyurethane foam HFC-365mfc Nano SiO2 Organic montmorillonite linearthermal expansion coefficient of low temperature|
Polyurethane foam is an important kind of synthetic-material．Rigid polyurethane foam iswidely used in the field of thermal insulation due to its low thermal conductivity, low densityand high specific strength. In the condition that traditional blowing agent CFC-11has beenbanned to be used and HCFC-141b, which is widely used right now, would be completelybanned in2020, people pay more and more attention on environmentally friendly blowingagent.Aiming at environmentally friendly blowing agent of HFC-365mfc and water, theinfluence of different chemical composition of the foaming system on the properties ofpolyurethane foam was analyzed by changing isocyanate index and dosage of blowing agent.By comparison with traditional blowing agent HCFC-141b, the advantages and disadvantagesof the environmentally friendly blowing agent HFC-365mfc and water was obtained, inaddition, the optimum formula with which to produce excellent rigid polyurethane foam was setup.In order to explore the unique role of nanotechnology in environmentally friendly rigidpolyurethane foam system, in this paper, a variety of types of SiO2nanoparticles and organicmontmorillonite were added in the foaming system based on environmentally friendly blowingagent HFC-365mfc. Through the XRD, TGA, SEM and universal testing machine, dispersionproperties of nanoparticles, compression strength of the foam, pore microstructure, and thermalstability of the foam was investigated and also, the effect of different types of nano-particle andadding amount on the rigid polyurethane foam properties was analyzed.In cryogenic engineering, The linear expansion coefficient at cryogenic temperature shouldbe matched with support structureand taken into account to avoid thermal insulation layer crackunder the stress resulted by large temperature differences. In this paper, based on the analysis ofmethod used to test linear thermal expansion coefficient under ambient and cryogenictemperatures a set of thermal linear expansion coefficient measuring device was set up with ameasuring range from liquid nitrogen temperature to room temperature. The linear thermalexpansion coefficient of environmentally friendly polyurethane foam and nano/polyurethanecomposite foam was measured and the influence of nano particles on the linear thermalcoefficient was analyzed.Aiming at environmentally friendly blowing agent HFC, the optimum formulation offaming system was investigated. Nano-SiO2and organic montmorillonite were adopted tooptimize the properties of this foam. A linear thermal expansion coefficient measuring deviceused in low temperatures was set up. With all the endeavors mentioned above, some clues may be provided to research the mechanical and thermal performances, as well as the foamingprocess of the environmentally friendly rigid polyurethane foam.