Construction Of High Performance Polyurethane Materials Based On Polyester Polyols With Different Structures

After more than 80 years of development,polyurethane has become an indispensable material in people’s lives.Many efforts have been made to modify,design,and apply polyurethane materials by using polyether polyols,polyester polyols,isocyanates,and other main raw materials to meet the requirements in different scenarios.It is worth noting that polyester polyols,as one kind of the important raw materials for polyurethane,have great potential for molecular structure design.Unfortunately,the research on the structure and performance of polyurethane materials has not been fully and systematically investigated.There are many kinds of polyurethane materials,among them,polyurethane adhesive has the widest application range,and polyurethane foam has the largest dosage.However,polyurethane adhesive is difficult to meet the requirements of high temperature resistance and strong bonding on low polarity surfaces,while polyurethane rigid foam is difficult to balance the mechanical performance and flame retardancy.Therefore,it is suggested that designing the molecular structure of polymers from basic acids and alcohols and establishing the relationship between molecular structure,condensed state,and performance are very important to produce high-performance polyurethane materials.In this work,the structure-property relationship of polyester polyols was investigated,a series of functional polyols,such as heat-resistant polyester polyols,compatibilized polyester polyols,phosphorus-containing polyols and branched copolymer polyols,have been designed and developed to meet the requirements of different application scenarios,and the effect of polyols on macroscopical properties and microphase structure of polyurethane was analyzed.Combined with the design of molecular structure and the condensed state,polyurethane adhesives with high temperature resistance,low polar surface adhesion and oxygen resistance for flexible package lamination were successfully synthesized,and rigid polyurethane foams for flame retardant and thermal insulation were prepared,which has addressed some major concerns in the application development of polyurethane.This research has important significance both in theory and practice,which provides an effective strategy for the further development of commercialized advanced functional polyurethane materials.First(Chapter 2),this work systematically investigated the influence of the microstructure of polyester polyols on their macroscopic properties by regulating the varieties and proportions of phthalic acid,polymer molecular weight,and side chain diols.FTIR,~1H NMR,DSC,TG and surface tension were employed to characterize the polyurethane material samples.The conformational relationship was also adopted to design different functional polyols.Secondly(chapters 3 and 4),polyester polyols with good heat resistance and high compatibilization were designed and prepared respectively,and their effects on the microphase structure and macroscopic performance of polyurethane adhesives were characterized by FTIR,TG,DMA,AFM,and contact angle test.The low-viscosity heat-resistant polyester polyols and HDI trimer were used to construct polyurethane adhesives with rich hydrogen bond content and excellent ductility.The lamination adhesion of high-temperature resistant mono-materialized polyester coating films was successfully prepared.A polyurethane adhesive with low hydrogen bonding density were synthesized by using the compatible polyester polyol and polyether modified MDI,which was applied on low-surface-energy polyolefin film.The“labyrinth”channels constructed by side chains improved the oxygen resistance of the materials.The hydrogen bonding degree and oxygen resistance mechanism of polyurethane materials were explained by the molecular dynamics simulation.The influence of polyurethane materials on the processing performance of lamination films during recycling was also evaluated and discussed.Thirdly(Chapters 5 and 6),phosphorus-containing polyols and branched copolyester polyols were developed using fermentation powder erythritol and glycerol hydrogenation 1,2-propanediol respectively,which were then used to prepare flame retardant thermal insulation polyurethane rigid foam.The thermal stability and flammability of the polyurethane materials were evaluated using TG,LOI,vertical burning,and CONE tests.The influence of the polyols on the microphase structure and macroscopic properties of the polyurethane materials was evaluated through mechanical properties,thermal conductivity testing,and DMA analysis.The flame retardant mechanism of the phosphorus-containing polyols and branched co-polyester polyols was elucidated using SEM,elemental analysis,Raman,and TG-IR techniques.The p HRR of the produced polyurethane rigid foam was significantly reduced,and the LOI was significantly increased to 32%,and the UL94 grade reached V-0.