scholarly journals TO/TMMP-TMTGE Double-Healing Composite Containing a Transesterification Reversible Matrix and Tung Oil-Loaded Microcapsules for Active Self-Healing

Polymers ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 1127 ◽  
Author(s):  
Nan Zheng ◽  
Jie Liu ◽  
Wenge Li
Keyword(s):  
Particle Size ◽  
Click Reaction ◽  
Average Particle Size ◽  
Core Shell ◽  
Average Particle ◽  
Self Healing ◽  
Tung Oil ◽  
The Core ◽  
Core Content ◽  
Healing System

Thermoset epoxies are widely used due to their excellent properties, but conventional epoxies require a complicated and time-consuming curing process, and they cannot self-healed, which limits their applications in self-healing materials. Extrinsic and intrinsic self-healing materials are applied in various fields due to their respective characteristics, but there is a lack of comparison between the two types of healing systems. Based on this, a thiol-epoxide click reaction catalyzed by an organic base was introduced to achieve the efficient preparation of thiol-epoxy. Furthermore, tung oil (TO)-loaded microcapsules were introduced into the thiol-epoxy matrix of dynamic transesterification to obtain a TO/TMMP-TMTGE self-healing composite with an intrinsic–extrinsic double-healing system. For comparison, a TMMP-TMTGE self-healing material with an intrinsic healing system was also prepared, which contained only thiol and epoxy curing chemistries. The effect of the core/shell ratio on the morphology, average particle size, and core content of TO-loaded microcapsules was studied. It was found that when the core/shell ratio was 3:1, the average particle size of the microcapsules was about 99.8 μm, and the microcapsules showed good monodispersity, as well as a core content of about 58.91%. The differential scanning calorimetry (DSC) results showed that the TO core was successfully encapsulated and remained effective after encapsulation. Furthermore, scanning electron microscopy (SEM), atomic force microscopy (AFM), tensile tests, and electrochemical tests were carried out for the two types of self-healing materials. The results showed that the TO/TMMP-TMTGE composite and TMMP-TMTGE material both had self-healing properties. In addition, the TO/TMMP-TMTGE composite was superior to the TMMP-TMTGE material due to its better self-healing performance, mechanical strength, and corrosion protection performance.

Synthesis of Crosslinkable Core-Shell Emulsion and Rheology of the Core-Shell/Amine Crosslinking Process

2009 ◽  
Vol 79-82 ◽  
pp. 2203-2206
Author(s):  
Jia Lu ◽  
Allan J. Easteal ◽  
Debes Bhattacharyya ◽  
Clive J. Bolt ◽  
Neil R. Edmonds
Keyword(s):  
Particle Size ◽  
Average Particle Size ◽  
Complex Viscosity ◽  
Shell Morphology ◽  
Core Shell ◽  
Average Particle ◽  
Crosslinking Reaction ◽  
Shear Moduli ◽  
The Core ◽  
Wide Range

Starve feed and semi-continuous seed emulsion polymerization were used to control the morphology of core shell latex particles with a vinyl acetate (VAc)/vinyl ester of versatic acid 10(VeoVa10) copolymer core surrounded by a poly(glycidyl methacrylate) (PGMA) shell. Pure core and core-shell structures were confirmed by TEM. The results suggest that core-shell morphology of the two stage emulsion was favoured by higher concentration of emulsifier in the seed latex: the particle size distribution of core-shell latex was broader than that of the core latex, and the average particle size of core-shell latex was larger than that of the core latex. The core-shell structure was not produced using seed emulsion with emulsifier concentration at or below the critical micelle concentration. The core shell emulsion containing epoxy functional group with added ethylene diamine showed an abrupt increase in dynamic shear moduli, G' and G'' and complex viscosity η* (several orders of magnitude) at about 35oC, during temperature ramps, over a wide range of angular frequencies. The time ramps showed that the crosslinking reaction did not occur at 15oC for the core-shell emulsion/amine system. The time for gel formation decreased with increase in temperature.

