Preparation and Characterization of Self-Healing Microcapsules Containing Two-Component

2013 ◽  
Vol 734-737 ◽  
pp. 2176-2180 ◽  
Author(s):  
Xiao Mei Tong ◽  
Chang Fu Li
Keyword(s):  
In Situ Polymerization ◽  
Urea Formaldehyde ◽  
Particle Surface ◽  
Average Diameter ◽  
Curing Temperature ◽  
Core Material ◽  
Gravimetric Analysis ◽  
Self Healing ◽  
Scanning Calorimetry ◽  
Two Component

Two component self-healing microcapsules were prepared by in situ polymerization with poly (melamine-urea-formaldehyde) as wall, epoxy resin and latent curing agent sebacate hydrazide as core. The ratio of two core material and the reaction process were studied. The size and distribution of particle, surface morphology, structure, thermal properties and content of core were measured and characterized by using particle size analyzer（PSA）, optical microscopy (OM), infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA). The results showed that the microcapsules have smooth and compact surfaces, and have spherical profiles. The average diameter of microcapsules is 30μm and core content of microcapsules is 70%. The heat resistance and solvent resistance of microcapsule are better. The curing temperature is 190°Cand the healing efficiency can be improved.

scholarly journals Utilization of Birch Bark as an Eco-Friendly Filler in Urea-Formaldehyde Adhesives for Plywood Manufacturing

Polymers ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 511
Author(s):  
Roman Réh ◽  
Ľuboš Krišťák ◽  
Ján Sedliačik ◽  
Pavlo Bekhta ◽  
Monika Božiková ◽  
...  
Keyword(s):  
Bending Strength ◽  
Urea Formaldehyde ◽  
Formaldehyde Emission ◽  
Birch Bark ◽  
Gravimetric Analysis ◽  
European Standard ◽  
Scanning Calorimetry ◽  
Wood Processing ◽  
Fagus Sylvatica L ◽  
Positive Effect

The potential of using ground birch (Betula verrucosa Ehrh.) bark as an eco-friendly additive in urea-formaldehyde (UF) adhesives for plywood manufacturing was investigated in this work. Five-ply plywood panels were fabricated in the laboratory from beech (Fagus sylvatica L.) veneers bonded with UF adhesive formulations comprising three addition levels of birch bark (BB) as a filler (10%, 15%, and 20%). Two UF resin formulations filled with 10% and 20% wheat flour (WF) were used as reference samples. The mechanical properties (bending strength, modulus of elasticity and shear strength) of the laboratory-fabricated plywood panels, bonded with the addition of BB in the adhesive mixture, were evaluated and compared with the European standard requirements (EN 310 and EN 314-2). The mechanical strength of the plywood with the addition of BB in the adhesive mixture is acceptable and met the European standard requirements. Markedly, the positive effect of BB in the UF adhesive mixture on the reduction of formaldehyde emission from plywood panels was also confirmed. Initially, the most significant decrease in formaldehyde release (up to 14%) was measured for the plywood sample, produced with 15% BB. After four weeks, the decrease in formaldehyde was estimated up to 51% for the sample manufactured with 20% BB. The performed differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA), and derivative thermogravimetry (DTG), also confirmed the findings of the study. As this research demonstrated, BB as a waste or by-product of wood processing industry, can be efficiently utilized as an environmentally friendly, inexpensive alternative to WF as a filler in UF adhesive formulations for plywood manufacturing.

Optimization of Curing Conditions and Nanofiller Incorporation for Production of High Performance Laminated Kevlar/Epoxy Nanocomposites

2018 ◽  
Author(s):  
Abdel-Hamid I. Mourad ◽  
Mouza S. Al Mansoori ◽  
Lamia A. Al Marzooqi ◽  
Farah A. Genena ◽  
Nizamudeen Cherupurakal
Keyword(s):  
Oil And Gas ◽  
Mechanical Performance ◽  
Thermo Gravimetric Analysis ◽  
Applied Pressure ◽  
Curing Temperature ◽  
Gravimetric Analysis ◽  
Epoxy Nanocomposites ◽  
Scanning Calorimetry ◽  
Curing Conditions ◽  
Weight Percentage

