Modification and Study on the Properties of Epoxy Resin

A special issue of Polymers (ISSN 2073-4360). This special issue belongs to the section "Polymer Processing and Engineering".

Deadline for manuscript submissions: closed (30 April 2024) | Viewed by 10197

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Key Laboratory for Special Area Highway Engineering of Ministry of Education, Chang’an University, Xi’an 710064, China
Interests: pavement materials; eco-friendly asphalt pavements; bridge deck pavements
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Special Issue Information

Dear Colleagues,

Epoxy resin as one of the extensively used thermosetting synthetic resins, has a wide range of applications in the field of structural and functional materials, seeing that the high degree of cross-linking between molecules leads to superior mechanical behaviors, anti-corrosion ability and certain thermostability, as well as good processing formability and insulation. However, the internal stress, crosslinking degree and brittleness exhibits an uptrend after the curing of epoxy resin, coupled with the reduction of toughness, interchain mobility and weather fastness, which place restrictions on its application in the field of advanced composite materials. During the practical design and manufacture, the microstructural optimization and performance enhancement utilizing modification technology with regard to epoxy resin as a hot topic for current research still needs further research and exploration.

The main motivation of Special Issue is to deliver new research perspectives and report recent research findings, The research field to be covered but are not limited to:

  • Physical blending and chemical copolymerization modification
  • Algorithm modeling
  • Practical applications.

Prof. Dr. Hongliang Zhang
Guest Editor

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Published Papers (6 papers)