Effect of Core/Shell Ratio on Performance of Paraffin/Polyurea Phase Change Microencapsules

2014 ◽  
Vol 556-562 ◽  
pp. 32-35 ◽  
Author(s):  
Wu Sheng Luo ◽  
Sheng Fei Yu ◽  
Jie Min Zhou
Keyword(s):  
Particle Size ◽  
Phase Change ◽  
Interfacial Polymerization ◽  
Average Particle Size ◽  
Energy Performance ◽  
Toluene Diisocyanate ◽  
Core Shell ◽  
Average Particle ◽  
Mass Ratio ◽  
Solid Liquid

In this paper, paraffin/polyurea (PU) phase change microencapsules were prepared through an interfacial polymerization method using composite paraffin with solid/liquid mass ratio 3:7 as core materials, 2,4 toluene diisocyanate (TDI) and ethylenediamine (EDA) as monomers, NP-10 as an emulsifier. It was explored the effect of the monomer mass ratio mEDA: mTDIon the yield of hollow PU microcapsules, and the effect of core/shell ratio on the particle size and coating efficiency and storage-energy performance of paraffin/PU phase change microencapsules. The experimental results showed the PU yield is increasing with the increasing of EDA:TDI mass ratio until 0.5:1,then keeps the constant. Paraffin/PU phase change microencapsules prepared with the core-shell ratio of 2:1 have better performance: the melting point of 28.1°C, the enthalpy of 58.4KJ/Kg, encapsulation efficiency of 87.5%, the average particle size of 4.32μm, and the uniform particle size distribution.

Magnetic Pt single and double core-shell structures for the catalytic selective hydrogenation of cinnmaladehyde

2020 ◽  
Vol 92 (3) ◽  
pp. 413-427 ◽  
Author(s):  
Robinson B. Dinamarca ◽  
Rodrigo Espinoza-González ◽  
Cristian H. Campos ◽  
Gina Pecchi
Keyword(s):  
Particle Size ◽  
Average Particle Size ◽  
Pt Nanoparticles ◽  
Magnetic Core ◽  
Shell Structures ◽  
Pt Catalyst ◽  
Core Shell ◽  
Average Particle ◽  
Cinnamyl Alcohol ◽  
Metal Support Interaction

AbstractThis study reports the catalytic preparation, characterization, and evaluation of nanoscale core-shell structures with a γ-Fe2O3 core covered by a SiO2 monoshell or by a SiO2@TiO2 multishell as a support for Pt nanoparticles (NPs) to synthesize active and operationally stable catalysts for selective liquid-phase cinnamaldehyde hydrogenation. The structures were designed with a magnetic core so they could be easily recovered from the catalytic bed by simple magnetization and with a SiO2 monoshell or a SiO2@TiO2 multishell to protect the magnetic core. At the same time, this study details the effect of the shell on the catalytic performance. Moreover, the effect of particle size on the selective production of cinnamyl alcohol was studied by preparing two families of catalysts with metal loadings of 1 wt% and 5 wt% Pt with respect to the core-shell. The particle size effect enabled the Fe2O3@SiO2-5%Pt system, with an average particle size of 5.6 nm, to reach 100 % conversion of cinnamaldehyde at 300 min of reaction, producing cinnamyl alcohol with 90 % selectivity; this result differed greatly from that of the Fe2O3@SiO2-1%Pt (dPt = 3.5 nm) system, which reached a maximum conversion at 600 min with 49 % selectivity for the product of interest. However, the Fe2O3@SiO2@TiO2-x%Pt systems showed lower levels of conversion and selectivity compared to those of the Fe2O3@SiO2-x%Pt catalysts, which is attributed to the fact that average metal particle sizes below 5.0 nm were obtained in both cases. After reduction in H2 at 773 K, the Fe2O3@SiO2@TiO2-1%Pt catalyst showed deactivation, reaching 10 % conversion at 600 min of reaction and 60 % selectivity for the product of interest. However, the reduced Fe2O3@SiO2@TiO2-5%Pt system showed 98 % conversion with 95 % selectivity for cinnamyl alcohol at 24 h of operation; the increase in selectivity is attributed to the combined effects of the increase in average particle size (~7.5 nm) and the presence of strong metal-support interaction – SMSI – effects after reduction. Finally, the most selective systems were tested for operational stability, where the Fe2O3@SiO2@-5%Pt catalyst could be reused in three consecutive operating cycles while maintaining its activity and selectivity for cinnamyl alcohol – unlike the Fe2O3@SiO2@TiO2-5%Pt reduced system, which was deactivated after the third reaction cycle due to active phase leaching.

