The Preparation Of Biodegradable Polyurethane Foams By Anaerobic Digestion Residue Of Pennisetum Purpureum Cv. Jujuncao And The Study Of Degrading Microflora

Anaerobic digestion residue of Pennisetum purpureum cv.Jujuncao was liquefied to bio-polyol.The reaction of bio-polyol and isocyanate formed polyurethane foams.We studied the microbial community structure of soil that landfilled polyurethane foams by high-throughput sequencing of 16S and ITS.The content of fully cellulose and lignin in the residue of Pennisetum purpureum cv.Jujuncao was similar to wood materials.It could be liquefied in the mixed solvent of concentrated sulfuric,PEG400 and glycerol.This paper mainly studied the influences of liquefaction temperature,liquefaction time,liquid-solid ratio,liquefied reagent composition and catalyst concentration on the process of liquefaction.The results showed that the higher liquefaction temperature it was,the better liquefaction rate it was.With the increasing mass ratio of liquid and solid,the residue rate was decreasing.The ratio of PEG400/glycerol was greater,the liquefaction of the residue of Pennisetum purpureum cv.Jujuncao was easier.With the increasing amount of concentrated sulfuric acid,the residue rate dropped firstly and rose later on.In terms of economic benefit,the optimal conditions were that mass ratio of PEG400 and glycerin was 1.5:1,mass ratio of liquid and solid was 2.9:1,mass fraction of sulfuric acid compared to the mixed solution was 5%,liquefaction temperature was 160 C and liquefaction time was 1.5 h.At this time the residue rate was 2.7%.In the process of the reaction that bio-polyol mingled isocyanate to form polyurethane foams.This study investigated the effect of the amount of bio-polyol,catalysts,foaming agents and foam stabilizer to polyurethane foams.The result showed when bio-polyol was replaced a portion of polyether polyol to form polyurethane foams,the compression strength became bigger.However,when overmuch dosage of the bio-polyol was used,the compression strength of polyurethane foams was reduced and the polyurethane foams became much more brittle.Although the amount of catalyst was small,it could effectively balance the reaction rate of gel and foaming.The foaming agent was added to promote the formation of the abscess,But excessive foaming would cause the collapse of the bubble,destroy foam crosslinked structure,lower the compression strength.An appropriate amount of the foam stabilizer could increase the compatibility of the polyurea foam substrate with polyurea and contribute to the formation of air bubbles.However,the excess foam stabilizer would result in closing bubble and reduce the compression strength of polyurethane foam.Combined with economic benefits and the performance of polyurethane foams,while half of the polyether polyol was instead of bio-polyols,the performance of polyurethane foam was best.The compression strength of rigid polyurethane foam was 0.21 MPa.And the density of rigid polyurethane foam was 38.7 kg·m-3.The thermal stability of rigid polyurethane foam that made from residue of Pennisetum purpureum cv.Jujuncao was similar to polyurethane foam.TGA occurred mainly between 210?460?.The degradation rate of the polyurethane foam made from the residue of Pennisetum purpureum cv Jujuncao was 12.5%,when it was buried seven months by soil.By analyzing the microbial community structure of the soil which buried polyurethane foams for 7 months,we found that the main bacteria played an important role in the degradation of polyurethane foams made from the residue of Pennisetum purpureum cv.Jujuncao were Comamonas,Flavobacterium,Aeromonas,Chitinophagaceae,Sphingomonas,Rhizobium and Cytophagaceae.The main fungus played an important role in the degradation were Metschnikowia,Fusarium,Candida,Ceratobasidium and Chaetomella.