Cure kinetics of PF/PVAc hybrid adhesive for manufacturing profiled wood-strand composites

Holzforschung ◽  
2010 ◽  
Vol 64 (5) ◽  
Author(s):  
Yi Wang ◽  
Vikram Yadama ◽  
Marie-Pierre Laborie ◽  
Debes Bhattacharyya
Keyword(s):  
Hot Pressing ◽  
Phenol Formaldehyde ◽  
Cure Kinetics ◽  
Roll Forming ◽  
Good Prediction ◽  
Forming Process ◽  
Scanning Calorimetry ◽  
Cross Sectional ◽  
Kinetics Of ◽  
Wood Strand

Abstract In thermoforming of profiled wood-strand composites, an adhesive system is needed to provide a weak initial bond to maintain mat integrity and architecture during the forming process and eventually a durable bond when the final cross-sectional shape is achieved. A hybrid adhesive composed of phenol formaldehyde (PF) and poly(vinyl acetate) (PVAc) is proposed in this study. The cure kinetics of this hybrid adhesive and bond development in a multi-step hot-pressing is discussed. Cure kinetics studied by differential scanning calorimetry indicated that adding PVAc slowed down the curing reaction of PF resin; however, the full cure of PF was not inhibited. The nth-order Borchardt Daniels (nth-BD) model provided good prediction for the curing of adhesives with a PF/PVAc ratio lower than 1:1. To simulate roll forming of wood-strand mats, a hot-pressing schedule at low temperature combined with multi-stage closing and opening was developed. The nth-BD model was able to predict the actual bond development for composites made with neat PF resin. The results indicated that cure kinetics of a PF/PVAc hybrid adhesive would not significantly differ from neat PF resin for blend ratios of 1:1 or lower, thus potentially providing a resin system for roll forming or matched-die forming of wood-strand composites.

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.

scholarly journals A Comparative Study on Cure Kinetics of Layered Double Hydroxide (LDH)/Epoxy Nanocomposites

2020 ◽  
Vol 4 (3) ◽  
pp. 111
Author(s):  
Zohre Karami ◽  
Seyed Mohammad Reza Paran ◽  
Poornima Vijayan P. ◽  
Mohammad Reza Ganjali ◽  
Maryam Jouyandeh ◽  
...  
Keyword(s):  
Layered Double Hydroxide ◽  
Cure Kinetics ◽  
Frequency Factor ◽  
Isoconversional Methods ◽  
Epoxide Ring ◽  
Epoxy Nanocomposites ◽  
Scanning Calorimetry ◽  
Noncatalytic Reaction ◽  
Double Hydroxide ◽  
Kinetics Of

Layered double hydroxide (LDH) minerals are promising candidates for developing polymer nanocomposites and the exchange of intercalating anions and metal ions in the LDH structure considerably affects their ultimate properties. Despite the fact that the synthesis of various kinds of LDHs has been the subject of numerous studies, the cure kinetics of LDH-based thermoset polymer composites has rarely been investigated. Herein, binary and ternary structures, including [Mg0.75 Al0.25 (OH)2]0.25+ [(CO32−)0.25/2∙m H2O]0.25−, [Mg0.75 Al0.25 (OH)2]0.25+ [(NO3−)0.25∙m H2O]0.25− and [Mg0.64 Zn0.11 Al0.25 (OH)2]0.25+ [(CO32−)0.25/2∙m H2O]0.25−, have been incorporated into epoxy to study the cure kinetics of the resulting nanocomposites by differential scanning calorimetry (DSC). Both integral and differential isoconversional methods serve to study the non-isothermal curing reactions of epoxy nanocomposites. The effects of carbonate and nitrate ions as intercalating agents on the cure kinetics are also discussed. The activation energy of cure (Eα) was calculated based on the Friedman and Kissinger–Akahira–Sunose (KAS) methods for epoxy/LDH nanocomposites. The order of autocatalytic reaction (m) for the epoxy/Mg-Al-NO3 (0.30 and 0.254 calculated by the Friedman and KAS methods, respectively) was smaller than that of the neat epoxy, which suggested a shift of the curing mechanism from an autocatalytic to noncatalytic reaction. Moreover, a higher frequency factor for the aforementioned nanocomposite suggests that the incorporation of Mg-Al-NO3 in the epoxy composite improved the curability of the epoxy. The results elucidate that the intercalating anions and the metal constituent of LDH significantly govern the cure kinetics of epoxy by the participation of nitrate anions in the epoxide ring-opening reaction.

Optimizing Roll Forming Processes with the Aid of a New Numerical Algorithm

2012 ◽  
Vol 504-506 ◽  
pp. 857-862 ◽  
Author(s):  
Ahmad Abrass ◽  
Thomas Kessler ◽  
Peter Groche
Keyword(s):  
Numerical Algorithm ◽  
Numerical Algorithms ◽  
Roll Forming ◽  
Design Parameters ◽  
Fe Model ◽  
Forming Process ◽  
Cross Sectional ◽  
Cross Sectional Profile ◽  
Sectional Profile ◽  
Roll Forming Process

For the manufacturing of large quantities of profile-shaped products, the roll forming process represents one of the most effective metal forming technologies. During this process, the sheet metal will be formed into a desired cross-sectional profile using successive pairs of forming rolls. This process is well known as a very complex process in industry because of the multiplicity of the process and design parameters. For that reason, the optimization of roll forming processes using numerical methods like the finite element method is very complex and time-consuming. In this paper, a numerical method will be introduced to accelerate the simulation and to optimize the roll forming process. The newly developed algorithm will be illustrated and validated by analyzing the roll forming process. The details of the FE-model and the numerical algorithm will be described. Furthermore, the results of the numerical simulation with and without the application of the numerical algorithms will be compared. Finally, the process will be optimized using the newly developed method.

scholarly journals Non-isothermal cure kinetics of aerogel/epoxy composites using differential scanning calorimetry

2019 ◽  
Vol 58 (16) ◽  
pp. 1757-1765 ◽  
Author(s):  
Suryanarayanan Krishnaswamy ◽  
Veronica Marchante ◽  
Hrushikesh Abhyankar ◽  
Zhaorong Huang ◽  
James Brighton
Keyword(s):  
Differential Scanning Calorimetry ◽  
Cure Kinetics ◽  
Epoxy Composites ◽  
Scanning Calorimetry ◽  
Isothermal Cure ◽  
Kinetics Of
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