scholarly journals Robust synthesis of epoxy resin-filled microcapsules for application to self-healing materials

2016 ◽  
Vol 374 (2061) ◽  
pp. 20150083 ◽  
Author(s):  
Patryk A. Bolimowski ◽  
Ian P. Bond ◽  
Duncan F. Wass
Keyword(s):  
Epoxy Resin ◽  
Size Distribution ◽  
Fibre Composite ◽  
Diglycidyl Ether ◽  
High Yield ◽  
Self Healing ◽  
Carbon Fibre Composite ◽  
Scanning Calorimetry ◽  
Water Emulsion ◽  
Oil In Water Emulsion

Mechanically and thermally robust microcapsules containing diglycidyl ether bisphenol A-based epoxy resin and a high-boiling-point organic solvent were synthesized in high yield using in situ polymerization of urea and formaldehyde in an oil-in-water emulsion. Microcapsules were characterized in terms of their size and size distribution, shell surface morphology and thermal resistance to the curing cycles of commercially used epoxy polymers. The size distribution of the capsules and characteristics such as shell thickness can be controlled by the specific parameters of microencapsulation, including concentrations of reagents, stirrer speed and sonication. Selected microcapsules, and separated core and shell materials, were analysed using thermogravimetric analysis and differential scanning calorimetry. It is demonstrated that capsules lose minimal 2.5 wt% at temperatures no higher than 120°C. These microcapsules can be applied to self-healing carbon fibre composite structural materials, with preliminary results showing promising performance.

scholarly journals In situ poly(melamine-formaldehyde) microencapsulation of diglycidyl ether of bisphenol-A epoxy and pentaerythritol tetrakis(3-mercaptopropionate) for self-healing applications

2022 ◽  
Vol 1217 (1) ◽  
pp. 012017
Author(s):  
H Ghazali ◽  
K Ghazali ◽  
R Yusoff
Keyword(s):  
Bisphenol A ◽  
Soxhlet Extraction ◽  
Diglycidyl Ether ◽  
Self Healing ◽  
Melamine Formaldehyde ◽  
Scanning Calorimetry ◽  
Water Emulsion ◽  
Core Content ◽  
Oil In Water ◽  
Oil In Water Emulsion

Abstract In this study, microcapsules as potential candidates for self-healing agents were prepared by in situ polymerisation, taking place in oil-in-water emulsion. Poly(melamine-formaldehyde) is employed as shell material and diglycidyl ether of bisphenol A as polymerisable core materials and Pentaerythritol Tetrakis(3-Mercaptopropionate) as its hardener. The geometry, shell features, size distributions, core content, and the reactivity of the microcapsules were studied by scanning electron microscopy (SEM), optical microscopy (OM), Soxhlet extraction method and differential scanning calorimetry (DSC). Microcapsules with different sizes and distributions were obtained by adjusting the stirring speeds during the preparation stage. From the results, it was established that the spherical microcapsules fabricated using this technique, resulted in satisfactory size and shell structure with shell thickness of less than 2 μm. The microcapsules possess high core content at about 90 wt.% for each size range of microcapsules and it was also observed that the viscosity of the core content decreased at an elevated temperature. The results obtained in this work indicate that these microcapsules possess the characteristics that can be potentially used for self-healing applications.

Wear Resistance of Polymers With Encapsulated Epoxy-Amine Self-Healing Chemistry

2015 ◽  
Vol 82 (5) ◽  
Author(s):  
Nay Win Khun ◽  
He Zhang ◽  
Jinglei Yang
Keyword(s):  
Epoxy Resin ◽  
Epoxy Matrix ◽  
In Situ Polymerization ◽  
Wear Test ◽  
Epoxy Composites ◽  
Self Healing ◽  
Matrix Composites ◽  
Water Emulsion ◽  
Healing Agent ◽  
Oil In Water Emulsion

In this study, epoxy resin was microencapsulated through in situ polymerization in an oil-in-water emulsion, and amine was loaded into etched glass bubbles (GBs) as a curing agent for the microencapsulated epoxy resin. The purpose was to develop a two-component-self-healing system. The two healing agent carriers were co-incorporated in the epoxy matrix to form novel epoxy composites for tribological applications. The tribological results clearly showed that an increase in healing agent carrier content significantly decreased the friction and wear of the epoxy composites tested against a 6 mm steel ball under different normal loads. This was due to the self-lubricating and self-healing of the composites with released core liquids via the rupture of healing agent carriers during the wear test. It could be concluded that the co-incorporation of two healing agent carriers was a potential way to achieve a significant improvement in the tribological properties of epoxy matrix composites.

