Synthesis and performance of flexible epoxy resin with long alkyl side chains via click reaction

Abstract

Epoxy resin is a thermosetting polymer with excellent performance and wide application. However, it suffers from low toughness and high brittleness because of its high crosslink density. To overcome these disadvantages, this study synthesizes a toughened, flexible, and hydrophobic epoxy resin (DGEBDBP) by introducing a flexible segment into the polymer network via a thiol-ene click reaction. The cured flexible epoxy resin is obtained by mixing E44, DGEBDBP, and polyamide curing agents of varying contents. The long alkyl side chains significantly improve the mechanical properties and hydrophobicity of the cured epoxy resin. The sample containing 75% DGEBDBP and 25% E44 achieve the highest breaking elongation that was nine times that of pure E44, the highest compressive strength of 112.8 MPa, and the highest contact angle of 101.4. The introduction of side chains through the thiol-ene click reaction can provide a simple and effective method for designing and preparing multifunctional epoxy resins.

Enhancement of Mechanical Properties and Bonding Properties of Flake-Zinc-Powder-Modified Epoxy Resin Composites

“…The toughening mechanism of inorganic nanoparticles is mainly in the crack-deflection mechanism, that is, when the system is subjected to external force, the well-dispersed inorganic nanoparticles deflect the crack to consume the fracture energy, so that the toughness is effectively improved [ 16 ], but the poor dispersion of nanoparticles is easy to agglomerate in the resin matrix, thus affecting the performance of the cured product. The flexible segment toughening epoxy resin mechanism occurs where the molecular design of the flexible segment is introduced into the curing agent or resin matrix, in the curing process of microscopic phase separation, causing the formation of two-phase structure, so as to improve the toughness of epoxy resin, impact resistance, etc., but this method with rubber elastomer toughening will appear with an elastic modulus, mechanical strength and heat resistance, and as such, the reduction of its application in structural materials is limited [ 17 , 18 , 19 ].…”

High Performance Shape Memory Epoxy Syntactic Foam Composites as Lost Circulation Material in Deep Drilling

“…The apparent cross‐linking density of SMEP samples was defined as ν c , the mols of cross‐linking points in unit volume (mol m −3 ). Based on rubber elasticity theory, ν c was calculated according to equation () [ 32–34,39 ] : $$$$\begin{equation}{\nu }_{\mathrm{c}} = \frac{{E{{\mathrm{^{\prime}}}}_r}}{{3RT}}\ \end{equation}$$$$…”

“…The apparent cross-linking density of SMEP samples was defined as 𝜈 c , the mols of cross-linking points in unit volume (mol m −3 ). Based on rubber elasticity theory, 𝜈 c was calculated according to equation ( 1) [32][33][34]39] :…”

“…[11,18,23] However, this often conflicts with the toughness and shape memory properties required for plugging with SMEPs. To develop SMEPs with adjustable switching temperature, mechanical and thermal properties, flexible components including flexible diamines [24,25] or other sulfide agents, [26] a linear epoxy monomer, [27] epoxy with flexible units, [28][29][30][31] or side chains, [32] or non-planar-ring epoxies and hardeners, [33] were used in epoxy curing systems, and double networks, [34] rigid-flexible networks, [35,36] and highly homogeneous networks [37] were constructed. The strength and toughness of SMEPs can be enhanced at the same time by controlling their crosslink density and chain flexibility.…”

Toughness enhancement of polyamide 6,12 with intermolecular hydrogen bonding with 3‐pentadecylphenol

“…The T g for all the composites declined gradually with increasing the amount of PDP from 65 C for the neat PA6,12 matrix to À6.7 C for composites with 30% PDP content (Figure 8b). Hence, PDP as plasticizers can obviously enhance chain mobility by increasing the free volume, 37,38 which is favorable for crystalline formation. According to DSC analysis (Figures 4 and 5), the crystalline behaviors (T c , t 1/2 ) for the PA6,12 composites were hindered.…”