scholarly journals Monitoring Strain Response of Epoxy Resin during Curing and Cooling Using an Embedded Strain Gauge

Sensors ◽  
2020 ◽  
Vol 21 (1) ◽  
pp. 172
Author(s):  
Hongyu Dong ◽  
Huiming Liu ◽  
Arata Nishimura ◽  
Zhixiong Wu ◽  
Hengcheng Zhang ◽  
...  
Keyword(s):  
Epoxy Resin ◽  
Strain Gauge ◽  
Standard Sample ◽  
Initial Point ◽  
Strain Response ◽  
Curing Process ◽  
Scanning Calorimetry ◽  
Temperature Changes ◽  
Epoxy Adhesives ◽  
Cryogenic Application

The present work describes the monitoring system of the real-time strain response on the curing process of epoxy resin from the initial point of curing to the end, and the change in strain during temperature changes. A simple mould was designed to embed the strain gauge, thermometer, and quartz standard sample into the epoxy resin, so that the strain and the temperature were simultaneously measured and recorded. A cryogenic-grade epoxy resin was tested and the Differential Scanning Calorimetry (DSC) was used to analyse the curing process. Based on the DSC results, three curing processes were adopted to investigate their influence on strain response as well as residual strain of the epoxy resin. Moreover, impact strength of the epoxy resin with various curing temperatures were tested and the results indicate that the curing plays a crucial role on the mechanical properties. The method will find cryogenic application of epoxy adhesives and epoxy resin based composites to monitor the strain during the curing process as well as the cryogenic service.

scholarly journals Curing Kinetics, Mechanical Properties and Thermomechanical Analysis of Carbon Fiber/epoxy Resin Laminates with Different Ply Orientations

2021 ◽  
Author(s):  
Chenglin Zhang ◽  
Guohua Gu ◽  
Shuhua Dong ◽  
Zhitao Lin ◽  
Chuncheng Wei ◽  
...  
Keyword(s):  
Carbon Fiber ◽  
Impact Strength ◽  
Epoxy Resin ◽  
Composite Laminates ◽  
Bending Strength ◽  
Fiber Composite ◽  
Curing Process ◽  
Scanning Calorimetry ◽  
The Impact ◽  
Carbon Fiber Epoxy

Abstract In this study, the nonisothermal differential scanning calorimetry (DSC) was carried out to evaluate the curing reaction of fiber/epoxy laminates. The optimal curing process of the prepreg was obtained by T-β extrapolation method and nth-order reaction curing kinetic equation. The bending strength, impact strength and thermodynamic properties of the composite laminates with different ply orientations were investigated, respectively. The results show that the apparent activation energy and the reaction order of the prepregs are 82.89 kJ/mol and 0.92, respectively. The curing process of carbon fiber/epoxy resin prepreg is 130 ℃ /60min + 160 ℃/30 min. The bending strength of [0]10 laminate is 1948.3 MPa, which is 11.8 times higher than that of [+ 45/-45]5s laminate, and 96.4% higher than that of [0/90]5s laminate. The impact strength of [0]10 laminate is higher than that of [+ 45/-45]5s and [0/90]5s laminates. The glass transition temperature (Tg) of the laminates is 142 ~ 146 ℃, and the loss factor of [0]10 laminate is significantly higher than that of [+ 45/-45]5s and [0/90]5s laminates. This research provides a theoretical basis for the further application of prepregs to fiber composite materials.

scholarly journals Exploring instantaneous micro-imprinting technology on semi-cured epoxy resin coating based on relationship between forming precision and curing degree

2016 ◽  
Vol 22 (1) ◽  
pp. 47-53
Author(s):  
Yuehao Luo ◽  
Robert Smith ◽  
Lork Green
Keyword(s):  
Epoxy Resin ◽  
External Pressure ◽  
Curing Process ◽  
Scanning Calorimetry ◽  
Manufacturing Efficiency ◽  
Practical Engineering ◽  
Forming Precision ◽  
Physical And Chemical ◽  
The Relationship ◽  
Micro Dimple

Nano/micro-imprinting technology base on polymer material coating has attracted the increasing attentions throughout the world in the past several decades, and it is progressively developing into the hot topic at present, in which, how to improve the manufacturing efficiency is becoming the urgent issue to be resolved. Polymer?s curing process is exactly complicated and sophisticated, which involves simultaneously performing physical and chemical changes, when the curing reaction reaches certain level, the system will abruptly transform into insoluble, non-melting gel with rapidly increased viscosity and rigidity, which can generate fixed deformation under persistent external pressure. In this paper, the plastic deformation capacity of epoxy resin in the curing process is investigated by the micro-dimple imprinting experiment, and the relationship between forming precision and curing degree is ascertained adopting the DSC (differential scanning calorimetry) method. In addition, the instantaneous micro-imprinting technology based on the micro-grooves is explored, and the experimental results indicate that the forming precision can surpass 90%. The paper will establish a novel avenue to apply the nano/micro imprinting technology into practical engineering.

