Study On The Preparation Of Modified PU By Degradation And Regeneration Of Waste PUU

Polyurethane-urea is a special polyurethane material with a large number of urea bonds in its molecular chain,which is widely used in various fields such as anti-corrosion and wear resistance because of its excellent properties,and therefore its waste accumulates in large quantities and is difficult to dispose of.However,there are few reports on the degradation of polyurethane materials,so based on the similarity of the chain segments of the two,polyurethane urea is recovered with reference to the degradation method of polyurethane,and the recovered oligomers can be reused for the synthesis of polyurethane rigid foam.However,since the compression properties of polyurethane rigid foam are poor compared with those of metal materials,for example,inorganic whisker materials can be introduced to modify them,thus constructing a process route for the degradation and regeneration of used polyurea to prepare modified polyurethane and realize the recycling of resources.This paper firstly investigates the process route of degradation of waste polyurethane urea elastomer materials by glycolysis.The influence law of the type of glycolysis agent,two-component glycolysis agent compounding ratio,catalyst addition,reaction temperature,reaction time and other conditions were discussed.The optimal glycolysis process parameters for the preparation of waste polyurethane-urea,as well as the maximum substitution amount of degradation products for the preparation of recycled polyurethane and the optimal addition amount of modifiers were determined as follows:(1)The best two-component glycolysis type and ratio is the compounding ratio of ethylene glycol:diethylene glycol=57:43,when the viscosity of degradation material is 632.2 m Pa·s and the compression strength of regenerated PU is 365.24 KPa.and the minimum density of regenerated PU is 35.04 Kg/m3at this time.(2)EG and DEG compounding thermal degradation of waste polyurethane urea optimal conditions:time 2.5h,temperature 180℃,catalyst 0.8g,at this time the viscosity of the degradation material is the viscosity of the degradation product is 642.2 m Pa·s,the density of regenerated PU is 28.31 kg/m3,the compression strength is 392.92 KPa.(3)When the replacement amount of liquefied polyol is 33%,the density of the prepared regenerated foam is 35.88 kg/m3and the compression strength is 393.52KPa;when the short whisker is added at 0.4wt%,the compression strength is 461.66 KPa,and the apparent density of PU is 45.08 kg/m~3;when the long whisker is added at 0.3wt%,the compression strength of regenerated PU is 460.59 KPa.The compressive strength of the regenerated PU nanocomposites was increased by about 17%compared with that without whisker modification,which fully met the commercially available standard for rigid polyurethane foam materials.