scholarly journals The Curing Kinetics of Multiscale [Ni(EDTA)]-2 Intercalated Zn-Al Layered Double Hydroxides: Glass Fiber–Epoxy Composite Prepreg

2021 ◽  
Vol 2021 ◽  
pp. 1-22
Author(s):  
Reza Darvishi ◽  
Mahdi Darvishi ◽  
Ali Moshkriz
Keyword(s):  
Glass Fiber ◽  
Layered Double Hydroxides ◽  
Cure Kinetics ◽  
Curing Kinetics ◽  
Scanning Calorimetry ◽  
Curing Behavior ◽  
Autocatalytic Model ◽  
Experimental Findings ◽  
Double Hydroxides ◽  
Kinetics Of

In the present research, the effect of Zn2Al layered double hydroxides (LDH) and nickel (II)-EDTA complex intercalated LDH (LDH-[Ni(EDTA)]-2) on the cure kinetics of glass fiber/epoxy prepreg (GEP) was explored using nonisothermal differential scanning calorimetry (DSC). The results showed that LDH caused a shift in the cure temperature toward lower temperatures while accelerating the curing of epoxy prepregs. The use of LDH-[Ni(EDTA)]-2 more profoundly influenced the acceleration of the curing process. The curing kinetics of prepregs was assessed through the differential isoconversional Friedman (FR) technique and the integration method of Flynn–Wall–Ozawa (FWO) and Kissinger–Akahira–Sunose (KAS). A decrease was detected in the E α value of glass fiber/LDH-[Ni(EDTA)]-2/epoxy (GELP) and glass fiber/LDH-[Ni(EDTA)]-2/epoxy (GELNiP) prepregs at small cure degrees relative to GEP, suggesting the catalytic effect of LDH or LDH-[Ni(EDTA)]-2 on the initial epoxy/amine reaction. Furthermore, LDH-[Ni(EDTA)]-2 performed better due to the catalyst role of nickel (II). Moreover, the activation energy exhibited lower reliance on the degree of conversion in the cases of GELP and GELNiP rather than pure epoxy prepregs. An autocatalytic model was used to evaluate the curing behavior of the system. Based on the results, the curing reaction of the epoxy prepreg can be described by the autocatalytic Šesták-Berggren model even after the incorporation of LDH or LDH-[Ni(EDTA)]-2. The kinetic parameters of the autocatalytic model (such as E α , A , m , n ) and the equations explaining the curing behavior of prepregs were introduced as well whose predictions were in line with the experimental findings.

scholarly journals Thermal Analysis On The Kinetics Of Magnesium-Aluminum Layered Double Hydroxides In Different Heating Rates

2015 ◽  
Vol 60 (2) ◽  
pp. 1357-1359 ◽  
Author(s):  
Y. Hongbo ◽  
C. Meiling ◽  
W. Xu ◽  
G. Hong
Keyword(s):  
Activation Energy ◽  
Thermal Analysis ◽  
Layered Double Hydroxides ◽  
Heating Rates ◽  
Scanning Calorimetry ◽  
Exponential Factor ◽  
Thermal Kinetic Parameters ◽  
Double Hydroxides ◽  
Kinetics Of ◽  
Dsc Curves

Abstract The thermal decomposition of magnesium-aluminum layered double hydroxides (LDHs) was investigated by thermogravimetry analysis and differential scanning calorimetry (DSC) methods in argon environment. The influence of heating rates (including 2.5, 5, 10, 15 and 20K/min) on the thermal behavior of LDHs was revealed. By the methods of Kissinger and Flynn-Wall-Ozawa, the thermal kinetic parameters of activation energy and pre-exponential factor for the exothermic processes under non-isothermal conditions were calculated using the analysis of corresponding DSC curves.

Cure Kinetics of Epoxy/DDS/ Epoxy-Grafted Nano-Aluminum Oxide

2011 ◽  
Vol 236-238 ◽  
pp. 2058-2062
Author(s):  
Hong Jun Zhou ◽  
Guo Qiang Yin ◽  
Miao Hong Zhuang ◽  
Jian Fang Ge ◽  
Xuan Lin
Keyword(s):  
Aluminum Oxide ◽  
Epoxy Resins ◽  
Cure Kinetics ◽  
Ozawa Method ◽  
Heating Rates ◽  
Scanning Calorimetry ◽  
Autocatalytic Model ◽  
Chain Mobility ◽  
Málek Method ◽  
Kinetics Of

The cure kinetics of epoxy/epoxy-grafted nano-aluminum oxide using 4, 4'-diaminodiphenylsulphone (DDS) as the curing agent was studied by nonisothermal differential scanning calorimetry (DSC) at different heating rates. The activation energy (Ea) was determined by Flynn-Wall-Ozawa method, and kinetic model was predicted by Málek method. TheEa values of epoxy/nano-aluminum oxide/DDS systems are generally higher than those of epoxy /DDS. These imply that the addition of nano-aluminum oxide would inhibit the chain mobility of the epoxy resins. Furthermore, autocatalytic model was found to be appropriate to describe the kinetics of above mentioned reactions. The predicted curves fit well with the experimentally obtained curves.

scholarly journals The Curing Kinetics of E-Glass Fiber/Epoxy Resin Prepreg and the Bending Properties of Its Products

Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4673
Author(s):  
Lvtao Zhu ◽  
Zhenxing Wang ◽  
Mahfuz Bin Rahman ◽  
Wei Shen ◽  
Chengyan Zhu
Keyword(s):  
Glass Fiber ◽  
Epoxy Resin ◽  
Composite Laminates ◽  
Curing Kinetics ◽  
Curing Temperature ◽  
Scanning Calorimetry ◽  
Three Point Bending ◽  
Reinforced Composite ◽  
Curing Kinetic ◽  
Kinetics Of

