Preparation and characterization of self‐healing microcapsules with poly(urea‐formaldehyde) grafted epoxy functional group shell

Abstract

Microcapsules were prepared by in situ polymerization technology with poly(urea-formaldehyde) (PUF)-grafted c-glycidoxypropyltrimethoxy silane (KH560) copolymer as a shell material and dicyclopentadiene (DCPD) as core materials. The aim was to improve the interfacial bond between microcapsules and epoxy matrix in composites through the epoxy functional group in KH560. The microcapsulating mechanism was discussed and the process was explained. The morphology and shell wall thickness of microcapsules were observed by using scanning electron microscopy. The size of microcapsules was measured using optical microscope and the size distribution was investigated based on data sets of at least 200 measurements. The chemical structure and thermal properties of microcapsules were characterized by Fourier transform infrared spectroscopy, X-ray photoelectron spectra, and thermogravimetric analysis. Results indicted that the PUF-graft KH560 microcapsules containing DCPD can be synthesized successfully; the epoxy functional group was grafted on the wall material. The microcapsule size is in the range of 40-190 lm with an average of 125 lm. The wall thickness of microcapsules sample is in the range of 2-5 lm and the core content of microcapsules is about 60%.

Self healing coatings containing dual active agent loaded urea formaldehyde (UF) microcapsules

“…The sample bag was placed in a Soxhlet apparatus after taking weight (W 1 ), extracted with acetone for 9 h, and finally dried in a vacuum oven at 70 • C. After cooling in a vacuum desiccator, the sample bag was weighed again (W 2 ). Eventually, the core content (A) of the microcapsules was calculated by following equation [37,38].…”

Interface Stability of Microencapsulated-Paraffin Filled Epoxy Composites: Effect of Methylation on Melamine–Formaldehyde Shell Material

“…However, some of the residues of this formaldehyde resin in shells can cause environmental and health problems. To resolve this challenge, molecules modified methods have been applied to fabricate microPCMs using resorcinol-modified melamine-formaldehyde shell material [16]. Interestingly, we have proved that the methanol-modified melamine-formaldehyde (MMF) can be applied as microcapsule shell materials.…”

Self-healing polymers and composites

“…4), which is important, for example, when fabricating thin self-healing coatings. In other reports, epoxy matrix/microcapsule adhesion was enhanced by grafting either silane coupling agents 90 or epoxy functional groups 91 to the surface of the ureaformaldehyde capsules. One especially interesting variant of these systems was a binary capsule consisting of a large, DCPD filled microcapsule (y140 mm) with smaller capsules (y1?4 mm) containing a second, different liquid at the periphery of the larger capsule 92 ( Fig.…”