Kevlar composite materials are getting scientific interest in repairing of oil and gas pipelines in both offshore and onshore due to their unique properties. Curing is one of the major factor in deciding the final mechanical performance of laminated Kevlar/epoxy nanocomposites. The parameters such as curing time, temperature and applied pressure during the hot pressing will affect chemistry of crosslinking of the epoxy matrix and interaction of epoxy with the Kevlar fiber. The present study is carried out to evaluate the optimal curing conditions of the Kevlar/epoxy nanocomposites. Three different nanofillers (namely Multi walled Carbon nanotubes (MWCNT), Silicon Carbide (SiC) and Aluminum Oxide (Al2O3)) are incorporated in different weight percentage. Differential Scanning Calorimetry (DSC) and Thermo-Gravimetric Analysis (TGA) tests are carried out to determine the thermal stability and optimal curing conditions. Mechanical performance is investigated by conducting flexure, and drop weight tests. The results show that, the optimal curing temperature for maximizing the mechanical properties is at 170°C. Peeling off the Kevlar layers are observed for nanocomposite samples cured under 100°C. Mechanical strength of the composites is enhanced by optimizing the curing conditions and nanofiller contents.

scholarly journals Influence of Single/Collective Use of Curing Agents on the Curing Behavior and Bond Strength of Soy Protein-Melamine-Urea-Formaldehyde (SMUF) Resin for Plywood Assembly

Polymers ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 1995 ◽  
Author(s):  
Zhigang Wu ◽  
Bengang Zhang ◽  
Xiaojian Zhou ◽  
Lifen Li ◽  
Liping Yu ◽  
...  
Keyword(s):  
Shear Strength ◽  
Water Resistance ◽  
Protein Hydrolysate ◽  
Soybean Protein ◽  
Urea Formaldehyde ◽  
Curing Temperature ◽  
Molar Ratio ◽  
Scanning Calorimetry ◽  
Curing Agents ◽  
Crosslinking Reactions

Soybean protein hydrolysate, melamine, urea, and concentrated formaldehyde were used to synthesize an environmentally friendly soybean protein-melamine-urea-formaldehyde (SMUF) co-condensation resin. (NH4)2SO4, (NH4)2HPO4, (NH4)2HPO4 + (NH4)2SO4, (NH4)2HPO4 + (NH4)2S2O8, and (NH4)2HPO4 + (NH4)2SO4 + (NH4)2S2O8 were employed as curing agents for SMUF resin. The curing and thermal behaviors of the SMUF resin were investigated using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). The results revealed the following: (1) (NH4)2SO4 alone could not cure the SMUF resin completely; thus, the final shear strength accomplished plywood with the resin was low, and its water resistance was poor, while the adhesive section was loose and porous/brittle after curing. (2) (NH4)2HPO4 could be hydrolyzed to generate H+ and promote SMUF curing, but it could also form polyphosphoric acids, resulting in crosslinking reactions with SMUF in parallel; thereby, the curing properties were improved. (3) When (NH4)2HPO4 + (NH4)2SO4 + (NH4)2S2O8 were engaged collectively as curing agent, the shear strength, water resistance, and heat resistance of SMUF attained were the best possible whereas the curing temperature was decreased and the heat released by curing was elevated substantially, which signifies maximized extent of crosslinking was achieved. Further, the adhesive section exhibited mostly a crosslinking intertexture as demonstrated by means of SEM. Accordingly, this study may serve as a guide for the curing of amino resins, with low-molar ratio of formaldehyde to amine in adhesives, which are applied to plywood production.

scholarly journals Electrospun Multiple-Chamber Nanostructure and Its Potential Self-Healing Applications

Polymers ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2413 ◽  
Author(s):  
Yubo Liu ◽  
Xinkuan Liu ◽  
Ping Liu ◽  
Xiaohong Chen ◽  
Deng-Guang Yu
Keyword(s):  
Electron Microscope ◽  
Electrochemical Corrosion ◽  
Average Diameter ◽  
Self Healing ◽  
Scanning Calorimetry ◽  
Uniform Size ◽  
Transmission Electron ◽  
Reactive Fluids ◽  
Amine Curing ◽  
First Time

