Dynamic Mechanical Properties of Structural Self-Healing Epoxy Resins

2011 ◽  
Vol 62 ◽  
pp. 95-105 ◽  
Author(s):  
Liberata Guadagno ◽  
Marialuigia Raimondo ◽  
Carlo Naddeo ◽  
Giuseppina Russo ◽  
Vittoria Vittoria ◽  
...  
Keyword(s):  
First Generation ◽  
Mechanical Performance ◽  
Urea Formaldehyde ◽  
Dynamic Mechanical Properties ◽  
Solid Particles ◽  
The Self ◽  
Self Healing ◽  
Repair Activity ◽  
Catalyst Powder ◽  
Curing Cycle

In this paper, we report the study and characterization of a multifunctional autonomically healing composite containing solid particles of Grubbs’ first generation catalyst and poly(urea-formaldehyde) microcapsules filled with liquid DCPD. This system, already reported in literature, in some respects shows great potential for epoxy structural composites: however, other aspects have to be explored in order to put to use in advanced applications. Here, we have determined the curing process to obtain the best mechanical performance without deactivating the self-repair activity of the material. It has been found that, for the same curing cycle, the presence of catalyst powder causes a slight decrease in the elastic modulus value with respect to the epoxy matrix. A large recovery in this performance is gained for the self-healing specimen, proving that the microcapsules contribute to improve the mechanical characteristics of the self-healing sample.

scholarly journals Self-Healing EPDM Rubbers with Highly Stable and Mechanically-Enhanced Urea-Formaldehyde (UF) Microcapsules Prepared by Multi-Step In Situ Polymerization

Polymers ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 1918 ◽  
Author(s):  
Hyeong-Jun Jeoung ◽  
Kun Won Kim ◽  
Yong Jun Chang ◽  
Yong Chae Jung ◽  
Hyunchul Ku ◽  
...  
Keyword(s):  
Mechanical Stability ◽  
In Situ Polymerization ◽  
Urea Formaldehyde ◽  
Testing Machine ◽  
Optical Microscope ◽  
The Self ◽  
Self Healing ◽  
Grubbs Catalyst ◽  
Healing Efficiency

The mechanically-enhanced urea-formaldehyde (UF) microcapsules are developed through a multi-step in situ polymerization method. Optical microscope (OM) and field emission scanning electron microscope (FE-SEM) prove that the microcapsules, 147.4 μm in diameter with a shell thickness of 600 nm, are well-formed. From 1H-nuclear magnetic resonance (1H-NMR) analysis, we found that dicyclopentadiene (DCPD), a self-healing agent encapsulated by the microcapsules, occupies ca. 40.3 %(v/v) of the internal volume of a single capsule. These microcapsules are mixed with EPDM (ethylene-propylene-diene-monomer) and Grubbs’ catalyst via a solution mixing method, and universal testing machine (UTM) tests show that the composites with mechanically-enhanced microcapsules has ca. 47% higher toughness than the composites with conventionally prepared UF microcapsules, which is attributed to the improved mechanical stability of the microcapsule. When the EPDM/microcapsule rubber composites are notched, Fourier-transform infrared (FT-IR) spectroscopy shows that DCPD leaks from the broken microcapsule to the damaged site and flows to fill the notched valley, and self-heals as it is cured by Grubbs’ catalyst. The self-healing efficiency depends on the capsule concentration in the EPDM matrix. However, the self-healed EPDM/microcapsule rubber composite with over 15 wt% microcapsule shows an almost full recovery of the mechanical strength and 100% healing efficiency.

scholarly journals Mechanical Properties Assessment of Low-Content Capsule-Based Self-Healing Structural Composites

2020 ◽  
Vol 10 (17) ◽  
pp. 5739
Author(s):  
Xenia Tsilimigkra ◽  
Dimitrios Bekas ◽  
Maria Kosarli ◽  
Stavros Tsantzalis ◽  
Alkiviadis Paipetis ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Flexural Strength ◽  
Mechanical Performance ◽  
Urea Formaldehyde ◽  
Healing Process ◽  
Experimental Results ◽  
Self Healing ◽  
Healing Efficiency ◽  
A Minor

Microcapsule-based carbon fiber reinforced composites were manufactured by wet layup, in order to assess their mechanical properties and determine their healing efficiency. Microcapsules at 10%wt. containing bisphenol-A epoxy, encapsulated in a urea formaldehyde (UF) shell, were employed with Scandium (III) Triflate (Sc (OTf)3) as the catalyst. The investigation was deployed with two main directions. The first monitored changes to the mechanical performance due to the presence of the healing agent within the composite. More precisely, a minor decrease in interlaminar fracture toughness (GIIC) (−14%), flexural strength (−12%) and modulus (−4%) compared to the reference material was reported. The second direction evaluated the healing efficiency. The experimental results showed significant recovery in fracture toughness up to 84% after the healing process, while flexural strength and modulus healing rates reached up to 14% and 23%, respectively. The Acoustic Emission technique was used to support the experimental results by the onsite monitoring.