Investigating the relationship between tack and degree of conversion in DGEBA-based epoxy resin cured with dicyandiamide and diuron

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Ali Kuliaei ◽  
Iraj Amiri Amraei ◽  
Seyed Rasoul Mousavi
Keyword(s):  
Epoxy Resin ◽  
Reaction Order ◽  
Theoretical Data ◽  
Cure Kinetics ◽  
Diglycidyl Ether ◽  
Degree Of Conversion ◽  
Ozawa Method ◽  
Heating Rates ◽  
Scanning Calorimetry ◽  
Kinetics Of

Abstract The purpose behind this research was to determine the optimum formulation and investigate the cure kinetics of a diglycidyl ether of bisphenol-A (DGEBA)-based epoxy resin cured by dicyandiamide and diuron for use in prepregs. First, all formulations were examined by the tensile test, and then, the specimens with higher mechanical properties were further investigated by viscometry and tack tests. The cure kinetics of the best formulation (based on tack test) in nonisothermal mode was investigated using differential scanning calorimetry at different heating rates. Kissinger and Ozawa method was used for determining the kinetic parameters of the curing process. The activation energy obtained by this method was 71.43 kJ/mol. The heating rate had no significant effect on the reaction order and the total reaction order was approximately constant ( m + n ≅ 2.1 $m+n\cong 2.1$ ). By comparing the experimental data and the theoretical data obtained by Kissinger and Ozawa method, a good agreement was seen between them. By increasing the degree of conversion, the viscosity decreased; as the degree of conversion increased, so did the slope of viscosity. The results of the tack test also indicated that the highest tack could be obtained with 25% progress of curing.

scholarly journals Preparation and Characterization of Green Epoxy Resin Composites and Its Use in Corrosion Resistance

2018 ◽  
Author(s):  
Abbas Hassan Faris
Keyword(s):  
Bisphenol A ◽  
Epoxy Resin ◽  
Electrolyte Solutions ◽  
Kraft Lignin ◽  
Diglycidyl Ether ◽  
Kraft Pulping ◽  
Palm Tree ◽  
Scanning Calorimetry ◽  
Ft Ir ◽  
Nano Titanium Dioxide

In this work, appropriate alternative for diglycidyl ether bisphenol A (DGEBA) was found to avoid the destructive effects of bisphenol A. Lignin, an aromatic compound from palm tree leaves, was used as a renewable material to synthesize a bio-based epoxy resin. Lignin extracted using Kraft pulping process. Kraft Lignin was epoxidized with epichlorohydrin in alkaline medium. Nano-titanium dioxide was used as filler with ratio of 10% to prepare the green epoxy composite. The structure of the Kraft lignin and lignin-based epoxy resin was proven via Infrared spectra (FT-IR) were recorded using solid KBr disk by testing Shimadzu (FT-IR-8300) spectrophotometer. The thermal properties of the curing process of lignin-based epoxy resin and composite were investigate using Differential scanning calorimetry (DSC) analysis. Potentiodynamic measurements data revealed that the anti-corrosion performance of the lignin based epoxy resin. The study demonstrates successful of epoxidation of Kraft lignin. In addition, lignin based eopxy resin showed effective inhibitor for carbon steel in 3.5 wt. % NaCl electrolyte solutions

scholarly journals Preparation of 5-Flurouracil Loaded Microspheres

2017 ◽  
Vol 6 (3) ◽  
pp. 185
Author(s):  
Chen Hong Dan ◽  
Yin Jing Bo ◽  
Chen Xue Si ◽  
Luo Kun ◽  
Cao Tian
Keyword(s):  
Spherical Surface ◽  
Silica Content ◽  
High Yield ◽  
Lower Amount ◽  
Water Evaporation ◽  
Nano Silica ◽  
Water Emulsion ◽  
Drug Content ◽  
Oil In Water ◽  
Oil In Water Emulsion

Polylactide (PLA) is a kind of biodegradable and biocompatible material. In recent years, polylactide (PLA) and its copolymers have received significant attention from researchers. 5-Fluorouracil (5-Fu) is an antimetabolite of the pyrimidine analog type and is widely used for cancer treatment. As many other kinds of hydrophilic medicines, 5-Fu is difficult to be encapsulated by a water-in-oil-in-water emulsion solvent evaporation technique and the drug content is affected by the volume of the internal phase the increase in which resultes in a decrease in the yield of microspheres. In this study, 5-Fu loaded PLA microspheres which has quite high yield were prepared by a particular oil-in-water evaporation method. During the process of microspheres preparation, nano-silica was used in order to achieve high drug content. The size and morphology of the microspheres were observed by the scanning electron microscope (SEM). According to the results, these microspheres have smooth, spherical surface structure, with no apparent evidence of collapsing which can ensure the even release of the drug. Their size depends on the concentration of dispersed phase and gelatin and the size of nano-silica particles. The nano-silica content was determined by thermogravimetry analyzer (TGA) and by a spectrophotometer, the 5-Fu content in the microspheres could be calculated. It was shown that the PLA microspheres containing lower amount of nano-silica have higher ability to incorporate 5-Fu.

