scholarly journals Recyclable High-Performance Epoxy-Anhydride Resins with DMP-30 as the Catalyst of Transesterification Reactions

Polymers ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 296
Author(s):  
Wenzhe Zhao ◽  
Le An ◽  
Shujuan Wang
Keyword(s):  
Epoxy Resins ◽  
High Performance ◽  
Low Cost ◽  
Epoxy Oligomer ◽  
Diglycidyl Ether ◽  
Hydroxyl Groups ◽  
Excellent Performance ◽  
Simple Method ◽  
Amine Groups ◽  
Alcoholic Hydroxyl

Epoxy-anhydride resins are widely used in engineering fields due to their excellent performance. However, the insolubility and infusibility make the recycling of epoxy resins challenging. The development of degradable epoxy resins with stable covalent networks provides an efficient solution to the recycling of thermosets. In this paper, 2,4,6-tris(dimethylaminomethyl)phenol (DMP-30) is incorporated into the epoxy-glutaric anhydride (GA) system to prepare high-performance epoxy resins that can be recycled below 200 °C at ordinary pressure via ethylene glycol (EG) participated transesterification. The tertiary amine groups in DMP-30 can catalyze the curing reaction of epoxy and anhydride, as well as the transesterification between ester bonds and alcoholic hydroxyl groups. Compared with early recyclable anhydride-cured epoxy resins, the preparation and recycling of diglycidyl ether of bisphenol A (DGEBA)/GA/DMP-30 systems do not need any special catalysts such as TBD, Zn(Ac)2, etc., which are usually expensive, toxic, and have poor compatibility with other compounds. The resulting resins have glass transition temperatures and strengths similar to those of conventional epoxy resins. The influences of GA content, DMP-30 content, and temperature on the dissolution rate were studied. The decomposed epoxy oligomer (DEO) is further used as a reaction ingredient to prepare new resins. It is found that the DEO can improve the toughness of epoxy resins significantly. This work provides a simple method to prepare readily recyclable epoxy resins, which is of low-cost and easy to implement.

scholarly journals Tuning Dielectric Loss of SiO2@CNTs for Electromagnetic Wave Absorption

Nanomaterials ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 2636
Author(s):  
Fenghui Cao ◽  
Jia Xu ◽  
Xinci Zhang ◽  
Bei Li ◽  
Xiao Zhang ◽  
...  
Keyword(s):  
Electromagnetic Wave ◽  
High Performance ◽  
Low Cost ◽  
Impedance Matching ◽  
3D Structure ◽  
Carbon Matrix ◽  
Current Approach ◽  
Matrix Composites ◽  
Simple Method ◽  
Absorption Performance

We developed a simple method to fabricate SiO2-sphere-supported N-doped CNTs (NCNTs) for electromagnetic wave (EMW) absorption. EMW absorption was tuned by adsorption of the organic agent on the precursor of the catalysts. The experimental results show that the conductivity loss and polarization loss of the sample are improved. Meanwhile, the impedance matching characteristics can also be adjusted. When the matching thickness was only 1.5 mm, the optimal 3D structure shows excellent EMW absorption performance, which is better than most magnetic carbon matrix composites. Our current approach opens up an effective way to develop low-cost, high-performance EMW absorbers.

scholarly journals Improved Mechanical and Electrochemical Properties of XNBR Dielectric Elastomer Actuator by Poly(dopamine) Functionalized Graphene Nano-Sheets

Polymers ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 218 ◽  
Author(s):  
Dan Yang ◽  
Xinxin Kong ◽  
Yufeng Ni ◽  
Mengnan Ruan ◽  
Shuo Huang ◽  
...  
Keyword(s):  
Electrochemical Properties ◽  
High Performance ◽  
Low Cost ◽  
Dielectric Strength ◽  
Dielectric Elastomer ◽  
Hydroxyl Groups ◽  
Butadiene Rubber ◽  
Functionalized Graphene ◽  
Filler Dispersion ◽  
Phenolic Hydroxyl Groups

