Synthesis And Properties Of Waterborne Polyurethane/Carbon Nanocomposites

Waterborne polyurethane(WPU)is widely used in coatings,adhesives and other fields due to its advantages of green,safe,reliable and excellent comprehensive performance.However,compared with traditional solvent-based polyurethanes,waterborne polyurethanes are still lacking in terms of thermal,mechanical and water resistance.In view of the above problems,t the present invention separately prepared graphene oxide and carbon nanotubes and introduced them into waterborne polyurethane to prepare aqueous polyurethane/graphene oxide carbon nanotube nanocomposite emulsion.The research focuses on the mechanical and electrical properties of nanocomposite films.The specific research contents are as follows:1.Go water dispersion was prepared by an improved Hummers method.MGO dispersion was prepared by 2-amino-4-hydroxy-6-methyl pyrimidine(MIS)and 1-ethyl-(3-dimethylaminopropyl)carbodiimine hydrochloride(EDC·HCL).The waterborne polyurethane/MIS modified graphene oxide(WPU/MGO)nanocomposite emulsion was prepared by introducing MGO dispersion into the aqueous polyurethane prepolymer emulsification process.The effects of GO and MGO on the mechanical properties,thermal properties and water resistance of nanocomposite films were systematically studied.SEM analysis showed that MGO can be uniformly dispersed in WPU.The introduction of MGO can significantly improve the mechanical properties,thermal stability and water resistance of WPU.When the MGO content is 1 wt%,the tensile strength is 58.02 MPa,and the Young's modulus is 49.65 MPa,elongation at break is 829%(204%,263%and 5%higher than WPU);the fastest decomposition rate increases from 318°C to 344°C,and the water absorption decreases from 23%to 7%.2.The carboxylated carbon nanotubes were modified by EDC/NHS,and then combined with aqueous polyurethane to prepare aqueous polyurethane/NHS modified carbon nanotubes(WPU/NTNMC)nanocomposite emulsion.The effects of NTNMC on the particle size of nanocomposite emulsion,mechanical properties,water resistance,light transmission,thermal properties and electrical conductivity of the composite film were systematically studied.The experimental results show that when the content of NTNMC8 is 5wt%,SEM shows that the dispersion of NTNMC8 in WPU matrix is better.The tensile strength of composite film is45.75 MPa,the Young's modulus is 18.35 MPa,and the elongation at break is 805%(increased by 145%,152%and 13%,respectively,compared with WPU).The surface conductivity of the composite coating increased with the content of NTNMC8,and the maximum content of NTNMC8 was up to 50wt%,and the corresponding conductivity was1.37×10~-11 S/cm.3.The graphene oxide was modified with EDC/NHS and blended with the aqueous polyurethane,and then reduced to obtain an aqueous polyurethane/graphene(WPU/NrGO)nanocomposite emulsion.Finally,the WPU/NrGO was mixed with WPU/TNMC8 for WPU/NrGO-TNMC8 nanocomposite emulsion.The effects of different content of graphene/carbon nanotubes on the particle size of nanocomposite emulsion,mechanical properties,thermal properties and electrical conductivity of the composite membrane were systematically studied.The experimental results show that when the content of TNMC8-NrGO is 5wt%,SEM analysis shows that the two nano-fillers in the nano-composite film form a three-dimensional structure,and the mechanical and thermal properties of the nano-composite film are significantly improved.The Young's modulus is 68.12 MPa,the maximum tensile strength is about 58.62 MPa,and the elongation at break is about 905%.The surface conductivity of the composite coating increases with the increase of TNMC8-NrGO content.When the content of TNMC8-NrGO reaches 50%,the conductivity of the nanocomposite film reaches 1.96×10~0 S/cm.The conductivity of the nanofiller TNMC8-NrGO is about 5.62 times of NTNMC8.This topic mainly explores the functional modification of two different carbon nanomaterials(graphene oxide and carbon nanotubes)in the aqueous phase and composites withwaterbornepolyurethanetopreparehighperformancewaterborne polyurethane/functionalized carbon nanocomposite emulsion.The three waterborne polyurethane/functionalized carbon nanocomposite films prepared have excellent mechanical and electrical properties,and all have practical application value.