Prediction and Analysis on Chemorheology of MeHHPA/Hydantoin Epoxy Resin

2017 ◽  
Vol 727 ◽  
pp. 497-502
Author(s):  
Ya Quan Xin ◽  
Ling Li ◽  
Li Yuan Fan
Keyword(s):  
Experimental Data ◽  
Epoxy Resin ◽  
Good Accuracy ◽  
Viscosity Model ◽  
Curing Process ◽  
Ann Model ◽  
Scanning Calorimetry ◽  
Low Viscosity ◽  
Different Temperatures ◽  
Hidden Neurons

Hydantoin epoxy resin, with a hydantoin group, is a kind of low viscosity nitrigen-containing epoxy resin. We prepared methyl hexahydrophalic anhydride (MeHHPY)/ hydantin epoxy resin, in which MeHHPA was used as cure agent. Non-isothermal differential scanning calorimetry was examined to follow the curing process. The variation of viscosity was measured the isothermal curing process by rotating viscometer respectively (70-90°C). A viscosity model, which parameters were determined by Arrhenius equation, was established on the basis of experimental data at three different temperatures. As the result showed, there is a minimum deviation comparing the dual Arrhenius viscosity model data and experimental data in the temperature range of this research. The potential of artificial neural network techniques (ANN) was employed to analyze and predict the chemorheological behavior of MeHHPA/hydatoin epoxy resin. A three layer feed forward ANN model having two input neurons, one output neuron and fourteen hidden neurons was developed to predict the chemorheologica behaviour of MeHHPA/hydatoin epoxy resin. The learning of ANN was accomplished by a backpropagation algorithm. The results display that prediction model has very good accuracy in the process of the whole experiment. Through the established ANN model, the variation characteristic of viscosity can be exactly predicted. Studying on chemorheology by ANN model can help to formulate and optimize technical process.

scholarly journals Kinetic Analysis of the Curing Process of Biobased Epoxy Resin from Epoxidized Linseed Oil by Dynamic Differential Scanning Calorimetry

Polymers ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1279
Author(s):  
Diego Lascano ◽  
Alejandro Lerma-Canto ◽  
Vicent Fombuena ◽  
Rafael Balart ◽  
Nestor Montanes ◽  
...  
Keyword(s):  
Differential Scanning Calorimetry ◽  
Epoxy Resin ◽  
Epoxy Resins ◽  
Linseed Oil ◽  
Single Step ◽  
Curing Process ◽  
Heating Rates ◽  
Scanning Calorimetry ◽  
Step Process ◽  
Epoxidized Linseed Oil

The curing process of epoxy resin based on epoxidized linseed oil (ELO) is studied using dynamic differential scanning calorimetry (DSC) in order to determine the kinetic triplet (Ea, f(α) and A) at different heating rates. The apparent activation energy, Ea, has been calculated by several differential and integral isoconversional methods, namely Kissinger, Friedman, Flynn–Wall–Ozawa (FWO), Kissinger–Akahira–Sunose (KAS) and Starink. All methods provide similar values of Ea (between 66 and 69 kJ/mol), and this shows independence versus the heating rate used. The epoxy resins crosslinking is characterized by a multi-step process. However, for the sake of the simplicity and to facilitate the understanding of the influence of the oxirane location on the curing kinetic, this can be assimilated to a single-step process. The reaction model has a high proportion of autocatalytic process, fulfilling that αM is between 0 and αp and αM < αp∞. Using as reference the model proposed by Šesták–Berggren, by obtaining two parameters (n and m) it is possible to obtain, on the one hand, the kinetic parameters and, on the other hand, a graphical comparison of the degree of conversion, α, versus temperature (T) at different heating rates with the average n and m values of this model. The good accuracy of the proposed model with regard to the actual values obtained by DSC gives consistency to the obtained parameters, thus suggesting the crosslinking of the ELO-based epoxy has apparent activation energies similar to other petroleum-derived epoxy resins.

scholarly journals Curing and Characteristics of N,N,N′,N′-Tetraepoxypropyl-4,4′-Diaminodiphenylmethane Epoxy Resin-Based Buoyancy Material

Polymers ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 1137 ◽  
Author(s):  
Sizhu Yu ◽  
Xiaodong Li ◽  
Xiaoyan Guo ◽  
Zhiren Li ◽  
Meishuai Zou
Keyword(s):  
Epoxy Resin ◽  
High Strength ◽  
Hollow Glass Microsphere ◽  
Low Density ◽  
Curing Process ◽  
Mass Ratio ◽  
Dsc Analysis ◽  
Scanning Calorimetry ◽  
Saturated Water ◽  
Thermal Analysis Kinetics