To address the life span of materials in the process of daily use, new types of structural nanofibers, fabricated by multifluid electrospinning to encapsulate both epoxy resin and amine curing agent, were embedded into an epoxy matrix to provide it with self-healing ability. The nanofibers, which have a polyacrylonitrile sheath holding two separate cores, had an average diameter of 300 ± 140 nm with a uniform size distribution. The prepared fibers had a linear morphology with a clear three-chamber inner structure, as verified by scanning electron microscope and transmission electron microscope images. The two core sections were composed of epoxy and amine curing agents, respectively, as demonstrated under the synergistic characterization of Fourier transform infrared spectroscopy, thermogravimetric analysis (TGA), and differential scanning calorimetry. The TGA results disclosed that the core-shell nanofibers contained 9.06% triethylenetetramine and 20.71% cured epoxy. In the electrochemical corrosion experiment, self-healing coatings exhibited an effective anti-corrosion effect, unlike the composite without nanofibers. This complex nanostructure was proven to be an effective nanoreactor, which is useful to encapsulate reactive fluids. This engineering process by multiple-fluid electrospinning is the first time to prove that this special multiple-chamber structure has great potential in the field of self-healing.

scholarly journals Preparation and Optimization of Waterborne Acrylic Core Microcapsules for Waterborne Wood Coatings and Comparison with Epoxy Resin Core

Polymers ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2366 ◽  
Author(s):  
Xiaoxing Yan ◽  
Yu Tao ◽  
Xingyu Qian
Keyword(s):  
In Situ Polymerization ◽  
Urea Formaldehyde ◽  
Paint Film ◽  
Bath Temperature ◽  
Water Bath ◽  
Core Material ◽  
Wall Material ◽  
Formaldehyde Resin ◽  
The Core ◽  
Resin Core

Microcapsules were prepared by in situ polymerization with urea formaldehyde resin as the wall material and Dulux waterborne acrylic acid as the core material. The effects of the core–wall ratio, water bath temperature and depositing time on the morphology, particle size, yield and encapsulation ratio of microcapsules were investigated by orthogonal experiment of three factors and two levels. The results showed that the core–wall ratio had the greatest influence on the performance of microcapsules. When the core–wall ratio was 0.58:1, the water bath temperature was 70 °C, and the depositing time was 5 d, the microcapsule performance was the best. With the increase in depositing time, the yield of microcapsule particles increased gradually, and the microcapsules appeared to show an adhesive phenomenon. However, the long-term depositing time did not lead to complete deposition and agglomeration of microcapsules. When 10.0% concentration of the waterborne acrylic microcapsules with 0.58:1 of core–wall ratio was added to the coatings, the mechanical and optical properties of the coatings did not decrease significantly, but the elongation at break increased significantly. Therefore, this study offers a new prospect for using waterborne acrylic microcapsules to improve the toughness of waterborne paint film which can be cured at room temperature on a wood surface.

Synthesis and Characterization of Caged Phosphate Microparticles Coated with Melamine Resin Based on Composite Properties of Materials

2012 ◽  
Vol 583 ◽  
pp. 236-239
Author(s):  
Xiao Min Fang ◽  
Yuan Qing Xu ◽  
Tao Ding
Keyword(s):  
Flame Retardants ◽  
In Situ Polymerization ◽  
Core Material ◽  
Gravimetric Analysis ◽  
Melamine Resin ◽  
Flame Retarded ◽  
Properties Of Materials ◽  
Loading Amount

In order to develop efficient “three in one” intumesent flame retardants, a novel caged bicyclic phosphate, tris(1-oxo-2,6,7-trioxa-1-phosphorbicyclo[2.2.2]octane methylene-4)phosphate (trimer) as the core material was encapsulated by melamine resin and etherified melamine resin as nitrogen resource respectively via in situ polymerization. The two microencapsulations were characterized by SEM, XPS and thermal gravimetric analysis. When they were used as intumesent flame retardant in epoxy they all exhibit good properties. With 20wt% loading amount the flame-retarded epoxy all can pass UL94 V-0 rating.

Microencapsulation of Epoxy Resins for Self-Healing Material

2010 ◽  
Vol 148-149 ◽  
pp. 1031-1035
Author(s):  
Yang Zhao ◽  
Wei Zhang ◽  
Le Ping Liao ◽  
Wu Jun Li ◽  
Yi Xin
Keyword(s):  
Epoxy Resins ◽  
In Situ Polymerization ◽  
Heating Temperature ◽  
Hot Water ◽  
Core Material ◽  
Agitation Rate ◽  
Self Healing ◽  
Water Emulsion ◽  
Oil In Water Emulsion