Boronic Ester-Polyurethane as a Self-Healing Coating Material for Offshore Top Side Structures Application

2021 ◽  
Author(s):  
Mohd Shamsul Farid Samsudin ◽  
Norfarah Diana Aba ◽  
Muzdalifah Zakaria ◽  
Azmi Mohammed Nor ◽  
Russell Varley ◽  
...  
Keyword(s):  
Mechanical Performance ◽  
Coating Layer ◽  
Salt Spray ◽  
The Self ◽  
Self Healing ◽  
Humidity Level ◽  
Healing System ◽  
Healing Efficiency ◽  
Harsh Conditions

Abstract Polymer coatings, especially epoxy and polyurethane paint systems, have been widely used to prevent corrosion of metallic components and structures. However, due to environmental and mechanical effects, the barrier efficiency of the coatings may be substantially compromised during transportation and service, as demonstrated by localized scratches, delamination, or stress-related microcracks. Application of a self-healing coating that can restore damages and recover its performance with minimal external intervention could prevent corrosion at the damaged coating. In this present work, the healing efficiency and long-term durability of Boronic Ester (BE) blended with Polyurethane (PU) as a self-healing system for top side coating of offshore platform structures was investigated. The BE was mixed at a ratio of 50:50 with PU resin and applied as a top layer on a PU coated steel plate with a thickness of approximately 300-350 μm. The healing efficiency, mechanical performance, and durability under simulated environmental conditions such as salt spray and UV were investigated according to the related ASTM standards. As a first step, the electrical impedance spectroscopy (EIS) and 3D profilemeter microscope were used to assess the healing ability of the scratched coating at room temperature and humidity level of 85 %. The mechanical performance of the self-healing coating layer was evaluated using a pull off adhesion test to investigate the compatibility of the self-healing system with the existing commercial PU topcoat system, while a long term 3000 hours salt spray and 4200 hours cyclic UV test were performed to evaluate the self-healing coating's durability in harsh conditions. Preliminary assessment using EIS and 3D profilemeter microscopes on the scratched PU/BE self-healing coating revealed significant healing efficiency of more than 80% for healing condition at ambient temperature and humidity level of 85%. The self-healing coating layer also demonstrated excellent adhesion efficiency, with adhesion greater than 300 psi suggesting good compatibility of the BE-PU layer with commercial PU coating. The salt spray and cyclic UV tests that were performed to determine the durability of the self-healing coating revealed that the 50BE/50PU layer remained intact and exhibited good healing performance with more than 80% efficiency even after exposure to harsh conditions. The findings from the study demonstrated that the BE/PU material has the potential to be used as a self-healing system for topside coating of offshore platforms structures, thereby lowering maintenance costs.

scholarly journals Preparation of Microcapsules of Urea Formaldehyde Resin Coated Waterborne Coatings and Their Effect on Properties of Wood Crackle Coating

Coatings ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 764 ◽  
Author(s):  
Xiaoxing Yan ◽  
Wenwen Peng
Keyword(s):  
In Situ Polymerization ◽  
Urea Formaldehyde ◽  
Impact Resistance ◽  
Acrylic Resin ◽  
Chromatic Aberration ◽  
Protective Role ◽  
The Self ◽  
Formaldehyde Resin ◽  
Self Healing ◽  
The Core

Urea formaldehyde coated waterborne acrylic resin microcapsules with core-wall ratios of 0.30, 0.45, 0.60, 0.67, and 0.75, and mass fractions of 1.0%, 4.0%, 7.0%, 10.0%, 13.0%, and 16.0% were prepared by in situ polymerization. Their micro morphology was examined by scanning electron microscope and infrared spectrum measurements. The gloss, color difference, adhesion, hardness, and impact resistance of the coating surface were investigated in detail. The influence of the core-wall ratio on the performance of the waterborne crackle coating on the wood surface and the self-healing performance were examined. The results showed that when the core-wall ratio of microcapsules was 0.67, an evenly dispersed powder state with particle size of about 3 μm microcapsules was obtained, and the highest coverage was achieved. When the mass fraction of the microcapsule was 4.0%, it had the optimum effect on surface performance. The adhesion was grade two, gloss was 10.9%, impact resistance was 15 kg·cm, chromatic aberration was 1.0, hardness was H, and it had the best effect on the healing of microcracks in the wood coating. As the coating added with microcapsules can inhibit the microcracks of the coating and plays a protective role for the substrate to achieve a self-healing effect, this study lays a technical foundation for the self-healing of surface cracks in coatings for wood.