Synthesis and Characterization of Co3O4-MnxCo3-xO4 Core-Shell Nanoparticles

MRS Advances ◽  
2018 ◽  
Vol 3 (47-48) ◽  
pp. 2899-2904
Author(s):  
Ning Bian ◽  
Robert A. Mayanovic ◽  
Mourad Benamara
Keyword(s):  
Electron Microscopy ◽  
Average Particle Size ◽  
Synthesis Method ◽  
Blocking Temperature ◽  
Core Shell ◽  
Average Particle ◽  
Shell Nanoparticles ◽  
X Ray ◽  
The Core ◽  
Core Shell Nanoparticles

ABSTRACTThe mixed-valence oxide Co3O4 nanoparticles, having the normal spinel structure, possess large surface area, active-site surface adsorption properties, and fast ion diffusivities. Consequently, they are widely used in lithium-ion batteries, as well as for gas sensing and heterogeneous catalysis applications. In our research, we use a two-step method to synthesize Co3O4–based core-shell nanoparticles (CSNs). Cobalt oxide (Co3O4) nanoparticles were successfully synthesized using a wet synthesis method employing KOH and cobalt acetate. Manganese was incorporated into the Co3O4 structure to synthesize inverted Co3O4@MnxCo3-xO4 CSNs using a hydrothermal method. By adjustment of pH value, we obtained two different morphologies of CSNs, one resulting in pseudo-spherical and octahedron-shaped nanoparticles (PS type) whereas the second type predominantly have a nanoplate (NP type) morphology. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and x-ray photoelectron spectroscopy (XPS) have been performed in order to determine the morphological and structural properties of our CSNs, whereas the magnetic properties have been characterized using a superconducting quantum interference device (SQUID) magnetometer. XRD and TEM results show that the CSNs have the same spinel crystal structure throughout the core and shell with an average particle size of ∼19.8 nm. Our Co3O4 nanoparticles, as measured prior to CSN formation, are shown to be antiferromagnetic (AFM) in nature as shown by the magnetization data. Our SQUID data indicate that the core-shell nanoparticles have both AFM (due to the Co3O4 core) and ferrimagnetic properties (of the shell) with a coercivity field of 300 Oe and 150 Oe at 5 K for the PS and NP samples, respectively. The magnetization vs temperature data show a spin order-disorder transition at ∼33 K and a superparamagnetic blocking temperature of ∼90 K for both batches.

scholarly journals Self-Healing Performance of Smart Polymeric Coatings Modified with Tung Oil and Linalyl Acetate

Polymers ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1609
Author(s):  
Norhan Ashraf Ismail ◽  
Adnan Khan ◽  
Eman Fayyad ◽  
Ramazan Kahraman ◽  
Aboubakr M. Abdullah ◽  
...  
Keyword(s):  
Electrochemical Impedance ◽  
In Situ Polymerization ◽  
Urea Formaldehyde ◽  
Average Particle Size ◽  
Average Particle ◽  
Self Healing ◽  
Polymeric Coatings ◽  
Linalyl Acetate ◽  
Tung Oil ◽  
Smart Coatings

This work focuses on the synthesis and characterization of polymeric smart self-healing coatings. A comparison of structural, thermal, and self-healing properties of two different polymeric coatings comprising distinct self-healing agents (tung oil and linalyl acetate) is studied to elucidate the role of self-healing agents in corrosion protection. Towards this direction, urea-formaldehyde microcapsules (UFMCs) loaded with tung oil (TMMCs) and linalyl acetate (LMMCs) were synthesized using the in-situ polymerization method. The synthesis of both LMMCs and TMMCs under identical experimental conditions (900 rpm, 55 °C) has resulted in a similar average particle size range (63–125 µm). The polymeric smart self-healing coatings were developed by reinforcing a polymeric matrix separately with a fixed amount of LMMCs (3 wt.% and 5 wt.%), and TMMCs (3 wt.% and 5 wt.%) referred to as LMCOATs and TMCOATs, respectively. The development of smart coatings (LMCOATs and TMCOATs) contributes to achieving decent thermal stability up to 450 °C. Electrochemical impedance spectroscopy (EIS) analysis indicates that the corrosion resistance of smart coatings increases with increasing concentration of the microcapsules (TMMCs, LMMCs) in the epoxy matrix reaching ~1 GΩ. As a comparison, LMCOATs containing 5 wt.% LMMCs demonstrate the best stability in the barrier properties than other developed coatings and can be considered for many potential applications.