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Research

18 pages, 10706 KiB  
Article
Wear Behavior of Epoxy Resin Reinforced with Ceramic Nano- and Microparticles
by Juana Abenojar, Yolanda Ballesteros, Mohsen Bahrami, Miguel Angel Martínez and Juan Carlos del Real
Polymers 2024, 16(7), 878; https://doi.org/10.3390/polym16070878 - 22 Mar 2024
Viewed by 660
Abstract
Cavitation erosion poses a significant challenge in fluid systems like hydraulic turbines and ship propellers due to pulsed pressure from collapsing vapor bubbles. To combat this, various materials and surface engineering methods are employed. In this study, nano and micro scale particles of [...] Read more.
Cavitation erosion poses a significant challenge in fluid systems like hydraulic turbines and ship propellers due to pulsed pressure from collapsing vapor bubbles. To combat this, various materials and surface engineering methods are employed. In this study, nano and micro scale particles of silicon carbide (SiC) or boron carbide (B4C) were incorporated as reinforcement at 6% and 12% ratios, owing to their exceptional resistance to abrasive wear and high hardness. Microparticles were incorporated to assess the damage incurred during the tests in comparison to nanoparticles. Wear tests were conducted on both bulk samples and coated aluminum sheets with a 1mm of composite. Additionally, cavitation tests were performed on coated aluminum tips until stability of mass loss was achieved. The results indicated a distinct wear behavior between the coatings and the bulk samples. Overall, wear tended to be higher for the coated samples with nanocomposites than bulk, except for the nano-composite material containing 12% SiC and pure resin. With the coatings, higher percentages of nanometric particles correlated with increased wear. The coefficient of friction remained within the range of 0.4 to 0.5 for the coatings. Regarding the accumulated erosion in the cavitation tests for 100 min, it was observed that for all nanocomposite materials, it was lower than in pure resin. Particularly, the composite with 6% B4C was slightly lower than the rest. In addition, the erosion rate was also lower for the composites. Full article
(This article belongs to the Special Issue Modification and Study on the Properties of Epoxy Resin)
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24 pages, 4785 KiB  
Article
Possibilities of Influencing the Crystallization Process of Bisphenol A- and Bisphenol F-Based Epoxy Resins Used for Hydrophobic Coatings on Concrete
by Michaela Seidlová, Jakub Hodul, Nikol Žižková and Ruben Paul Borg
Polymers 2023, 15(19), 3871; https://doi.org/10.3390/polym15193871 - 24 Sep 2023
Viewed by 1711
Abstract
Crystallization of bisphenol A (DGEBA)- and bisphenol F (DGEBF)-based epoxy resins is a natural property of these oligomers. However, manufacturers of coatings and other systems based on these epoxy resins are making efforts to slow down the crystallization process as much as possible, [...] Read more.
Crystallization of bisphenol A (DGEBA)- and bisphenol F (DGEBF)-based epoxy resins is a natural property of these oligomers. However, manufacturers of coatings and other systems based on these epoxy resins are making efforts to slow down the crystallization process as much as possible, thereby extending the shelf life and improving the competitiveness of their products. This paper focuses on the kinetics of the crystallization process of epoxy resins and the effect of the presence of a certain degree of crystallinity on selected parameters of epoxy-based materials. Furthermore, an analysis of the impact of a certain degree of crystallinity of the epoxy base on the resulting coating parameters was carried out. The highest value of crystallinity (17%) was achieved in the sample containing the highest proportion of DGEBF in the crystallization phase “c”, and the enthalpy of melting (Ht) of the crystalline DGEBF sample was 6.3 J/g. Mechanical parameters as well as chemical and thermal resistance of hydrophobic epoxy systems were investigated. The best abrasion resistance (1.5 cm3/50 cm2) was achieved with the blend containing only amorphous DGEBA. The adhesion of the epoxy samples on concrete was greater than 6.5 MPa. The chemical resistance tests performed showed that, in general, the chemical resistance of epoxy systems decreases with increasing crystallinity content. The tighter arrangement of molecules in the crystalline regions of the epoxy matrix results in an increase in density, strength and hardness. This study presents a comprehensive examination of the crystallization of DGEBA and DGEBF, which is, as yet virtually unavailable. It also contributes to knowledge by outlining the possibility of speeding up or slowing down the crystallization process of epoxy resins, including the principle of selecting nucleating agents. Full article
(This article belongs to the Special Issue Modification and Study on the Properties of Epoxy Resin)
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17 pages, 7927 KiB  
Article
Identification of Electrical Tree Aging State in Epoxy Resin Using Partial Discharge Waveforms Compared to Traditional Analysis
by Roger Schurch, Osvaldo Munoz, Jorge Ardila-Rey, Pablo Donoso and Vidyadhar Peesapati
Polymers 2023, 15(11), 2461; https://doi.org/10.3390/polym15112461 - 26 May 2023
Cited by 2 | Viewed by 1764
Abstract
Electrical treeing is one of the main degradation mechanisms in high-voltage polymeric insulation. Epoxy resin is used as insulating material in power equipment such as rotating machines, power transformers, gas-insulated switchgears, and insulators, among others. Electrical trees grow under the effect of partial [...] Read more.
Electrical treeing is one of the main degradation mechanisms in high-voltage polymeric insulation. Epoxy resin is used as insulating material in power equipment such as rotating machines, power transformers, gas-insulated switchgears, and insulators, among others. Electrical trees grow under the effect of partial discharges (PDs) that progressively degrade the polymer until the tree crosses the bulk insulation, then causing the failure of power equipment and the outage of the energy supply. This work studies electrical trees in epoxy resin through different PD analysis techniques, evaluating and comparing their ability to identify tree bulk-insulation crossing, the precursor of failure. Two PD measurement systems were used simultaneously—one to capture the sequence of PD pulses and another to acquire PD pulse waveforms—and four PD analysis techniques were deployed. Phase-resolved PD (PRPD) and pulse sequence analysis (PSA) identified tree crossing; however, they were more sensible to the AC excitation voltage amplitude and frequency. Nonlinear time series analysis (NLTSA) characteristics were evaluated through the correlation dimension, showing a reduction from pre- to post-crossing, and thus representing a change to a less complex dynamical system. The PD pulse waveform parameters had the best performance; they could identify tree crossing in epoxy resin material independently of the applied AC voltage amplitude and frequency, making them more robust for a broader range of situations, and thus, they can be exploited as a diagnostic tool for the asset management of high-voltage polymeric insulation. Full article
