Construction And Performance Research Of Self-Healing Epoxy System Coordinated And Controlled By Cellulose Nanofiber

Furfuryl alcohol(FA)and polycaprolactone(PCL)were utilized in this study to modify epoxy resin(EP).Two types of self-healing epoxy resin systems were constructed based on the Diels-Alder reaction and phase separation principles,and cellulose nanofibers(CNF)were added for enhanced regulation.The main results are as follows:(1)Polyfurfuryl alcohol(PFA),which was produced by the condensation reaction of FA with the acid catalysis was blended with the epoxy resin to build the EP/PFA/D230 cross-linked network systems.The effect of PFA on the structure and performance of the EP/PFA/D230 system was explored The results indicated that the addition of PFA reduced the activation energy of the curing reaction of the epoxy resin,and the thermal stability of the system was improved as a whole.And the enhancemet of mechanical properties were displayed by the mechanical data.When the PFA content was located at15%,the optimum mechanical properties of the system were obtained.Compared with the pure epoxy resin,the tensile strength and tensile modulus are increased by 4.8%and 4.3%,and the flexural strength and flexural modulus are increased by 18.4%and 25.9%,respectively.(2)The dual crosslinked network system of PFA/BMI/EP was constructed based on the Diels-Alder reaction of PFA and bismaleimide(BMI),and the epoxy resin-polyether amine The DA reaction temperature was 67~oC,the reaction time was 24h,and the reverse DA reaction was carried out at about 130~oC.The good thermal reversibility and repair performance of the PFA/BMI system was proved through a series of thermal reversibility and thermal repair performance testshas.The flexibility of the PFA/BMI system was effectively adjusted by adding EP.The tensile strain at break for the PFA/BMI/EP10 system was increased from 27.1%to 57.3%for the smaple of PFA/BMI/EP50.The addition of CNF enhanced the tensile strength and tensile strain at break as well as the thermal repair performance of the PFA/BMI/EP system to a certain extent.(3)The EP/PCL/CNF healing compositeswas prepared by a combination of solvent exchange and melt blending method,and the influence of the introduction of CNF on the morphology and mechanical properties of the system was discussed.As the curing reaction progressed,the compatibility between EP and PCL component was decreased,resulting in the phase separation.When the PCL content reached20%,the EP/PCL system showed an obvious bi-continuous structure.The PCL phase flowing out upon heating could act as the binder for the broken parts of the sample,and thus the self-repairing abitiy was achieved for composites.The mechanical repairing analysis showed that the thermal repairing rate of EP/PCL20 was about 65.1%.Adding CNF to the system inhibited the phase separation of EP/PCL blends,which reducd the size of the phase separated domains.At the same time,the mechanical properties of the composite system was improved.The thermal repairing capability of EP/PCL20/CNF0.2 was increased to the value of 73.8%.