ToF‐SIMS investigation of epoxy resin curing reaction at different resin to hardener ratios

Abstract

Time-of-flight secondary ion mass spectrometry (ToF-SIMS) and principal components analysis (PCA) were used to analyze diglycidyl ether of bisphenol A (DGEBA) and diglycidyl ether of bisphenol F (DGEBF) epoxy resin blend cured with isophorone diamine (IPD) hardener at different resin to hardener ratios. The aim was to establish correlations between the hardener concentration and the nature and progress of the crosslinking reaction. Insights into the cured resin structure revealed using ToF-SIMS are discussed. showed variance related to the completion of the curing reaction. Relative intensities of C x H y N z þ ions in the cured resin samples are indicative of the un-reacted and partially reacted hardener molecules, and are found to be proportional to the resin to hardener mixing ratio. The relative ion intensities of the aliphatic hydrocarbon ions are shown to relate to the cured resin crosslinking density.

Investigation of the postcure reaction and surface energy of epoxy resins using time‐of‐flight secondary ion mass spectrometry and contact‐angle measurements

“…Another significant contribution is related to the relative ion intensities of C 7 H 7 O + and CH 4 N + ions. The concentration of the C 7 H 7 O + relative ion intensity in PC1 is related to the development of branching reactions and to the curing reaction conversion 18. The relative ion intensity of C 7 H 7 O + initially increases with an increasing branching reaction rate and then decreases as the curing reaction conversion increases 18.…”

“…The concentration of the C 7 H 7 O + relative ion intensity in PC1 is related to the development of branching reactions and to the curing reaction conversion 18. The relative ion intensity of C 7 H 7 O + initially increases with an increasing branching reaction rate and then decreases as the curing reaction conversion increases 18. This is because the C 7 H 7 O + relative ion intensity increases in response to the easier and lower energy secondary ion fragmentation of the small coupling and branching structures and decreases as the larger crosslinking structures form, which require much more energy for ionization 18, 28.…”

“…Time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS) has been used previously to provide insight into the curing and postcuring reactions of diglycidyl ether of bisphenol A (DGEBA)/isophorone diamine (IPD) hardeners under different conditions 17, 18. Awaja et al17 showed with a real‐time monitoring system using ToF‐SIMS that three reaction pathways were generated; these were monitored over a curing time of 24 h. It was found, through the changes in the intensity of the aliphatic hydrocarbon ions, that coupling and branching reactions occurred much faster than crosslinking and blocking reactions in the initial stage of the reaction.…”

“…The changes in the relative intensities of the C 21 H 24 O 4 + , C 14 H 7 O + , and C 7 H 7 O + ions provided a measure of the total conversion of the curing reaction at any given reaction time. Furthermore, it was shown that at different resin/hardener ratios,18 the changes in the relative ion intensity of the C x H y N z + ions were indicative of the unreacted and partially reacted hardener molecules and were proportional to the hardener concentration. The relative ion intensity of the listed aliphatic hydrocarbon ions was related to the crosslinking density of the epoxy resin.…”

Tailoring the surface chemistry of carbon fiber and E‐glass composites for improved adhesion

“…ToF‐SIMS peak identification was based on reported characteristic reference peaks for epoxy resin that showed significant intensity42–45 These peaks were assigned and verified using the libraries and mass calculator function of the Ionspec software package (Ion‐TOF GmbH, Germany). Peaks corresponding to hydrocarbon and fragment ions attributed to resin composite materials and not previously reported, were assigned in the same manner.…”