Thermo-oxidative aging of epoxy coating systems (original) (raw)
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Journal of Applied Polymer Science, 2006
The physical aging of the epoxy network consisting of a diglycidyl ether of bisphenol A, m-xylylenediamine, and polyetherimide was studied by differential scanning calorimetry. The glass transition temperature and the variation of the specific heat capacities have been calculated using the method, based on the intersection of both enthalpy-temperature lines for glassy and liquid states. The apparent activation energy (E H) was calculated using a single method that involved separate temperature and excess enthalpy dependency. All calorimetric data were compared with those obtained for the epoxy network without thermoplastic.
Physical aging for an epoxy network diglycidyl ether of bisphenol A/m-xylylenediamine
Polymer, 2003
The physical aging of the epoxy network consisting of a diglycidyl ether of bisphenol A (BADGE n ¼ 0) and m-xylylenediamine (m-XDA) were studied by differential scanning calorimetry. The following aging temperatures have been used in this work: 60, 70, 80, 90, 100 and 110 8C. The glass transition temperature and the variation of the specific heat capacities have been calculated using the method based on the intersection of both enthalpy-temperature lines for glassy and liquid states. The endothermic aging peak, relaxation enthalpy and fictive temperature were also calculated for each aging temperature and aging time.
Physical aging of linear and network epoxy resins
Polymer Engineering and Science, 1981
Network and linear epoxy resins principally based on the diglycidyl ether of bisphenol-A and its oligomers have been prepared and studied. Both diamine and anhydride crosslinking agents were utilized. In addition, some rubber modified epoxies and a carbon fiber reinforced composite was investigated. All of these materials display time-dependent changes in many of their properties when they are stored (following quenching) at temperatures below their glass transition temperature (sub-T,/ annealing). For example, the degree of stress relaxation for a given time period is observed to decrease in a linear fashion with the logarithm of time during sub-T, annealing. Young's modulus and yield stress were also found to increase in physical aging. Solvent sorption experiments initiated after different sub-T,) annealing times have demonstrated that the rate of solvent uptake can be indirectly related to the free volume of the epoxy resins. The effect of water on the physical aging of these epoxy resins was not found to be a significant variable, Residual thermal stresses were also found to have little effect on the physical aging process, although this variable was not studied in detail. Finally, the physical aging process also affected the sub-T, properties of uniaxial carbon fiber reinforced epoxy material and the effects were as expected. The importance of the recovery or physical aging phenomenon, which affects the durability of epoxy glasses, is considered in view of the widespread applications for these resins as structural materials.
Thermal and photochemical ageing of epoxy resin – Influence of curing agents
Polymer Degradation and Stability, 2006
The thermal and photochemical ageing of epoxy resin was studied using photoacoustic-FTIR spectroscopy. This technique was satisfactory for both unfilled resin and glass fibre filled epoxy composite. The influence of the curing agent (anhydride or amine) was significant for ageing. The durability of anhydride–epoxy system was the best for both thermal and photoageing.
Isothermal degradation and thermooxidative degradation of an epoxy powder coating
Journal of Thermal Analysis and Calorimetry, 2005
Thermogravimetry was used to study the kinetics of isothermal degradation of an epoxy thermoset powder coating in a nitrogen atmosphere and in oxidising atmospheres of air and pure oxygen. An integral isoconversional procedure was used to analyse how the activation energy varies depending on the degree of conversion and depending on the atmospheres used. In the case of degradation in a nitrogen atmosphere, in addition to the activation energy, the kinetic triplet was completed using an Avrami reaction model and the pre-exponential factor. With this atmosphere, the conclusion was reached that the isothermal and non-isothermal kinetics are equivalent. It was shown that the thermooxidative degradation process is more complex and consists of a two-stage process. The first stage of degradation is similar whether nitrogen, oxygen or air are present. Chain scission occurs and it seems that there is formation of thermally more stable compounds. The second stage of degradation, involving several phenomena, occurs only in the presence of oxygen or air and leads to the total disappearance of the organic material by thermooxidation. These stages are very similar under non-isothermal or isothermal conditions.