scholarly journals A Novel Self-Healing Epoxy System with Microencapsulated Epoxy and Imidazole Curing Agent

2007 ◽  
Vol 16 (5) ◽  
pp. 096369350701600 ◽  
Author(s):  
Min Zhi Rong ◽  
Ming Qiu Zhang ◽  
Wei Zhang
Keyword(s):  
Urea Formaldehyde ◽  
Weight Ratio ◽  
The Self ◽  
Wall Material ◽  
Self Healing ◽  
Epoxy System ◽  
Water Emulsion ◽  
Fracture Toughness Measurement ◽  
Healing Agent ◽  
Oil In Water Emulsion

This work reported a novel epoxy system that can perform a self-repairing operation against cracks at elevated temperature. For this purpose, a two-component healing agent consisting of microencapsulated epoxy and imidazole was pre-embedded into epoxy matrix. The microencapsulated epoxy was self-synthesized in advance using poly(urea-formaldehyde) as the wall material through a two-step polymerization approach in an oil-in-water emulsion. The performance of the self-healing epoxy composite was evaluated by fracture toughness measurement. It was found that the self-healing epoxy containing 20wt.% healing agent received a healing efficiency of 106% at the optimum capsulated imidazole-to-epoxy weight ratio of 0.2.

scholarly journals Detailed Analysis of the Influencing Parameters on the Self-Healing Behavior of Dynamic Urea-Crosslinked Poly(methacrylate)s

Molecules ◽  
2019 ◽  
Vol 24 (19) ◽  
pp. 3597 ◽  
Author(s):  
Abend ◽  
Zechel ◽  
Schubert ◽  
Hager
Keyword(s):  
Detailed Analysis ◽  
Mechanical Performance ◽  
Healing Process ◽  
Polymer Networks ◽  
Healing Time ◽  
The Self ◽  
Self Healing ◽  
Influencing Parameters ◽  
The Impact

For this paper, the self-healing ability of poly(methacrylate)s crosslinked via reversible urea bonds was studied in detail. In this context, the effects of healing time and temperature on the healing process were investigated. Furthermore, the impact of the size of the damage (i.e., area of the scratch) was monitored. Aging processes, counteracting the self-healing process, result in a decrease in the mechanical performance. This effect diminishes the healing ability. Consequently, the current study is a first approach towards a detailed analysis of self-healing polymers regarding the influencing parameters of the healing process, considering also possible aging processes for thermo-reversible polymer networks.

scholarly journals Evaluation of the Self-Healing Ability of Mortar Mixtures Containing Superabsorbent Polymers and Nanosilica

Materials ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 380 ◽  
Author(s):  
Gerlinde Lefever ◽  
Didier Snoeck ◽  
Dimitrios G. Aggelis ◽  
Nele De Belie ◽  
Sandra Van Vlierberghe ◽  
...  
Keyword(s):  
Crack Width ◽  
Mechanical Performance ◽  
Cementitious Material ◽  
The Self ◽  
Optical Measurements ◽  
Self Healing ◽  
Superabsorbent Polymers ◽  
Healing Efficiency ◽  
Good Healing ◽  
External Conditions

Addition of superabsorbent polymers (SAPs) to cementitious mixtures promotes the self-healing ability of the material. When cracking occurs; SAPs present inside the crack will swell upon contact with water and subsequently release this water to stimulate the further hydration of unhydrated cement particles and the calcium carbonate crystallization. However; the inclusion of SAPs affects the mechanical performance of the cementitious material by the creation of macro-pores as water is retracted from the swollen SAP. To counteract the reduction in strength, part of the cement is replaced by nanosilica. In this research, different mixtures containing either SAPs or nanosilica and a combination of both were made. The samples were subjected to wet–dry cycles simulating external conditions, and the self-healing efficiency was evaluated by means of the evolution in crack width, by optical measurements, and a water permeability test. In samples containing SAPs, an immediate sealing effect was observed and visual crack closure was noticed. The smaller influence on the mechanical properties and the good healing characteristics in mixtures containing both nanosilica and SAPs are promising as a future material for use in building applications.

scholarly journals A Self-healing Hydrogel Electrolyte Towards All-in-one Flexible Supercapacitors

2021 ◽  
Author(s):  
Wen-Bin Ma ◽  
Ke-Hu Zhu ◽  
Shi-Fang Ye ◽  
Yao Wang ◽  
Lin Guo ◽  
...  
Keyword(s):  
Electrode Materials ◽  
Mechanical Performance ◽  
In Situ Polymerization ◽  
The Self ◽  
Poly Vinyl Alcohol ◽  
Physical Interaction ◽  
Self Healing ◽  
Wearable Electronics ◽  
Pva Hydrogel