Soft ionisation analysis of evolved gas for oxidative decomposition of an epoxy resin/carbon fibre composite

2007 ◽  
Vol 454 (2) ◽  
pp. 109-115 ◽  
Author(s):  
G. Jiang ◽  
S.J. Pickering ◽  
G.S. Walker ◽  
N. Bowering ◽  
K.H. Wong ◽  
...  
Keyword(s):  
Carbon Fibre ◽  
Epoxy Resin ◽  
Fibre Composite ◽  
Carbon Fibre Composite ◽  
Evolved Gas ◽  
Oxidative Decomposition

Curing study and evaluation of epoxy resin with amine functional chloroaniline acetaldehyde condensate

2015 ◽  
Vol 44 (1) ◽  
pp. 19-25
Author(s):  
T. Maity ◽  
B.C. Samanta
Keyword(s):  
Mechanical Properties ◽  
Molecular Weight ◽  
Epoxy Resin ◽  
Ph Value ◽  
Kinetic Studies ◽  
Diglycidyl Ether ◽  
Curing Agent ◽  
Scanning Calorimetry ◽  
Content Type ◽  
Curing Reaction

Purpose – The purpose of this paper was to check effectiveness of amine functional chloroaniline acetaldehyde condensate (AFCAC) as a new curing agent for diglycidyl ether of bisphenol A (DGEBA) resin. For this purpose, first AFCAC was synthesised, characterised and then curing reaction was carried out. Design/methodology/approach – Equimolecular mixture of AFCAC and DGEBA was subjected to curing reaction, and the reaction was followed by differential scanning calorimetry (DSC) analysis. The kinetic studies of this curing reaction were also carried out from those DSC exotherms. The mechanical properties, dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA) of cured epoxy were also reported. Findings – DSC results reflected the effective first order curing reaction of AFCAC with epoxy resin. Mechanical properties reflected appreciable rigidity of AFCAC cured epoxy matrix and TGA showed that the cured epoxy networks were thermally stable up to around 297°C. Research limitations/implications – The curing agent AFCAC was synthesised by using chloroaniline and acetaldehyde in acid medium. There are some limitations for this procedure. The synthetic procedure is pH dependent. So reaction cannot be done at any pH value. The reaction must also be carried out at room temperature without any heating. To obtain low molecular weight curing agent, chloroaniline and acetaldehyde cannot be taken in equimolecular ratio because the equimolecular mixture of them produces high molecular weight condensate. This was shown in our previous publication. Some implications are also there. By changing amine and aldehyde other curing agents could be synthesised and the curing efficiency of those for epoxy resin could also be studied. Originality/value – Experimental results revealed the greater suitability of AFCAC as curing agent for DGEBA resin and novelty of AFCAC cured matrix in the field of protective coating, casting, adhesives, etc.

Synthesis of Carboxymethyl Starch-Bio-Based Epoxy Resin and their Impact on Mechanical Properties

2020 ◽  
Vol 234 (11-12) ◽  
pp. 1759-1769 ◽  
Author(s):  
Tariq Aziz ◽  
Hong Fan ◽  
Farman Ullah Khan ◽  
Roh Ullah ◽  
Fazal Haq ◽  
...  
Keyword(s):  
Epoxy Resin ◽  
Interfacial Adhesion ◽  
Diglycidyl Ether ◽  
Scanning Calorimetry ◽  
Adhesive Properties ◽  
Toxic Side Effect ◽  
Dimethyl Siloxane ◽  
Naturally Occurring ◽  
Lower Viscosity ◽  
Chain Lengths

AbstractIn the current research, we observed numerous suggestions are promoting the use of bio-based epoxy resins, replacing the petroleum-based products like Diglycidyl ether of bisphenol A type epoxy resin DGEBA. With the passage of time, the impending challenges include preparation of environmentally-friendly epoxy with minimum toxic side effect and improved properties. Therefore, we describe a very useful method for preparing new silicone-bridged dimethyl siloxane monomers in high quantity, derived from naturally occurring eugenol. By putting the methyl siloxane, computed with different chain lengths into their molecular backbone. Such epoxy monomers have different molecular structure with high purity. This dimethyl siloxane epoxy, with lower viscosity than commercial DGEBA epoxy, has superior thermal properties, which were evaluated using differential scanning calorimetry DSC. Modification of CMS increases the hydrophilicity. Bio-based epoxy (self-prepared) resin improved adhesive properties, with the help of modified CMS. This study presents a very easy and effective chemical modification to enhance interfacial adhesion composites with superior properties.

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.

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