Research On Recycling Process And Experiment Of Waste Thermosetting Polyurethane

Thermosetting polyurethane has good stability,corrosion resistance,low density and thermal conductivity.Widely used in construction,automobile,coating,household appliances,clothing,aviation and other industries.However,with the production and consumption of polyurethane,a huge amount of waste polyurethane has been produced.How to deal with the waste polyurethane has become an important practical problem to save energy,protect the environment and realize the sustainable economic development of our country.The traditional landfill and incineration methods waste resources and easy to cause secondary pollution to the environment.After thermosetting polyurethane is heated and cured,it forms a cross-linked network structure,which also loses its solubility and cannot be melted and regenerated like thermoplastics.At present,the recycling method of thermosetting polyurethane is mainly physical crushing as filler.This paper discusses the application of mechanochemical methods in the recycling of thermoset polyurethanes.The mechanochemical method is to apply the long-term mechanical force to the polyurethane.While reducing the particle size of the polyurethane,its chemical bonds are broken,so that the cross-linking density of the polyurethane powder is reduced and plasticity is restored.The main research work of this paper is as follows:（1）The crushing mechanism of thermosetting plastics and the theoretical basis of computational fluid dynamics are expounded.A special crusher for thermosetting plastics is designed,and its closed crushing area is simulated by CFD.The fluid distribution in the crushing bin is explored,and the influence of rotor speed and the number of cutter teeth on the flow field is studied.（2）Taking the rigid polyurethane insulation board as the research object,the crushing test was carried out by orthogonal design.The effects of rotational speed,grinding time and feed rate of the crusher on the crushing effect were studied.Taking 200 mesh powder ratio and energy retention rate as evaluation indexes,the evaluation system of crushing effect was established by using multi-decision maker scoring method.The test results were analyzed by intuitive analysis,range analysis and variance analysis respectively.A variety of instruments are used to characterize the mechanochemical reaction in the grinding process.（3）The recycling test of polyurethane powder was carried out with the help of hot pressing method.Taking the number of polyurethane powder,the proportion of polyurethane powder,hot pressing time and hot pressing temperature as input parameters,and the mechanical properties and thermal insulation properties of recycled plates as output parameters,the relationship between them was explored.Range analysis and variance analysis were used to judge the significance ranking of the four input parameters.The optimal process parameters are given from three directions: the lowest thermal conductivity,the maximum tensile strength and the balance.Figure[32] table[16] reference[77]...