Study On Synthesis Technology Of Biodegradable Polyurethane Material Based On Glycolic Acid

Since polyurethane materials are not degradable after use,they have caused serious environmental pollution.Glycolic acid is a high-end degradable material derived from coal chemical industry,which can be biodegraded into carbon dioxide and water.With the development of the coal chemical industry,the production capacity of glycolic acid has increased rapidly,and the production cost has been greatly reduced,and it is urgent to expand the application field.This dissertation uses glycolic acid as raw material to synthesize degradable polyurethane foam through chemical process design.The process parameters were optimized,the degradation performance of the polyurethane foam was studied,and the graphene-modified polyurethane foam was finally prepared.The specific work and results are as follows:(1)Glycolic acid is polymerized-cleaved to generate glycolide.The effects of reaction temperature,reaction time,catalyst type and dosage on the yield of glycolide were investigated respectively.The optimal reaction conditions are as follows:the polymerization temperature is 160°C,the reaction time is 3 h,the depolymerization temperature is 240°C,and the reaction time is 3 h,the catalyst is Sb₂O₃,the catalyst dosage is 0.375%of the mass of glycolic acid.The yield of the obtained glycolide was 60.7%.(2)Glycolide is used as raw material,?-caprolactone and 1,4-butanediol are used as modifiers,and stannous octoate is used as catalyst to form low molecular weight polyester polyol by ring-opening copolymerization.The effects of reaction temperature,reaction time,initiator dosage and monomer ratio on the hydroxyl value and acid value of polyester polyol were investigated respectively.The results showed that the optimal reaction conditions were as follows:the reaction temperature was 140?,the reaction time was 8 h,the amount of1,4-butanediol was 40%of the total moles of monomers,n(glycolide):n(?-caprolactone)ester)=2:8.The hydroxyl value of the obtained polyester polyol was 266.5 mg KOH/g,the acid value was 10.2 mg KOH/g,the viscosity was 165 cps,and the water content was 0.3%.(3)Polyester polyol reacted with isocyanate and various additives to prepare polyurethane foam.The effects of silicone oil quality,distilled water quality and isocyanate index on the performance of polyurethane foam were investigated respectively.The results showed that the best process conditions:m(silicone oil)/m(polyester polyol)=1.5%,m(distilled water)/m(polyester polyol)=1.5%and the isocyanate index is 1.1,the resulting polyurethane foam has a compressive strength of 0.26 MPa and an apparent density of 72.9Kg/m³.(4)The degradability of polyurethane foam was investigated.When the degradation environment is alkaline,the degradation effect is the best;the acidity is the second,and the neutrality is the worst.When n(glycolide):n(?-caprolactone)=2:8 in polyurethane foam,and the degradation rate is 20 days,the weight loss rate of polyurethane foam is 15%in alkaline environment,10%in acidic environment,neutral Ambient is 3%.With the increase of glycolide content in polyurethane foam,the degradation effect is better.After being degraded in an alkaline environment for 20 days,when n(glycolide):n(?-caprolactone)=5:5 in the polyurethane foam,the weight loss rate of the polyurethane foam is 42%.(5)Preparation and Properties of Graphene Modified Polyurethane Foam.The effect of graphene addition on the mechanical properties and microstructure of polyurethane foams was investigated.When the amount of graphene added is 0.2%of the mass of polyester polyol,the compressive strength of graphene-modified polyurethane foam is 0.28 MPa,the apparent density is 57.1 Kg/m³,the cell distribution is uniform.