Recycling of Carbon Fiber-reinforced Epoxy Resin-based Composites Using a Benzyl Alcohol/Alkaline System

Lianwei Ye,Ke Wang,Hai Feng,Yu Wang 한국섬유공학회 2021 Fibers and polymers Vol.22 No.3

High-efficiency recycling of carbon fiber-reinforced epoxy resin-based composites is difficult because of theirthree-dimensional network structure. In this article, a benzyl alcohol/alkaline system was used to recycle carbon fiberreinforcedepoxy resin-based composites cured by an anhydride. The degradation rate, mechanical properties and degradationmechanism of the recycled carbon fiber were determined by gas chromatography-mass spectrometry, Fourier transforminfrared spectroscopy, liquid chromatography-mass spectrometry, scanning electron microscope and X-ray photoelectronspectroscopy. The experimental results indicated that there were two steps in benzyl alcohol/K3PO4 degradation system. Thefirst was transesterification by benzyloxy selective attack to give small-molecule esters. Then the esters were saponified bythe alkaline materials. After degradation, the stratification of resin and benzyl alcohol occurred, which was conducive to theirseparation. The optimal degradation time was 40 min under the weight ratio of alkaline material to benzyl alcohol of 1:10,atmospheric pressure, and temperature of 195 oC and the decomposition efficiency exceeded 90 %. A clean carbon fibersurface was obtained with an oxygen content comparable to that of the original carbon fiber. The tensile strength of therecycled carbon fiber was above 90 % of the original value.

Partial Discharge Process and Characteristics of Oil-Paper Insulation under Pulsating DC Voltage

Lianwei Bao,Jian Li,Jing Zhang,Tianyan Jiang 대한전기학회 2016 Journal of Electrical Engineering & Technology Vol.11 No.2

Oil-paper insulation of valve-side windings in converter transformers withstand electrical stresses combining with AC, DC and strong harmonic components. This paper presents the physical mechanisms and experimental researches on partial discharge (PD) of oil-paper insulation at pulsating DC voltage. Theoretical analysis showed that the phase-resolved distributions of PDs generated from different insulated models varied as the increase of the applied voltages following a certain rule. Four artificial insulation defect models were designed to generate PD signals at pulsating DC voltages. Theoretical statements and experimental results show that the PD pulses first appear at the maximum value of the applied pulsating DC voltage, and the resolved PD phase distribution became wider as the applied voltage increased. The PD phase-resolved distributions generated from the different discharge models are also different in the phase-resolved distributions and development progress. It implies that the theoretical analysis is suitable for interpretation of PD at pulsating DC voltage.

Electrical Breakdown Properties of Oil-paper Insulation under Pulsating Voltage Influenced by Temperature

Lianwei Bao,Jian Li,Jing Zhang,Xudong Li 대한전기학회 2016 Journal of Electrical Engineering & Technology Vol.11 No.6

Insulation of valve-side windings in converter transformer withstands pulsating voltages, which will produce more serious insulation problems. In this paper, the electric breakdown experiments of oil-paper insulation specimens were executed at pulsating voltages and different temperatures. Experiment and analysis results showed that the breakdown voltage decreased with increasing temperature under pulsating voltage. The influence of temperature proves to be more significant once the temperature exceeds a limitation threshold. A fitting formula between breakdown voltage and the temperature was reported. Finally, in order to clearly understand the breakdown properties under pulsating voltage, the electric field distribution and space charge behavior under pulsating voltage at different temperature were discussed.

Partial Discharge Process and Characteristics of Oil-Paper Insulation under Pulsating DC Voltage

Bao, Lianwei,Li, Jian,Zhang, Jing,Jiang, Tianyan,Li, Xudong The Korean Institute of Electrical Engineers 2016 Journal of Electrical Engineering & Technology Vol.11 No.2

Oil-paper insulation of valve-side windings in converter transformers withstand electrical stresses combining with AC, DC and strong harmonic components. This paper presents the physical mechanisms and experimental researches on partial discharge (PD) of oil-paper insulation at pulsating DC voltage. Theoretical analysis showed that the phase-resolved distributions of PDs generated from different insulated models varied as the increase of the applied voltages following a certain rule. Four artificial insulation defect models were designed to generate PD signals at pulsating DC voltages. Theoretical statements and experimental results show that the PD pulses first appear at the maximum value of the applied pulsating DC voltage, and the resolved PD phase distribution became wider as the applied voltage increased. The PD phase-resolved distributions generated from the different discharge models are also different in the phase-resolved distributions and development progress. It implies that the theoretical analysis is suitable for interpretation of PD at pulsating DC voltage.

Electrical Breakdown Properties of Oil-paper Insulation under Pulsating Voltage Influenced by Temperature

Bao, Lianwei,Li, Jian,Zhang, Jing,Li, Xudong The Korean Institute of Electrical Engineers 2016 Journal of Electrical Engineering & Technology Vol.11 No.6

Insulation of valve-side windings in converter transformer withstands pulsating voltages, which will produce more serious insulation problems. In this paper, the electric breakdown experiments of oil-paper insulation specimens were executed at pulsating voltages and different temperatures. Experiment and analysis results showed that the breakdown voltage decreased with increasing temperature under pulsating voltage. The influence of temperature proves to be more significant once the temperature exceeds a limitation threshold. A fitting formula between breakdown voltage and the temperature was reported. Finally, in order to clearly understand the breakdown properties under pulsating voltage, the electric field distribution and space charge behavior under pulsating voltage at different temperature were discussed.