With the development of the embedded microcapsule concept for self-healing material, the preparation of microcapsule has been paid more attentions. A new series of microcapsules were prepared by in situ polymerization technology in an oil-in-water emulsion with polyoxymethylene urea (PMU) as shell material and a mixture of epoxy resins as core material. The PMU microcapsules were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electronic microscopy (SEM), particle size analyzer and thermo gravimetric analyzer (TGA) to investigate their chemical structure, surface morphology, size distribution and thermal stability, respectively. The results indicate that PMU microcapsules containing epoxy resins can be synthesized successfully. The optimized reaction parameters were obtained as follow: agitation rate 600 rpm, 60°C water bath, pH=3.5, core material 20ml and hot water dilution by in-situ polymerization. The size is around 116 μm. The rough outer surface of microcapsule is composed of agglomerated PMU nanoparticles. The microcapsules basically exhibit good storage stability at room temperature, and they are chemically stable before the heating temperature is up to approximately 200°C.

Synthesis and properties of a novel high-temperature vinylpyridine-based phthalonitrile polymer

2018 ◽  
Vol 31 (7) ◽  
pp. 820-830 ◽  
Author(s):  
Haifeng Wang ◽  
Zhenjiang Zhang ◽  
Puguang Ji ◽  
Xiaoyan Yu ◽  
Kimiyoshi Naito ◽  
...  
Keyword(s):  
Complex Viscosity ◽  
Mechanical Analysis ◽  
Curing Temperature ◽  
Gravimetric Analysis ◽  
Test Results ◽  
Scanning Calorimetry ◽  
Excellent Thermal Stability ◽  
Rheological Analysis ◽  
Dsc Analyses ◽  
Low Complex

A novel vinylpyridine-based phthalonitrile monomer, 2,6-bis[3-(3,4-dicyanophenoxy)styryl]pyridine (BDSP), was resoundingly produced by a nucleophilic substitution reaction of 2,6-bis(3-hydroxystyryl)pyridine with 4-nitrophthalonitrile in the presence of potassium carbonate. The chemical structure of the synthesized BDSP was confirmed by proton (1H) and carbon (12C) nuclear magnetic resonance (NMR) as well as Fourier transform infrared (FTIR) analysis. The curing behavior of BDSP was investigated by FTIR and differential scanning calorimetry (DSC) analyses. The resin showed a low complex viscosity in the wide processing window between the monomer melting temperature and the curing temperature of the polymer, as discovered by rheological analysis. In addition, the properties of the polymer were studied by thermal gravimetric analysis (TGA) and dynamic mechanical analysis (DMA). Based on the test results, the BDSP polymer demonstrated superior processing performance, excellent thermal stability, outstanding mechanical properties, and low water uptake, and these advanced performance characteristics are critical to many fields.

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.

Melamine Resin-Walled Microcapsules Containing Styrene: Preparation and Characterization

2008 ◽  
Vol 47-50 ◽  
pp. 286-289 ◽  
Author(s):  
Hai Ping Wang ◽  
Yan Chao Yuan ◽  
Min Zhi Rong ◽  
Ming Qiu Zhang
Keyword(s):  
In Situ Polymerization ◽  
Weight Ratio ◽  
Processing Parameters ◽  
Optical Microscope ◽  
Resonance Spectroscopy ◽  
Self Healing ◽  
Melamine Formaldehyde ◽  
Scanning Calorimetry ◽  
Water Emulsion ◽  
Core Content

For purposes of developing a novel self-healing chemistry for polymer composites, melamine-formaldehyde (MF) resin-walled microcapsules containing styrene were prepared by in-situ polymerization in an oil-in-water emulsion. Chemical structure of the microcapsules was identified by Fourier-transform infrared spectroscopy (FTIR) and proton magnetic resonance spectroscopy (1H NMR), respectively. In addition, scanning electron microscope (SEM) and optical microscope (OM) were used to investigate morphology and geometry of the product. The effects of dispersion rate, weight ratio of core to shell and emulsifier concentration were carefully analyzed. It was found that poly(melamine-formaldehyde) (PMF) microcapsules containing styrene were successfully synthesized through the proposed technical route, and their mean diameters fall in the range of 20~71 µm. The rough surface of the microcapsules is composed of agglomerated PMF nanoparticles. Both core content and size of the microcapsule can be adjusted by selecting different processing parameters. The highest loading of styrene in the capsules is about 60% and the emulsifier with lower molecular weight used to result in higher core content. In terms of differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), thermal behavior and storage stability of the capsules were studied. The results indicated that the microcapsules can be handled up to 72 oC.

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