Curing Behavior and Mechanical Properties of Tetra-Functional Epoxy Reinforced with Polyethyleneimine-Functionalized MXene

Abstract

The aerospace industry has started shifting toward polymer composites, especially epoxy-based composites. Because epoxy is inherently brittle, it must be suitably reinforced to enhance its fracture properties and make it suitable for aerospace applications. In this regard, we studied surface-modified Ti 3 C 2 nanosheets as toughening agents for aerospace-grade epoxy composites. Ti 3 C 2 T x (T = O, OH, and F) nanosheets were synthesized by acid etching of the Ti 3 AlC 2 precursor and further functionalized with polyethyleneimine (PEI) to improve their degree of exfoliation and enhance their degree of interaction with the epoxy matrix. Epoxy composites containing 0.1, 0.5, and 1.0 wt % PEI−Ti 3 C 2 T x nanosheets were synthesized. These composites were studied for their curing behavior and mechanical properties. The isoconversional Starink method was used to calculate the curing activation energy. Compared to neat epoxy, the PEI−Ti 3 C 2 T x nanosheets showed a catalytic effect on curing by lowering the curing activation energy. A 40% higher compressive strength was observed in 0.5 wt % PEI−Ti 3 C 2 T x /epoxy composites, compared to neat epoxy. The K IC and G IC of the 0.5 wt % PEI−Ti 3 C 2 T x /epoxy composite were 70 and 140% higher than those of neat epoxy, respectively. The fracture properties improved due to crack deflection, crack blunting, and enhanced filler−matrix interaction. At 1.0 wt % PEI−Ti 3 C 2 T x loading, the nanosheets began agglomerating, which caused a reduction in the mechanical properties. The storage modulus and T g of the PEI− Ti 3 C 2 T x /epoxy composites were also significantly higher than those of neat epoxy. It was observed that blank Ti 3 C 2 T x did not cause a remarkable improvement in the properties of epoxy composites. Hence, PEI functionalization was instrumental in achieving uniform filler dispersion and favorable filler−matrix interaction.

High-Performance Recyclable and Malleable Epoxy Resin with Vanillin-Based Hyperbranched Epoxy Resin Containing Dual Dynamic Bonds

“…The increase in Δ H is due to the large number of hydroxyl groups of VEHBP that catalyze the epoxy-amine curing reaction. Such results suggested that VEHBP effectively catalyzed the curing reaction as a result of the autocatalytic properties of VEHBP with abundant hydroxyl groups . The FT-IR spectra of 5%VEHBP/DGEBA/4-AFD at 120 °C during curing are shown in Figure c,d and Figure S5.…”

“…Such results suggested that VEHBP effectively catalyzed the curing reaction as a result of the autocatalytic properties of VEHBP with abundant hydroxyl groups. 50 The FT-IR spectra of 5%VEHBP/DGEBA/4-AFD at 120 °C during curing are shown in Figure 1c,d and Figure S5. As the reaction proceeded, the characteristic peak at 914 cm −1 for the epoxy group significantly decreased and finally disappeared, indicating that the epoxy group was completely consumed at the end of curing.…”

Hybrid Ti3C2Tx MXene and Carbon Nanotube Reinforced Epoxy Nanocomposites for Self-Sensing and Structural Health Monitoring

“…These properties make MXenes an appealing choice for improving mechanical, optical, and electromagnetic interference shielding , properties of polymer nanocomposites. Recently, studies on the properties of MXene-incorporated epoxy nanocomposites started to receive attention. , It has been shown that the incorporation of MXene nanoplatelets can improve mechanical properties, , thermal conductivity, , and electrical conductivity , of epoxy nanocomposites. For example, the thermal conductivity of epoxy resin was improved by 141.3% to 0.587 W/mk with 1.0 wt % Ti 3 C 2 MXene filler .…”

Improving the Fracture Toughness and Strength of Epoxy Resin Using NH2‐silica‐C8H17 Janus Nanosheets

“…[15,16] As a result, in order to substantially promote such interfacial interaction strength, using the chemicals having highly reactive functional groups that can directly react with epoxies and/or hardeners to decorate nanofillers was the most widespread method. [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32] In this respect, since a large number of chemical bonds were formed between nanofillers and epoxies, nanofillers could be facilely incorporated into epoxy matrices and the high-quality interphase was constructed in the vicinity of nanofillers, thus imparting more energy absorption/dissipation. Theoretically, Janus particles, characterized by the amphiphilic and asymmetric nature, [33,34] can synchronously achieve the high dispersion extent and the strong chemical linkage via modifying the organic segments (e. g., short carbon chains) on one side of nanofillers (especially for nanosheets) and the reactive functional groups on the other side, respectively.…”