The curing kinetics can influence the final macroscopic properties, particularly the three-point bending of the fiber-reinforced composite materials. In this research, the curing kinetics of commercially available glass fiber/epoxy resin prepregs were studied by non-isothermal differential scanning calorimetry (DSC). The curing kinetic parameters were obtained by fitting and the apparent activation energy Ea of the prepreg, the pre-exponent factor, and the reaction order value obtained. A phenomenological nth-order curing reaction kinetic model was established according to Kissinger equation and Crane equation. Furthermore, the optimal curing temperature of the prepregs was obtained by the T-β extrapolation method. A vacuum hot pressing technique was applied to prepare composite laminates. The pre-curing, curing, and post-curing temperatures were 116, 130, and 153 °C respectively. In addition, three-point bending was used to test the specimens’ fracture behavior, and the surface morphology was analyzed. The results show that the differences in the mechanical properties of the samples are relatively small, indicating that the process settings are reasonable.

Curing Kinetics of Cyano Functionalized Benzoxazine

2011 ◽  
Vol 233-235 ◽  
pp. 2337-2340
Author(s):  
Wen Jin Chen ◽  
Xiao Bo Liu
Keyword(s):  
Activation Energy ◽  
Thermal Stability ◽  
Differential Scanning Calorimetry ◽  
Theoretical Calculations ◽  
Curing Kinetics ◽  
High Thermal Stability ◽  
Order Model ◽  
Scanning Calorimetry ◽  
Autocatalytic Model ◽  
Kinetics Of

A multifunctional benzoxazine monomer (BZCN) was synthesized, which has several outstanding properties, such as high thermal stability and high glass transition. To better understand the curing kinetics of BZCN, isothermal differential scanning calorimetry measurements were used to determine the kinetic parameters and the kinetic models of the curing processes of benzoxazine monomer with cyano functionality. The result shows the mechanism of the curing reaction of BZCN exhibits autocatalytic model, but doesn’t meet nth-order model. Owing to the effects of catalysis of cyano functionality, the activation energy is 89.65KJ•mol-1and the total order of reaction is 1.84, which is quite different from that of normal benzoxazine. The theoretical calculations matched reasonably well with the experimental results.

scholarly journals Curing Kinetics of Hybrid Networks Composed of Benzoxazine and Multifunctional Novolac Epoxy

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Wu Ke ◽  
Wang Rumin ◽  
Zeng Jinfang
Keyword(s):  
Thermogravimetric Analysis ◽  
Curing Kinetics ◽  
Hybrid Networks ◽  
Hybrid Network ◽  
Scanning Calorimetry ◽  
Autocatalytic Model ◽  
Novolac Epoxy ◽  
Kinetics Of ◽  
Mixture System ◽  
Reactive Mechanism

A novel hybrid network composed of benzoxazines (BZ) and novolac epoxy resin (F-51) was prepared successfully. Thermal properties, curing kinetics, and decomposition process were studied using isothermal differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) in this paper. The reactive mechanism of F-51/BZ mixture system is different from the BZ homopolymers at low temperatures; two resin systems follow the autocatalytic model mainly at high temperatures. Thermogravimetric analysis indicates that F-51 can have no significant effect on thermal degradation temperatures and on increasing char yield.

Effects of additives on the cure kinetics of vinyl ester pultrusion resins

2021 ◽  
pp. 002199832110015
Author(s):  
Alexander Vedernikov ◽  
Yaroslav Nasonov ◽  
Roman Korotkov ◽  
Sergey Gusev ◽  
Iskander Akhatov ◽  
...  
Keyword(s):  
Vinyl Ester ◽  
Mean Squared Error ◽  
Cure Kinetics ◽  
Zinc Stearate ◽  
Heating Rates ◽  
Scanning Calorimetry ◽  
Different Temperatures ◽  
Predicted Values ◽  
Kinetics Of ◽  
Final Degree

Pultrusion is a highly efficient composite manufacturing process. To accurately describe pultrusion, an appropriate model of resin cure kinetics is required. In this study, we investigated cure kinetics modeling of a vinyl ester pultrusion resin (Atlac 430) in the presence of aluminum hydroxide (Al(OH)3) and zinc stearate (Zn(C18H35O2)2) as processing additives. Herein, four different resin compositions were studied: neat resin composition, composition with Al(OH)3, composition comprising Zn(C18H35O2)2, and composition containing both Al(OH)3 and Zn(C18H35O2)2. To analyze each composition, we performed differential scanning calorimetry at the heating rates of 5, 7.5, and 10 K/min. To characterize the cure kinetics of Atlac 430, 16 kinetic models were tested, and their performances were compared. The model based on the [Formula: see text]th-order autocatalytic reaction demonstrated the best results, with a 4.5% mean squared error (MSE) between the experimental and predicted data. This study proposes a method to reduce the MSE resulting from the simultaneous melting of Zn(C18H35O2)2. We were able to reduce the MSE by approximately 34%. Numerical simulations conducted at different temperatures and pulling speeds demonstrated a significant influence of resin composition on the pultrusion of a flat laminate profile. Simulation results obtained for the 600 mm long die block at different die temperatures (115, 120, 125, and 130 °C) showed that for a resin with a final degree of cure exceeding 95% at the die exit, the maximum difference between the predicted values of pulling speed for a specified set of compositions may exceed 1.7 times.

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.

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