High mechanical properties of epoxy networks with dangling chains and tunable microphase separation structure

Huang, Yizhou; Tian, Yazhou; Li, Yuanyuan; Tan, Xiaocun; Li, Qing; Cheng, Jianhua; Zhang, Junying

doi:10.1039/c7ra08886h

Cited by 33 publications

(43 citation statements)

References 34 publications

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“…After gelation, the vitrification process starts and the reaction shifts from chemical to diffusion‐controlled. The high viscosity (increase in molecular weight) impedes the diffusion of reactive sites and hence, the resin conversion 43,44 …”

Section: Resultsmentioning

confidence: 99%

Curing of epoxidized linseed oil: Investigation of the curing reaction with different hardener types

Todorovic

Resch‐Fauster

Mahendran

et al. 2020

J of Applied Polymer Sci

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The effect of the hardener type and amount on the curing reaction and the resulting thermal and mechanical performance characteristics of epoxidized linseed oil are studied in detail. The analysis of the curing mechanism reveals that due to steric hindrance, side reactions and/or fast gelation, the optimal mixing ratio of bio‐based epoxy resins and hardeners has to be determined experimentally and cannot be calculated. The investigated thermosets exhibit a glass transition temperature of 12, 54, and 145°C after curing. The overall mechanical performance of the resulting resin ranges from soft and flexible to stiff and rigid, depending on the hardener type applied, which can be utilized in the formation of epoxy composites and coatings.

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Section: Resultsmentioning

confidence: 99%

Curing of epoxidized linseed oil: Investigation of the curing reaction with different hardener types

Todorovic

Resch‐Fauster

Mahendran

et al. 2020

J of Applied Polymer Sci

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show abstract

“…The reason for the above trend is as follows. In the initial stage of the crosslinking reaction, the free volume in the crosslinking network was occupied by a dangling chain appearing [36,37]; therefore, the FFV of the system decreased slightly. Subsequently, the formation of a crosslinking network and the decrease of the dangling segment led to the increase of the free volume.…”

Section: Simulation Results and Model Parametersmentioning

confidence: 99%

Micro-Structure and Thermomechanical Properties of Crosslinked Epoxy Composite Modified by Nano-SiO2: A Molecular Dynamics Simulation

Xie

Liang

et al. 2018

Polymers

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Establishing the relationship among the composition, structure and property of the associated materials at the molecular level is of great significance to the rational design of high-performance electrical insulating Epoxy Resin (EP) and its composites. In this paper, the molecular models of pure Diglycidyl Ether of Bisphenol A resin/Methyltetrahydrophthalic Anhydride (DGEBA/MTHPA) and their nanocomposites containing nano-SiO 2 with different particle sizes were constructed. The effects of nano-SiO 2 dopants and the crosslinked structure on the micro-structure and thermomechanical properties were investigated using molecular dynamics simulations. The results show that the increase of crosslinking density enhances the thermal and mechanical properties of pure EP and EP nanocomposites. In addition, doping nano-SiO 2 particles into EP can effectively improve the properties, as well, and the effectiveness is closely related to the particle size of nano-SiO 2 . Moreover, the results indicate that the glass transition temperature (T g ) value increases with the decreasing particle size. Compared with pure EP, the T g value of the 6.5 Å composite model increases by 6.68%. On the contrary, the variation of the Coefficient of Thermal Expansion (CTE) in the glassy state demonstrates the opposite trend compared with T g . The CTE of the 10 Å composite model is the lowest, which is 7.70% less than that of pure EP. The mechanical properties first increase and then decrease with the decreasing particle size. Both the Young's modulus and shear modulus reach the maximum value at 7.6 Å, with noticeable increases by 12.60% and 8.72%, respectively compared to the pure EP. In addition, the thermal and mechanical properties are closely related to the Fraction of Free Volume (FFV) and Mean Squared Displacement (MSD). The crosslinking process and the nano-SiO 2 doping reduce the FFV and MSD value in the model, resulting in better thermal and mechanical properties.

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“…The ∆ H and T g of the cured DGEB/DCHI in the presence of DCHI-Fe 3 O 4 ( Table 3, Figures 9 and 10a) decreased with the increasing wt.% of DCHI-Fe 3 O 4 in the first curing exothermic peak, and slightly increased in the second curing peak. This observation means that the incorporation of DCHI-Fe 3 O 4 cured epoxy produces dangling chains that have free thermal motion to increase the flexibility of the produced epoxy chains [40]. The DGEB/DCHI network limits the aggregation and assists in the self-assembly of the DCHI-Fe 3 O 4 to increase their compatibility with epoxy matrix containing the same hardener DCHI system.…”

Section: Curing Characteristics Of Dgeb With Hphi or Dchi And Their Mmentioning

confidence: 99%

Hydrophobic and Superhydrophobic Bio-Based Nano-Magnetic Epoxy Composites as Organic Coating of Steel

et al. 2020

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New epoxy resin hardeners were prepared from the reaction of p-nonylphenol and cardanol glycidylether with pentaethylenehexamine (PEHA) to produce hydrophobic polyamines. They were used as capping to produce superhydrophobic magnetite nanoparticles (Fe3O4 NPs). The chemical structures, thermal stability, morphologies, and particle sizes diameters were evaluated to confirm the hydrophobicity of dicardanoxy (DCHI) and dinonylphenoxy (HPHI) polyamines. The curing exothermic reaction of bisphenol A diglycidyl ether (DGEB) epoxy resin with DCHI, HPHI, or their Fe3O4 NPs was investigated by dynamic mechanical analyzer and differential scanning calorimetry. The cured epoxy networks crosslinking densities, storage modulus, and glass transition temperatures were determined and correlated to epoxy networks chemical compositions. DGEB/DCHI and DGEB/HPHI with their stoichiometric ratio embedded with their Fe3O4 NPs were applied on the rough steel surface to produce hydrophobic and superhydrophobic epoxy coatings. The wetting characteristics of the cured epoxy nanocomposites were evaluated from seawater contact angle (WCA) measurements to prove the formation of superhydrophobic coatings in the presence of DCHI-Fe3O4 NPs having WCA > 150°. The excellent adhesion, mechanical, and anti-corrosion performances using DGEB/DCHI and DGEB/HPHI epoxy nanocomposites were obtained on the steel surfaces in the presence of seawater corrosive environment.

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High mechanical properties of epoxy networks with dangling chains and tunable microphase separation structure

Abstract: The microphase separation was related to the compatibility and rigidity of the backbone.

Cited by 33 publications

References 34 publications

Curing of epoxidized linseed oil: Investigation of the curing reaction with different hardener types

Curing of epoxidized linseed oil: Investigation of the curing reaction with different hardener types

Micro-Structure and Thermomechanical Properties of Crosslinked Epoxy Composite Modified by Nano-SiO2: A Molecular Dynamics Simulation

Hydrophobic and Superhydrophobic Bio-Based Nano-Magnetic Epoxy Composites as Organic Coating of Steel

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