Synthesis and characterization of high thermally stable poly(Schiff) epoxy coatings
Progress in Organic Coatings, 2006
Epoxy resins were prepared from Schiff base monomer and polymer through two steps. The first step is based on reaction of salicyladehyde or 5,5 − -methylene-bis-salicylaldehyde with o-phenylene diamine. The second step includes the reaction between Schiff base monomer or polymer with epichlorohydrine (EC) to produce epoxy resins. The chemical structures of both Schiff base monomers and polymers were determined by elemental analysis, IR and 1 HNMR spectral analyses. The molecular weights of the produced epoxy resins were determined by GPC technique. The chemical structures and epoxy functionality were determined by 1 HNMR analysis. The prepared epoxy resins were cured with diamine based on pentaethylene hexamine (PEHA) and p-phenylene diamine (PDA). The thermal stability of the cured resins was evaluated by DSC and TGA analysis. Thermal stability data indicate that the cured epoxy resins with aromatic amine possess higher thermal stability than that cured with aliphatic amine. The cured epoxy-amine systems were evaluated in coating applications of steel by measuring the mechanical properties and chemical resistance of the cured films.
International Journal of Polymer Science, 2016
Epoxy resin (ER) was modified with four different epoxide compounds, 4,5-epoxy-4-methyl-pentane-2-on (EMP), 3-phenyl-1,2-epoxypropane (PhEP), 1-chloro-2,3-epoxy-5-(chloromethyl)-5-hexene (CEH), and a fatty acid glycidyl ester (FAGE), to improve its chemical and physical properties. The effects of the addition and amount of these modifiers on mechanical, thermal, and coating properties were investigated. Atomic force microscopy was used to observe the changes obtained with the modification. The influence of the modifying agents on the curing process was monitored through FTIR spectroscopy. The curing degrees of ER and modified ERs (M-ERs) were found to be over 91%. The results showed that tensile strength of ER improved till 30% (wt.) with addition of the modifier content. Modification with EMP and PhEP remarkably enhanced the thermal stability of ER to be highly resistant to the corrosive media.
Thermodegradation kinetics of a hybrid inorganic–organic epoxy system
European Polymer Journal, 2005
Lifetime of the epoxy system formed by diglycidyl ether of bisphenol A, DGEBA/4,4 0 -diaminediphenylmethane, DDM, modified with the silsesquioxane, glycidylisobutyl-POSS, was calculated from thermogravimetric analysis. The activation energy of the decomposition of this system was evaluated by the integral method developed by Flynn-Wall-Ozawa (E = 88.9 ± 2.1 kJ mol À1 ) and by Coats and Redfern method (E = 85.2 ± 1.5 kJ mol À1 ). The kinetic parameters have been used to estimate the lifetime of the system POSS/DGEBA/DDM. The obtained results by two different ways are similar.
Progress in Organic Coatings, 2006
Epoxy binders were prepared from Schiff base monomers through two steps. The first step is based on condensation of hydroxy benzaldehyde derivatives with o-and p-phenylenediamine. The second step includes the reaction between Schiff base monomers with epichlorohydrin (EC) to produce epoxy binder. The synthesized epoxy binders were characterized by determination of epoxy contents and epoxy functionalities. The chemical structures and epoxy functionalities were determined by 1 H NMR analysis. The thermal stability and characteristics of the prepared Schiff base monomers and polymers as well as their epoxy resins were measured and evaluated by DSC and TGA analysis. The prepared epoxy resins were cured with polyamine. In this respect, pentaethylenehexamine (PEHA) and p-phenylenediamine (PDA) were used as aliphatic and aromatic amine, respectively. Thermal stability data indicate that epoxy resins cured with aromatic amine possess higher thermal stability than that cured with aliphatic amine. The cured epoxy polyamine systems were evaluated in coating applications of steel by measuring the mechanical properties and chemical resistance of the cured films. (A.M. Atta). of processing. Their main problem is relatively poor thermal stability and flame resistance which limits their applications in more demanding areas such as aerospace and electronic industry [6-9]. Use of metal-containing epoxy resins allows the possibility of producing epoxy polymers with good mechanical properties and high thermal stability as well achieving low processing temperature . Almost of these polymers are based on metal-containing epoxy polymers. In this respect, the present work aims to prepare epoxy resins based on condensation aromatic aldehyde (o-, m-and p-hydroxybenzaldehyde) with o-phenylene and p-phenylenediamine. The prepared epoxy resins were cured with p-phenylenediamine and pentaethylenehexamine as aromatic and aliphatic polyamine hardener, respectively. In this work we have provided comprehensive results of a long-term study regarding the influence of types of epoxy resins, and types of amine hardeners on the chemical resistance of epoxy coating systems.