In this work, graphene nano-sheets (GNS) functionalized with poly(dopamine) (PDA) (denoted as GNS-PDA) were dispersed in a carboxylated nitrile butadiene rubber (XNBR) matrix to obtain excellent dielectric composites via latex mixing. Because hydrogen bonds were formed between –COOH groups of XNBR and phenolic hydroxyl groups of PDA, the encapsulation of GNS-PDA around XNBR latex particles was achieved, and led to a segregated network structure of filler formed in the GNS-PDA/XNBR composite. Thus, the XNBR composite filled with GNS-PDA showed improved filler dispersion, enhanced dielectric constant and dielectric strength, and decreased conductivity compared with the XNBR composite filled with pristine GNS. Finally, the GNS-PDA/XNBR composite displayed an actuated strain of 2.4% at 18 kV/mm, and this actuated strain was much larger than that of pure XNBR (1.3%) at the same electric field. This simple, environmentally friendly, low-cost, and effective method provides a promising route for obtaining a high-performance dielectric elastomer with improved mechanical and electrochemical properties.

Porous micro-spherical LiFePO4/CNT nanocomposite for high-performance Li-ion battery cathode material

RSC Advances ◽  
2015 ◽  
Vol 5 (47) ◽  
pp. 37830-37836 ◽  
Author(s):  
Wei Wei ◽  
Linlin Guo ◽  
Xiaoyang Qiu ◽  
Peng Qu ◽  
Maotian Xu ◽  
...  
Keyword(s):  
Electrochemical Performance ◽  
Cathode Material ◽  
High Performance ◽  
Large Scale ◽  
Low Cost ◽  
Scale Production ◽  
Li Ion Battery ◽  
Excellent Performance ◽  
Large Scale Production ◽  
Li Ion

Although many routes have been developed that can efficiently improve the electrochemical performance of LiFePO4 cathodes, few of them meet the urgent industrial requirements of large-scale production, low cost and excellent performance.

Analysis of the effect and mechanism of microwave curing on the chemical shrinkage of epoxy resins

2016 ◽  
Vol 29 (10) ◽  
pp. 1165-1174 ◽  
Author(s):  
Xiaochun Wu ◽  
Yingguang Li ◽  
Nanya Li ◽  
Jing Zhou ◽  
Xiaozhong Hao
Keyword(s):  
Epoxy Resins ◽  
Diglycidyl Ether ◽  
Heating Process ◽  
Hydroxyl Groups ◽  
Chemical Shrinkage ◽  
Positron Annihilation Lifetime ◽  
Microwave Curing ◽  
Diaminodiphenyl Sulfone ◽  
Influencing Mechanism ◽  
Lower Tensile Strength

The microwave cure–induced chemical shrinkage of epoxy resins in composite materials was researched in this article. Four kinds of epoxy resins were cured using the microwave and thermal heating process. An improved device containing fiber Bragg grating sensors was applied to accurately measure the chemical shrinkage–induced linear strains in those samples. Experimental results indicated that the chemical shrinkage of diglycidyl ether of bisphenol A (DGEBA)/polyetheramine (PEA) and tetraglycidyl diaminodiphenylmethane/4,4′-diaminodiphenyl sulfone epoxy resins was significantly reduced by microwave curing, and the reductions about 37.1 and 38.4% were achieved compared with the thermal-cured counterparts. However, the chemical shrinkage of the thermal- and microwave-cured samples was almost the same for DGEBA/methyl tetrahydrophthalic anhydride and DGEBA/dicyandiamide epoxies. In order to analyze the influencing mechanism of microwaves on the chemical shrinkage, the chemical structure of various samples was characterized by using Fourier-transform infrared spectroscopy, and the free volume was measured by positron annihilation lifetime spectrometer. It was found that microwaves can greatly decrease the contents of hydroxyl groups in epoxy resins, leading to the reduction of the chemical shrinkage. Furthermore, the mechanical properties of both microwave- and thermal-cured DGEBA/PEA epoxies were studied, and the results showed that the microwave-cured specimens have a higher impact strength but a lower tensile strength.

