Preparation And Properties Of Waste Biomass-based Polyurethane

Polyurethane materials have the advantages of oil resistance,wear resistance,aging resistance,and high mechanical strength,and are widely used in electronics,automobiles,medicine,and chemical industries.In order to alleviate the energy crisis and solve the environmental pollution and resource waste caused by waste biomass resources,this paper uses biomass resources to replace non-renewable petroleum-based polyols to prepare polyurethane materials to realize the resource utilization of waste biomass.In this study,citric acid residue-based polyurethane film was successfully prepared,and waste corn stalks were liquefied,and waste biomass-based flexible polyurethane foam was prepared and applied to heavy metal adsorption.This article explores the preparation process of citric acid fermentation waste-based polyurethane film.The optimal conditions in the preparation process,such as reaction time,plasticizer dosage,polyvinyl alcohol ratio,etc.,were determined and their effects on film properties were determined.It is proved that citric acid fermentation waste biomass can be used as a substitute for petroleum-based polyols,and the synthesized polyurethane film has higher gel fraction,excellent water resistance,mechanical properties and thermal stability.The optimal preparation process of isocyanate index of 3,reaction time of 2.5h,and 70%of polyvinyl alcohol is determined by the controlled variable method.At this time,the elongation at break of the citric acid fermentation waste-based polyurethane film is 50%,the tensile strength is 15MPa,The water solubility is only 14%,and the gel fraction is as high as 98%.And the crosslinked structure was confirmed by infrared spectroscopy.The optimal liquefaction process of corn stalks was explored.In order to increase the content of hydroxyl functional groups in corn stover biomass,this paper uses the method of liquefaction to modify it.The optimal liquefaction conditions were determined at 110?,PEG/glycerol=7/3,3%concentrated sulfuric acid content,20%corn stover content,and 90min reaction time.At this time,the residue rate of the liquefied product was 7.48%,and the hydroxyl value was 587.88 mg.KOH/g,the acid value is 13.14 mg KOH/g.The changes in the molecular structure of corn stalks before and after liquefaction were determined by infrared spectroscopy.The waste biomass-based flexible polyurethane foam was prepared and successfully applied to the adsorption of heavy metal Cr(?).The optimal ratio of foaming agent and catalyst content in the preparation process and the influence on the foaming time and density of the polyurethane foam were explored by the controlled variable method.100 parts of polyol(70 parts of liquefied straw,30 parts of citric acid fermentation waste),3 parts of foaming agent water,7.5 parts of catalyst dibutyltin dilaurate,3 parts of foam stabilizer AK-158,and hexamethylene diisocyanate 72 servings of its best formula.The results show that the polyurethane foam has excellent water absorption properties,and the best water absorption can reach 492%within 40 minutes.The changes of molecular structure before and after the reaction were confirmed by infrared spectroscopy,and the polyurethane foam has excellent thermal stability.The polyurethane foam was modified with N-methyldiethanolamine to increase the surface potential for the adsorption of heavy metal Cr(VI).The optimal addition amount of the adsorbent was determined to be 4g/L.This research uses waste biomass resources to prepare polyurethane materials with excellent performance,solves the problem of the lack of polyurethane petroleum-based raw materials,improves the utilization rate of biomass resources,and realizes its high value-added applications.