Room‐Temperature Green Recyclable Epoxy Composites with Enhanced Mechanical and Thermal Properties Cross‐Linked via B−O−C Bonds

Abstract

Without any catalyst, a novel way for the preparation of epoxy (EDSPs) and their composites by cross-link via dynamic BÀ OÀ C bonds was presented. The EDSPs with a glass transition temperature (T g ) of 194 °C were resistant to various solvents and can be green degraded in ethanol at room temperature. The dynamic properties of EDSPs also give the composites excellent recyclability, as the expensive carbon and glass fibers can be recovered intact from the composites under mild conditions at room temperature. Mechanical performance tests showed that the carbon fiber composites (CF/EDSPs) can achieve a flexural strength of 849 MPa and an interlaminar shear strength of 58 MPa. Even after recycling and re-preparation, 99 % of the original flexural strength and 93 % of the original interlaminar shear strength are still maintained. Scratch repair experiments shown that scratch self-healing can be achieved in only 10 s at 200 °C.

Phosphonate‐influenced Diels‐Alder chemistry toward multi‐path recyclable, fire safe thermoset and its carbon fiber composites

“…Specifically, ILSS of BMI‐EP/CF and BMP‐EP/CF reached up to 78.6 ± 3.7 and 72.6 ± 3.5 MPa compared with that of DGEBA‐EP/CF, with an increase of 23.8% and 14.3%, respectively, this improvement was mainly attributed to the good processability and affinity of between the matrices and CF. In fact, as presented in Figure 5C, Table S6, BMP‐EP/CF possessed the better mechanical properties than analogous recyclable fiber‐reinforced epoxy thermosets composites, 13,19,22,41,57–60 and other systems through the interfacial modification 61–64 reported in previous studies.…”

“…In the past two decades, a series of versatile dynamic covalent reactions, including Diels‐Alder (DA) reaction, 6,7 transesterification, 8–12 disulfide exchange, 13–15 imide exchange, 16–19 vinylogous urethanes, 20,21 boroxine exchange, 22,23 and siloxane exchange 24 endowed the resulting materials with repairability and malleability, which have illustrated their great potentials in the development of the recyclable epoxy thermosets and their composites to achieve the goal of circular economy. Nevertheless, the resulting thermosets usually exhibited an Achilles' heel of the vulnerable to creep, 25 losing the inherent advantage of the stability as the robust polymer matrices in CF composites.…”

Synthesis and Crosslinking Mechanism of Colloidal Graphene Oxide Crosslinker for Crosslinking Low-Concentration Hydroxypropyl Guar Gum Fracturing Fluids

“…The above research focused on the synthesis and properties of nano-crosslinkers using spherical and rod-shaped nanoparticles. It has been shown that nano-crosslinkers can improve the temperature resistance and shear resistance of guar gum fracturing fluid and reduce the amount of guar gum . However, the explanation of the crosslinking mechanism is not clear.…”

“…It has been shown that nanocrosslinkers can improve the temperature resistance and shear resistance of guar gum fracturing fluid and reduce the amount of guar gum. 22 However, the explanation of the crosslinking mechanism is not clear. There is a lack of visual observation and analysis of the micromorphology of guar gum fracturing fluid gels as well as the distribution state of nanoparticles in gels.…”