Construction And Properties Of Multifunctional High-Performance Epoxy/Glass Fiber Composites Containing Dynamic Disulfide Bonds

Damage prediction of glass-fiber-reinforced composites（GFRCs）can re-duce the failure rate of structural components,save costs and even save lives.However,current GFRCs with damage self-reporting properties usually involve complex modifications to the matrix or fibers,and when mechanochromic ad-ditives are used,interfacial defects are inevitably generated,affecting the mate-rial properties.In addition,the inherent three-dimensional cross-linked network properties of thermoset matrices make them difficult to recycle once damaged or reaching the end of their useful life.Therefore,it is of great importance to design high-performance recyclable GFRCs with damage self-reporting.In this dissertation,the high-performance DGEAC/AFD and DGEAC/AFD/SA crosslinking networks are prepared by curing 4,5-epoxy-hex-ane-1,2-dicarboxylic acid diglycidyl ester（DGEAC）with 4,4’-dithioluidine（AFD）and sebacic acid（SA）.The fundamental mechanical/thermal properties,UV-shielding and networks rearrangement behavior are systematically studied,as well as the mechanochromism mechanism.Using the above matrices,the high-performance degradable GFRCs are obtained by compounding with glass fiber（GF）,which is then applied in the field of composite damage monitoring.The main research results are as follows:1.The DGEAC/AFD crosslinked networks exhibits excellent solvent re-sistance,good thermal/mechanical properties（T_g≥206℃,tensile strength 70MPa）and UV-shielding ability.Due to the exchange reaction of disulfide bonds,the DGEAC/AFD networks can undergo network rearrangement at high tem-perature.The strong interface between the matrix and the fiber enables the GF/DGEAC/AFD composites to exhibit excellent mechanical properties（ten-sile strength 470 MPa）.Benefiting from the inherent mechanical mecha-nochromic properties of epoxy resin matrix,GF/DGEAC/AFD composites can self-report damage in time through color changing.In addition,the GF/DGEAC/AFD composites can achieve non-destructive recovery of fibers in the DMF solution of dithiothreitol（DTT）.The surface morphology and ele-mental composition of the recycled fibers are consistent with that of virgin fi-bers.This work provides a new strategy for fabricating high-performance and recyclable composites with damage early warning.2.The DGEAC/AFD/SA crosslinked networks exhibits good solvent re-sistance,thermal stability(T_d5≥259℃),and tunable mechanical properties（tensile strength ranging from 3 to 55 MPa）and excellent UV-shielding ability.In addition,the DGEAC/AFD/SA networks shows good dynamic properties such as self-healing,welding,remodeling,physical recycling（83%efficiency）and shape memory function.Among them,V4,V5 and V6 have the mecha-nochromic properties.Using V4 as the matrix,the prepared GF/DGEAC/AFD/SA composites exhibits high tensile properties（tensile strength of 302 MPa and modulus of 8.2 GPa）.This work addresses the chal-lenge of combining high-performance with fast topological network rearrange-ment,providing an effective strategy for fabricating high-performance glass fi-ber reinforced composites.