Buoyancy material is a type of low-density and high-strength composite material which can provide sufficient buoyancy with deep submersibles. A new buoyancy material with N,N,N′,N′-tetraepoxypropyl-4,4′-diaminodiphenylmethane epoxy resin (AG-80) and m-xylylenediamine (m-XDA) curing agent as matrix and hollow glass microsphere (HGM) as the filler is prepared. The temperature and time of the curing process were determined by the calculations of thermal analysis kinetics (TAK) through differential scanning calorimetry (DSC) analysis. The results show that the better mass ratio of AG-80 with m-XDA is 100/26. Combined TAK calculations and experimental results lead to the following curing process: pre-curing at 75 °C for 2 h, curing at 90 °C for 2 h, and post-curing at 100 °C for 2 h. The bulk density, compressive strength, and saturated water absorption of AG-80 epoxy resin-based buoyancy material were 0.729 g/cm3, 108.78 MPa, and 1.23%, respectively. Moreover, this type of buoyancy material can resist the temperature of 250 °C.

Application of pyrometer and standard sample to determine surface temperature of studied materials

2019 ◽  
pp. 9-13
Author(s):  
V.Ya. Mendeleyev ◽  
V.A. Petrov ◽  
A.V. Yashin ◽  
A.I. Vangonen ◽  
O.K. Taganov
Keyword(s):  
Composite Material ◽  
Surface Temperature ◽  
Relative Error ◽  
Wavelength Range ◽  
Standard Sample ◽  
A Priori ◽  
Temperature Changes ◽  
Surface Temperatures ◽  
Relative Errors ◽  
Normal Emissivity

Determining the surface temperature of materials with unknown emissivity is studied. A method for determining the surface temperature using a standard sample of average spectral normal emissivity in the wavelength range of 1,65–1,80 μm and an industrially produced Metis M322 pyrometer operating in the same wavelength range. The surface temperature of studied samples of the composite material and platinum was determined experimentally from the temperature of a standard sample located on the studied surfaces. The relative error in determining the surface temperature of the studied materials, introduced by the proposed method, was calculated taking into account the temperatures of the platinum and the composite material, determined from the temperature of the standard sample located on the studied surfaces, and from the temperature of the studied surfaces in the absence of the standard sample. The relative errors thus obtained did not exceed 1,7 % for the composite material and 0,5% for the platinum at surface temperatures of about 973 K. It was also found that: the inaccuracy of a priori data on the emissivity of the standard sample in the range (–0,01; 0,01) relative to the average emissivity increases the relative error in determining the temperature of the composite material by 0,68 %, and the installation of a standard sample on the studied materials leads to temperature changes on the periphery of the surface not exceeding 0,47 % for composite material and 0,05 % for platinum.

scholarly journals Improved Processing and Properties for Polyphenylene Oxide Modified by Diallyl Orthophthalate Prepolymer

Polymers ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 2016
Author(s):  
Honghua Wang ◽  
Qilin Mei ◽  
Yujie Ding ◽  
Zhixiong Huang ◽  
Minxian Shi
Keyword(s):  
Differential Scanning Calorimetry ◽  
Thermal Properties ◽  
Phase Separation ◽  
Dilution Effect ◽  
Gradual Decrease ◽  
Gel Point ◽  
Dynamic Mode ◽  
Curing Process ◽  
Scanning Calorimetry ◽  
Polyphenylene Oxide

Diallyl orthophthalate (DAOP) prepolymer was investigated as a reactive plasticizer to improve the processability of thermoplastics. The rheology of blends of DAOP prepolymer initiated by 2,3-dimethyl-2,3-diphenylbutane (DMDPB) and polyphenylene oxide (PPO) was monitored during the curing process, and their thermal properties and morphology in separated phases were also studied. Differential scanning calorimetry (DSC) results showed that the cure degree of the reactively plasticized DAOP prepolymer was reduced with increasing PPO due to the dilution effect. The increasing amount of the DAOP prepolymer led to a gradual decrease in the viscosity of the blends and the rheology behavior was consistent with the chemical gelation of DAOP prepolymer in blends. This indicated that the addition of the DAOP prepolymer effectively improved processability. The phase separation occurring during curing of the blend and the transition from the static to dynamic mode significantly influences the development of the morphology of the blend corresponding to limited evolution of the conversion around the gel point.

A dynamic DSC study of the curing process of epoxy resin

1997 ◽  
Vol 49 (1) ◽  
pp. 123-129 ◽  
Author(s):  
Susumu Tatsumiya ◽  
Katsumasa Yokokawa ◽  
Kyosuke Miki
Keyword(s):  
Epoxy Resin ◽  
Curing Process
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