scholarly journals MECHANICAL CHARACTERISTICS FOR COMPOSITE MATERIALS USING COMMERCIAL EPOXY RESINS AND DIFFERENT FILLERS

2021 ◽  
Vol 56 (5) ◽  
pp. 179-185
Author(s):  
Omar A. Amin ◽  
S. A. Hassan ◽  
M. A. Sadek ◽  
M. A. Radwan ◽  
Hany A. Elazab
Keyword(s):  
Mechanical Properties ◽  
Epoxy Resin ◽  
Epoxy Resins ◽  
Three Dimensional ◽  
Mechanical Tests ◽  
Diglycidyl Ether ◽  
Dimensional Structure ◽  
Polymeric Chain ◽  
Hydroxyl Groups ◽  
Different Types

Epoxy resins are thermoset polymers that consist of epoxide groups in their molecular structure. It shows many attractive characteristics like strong adhesion, excellent mechanical strength, low shrinkage, excellent insulator, excellent chemical stability for acidic and basic environments, and microbial resistance due to the presence of hydroxyl groups and ether bonds and its three-dimensional structure. Many of these characteristics can be modified by adding strong bindings in the polymeric chain to give more improved characteristics. This research aims to prepare a composite material using epoxy resin and different types of fillers to achieve resistance to high kinetic energy impact. Experimental work is focused on preparing cured epoxy resin samples by using diglycidyl ether of bisphenol A (DGEBA) resin with tertiary amine as a hardener. In order to obtain different samples with different properties, we add different types of fillers, then mechanical tests are used to measure the mechanical properties of the samples. The results have proved that fiberglass is the best filler added to epoxy resins to improve its mechanical properties.

scholarly journals Investigation of bisphenol a diglycidyl ether, bisphenol f diglycidyl ether and their hydroxy and chlorohydroxy derivatives stability in water-based food simulants

2004 ◽  
Vol 22 (SI - Chem. Reactions in Foods V) ◽  
pp. S272-S275
Author(s):  
I. Poustková ◽  
J. Dobiáš ◽  
J. Poustka ◽  
M. Voldřich
Keyword(s):  
Acetic Acid ◽  
Bisphenol A ◽  
Epoxy Resins ◽  
High Performance ◽  
Diglycidyl Ether ◽  
Phase Gradient ◽  
Bisphenol F ◽  
Food Simulants ◽  
Bisphenol A Diglycidyl Ether ◽  
Food Simulant

Varnishes used as the inner coatings of food cans are often based on epoxy resins or vinylic organosols. The epoxy resins can be produced from bisphenol A (BPA) and bisphenol F (BPF) and they also contain bisphenol A diglycidyl ether (BADGE) of bisphenol F diglycidyl ether (BFDGE) as stabilising components. These compounds may break down during storage and also by influence of food simulants. The stability of BADGE and BFDGE was studied using reverse-phase gradient high performance liquid chromatography (RP-HPLC) with fluorescence detection (FLD). Four experiments were compared: (i) BPA solution at the concentration 3 μg/ml of each food simulant, (ii) BADGE solution at the concentration 3 μg/ml of each food simulant, (iii) BFDGE solution at the concentration 3 μg/ml of each food simulant and (iv) mixture of all bisphenols solution at the concentration 3 μg/ml of each food simulant. Distilled water, 10% ethanol, 95% ethanol and 3% acetic acid were used as food simulants. It was observed that BPA, BADGE and BFDGE were most stabile in 95% ethanol and least stabile in 3% acetic acid. Creation of hydroxy and chlorohydroxy derivatives was in each food simulant different so it cannot be predicted.

scholarly journals A simple method for the quantification of diclofenac potassium in oral suspension by high-performance liquid chromatography with UV-detection