Formation of Hyperbranched Amphiphilic Terpolymers and Unimolecular Micelles in One-pot Copolymerization

Xu Wang,Lianwei Li,Weidong He,Chi Wu 한국고분자학회 2016 한국고분자학회 학술대회 연구논문 초록집 Vol.41 No.2

Immune Effect of Newcastle Disease Virus DNA Vaccine with C3d as a Molecular Adjuvant

( Kai Zhao ),( Xutong Duan ),( Lianwei Hao ),( Xiaohua Wang ),( Yunfeng Wang ) 한국미생물생명공학회(구 한국산업미생물학회) 2017 Journal of microbiology and biotechnology Vol.27 No.11

Newcastle disease is a serious infectious disease in the poultry industry. The commercial vaccines can only offer limited protection and some of them are expensive and need adjuvants. At present, DNA vaccines are widely used. However, the immune responses induced by DNA vaccines are too slow and low. Here, we constructed the transfer vectors with a different number of C3d as molecular adjuvants (n = 1, 2, 4, or 6), and the vectors were cloned into the optimal eukaryotic expression plasmid (pVAXI-optiF) that expressed the F gene of Newcastle disease virus (NDV), and named pVAXI-F(o)-C3d1, pVAXI -F(o)-C3d2, pVAXI-F(o)-C3d4, and pVAXI-F(o)-C3d6, respectively. Cell transfection test indicated that pVAXI-F(o)-C3d6 showed the highest expression. In vivo immunization showed that the chickens immunized with pVAXI-F(o)-C3d6 intramuscularly induced better immune responses than the chickens immunized with the other plasmids. The protective efficacy of pVAXI-F(o)-C3d6 was 80% after challenge with the highly virulent NDV strain F48E9. The results in this study showed that C3d6 could be used as a molecular adjuvant to quickly induce an effective immune response to control NDV.

Two Factors Failure Model of Oil-Paper Insulation Aging under Electrical and Thermal Multistress

Jian Li,Yan Wang,Lianwei Bao 대한전기학회 2014 Journal of Electrical Engineering & Technology Vol.9 No.3

Converter transformers play important roles in high-voltage direct current transmission systems. This paper presents experimental and analysis results of the combined electrical and thermal aging of oil-impregnated paper at pulsating DC voltages. Breakdown voltages and time-tobreakdown of oil-paper specimens were measured by using short-time and constant-stress tests. The breakdown characteristics of combined electrical and thermal aging on insulation system were discussed. According to the relationship between failure time and aging temperature, the twoparameter Weibull model was improved. On the basis of the competing risk algorithm and the improved Weibull model, the two factors failure model was calculated. And the influence of temperature in the insulation system has been analyzed. This model performs better than the twoparameter Weibull model when both time and temperature are considered as variables in estimating the lifetime of oil-paper insulation.

Space Charge Behavior of Oil-Impregnated Paper Insulation Aging at AC-DC Combined Voltages

Li, Jian,Wang, Yan,Bao, Lianwei The Korean Institute of Electrical Engineers 2014 Journal of Electrical Engineering & Technology Vol.9 No.2

The space charge behaviors of oil-paper insulation affect the stability and security of oil-filled converter transformers of traditional and new energies. This paper presents the results of the electrical aging of oil-impregnated paper under AC-DC combined voltages by the pulsed electro-acoustic technique. Data mining and feature extractions were performed on the influence of electrical aging on charge dynamics based on the experiment results in the first stage. Characteristic parameters such as total charge injection and apparent charge mobility were calculated. The influences of electrical aging on the trap energy distribution of an oil-paper insulation system were analyzed and discussed. Longer electrical aging time would increase the depth and energy density of charge trap, which decelerates the apparent charge mobility and increases the probability of hot electron formation. This mechanism would accelerate damage to the cellulose and the formation of discharge channels, enhance the acceleration of the electric field distortion, and shorten insulation lifetime under AC-DC combined voltages.

Two Factors Failure Model of Oil-Paper Insulation Aging under Electrical and Thermal Multistress

Li, Jian,Wang, Yan,Bao, Lianwei The Korean Institute of Electrical Engineers 2014 Journal of Electrical Engineering & Technology Vol.9 No.3

Converter transformers play important roles in high-voltage direct current transmission systems. This paper presents experimental and analysis results of the combined electrical and thermal aging of oil-impregnated paper at pulsating DC voltages. Breakdown voltages and time-to-breakdown of oil-paper specimens were measured by using short-time and constant-stress tests. The breakdown characteristics of combined electrical and thermal aging on insulation system were discussed. According to the relationship between failure time and aging temperature, the two-parameter Weibull model was improved. On the basis of the competing risk algorithm and the improved Weibull model, the two factors failure model was calculated. And the influence of temperature in the insulation system has been analyzed. This model performs better than the two-parameter Weibull model when both time and temperature are considered as variables in estimating the lifetime of oil-paper insulation.