(This article belongs to the Special Issue Modification and Study on the Properties of Epoxy Resin)
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17 pages, 5164 KiB  
Article
Rheological and Aging Properties of Vegetable Oil-Based Polyurethane (V-PU) Modified Asphalt
by Lei Xia, Dongwei Cao and Hongliang Zhang
Polymers 2023, 15(9), 2158; https://doi.org/10.3390/polym15092158 - 30 Apr 2023
Cited by 6 | Viewed by 1523
Abstract
To study the rheological and aging properties of vegetable oil–based polyurethane (V-PU) modified asphalt, V-PU terminated with an –NCO group was synthesized from renewable castor oil, and liquefied MDI-100LL and 10–40 wt% V-PU modified asphalts were prepared. Temperature classification, multiple stress creep recovery [...] Read more.
To study the rheological and aging properties of vegetable oil–based polyurethane (V-PU) modified asphalt, V-PU terminated with an –NCO group was synthesized from renewable castor oil, and liquefied MDI-100LL and 10–40 wt% V-PU modified asphalts were prepared. Temperature classification, multiple stress creep recovery (MSCR), and linear amplitude scanning (LAS) tests were carried out. The results showed that the modulus, the creep recovery rate (R), and the yield stress and yield strain of the V-PU modified asphalts significantly increased in the order: 0 wt% < 10 wt% < 20 wt% < 40 wt% < 30 wt%, while the phase angle and the unrecoverable creep compliance (Jnr) changed in the opposite order, and the high temperature grade of 30 wt% V-PU modified asphalt was 4 grades higher than that of the base asphalt, which indicated that the addition of V-PU enhanced the fatigue, permanent deformation, and recovery deformation resistance. The 30 wt% sample exhibited phase inversion had the best performance. Comprehensive FTIR, GPC, and fluorescence microscopy analyses showed that the molecular weight significantly increased and the V-PU molecules agglomerated after aging. The excess –NCO groups of V-PU prepolymer react with water in the air and the active hydrogen in the asphalt system and finally form a cross-linked three-dimensional network structure with the asphalt to improve performance. The mechanism of intramolecular cementation reaction and the aging process of V-PU modified asphalt was creatively derived. Full article
(This article belongs to the Special Issue Modification and Study on the Properties of Epoxy Resin)
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15 pages, 4793 KiB  
Article
Epoxy-Modified Bismaleimide Structural Adhesive Film Toughened Synergistically with PEK-C and Core–Shell Polymers for Bonding CFRP
by Liwei Zhao, Xin Xu, Wanbao Xiao, Hongfeng Li, Hao Feng, Changwei Liu, Yingjie Qiao, Xuefeng Bai, Dezhi Wang and Chunyan Qu
Polymers 2023, 15(6), 1436; https://doi.org/10.3390/polym15061436 - 14 Mar 2023
Cited by 2 | Viewed by 2054
Abstract
Bismaleimide (BMI) resin-based structural adhesives have excellent heat resistance, with important applications demonstrated in the bonding of high-temperature BMI composites. In this paper, we report an epoxy-modified BMI structural adhesive with excellent properties for bonding BMI-based CFRP. We prepared the BMI adhesive using [...] Read more.
Bismaleimide (BMI) resin-based structural adhesives have excellent heat resistance, with important applications demonstrated in the bonding of high-temperature BMI composites. In this paper, we report an epoxy-modified BMI structural adhesive with excellent properties for bonding BMI-based CFRP. We prepared the BMI adhesive using epoxy-modified BMI as the matrix and PEK-C and core–shell polymers as synergistic tougheners. We found that the epoxy resins improve the process and bonding properties of BMI resin but slightly reduce thermal stability. PEK-C and core–shell polymers synergistically improve the toughness and bonding performances of the modified BMI adhesive system and allow the maintenance of heat resistance. The optimized BMI adhesive exhibits excellent heat resistance, with a high glass transition temperature of 208.6 °C and a high thermal degradation temperature of 425.4 °C. Most importantly, the optimized BMI adhesive exhibits satisfactory intrinsic bonding and thermal stability. It has a high shear strength of 32.0 MPa at room temperature and up to 17.9 MPa at 200 °C. The BMI adhesive-bonded composite joint has a high shear strength of 38.6 and 17.3 MPa at room temperature and 200 °C, respectively, indicating effective bonding and excellent heat resistance. Full article
(This article belongs to the Special Issue Modification and Study on the Properties of Epoxy Resin)
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17 pages, 4192 KiB  
Article
Synthesis of Hyperbranched Flame Retardants with Varied Branched Chains’ Rigidity and Performance of Modified Epoxy Resins
by Jingyuan Hu, Liyue Zhang, Mingxuan Chen, Jinyue Dai, Na Teng, Hongchi Zhao, Xinwu Ba and Xiaoqing Liu
Polymers 2023, 15(2), 449; https://doi.org/10.3390/polym15020449 - 14 Jan 2023
Cited by 1 | Viewed by 1576
Abstract
To overcome the high flammability and brittleness of epoxy resins without sacrificing their glass transition temperature (Tg) and mechanical properties, three epoxy-terminated hyperbranched flame retardants (EHBFRs) with a rigid central core and different branches, named EHBFR-HB, EHBFR-HCM, and EHBFR-HBM, were [...] Read more.
To overcome the high flammability and brittleness of epoxy resins without sacrificing their glass transition temperature (Tg) and mechanical properties, three epoxy-terminated hyperbranched flame retardants (EHBFRs) with a rigid central core and different branches, named EHBFR-HB, EHBFR-HCM, and EHBFR-HBM, were synthesized. After chemical structure characterization, the synthesized EHBFRs were introduced into the diglycidyl ether of bisphenol A (DGEBA) and cured with 4, 4-diaminodiphenylmethane (DDM). The compatibility, thermal stability, mechanical properties, and flame retardancy of the resultant resins were evaluated. Results showed that all three EHBFRs could significantly improve the fire safety of cured resins, and 30 wt. % of EHBFRs (less than 1.0 wt. % phosphorus content) endowed cured DGEBA with a UL-94 V-0 rating. In addition, the increased rigidity of branches in EHBFRs could increase the flexural strength and modulus of cured resins, and the branches with appropriate rigidity were also beneficial for improving their room temperature impact strength and Tg. Full article
(This article belongs to the Special Issue Modification and Study on the Properties of Epoxy Resin)
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