2013 ◽  
Vol 49 (3) ◽  
pp. 589-597 ◽  
Author(s):  
Alexandre Machado Rubim ◽  
Jaqueline Bandeira Rubenick ◽  
Luciane Varine Laporta ◽  
Clarice Madalena Bueno Rolim
Keyword(s):  
High Performance ◽  
Low Cost ◽  
Oral Suspension ◽  
Reverse Phase ◽  
Intermediate Precision ◽  
Simple Method ◽  
Ultraviolet Detection ◽  
Relative Standard ◽  
Validation Parameters

A rapid, simple and low cost method was developed to determine diclofenac potassium (DP) in oral suspension, using a reverse-phase column (C8, 150 mm x 4.6 mm, 5 µm), mobile phase containing methanol/buffer phosphate (70:30 v/v, pH 2.5), at a flow rate of 1.0 mL/min, isocratic method, and ultraviolet detection at 275 nm. A linear response (r = 1.0000) was observed in the range of 10.0-50.0 µg/mL. Validation parameters such as linearity, specificity, precision, accuracy and robustness were evaluated. The method presented precision (repeatability: relative standard deviation = 1.21% and intermediate precision: between-analyst = 0.85%). The specificity of the assay was evaluated by exposure of diclofenac potassium under conditions of stress such as hydrolysis, photolysis, oxidation and high temperature. The method presented accuracy values between 98.28% and 101.95%. The results demonstrate the validity of the proposed method that allows determination of diclofenac potassium in oral suspension and may be used as an alternative method for routine analysis of this product in quality control.

scholarly journals ZrO2/g-C3N4 Hybrid Nanocomposite: An Efficient and Eco-Friendly Recyclable Catalyst for the Trimethylsilyl Protection of Hydroxyl Groups and Synthesis of α-Aminophosphonates

Proceedings ◽  
2018 ◽  
Vol 9 (1) ◽  
pp. 51
Author(s):  
Hossein Ghafuri ◽  
Ghazaleh Jafari ◽  
Nahal Goodarzi ◽  
Afsaneh Rashidizadeh
Keyword(s):  
High Performance ◽  
Heterogeneous Catalysts ◽  
Low Cost ◽  
Catalyst Support ◽  
Van Der Waals Interactions ◽  
Hydroxyl Groups ◽  
Hybrid Nanocomposite ◽  
Interesting Phenomenon ◽  
Solvent Free Conditions ◽  
Earth Abundant

Recently, considerable attention has been devoted to heterogeneous catalysts. Generally, heterogeneous catalysts offer several advantages, such as mild reaction conditions, high throughput, and ease of work-up procedures. Among the heterogeneous catalysts investigated, polymeric mesoporous graphitic carbon nitrides (g-C3N4) have attracted much attention recently due to strong van der Waals interactions between the layers. g-C3N4 is chemically stable against acidic, basic, and organic solvents, and thermogravimetric analysis (TGA) also reveals that g-C3N4 is thermally stable even in air up to 600 °C, which can be attributed to its aromatic C-N heterocycles. More importantly, g-C3N4 is only composed of two earth-abundant elements: carbon and nitrogen. This not only suggests that it can be easily prepared at low cost, but also that its properties can be tuned by simple strategies without significant alteration of the overall composition. The last approach is considered to be the most efficient way to design high-performance heterogeneous catalysts utilizing g-C3N4 as a catalyst support. An interesting phenomenon is that the modification is mainly focused on metal oxides. Zirconia (ZrO2) is a physically rigid material with chemical inertness. It has high resistance against attacks by acids, alkalis, oxidants, and reductants. In this study, a ZrO2/g-C3N4 hybrid nanocomposite was shown to be an excellent catalyst for the conversion of alcohols and phenols into their corresponding trimethylsilyl ethers with hexamethyldisilazane (HMDS) under solvent-free conditions and for the synthesis of α-aminophosphonates. In addition, ZrO2/g-C3N4 could easily be recycled after separation from the reaction mixture without considerable loss in catalytic activity.

