Preparation Of Fiber-Reinforced Silica Aerogel Insulation Material And Weathering Resistance Simulation Under Temperature And Moisture Conditions

SiO₂ aerogel possesses wide application prospects as a heat-insulating material,but it needs to be evaluated as external wall heat-insulating material for its strength,temperature and humidity weather resistance.There are few studies on the temperature,humidity and weather resistance of external wall insulation materials,and there is no relevant data.In the current external wall insulation industry,there is no domestic weather resistance test equipment and corresponding standards and specifications for fiber-reinforced aerogel exterior insulation systems.By contrast,the numerical simulation can greatly reduce the economic and time costs,calculate a variety of working conditions,and thus become an important auxiliary means to study the temperature and humidity weatherability of the system.In this paper,the fiber-reinforced SiO₂ aerogel insulation slurry was used as the main thermal insulation component to construct the external thermal insulation system,and the finite element model of the temperature field,humidity field,stress and displacement of the system was established by using the data obtained from the experiment.The temperature and humidity weatherability as well as strength safety of the slurry are evaluated by application feasibility simulation,and then it is predicted whether it can meet the application requirements of external wall thermal insulation materials.The results show that when the ratio of aerogel to silane treatment agent is 5:1,the thermal conductivity of prepared insulation sample is the lowest.After adjusting the formulation of the thermal insulation material through simulation results,when the mass fraction of polypropylene fiber is 3%,the highest flexural strength of the sample is 1.76 MPa.After being soaked for 120 minutes,the water absorption rate of the sample remains stable at 1.9%.The stress simulation of the fiber-reinforced aerogel external insulation system was carried out with the experimental parameters.It was found that the maximum stress at the boundary of the insulation slurry layer was 1.215 MPa,which exceeded the experimentally measured strength of insulation material.According to the simulation results,the main parameters affecting the stress were analyzed,and the flexural strength of the heat-insulating material was increased to 1.76 MPa through experimental adjustment of the amount of reinforcing component fibers,and the strength of the heat-insulating material after optimized was evaluated again to confirm that its strength reached the application requirements.The performance parameters of the thermal insulation slurry were measured by the moisture absorption test,and the humidity field numerical simulation was performed on the thermal insulation system using the obtained parameters.The difference of moisture content between inner and outer surface of the insulation layer is 0.240%,while that of the inner and outer surface of primary wall is only 0.005%.In this paper,the temperature and humidity weather resistance of fiber-reinforced aerogel insulation materials was simulated and evaluated,which provides a reference for the research of safety as well as temperature and humidity weatherability of the actual wall insulation engineering.