Study on the Self-healing Performance of Urea-Formaldehyde–Dicyclopentadiene (UF–DCPD) Microcapsules-Incorporated SBS Polymer-Modified Asphalt

2022 ◽  
Author(s):  
Junxian Huang ◽  
Yaseen Muhammad ◽  
Jiaqing Li ◽  
Jing Li ◽  
Caili Yang
Keyword(s):  
Urea Formaldehyde ◽  
The Self ◽  
Self Healing ◽  
Modified Asphalt ◽  
Polymer Modified Asphalt

scholarly journals The Self-Healing Performance of Carbon-Based Nanomaterials Modified Asphalt Binders Based on Molecular Dynamics Simulations

2021 ◽  
Vol 7 ◽  
Author(s):  
Yan Gong ◽  
Jian Xu ◽  
Er-hu Yan ◽  
Jun-hua Cai
Keyword(s):  
Healing Process ◽  
Asphalt Binder ◽  
Mean Square Displacement ◽  
The Self ◽  
Asphalt Binders ◽  
Self Healing ◽  
Modified Asphalt ◽  
Healing Efficiency ◽  
Carbon Based Nanomaterials ◽  
Carbon Based

In this study, the molecular dynamics simulation was used to explore the effects of carbon-based nanomaterials as binder modifiers on self-healing capability of asphalt binder and to investigate the microscopic self-healing process of modified asphalt binders under different temperature. An asphalt average molecular structure model of PEN70 asphalt binder was constructed firstly. Further, three kinds of carbon-based nanomaterials were added at three different percentages ranging from 0.5 to 1.5% to the base binder to study their effects on the self-healing capability, including two carbon nanotubes (CNT1 and CNT2) and graphene nanoflakes. Combining with the three-dimensional (3D) microcrack model to simulate the asphalt self-healing process, the density analysis, relative concentration analysis along OZ direction, and mean square displacement analysis were performed to investigate the temperature sensitive self-healing characters. Results showed that the additions of CNTs were effective in enhancing the self-healing efficiency of the plain asphalt binder. By adding 0.5% CNT1 and 0.5% CNT2, about 652% and 230% of the mean square displacement of plain asphalt binder were enhanced at the optimal temperatures. However, the use of graphene nanoflakes as an asphalt modifier did not provide any noticeable changes on the self-healing efficiency. It can be found that the self-healing capability of the asphalt was closely related to the temperature. For base asphalt, the self-healing effect became especially high at the phase transition temperature range, while, for the modified asphalt, the enhancement of the self-healing capability at the low phase transition temperature (15°C) became negligible. In general, the optimal healing temperature range of the CNTs modified asphalt binders is determined as 45–55°C and the optimal dosage of the CNTs is about 0.5% over the total weight of the asphalt binder. Considering the effect of carbon-based nanomaterials on the self-healing properties, the recommended carbon-based nanomaterials modifier is CNT1 with the aspect ratio of 1.81.

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.

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 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 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.

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