scholarly journals An 8.8 ps RMS Resolution Time-To-Digital Converter Implemented in a 60 nm FPGA with Real-Time Temperature Correction

Sensors ◽  
2020 ◽  
Vol 20 (8) ◽  
pp. 2172 ◽  
Author(s):  
Zhipeng Song ◽  
Zhixiang Zhao ◽  
Hongsen Yu ◽  
Jingwu Yang ◽  
Xi Zhang ◽  
...  
Keyword(s):  
Real Time ◽  
High Performance ◽  
Low Cost ◽  
Propagation Delay ◽  
Temperature Correction ◽  
Digital Converter ◽  
Simple Method ◽  
Time To Digital Converter ◽  
Propagation Delays ◽  
Field Programmable

This paper presented a non-uniform multiphase (NUMP) time-to-digital converter (TDC) implemented in a field-programmable gate array (FPGA) with real-time automatic temperature compensation. NUMP-TDC is a novel, low-cost, high-performance TDC that has achieved an excellent performance in Altera Cyclone V FPGA. The root mean square (RMS) for the intrinsic timing resolution was 2.3 ps. However, the propagation delays in the delay chain of some FPGAs (for example, the Altera Cyclone 10 LP) vary significantly as the temperature changes. Thus, the timing performances of NUMP-TDCs implemented in those FPGAs are significantly impacted by temperature fluctuations. In this study, a simple method was developed to monitor variations in propagation delays using two registers deployed at both ends of the delay chain and compensate for changes in propagation delay using a look-up table (LUT). When the variations exceeded a certain threshold, the LUT for the delay correction was updated, and a bin-by-bin correction was launched. Using this correction approach, a resolution of 8.8 ps RMS over a wide temperature range (5 °C to 80 °C) had been achieved in a NUMP-TDC implemented in a Cyclone 10 LP FPGA.

scholarly journals Determination of bisphenol A, bisphenol F, bisphenol A diglycidyl ether and bisphenol F diglycidyl ether migrated from food cans using Gas Chromatography-Mass Spectrometry

2011 ◽  
Vol 21 (No. 3) ◽  
pp. 85-90 ◽  
Author(s):  
I. Jordáková ◽  
J. Dobiáš ◽  
M. Voldřich ◽  
J. Postka
Keyword(s):  
Gas Chromatography ◽  
Bisphenol A ◽  
Epoxy Resins ◽  
Diglycidyl Ether ◽  
Gas Chromatography Mass Spectrometry ◽  
Simple Method ◽  
Bisphenol F ◽  
Mass Spectrometric Detector ◽  
Bisphenol A Diglycidyl Ether

Varnishes used for the inner coatings of food cans are mostly based on epoxy resins or vinylic organosols. The epoxy resins are produced from bisphenol A and bisphenol F and they also contain BADGE or BFDGE as stabilising components. A simple method for the quantitative determination of bisphenol A (BPA), bisphenol F (BPF), bisphenol A diglycidyl ether (BADGE), and bisphenol F diglycidyl ether (BFDGE) migrated from food packaging materials was optimised. The can sample was extracted with acetonitrile or with food simulants (distilled water, 3% acetic acid and 10% ethanol) and the extract obtained was analysed by gas chromatography coupled with mass spectrometric detector. The limits of detection and quantification ranged between 0.15&ndash;0.86 and 0.51&ndash;2.77 &micro;g/dm<sup>2</sup>, respectively. The migrating levels of bisphenols found in various can samples were for BPA and for BADGE in the range from 0.63 &times; 10<sup>&ndash;3</sup> to 0.34 mg/dm<sup>2</sup>, and from 1.49 &times; 10<sup>&ndash;3</sup> to 3.67 mg/dm<sup>2</sup>, respectively. BPF and BFDGE were practically not detected in the can samples. &nbsp;

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