Improving the heat‐resistance and toughness performance of phenolic resins by adding a rigid aromatic hyperbranched polyester

Liú, Dan; Wang, Hongmei; Jiang, Huasheng; Zhou, Dapeng

doi:10.1002/app.42734

Cited by 22 publications

(19 citation statements)

References 42 publications

(43 reference statements)

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“…Such a result is also observed in other reports that introducing a hyperbranched polymer into epoxy networks can increase the free volume. It should be noted that these increase in free volume could significantly improve the toughness in cured thermosets [ 22 , 23 , 24 , 34 , 35 , 36 ].…”

Section: Resultsmentioning

confidence: 99%

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Tannic Acid as a Bio-Based Modifier of Epoxy/Anhydride Thermosets

et al. 2016

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Abstract:Toughening an epoxy resin by bio-based modifiers without trade-offs in its modulus, mechanical strength, and other properties is still a big challenge. This paper presents an approach to modify epoxy resin with tannic acid (TA) as a bio-based feedstock. Carboxylic acid-modified tannic acid (TA-COOH) was first prepared through a simple esterification between TA and methylhexahydrophthalic anhydride, and then used as a modifier for the epoxy/anhydride curing system. Owing to the chemical modification, TA-COOH could easily disperse in epoxy resin and showed adequate interface interaction between TA-COOH and epoxy matrix, in avoid of phase separation. The use of TA-COOH in different proportions as modifier of epoxy/anhydride thermosets was studied. The results showed that TA-COOH could significantly improve the toughness with a great increase in impact strength under a low loading amount. Moreover, the addition of TA-COOH also simultaneously improved the tensile strength, elongation at break and glass transition temperature. The toughening and reinforcing mechanism was studied by scanning electron microscopy (SEM), dynamic mechanical analysis (DMA) and thermal mechanical analysis (TMA), which should be owned to the synergistic effect of good interface interaction, aromatic structure, decreasing of cross linking density and increasing of free volume. This approach allows us to utilize the renewable tannic acid as an effective modifier for epoxy resin with good mechanical and thermal properties.

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Section: Resultsmentioning

confidence: 99%

“…It has been proved that a highly branched structure can introduce more internal cavities or free volumes in cured thermosets, which is favor of improving toughness [ 22 , 23 , 24 ]. In addition, an aromatic structure is beneficial to the T g and modulus of cured epoxy thermoset.…”

Section: Introductionmentioning

confidence: 99%

Tannic Acid as a Bio-Based Modifier of Epoxy/Anhydride Thermosets

et al. 2016

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“…As shown in Figure S3 , the monosubstituted, disubstituted, and trisubstituted diphenolic acid, corresponded to the terminal, linear, and dendritic units, peaks at 44.24, 44.33, and 44.42, respectively. 22 The detailed values of DB calculated according to the formula are listed in Table 1 . Just as we expected, a higher amount of DBB consumes more functional groups of DPA, contributing to more dendritic units and a higher DB ( Table 1 ).…”

Section: Resultsmentioning

confidence: 99%

Diphenolic Acid-Derived Hyperbranched Epoxy Thermosets with High Mechanical Strength and Toughness

Xiao¹,

Li²,

Li³

et al. 2021

ACS Omega

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Diglycidyl ether of bisphenol A (DGEBA) is a kind of widely used epoxy resin, but its thermosets normally show high brittleness and poor impact resistance due to the intrinsic rigid aromatic rings, which limit its application greatly. To avoid this drawback, we proposed a method to prepare a series of hyperbranched epoxies (HBEPs) with different molecular weights. After HBEPs were cured with methyl tetrahydrophthalic anhydride (MTHPA), characterizations were carried out to evaluate the properties of the cured HBEP samples. Testing results indicate that the hyperbranched thermosets can achieve excellent mechanical strength and toughness (tensile strength: 89.2 MPa, bending strength: 129.6 MPa, elongation at break: 6.1%, toughness: 4.5 MJ m –3 , and impact strength: 6.7 kJ m –2 ), which are superior to those of the thermosets of commercial DGEBA (tensile strength: 81.2 MPa, bending strength: 108.2 MPa, elongation at break: 3.0%, toughness: 1.5 MJ m –3 , and impact strength: 4.2 kJ m –2 ). In addition, HBEP with the highest molecular weight and degree of branching shows the best comprehensive mechanical properties. All hyperbranched thermosets exhibit high glass-transition temperatures ( T g ) and thermostability, which further illustrates the potential application value of HBEPs.

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“…The improvement of the fracture behavior could be attributable to:reduction of the crosslink density which affects the internal stress level induced during the epoxy cure [26];induction of a triaxial stress state in the matrix around CSNPs due to the presence of the inorganic core and thus promoting the plastic deformation mechanism in the polymeric phase and then crack tip blunting [27];further promotion of plastic deformation associated with the presence of the HBP shell [28]. …”

Section: Resultsmentioning

confidence: 99%

“…reduction of the crosslink density which affects the internal stress level induced during the epoxy cure [26];…”

Section: Resultsmentioning

confidence: 99%

Thermal Properties and Fracture Toughness of Epoxy Nanocomposites Loaded with Hyperbranched-Polymers-Based Core/Shell Nanoparticles

et al. 2019

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Synthesized silicon oxide (silica) nanoparticles were functionalized with a hyperbranched polymer (HBP) achieving a core/shell nanoparticles (CSNPs) morphology. CSNPs were characterized by Fourier Transform Infrared (FTIR) spectroscopy, Transmission Electron Microscopy (TEM), and Thermogravimetric Analysis (TGA). A core diameter of about 250 nm with a 15 nm thick shell was revealed using TEM images. An aeronautical epoxy resin was loaded with the synthesized CSNPs at different percentages and thermal properties, such as thermal stability and dynamic mechanical properties, were investigated with the use of different techniques. Although the incorporation of 2.5 wt% of CSNPs induces a ~4 °C reduction of the hosting matrix glass transition temperature, a slight increase of the storage modulus of about ~10% was also measured. The Kissinger Method was employed in order to study the thermal stability of the nanocomposites; the degradation activation energies that resulted were higher for the sample loaded with low filler content with a maximum increase of both degradation step energies of about ~77% and ~20%, respectively. Finally, fracture toughness analysis revealed that both the critical stress intensity factor (KIC) and critical strain energy release rate (GIC) increased with the CSNPs content, reporting an increase of about 32% and 74%, respectively, for the higher filler loading.

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Improving the heat‐resistance and toughness performance of phenolic resins by adding a rigid aromatic hyperbranched polyester

Cited by 22 publications

References 42 publications

Tannic Acid as a Bio-Based Modifier of Epoxy/Anhydride Thermosets

Tannic Acid as a Bio-Based Modifier of Epoxy/Anhydride Thermosets

Diphenolic Acid-Derived Hyperbranched Epoxy Thermosets with High Mechanical Strength and Toughness

Thermal Properties and Fracture Toughness of Epoxy Nanocomposites Loaded with Hyperbranched-Polymers-Based Core/Shell Nanoparticles

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