Synthesis and Characterization of PBA/aPS Core-Shell Latex Particles

2013 ◽  
Vol 631-632 ◽  
pp. 588-591
Author(s):  
Ming Jue Li ◽  
Ying Yan Diao ◽  
Xi Jun Liu
Keyword(s):  
Particle Size ◽  
Shell Structure ◽  
Average Particle Size ◽  
Morphological Structure ◽  
Shell Morphology ◽  
Polymerization Process ◽  
Core Shell ◽  
Average Particle ◽  
Latex Particles ◽  
Core Shell Structure

The core-shell structure copolymer of PBA/PS was prepared using pre-emulsion and semi-continues polymerization process. The particle size of core-shell latex and the St conversion of shell monomer were affected by emulsifier, initiator, pH and temperature etc. Meanwhile, the laser particle size analyzer, transmission electron microscope and other test methods were utilized to study latex particle average particle size, size distribution and morphological structure, respectively. The kinetics of polymerization was investigated. Well-defined core-shell structure and narrow particle sizedistribution could be achieved under starved conditions of monomer feeding. By the means of TEM found that PBA/PS latex particles had clearly core/shell morphology.

scholarly journals Effect of Silica Size and Content on Superamphiphobic Properties of Silica-Fluoropolymer Core-Shell Coatings

Polymers ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 2864
Author(s):  
Jiyoung Lee ◽  
Ha Soo Hwang ◽  
Tien N. H. Lo ◽  
Won-Gun Koh ◽  
In Park
Keyword(s):  
Heat Treatment ◽  
Average Particle Size ◽  
Composite Layer ◽  
Hierarchical Structures ◽  
Spray Coating ◽  
Silica Content ◽  
Core Shell ◽  
Average Particle ◽  
The Core ◽  
Shell Particles

We present a facile approach to fabricate superamphiphobic surfaces by spray coating silica-fluoropolymer core-shell particles without substrate pretreatment with an additional binder resin. A series of SiO2@poly(1H,1H,2H,2H-heptadecafluorodecyl methacrylate) (SiO2@PFMA) core-shell particles with core particles of different sizes were prepared via thiol-lactam initiated radical polymerization (TLIRP). The surface of each SiO2 particle with an average particle size of 12, 80, 150, and 350 nm was modified with (3-mercaptopropyl) trimethoxysilane and used as a seed for TLIRP. The SiO2@PFMA particles with various SiO2 sizes and contents were coated on aluminum substrates by a spray gun and then thermally treated to form a stable, rough composite layer. During the spray coating, the core-shell particles were aggregated by rapid evaporation of the solvent and then irregularly adhered to the substrate resulting in hierarchical structures. In the case of SiO2@PFMAs with low SiO2 contents, the roughness created mainly by the polymer shell disappeared during heat treatment. However, the substrates coated with SiO2@PFMAs with high SiO2 contents maintained the roughness even after heat treatment. The core-shell particles prepared with 12 nm SiO2 formed a stable superamphiphobic surface. The water/hexadecane contact and sliding angles on an aluminum plate coated with SiO2@PFMA, prepared using 12 nm silica at 46 wt% silica content (12 nm-SiO2(46)@PFMA), were 178.5°/159.2° and 1°/7°, respectively. The cross-cut tape test showed that adhesion between the 12nm-SiO2(46)@PFMA and the aluminum substrate was classified as 5B. A glass surface spray-coated with the core-shell composite particles exhibited transparent superhydrophobicity and translucent superamphiphobicity by controlling the concentration of the coating solution.

The Effects of Synthesis Conditions on PUF Microcapsule Morphology

2012 ◽  
Vol 217-219 ◽  
pp. 661-665
Author(s):  
Ning Ning Hu ◽  
Hao Han Huang ◽  
Hong Zhi Cui
Keyword(s):  
Particle Size ◽  
In Situ Polymerization ◽  
Average Particle Size ◽  
Wall Material ◽  
Average Particle ◽  
Self Healing ◽  
Test Results ◽  
Synthesis Conditions ◽  
Wide Range

In this paper, self-healing PUF microcapsules were prepared by in situ polymerization. The test results show that: 1) the ratio of core/wall material can had a significant effect on the average particle size of microcapsules. The ratio happens to be 1.0 to 1.0, best coating, relatively dense surface can be achieved. When the ratio reaches 1.4 to 1.0, the microcapsules have worst coating, particle size, distribution of wide range, and comparatively rough surface. When the ratio is 0.8 to 1.0 or 1.2 to 1.0, preferable coating, uniform particle size and its distribution, as well as smooth and dense surface can be obtained. 2) The faster the stirring speed, the smaller the particle size of microcapsule will be. And the size becomes bigger and varied with the stirring speed decreasing.

