Bio-Based Hyperbranched Toughener From Tannic Acid and Its Enhanced Solvent-Free Epoxy Resin with High Performance

Abstract

It is essential to design economic and efficient tougheners to prepare high-performance epoxy resin; however, this has remained a huge challenge. Herein, an eco-friendly, low-cost, and facile-fabricated bio-based hyperbranched toughener, carboxylic acid-functionalized tannic acid (CATA), was successfully prepared and applicated to the preparation of solvent-free epoxy resins. The mechanical performance, morphology, structural characterization, and thermal characterization of toughened epoxy resin system were studied. The toughened epoxy resin system with only 1.0wt% CATA reached the highest impact strength, 111% higher than the neat epoxy resin system. Notably, the tensile strength and elongation at break of toughened epoxy resin systems increased moderately with increasing CATA loading. Nonphase-separated hybrids with significant toughening effect were obtained. Additionally, the thermal stabilities of toughened epoxy resin systems decreased with increasing CATA loading. This study provides an eco-friendly, cost-effective, and facile approach for the preparation of high-performance, solvent-free epoxy resins with potential for practical applications in sealing integrated circuits and electrical devices fields.

Novel Multifunction Epoxy Thermoset Designed by Manipulating the Silicon-Oxidation Flexible-Rigid Network Topology: Toughening, Strengthening, and Acid/Alkali Resistance

“…The third lifetime (τ 3 ) measured using PALS is acquired by annihilating the positronium in the free volume. Typically, τ 3 is used to reflect the size of the free volume, and the intensity of τ 3 ( I 3 ) describes the concentration of the free volume. – As shown in Figure a, the τ 3 and I 3 of ESi-N1 are higher than those of EP, indicating that ESi-N1 has a larger free volume size and concentration. The small molecular size of resin and rigid molecular chains make it difficult for EP to form a large free volume.…”

“…Moreover, the free volume acts as a cavity to toughen the epoxy thermoset. On the one hand, the cavities absorb energy and prevent crack propagation through shear deformation. , On the other hand, cavities have the function of blunting cracks . For example, ESi-D1 has a higher occurrence probability to large cavities (2.766–2.956 Å) than EP, which endows ESi-D1 with a better ability in plastic deformation and blunting cracks. , …”

“…44,45 On the other hand, cavities have the function of blunting cracks. 25 For example, ESi-D1 has a higher occurrence probability to large cavities (2.766−2.956 Å) than EP, which endows ESi-D1 with a better ability in plastic deformation and blunting cracks. 33,45 Based on the above analysis, the toughening mechanism of the ESi thermosets is described in Figure 6d.…”

Self-extracted corn-stalk cellulose/epoxy resin composites

“…Toughened epoxy resin is always a hot topic in epoxy resin research [1][2][3][4] . The common method of toughening epoxy resin is to add toughening agent, such as nano particles [5][6][7] , liquid crystal polymer 8 , fiber 9,10 , polymer 11,12 , Lignin 13 , block polymer 14,15 , hyperbranched polymer 16 , and natural fills [17][18][19][20][21] etc., which can effectively improve the brittleness of epoxy resin, and broaden its application in the industrial field. Biomass toughened epoxy resin has become a research hotspot due to its green and sustainable development [22][23][24] .…”

Synthesis of Hyperbranched Flame Retardants with Varied Branched Chains’ Rigidity and Performance of Modified Epoxy Resins

“…Epoxy resins are widely used as adhesives, coatings, and paints, as well as structural composites, in our daily lives because of their excellent chemical resistance, thermal stability, electrical insulation, and mechanical properties [ 1 ]. However, the traditional epoxy, i.e., diglycidyl ether of bisphenol A (DGEBA), is highly flammable and brittle, which greatly restricts its application fields [ 2 , 3 ].…”