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

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.

Download Full-text

Investigating the relationship between tack and degree of conversion in DGEBA-based epoxy resin cured with dicyandiamide and diuron

Journal of Polymer Engineering ◽

10.1515/polyeng-2020-0340 ◽

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.

Download Full-text

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

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.236-238.2058 ◽

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.

Download Full-text

Kinetics of the Curing Reaction of a Diglycidyl Ether of Bisphenol with a Methanol Etherified Amino Resin

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.380.60 ◽

2011 ◽

Vol 380 ◽

pp. 60-63 ◽

Cited By ~ 2

Author(s):

Yong Lv ◽

Zhu Long ◽

Shi Yong Luo ◽

Lei Dai

Keyword(s):

Cure Kinetics ◽

Frequency Factor ◽

Diglycidyl Ether ◽

Heating Rates ◽

Scanning Calorimetry ◽

Curing Reaction ◽

Before And After ◽

Amino Resin ◽

Chemical Products ◽

Kinetics Of

Subscript text Subscript textEpoxy resins have been widely used for inner coating in food can and other chemical products storage containers. Differential scanning calorimetry (DSC) was used at different heating rates to study the cure kinetics of the diglycidyl ether of bisphenol A (DGEBA) with a methanol etherified amino resin (MEAR). The apparent activation energy derived from Kissinger and Ozawa methods is 35.67KJ/mol and 40.27kJ/mol, respectively. The reaction order evaluated by Crane equation is 0. 95 and the frequency factor is 1.12×104s-1. Reaction mechanism was monitored by FTIR spectra of the reaction mixtures before and after curing. The curing reaction below 200°C is between alkoxylmethyl (>NCH2OCH3) and epoxide group, not between alkoxylmethyl and hydroxyls.

Download Full-text

Estimation of Cure and Thermal Degradation Kinetics of Epoxy/Organoclay Nanocomposite

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.123-125.667 ◽

2010 ◽

Vol 123-125 ◽

pp. 667-670 ◽

Cited By ~ 2

Author(s):

Jae Young Lee ◽

Bum Choul Choi ◽

Hong Ki Lee

Keyword(s):

Activation Energy ◽

Thermal Degradation ◽

Epoxy Matrix ◽

Degradation Kinetics ◽

Cure Kinetics ◽

Diglycidyl Ether ◽

Thermal Degradation Kinetics ◽

Heating Rates ◽

Scanning Calorimetry ◽

Kinetics Of

Polymer nanocomposite was synthesized through the intercalation and exfoliation of organoclay in an epoxy matrix. The epoxy matrix was composed of diglycidyl ether of bisphenol A (DGEBA, epoxy base resin), 4,4'-methylene dianiline (MDA, curing agent) and malononitrile (MN, chain extender) and organoclay was prepared by treating the montmorillonite with octadecyltrimethylammonium bromide (ODTMA). The intercalation of the organoclay was estimated by wide angle X-ray diffraction (WAXD) and transmission electron microscope (TEM) analyses. In order to measure the cure rate of DGEBA/MDA (30 phr)/MN (5 phr)/Organoclay (5 phr), differential scanning calorimetry (DSC) analysis were performed at the heating rates of 5, 10, 15 and 20 oC/min, and the data was interpreted by Kissinger equation. Thermal degradation kinetics of the epoxy nanocomposite was also studied by thermogravimetric analysis (TGA). The epoxy sample was decomposed in the TGA furnace at the heating rates of 5, 10, 15 and 20 oC/min with nitrogen atmosphere of 50 ml/min. The TGA data was introduced to the Ozawa equation and the degradation activation energy was calculated according to the degradation ratio. The activation energy for cure kinetics was 43.3 kJ/mol and that for thermal degradation was 171.5 kJ/mol.

Download Full-text

Dimeric Liquid Crystalline Epoxy Resins Containing Azo Group: Mesogenic Behavior and Curing with Anhydride

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.123-125.955 ◽

2010 ◽

Vol 123-125 ◽

pp. 955-958

Author(s):

De Wen Zhou ◽

Li Yan Liang ◽

Man Geng Lu

Keyword(s):

Epoxy Resins ◽

Liquid Crystalline ◽

Cure Kinetics ◽

X Ray Diffraction ◽

Melting Points ◽

Heating Rates ◽

Scanning Calorimetry ◽

X Ray ◽

Azo Group ◽

Kinetics Of

A series of dimeric liquid crystalline (LC) epoxy monomers containing azo groups with different length of central spacers were synthesized. The mesogenic behavior of these monomers was characterized by differential scanning calorimetry(DSC), polarized optical microscopy (POM) and wide-angle X-Ray diffraction(WAXS). Like other dimeric LC epoxy monomers, the melting points, clear points and mesophase of these compounds were influenced by the carbon numbers of the central spacers. Cure kinetics of these monomers with anhydride was studied by non-isothermal DSC at different heating rates. With the increasing of conversion, the values of activation energy show a tendency to decrease. The formation and development of LC phase during curing were also studied by POM. Finally LC thermosets with nematic phase were obtained.

Download Full-text

Cure and Dynamic-Mechanical Behaviors of Vinyl Ester Resinfilled with Multi-Walled Carbon Nanotubes

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.150-151.1413 ◽

2010 ◽

Vol 150-151 ◽

pp. 1413-1416 ◽

Cited By ~ 2

Author(s):

Hong Yan Chen ◽

Zhen Xing Kong ◽

Ji Hui Wang

Keyword(s):

Carbon Nanotubes ◽

Vinyl Ester ◽

Mechanical Response ◽

Cure Kinetics ◽

Crosslinking Density ◽

Vinyl Ester Resin ◽

Scanning Calorimetry ◽

Dynamic Mechanical ◽

Multi Walled Carbon Nanotubes ◽

Walled Carbon Nanotubes

The cure kinetics of Derakane 411-350, a kind of vinyl ester resin, and its suspensions containing multi-walled carbon nanotubes( MWCNTs) were investigated via non-isothermal dynamic scanning calorimetry (DSC) measurements. The results showed that incorporation of MWCNTs into vinyl ester resin excessively reduces polymerization degree and crosslinking density of vinyl ester resin. For suppressing the negative effect caused by nanotubes, the higher temperature initiator combined with the initiator MEKP was used. Dynamic-mechanical Behavior testing was then carried out on the cured sample in order to relate the curing behavior of MWCNTs modified resin suspensions to mechanical response of their resulting nanocomposites. It was revealed that nanocomposites containing MWCNTs possessed larger storage modulus values as well as higher glass transition temperatures (Tg) as compared to those without MWCNTs after using mixed intiators system to improve the degree of cure.

Download Full-text