Determination of grinding parameters of fenugreek seed

1970 ◽  
Vol 26 (1) ◽  
pp. 16 ◽  
Author(s):  
S Balasubramanian ◽  
Rajkumar Rajkumar ◽  
K K Singh
Keyword(s):  
Particle Size ◽  
Energy Consumption ◽  
Moisture Content ◽  
Specific Energy ◽  
Feed Rate ◽  
Average Particle Size ◽  
Specific Energy Consumption ◽  
Average Particle ◽  
Fenugreek Seeds ◽  
Fenugreek Seed

Experiment to identify ambient grinding conditions and energy consumed was conducted for fenugreek. Fenugreek seeds at three moisture content (5.1%, 11.5% and 17.3%, d.b.) were ground using a micro pulverizer hammer mill with different grinding screen openings (0.5, 1.0 and 1.5 mm) and feed rate (8, 16 and 24 kg h-1) at 3000 rpm. Physical properties of fenugreek seeds were also determined. Specific energy consumptions were found to decrease from 204.67 to 23.09 kJ kg-1 for increasing levels of feed rate and grinder screen openings. On the other hand specific energy consumption increased with increasing moisture content. The highest specific energy consumption was recorded for 17.3% moisture content and 8 kg h-1 feed rate with 0.5 mm screen opening. Average particle size decreased from 1.06 to 0.39 mm with increase of moisture content and grinder screen opening. It has been observed that the average particle size was minimum at 0.5 mm screen opening and 8 kg h-1 feed rate at lower moisture content. Bond’s work index and Kick’s constant were found to increase from 8.97 to 950.92 kWh kg-1 and 0.932 to 78.851 kWh kg-1 with the increase of moisture content, feed rate and grinder screen opening, respectively. Size reduction ratio and grinding effectiveness of fenugreek seed were found to decrease from 4.11 to 1.61 and 0.0118 to 0.0018 with the increase of moisture content, feed rate and grinder screen opening, respectively. The loose and compact bulk densities varied from 219.2 to 719.4 kg m-3 and 137.3 to 736.2 kg m-3, respectively.  

Formulating SLN and NLC as Innovative Drug Delivery Systems for Non-Invasive Routes of Drug Administration

2020 ◽  
Vol 27 (22) ◽  
pp. 3623-3656 ◽  
Author(s):  
Bruno Fonseca-Santos ◽  
Patrícia Bento Silva ◽  
Roberta Balansin Rigon ◽  
Mariana Rillo Sato ◽  
Marlus Chorilli
Keyword(s):  
Drug Delivery ◽  
Particle Size ◽  
Drug Release ◽  
Drug Loading ◽  
Average Particle Size ◽  
Delivery Systems ◽  
Average Particle ◽  
Minor Importance ◽  
Routes Of Administration ◽  
Non Invasive

Colloidal carriers diverge depending on their composition, ability to incorporate drugs and applicability, but the common feature is the small average particle size. Among the carriers with the potential nanostructured drug delivery application there are SLN and NLC. These nanostructured systems consist of complex lipids and highly purified mixtures of glycerides having varying particle size. Also, these systems have shown physical stability, protection capacity of unstable drugs, release control ability, excellent tolerability, possibility of vectorization, and no reported production problems related to large-scale. Several production procedures can be applied to achieve high association efficiency between the bioactive and the carrier, depending on the physicochemical properties of both, as well as on the production procedure applied. The whole set of unique advantages such as enhanced drug loading capacity, prevention of drug expulsion, leads to more flexibility for modulation of drug release and makes Lipid-based nanocarriers (LNCs) versatile delivery system for various routes of administration. The route of administration has a significant impact on the therapeutic outcome of a drug. Thus, the non-invasive routes, which were of minor importance as parts of drug delivery in the past, have assumed added importance drugs, proteins, peptides and biopharmaceuticals drug delivery and these include nasal, buccal, vaginal and transdermal routes. The objective of this paper is to present the state of the art concerning the application of the lipid nanocarriers designated for non-invasive routes of administration. In this manner, this review presents an innovative technological platform to develop nanostructured delivery systems with great versatility of application in non-invasive routes of administration and targeting drug release.

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