Abstract The autonomously self-healable all-in-one supercapacitor is prepared by in situ rapid polymerization of electrode materials on the surface of self-healing poly (vinyl alcohol) (PVA) hydrogel electrolyte containing sulphuric acid (H2SO4). The self-healing PVA electrolyte has been achieved by physical interaction, in which dynamic hydrogen bonds between PVA chains can readily break and reform, allowing PVA hydrogel electrolyte to self-heal and regain its mechanical and electrochemical properties. The obtained PVA hydrogel displays fast self-healing capability, reliable mechanical performance (stress at 290 KPa after stretching to 238 %) and high ionic conductivity (57.8 mS cm− 1). Based on these excellent properties, an all-in-one supercapacitor with self-healing characteristics is assembled by in situ polymerization of aniline on the surface of self-healable PVA electrolyte. The self-healable all-in-one supercapacitor exhibits specific capacitance 470 mF cm− 2 at current density of 0.2 mA cm− 2 and energy density 32 µWh cm− 2 at power density 100 µW cm− 2. The broken device can be repaired itself and there is a 63% capacitance retention for the healable supercapacitor. This self-healing supercapacitor will promote the development of self-healing energy storage devices in wearable electronics.

scholarly journals Self-Healing Coatings Based on Linseed-Oil-Loaded Microcapsules for Protection of Cementitious Materials

Coatings ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 404 ◽  
Author(s):  
Dong-Min Kim ◽  
In-Ho Song ◽  
Ju-Young Choi ◽  
Seung-Won Jin ◽  
Kyeong-Nam Nam ◽  
...  
Keyword(s):  
Protective Coating ◽  
Linseed Oil ◽  
Urea Formaldehyde ◽  
Cementitious Materials ◽  
The Self ◽  
Wall Material ◽  
Self Healing ◽  
Sorptivity Test ◽  
Coating Formulation ◽  
Coating Formulations

Linseed oil undergoes an oxidative drying reaction upon exposure to air, resulting in a soft film. The reaction conversion after 48 h reached 88% and 59% when it reacted at room temperature and −20 °C, respectively. Linseed-oil-loaded microcapsules were prepared using a urea-formaldehyde polymer as the shell wall material. The microcapsules were integrated into a commercially available protective coating formulation to prepare self-healing coating formulations with different capsule loadings. The coating formulations were applied on mortar specimens to prepare self-healing coatings. The effect of capsule loading on adhesion strength of the self-healing coating was studied. The self-healing function of the coating was investigated by SEM, a water sorptivity test and an accelerated carbonation test. Successful self-healing was demonstrated for both scratch and crack damage in the coatings. Low-temperature self-healing was demonstrated with a saline solution sorptivity test conducted at −20 °C. The linseed-oil-based microcapsule-type self-healing coating system is a promising candidate as a protective coating for cementitious materials.

scholarly journals SYNTHESIS OF SULFUR-CONTAINED MICROCAPSULES AND POTENTIAL APPLICATION IN RUBBER

2019 ◽  
Vol 57 (3A) ◽  
pp. 29
Author(s):  
La Thi Thai Ha ◽  
Chau Ngoc Mai
Keyword(s):  
Crucial Role ◽  
Potential Application ◽  
Urea Formaldehyde ◽  
The Self ◽  
Self Healing ◽  
Core Content ◽  
Rubber Compounds ◽  
Rubber Surface ◽  
Average Size ◽  
Vulcanize Rubber

Microcapsule-based material is potentially utilized in a variety of fields such as pharmaceuticals, food, biology, self-healing materials, etc. More remarkedly, in the rubber-related fields, this outstanding material is able to have a crucial role to play as an alternative of sulfur in compounding and vulcanizing process with regard to the self-healing ability after cracking. In this research, the interface polymerization was applied to generate microcapsules, whose shell was synthesized from Urea-formaldehyde pre-polymer modified by 0.25 wt% melamine containing sulfur (S) as a core substance. When the synthesizing process was carried out at 80 C and stirring rate of 300 rpm in 2 hours, the microcapsule product was spherical with the average size of 115 m and contained 60% of core content that was examined by FTIR, DLS, SEM, TGA and experimented the potential application. As a result, the amount of 8 phr of produced microcapsules utilized in NBR rubber compounds necessitated a longer time to vulcanize rubber at 160 C  compared to using 5 phr free S. Besides, the mechanical strength of the microcapsules-contained product was insignificantly changed but bloom-like phenomenon on the rubber surface was markedly improved. It is noticeable that the vulcanized NBR rubber with the presence of these microcapsules are well able to heal its crack or cut when heated up to 150 C in 10 minutes while the free S-vulcanized NBR rubber is definitely unable to be self-healing in the same conditions.

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