Characterization of solvent-filled polyurethane/urea–formaldehyde core–shell composites.

Saved in:
Bibliographic Details
Title: Characterization of solvent-filled polyurethane/urea–formaldehyde core–shell composites.
Authors: Neuser, S.1, Manfredi, E.1, Michaud, V.1 veronique.michaud@epfl.ch
Source: Materials Chemistry & Physics. Feb2014, Vol. 143 Issue 3, p1018-1025. 8p.
Subjects: Polyurethanes, Formaldehyde, Composite materials, Solvents, Microencapsulation, Self-healing materials
Abstract: Abstract: Encapsulation of liquid phases is a crucial step in many self-healing material systems where a healing agent has to be protected during processing and then released during a damage event. In this work, the mechanical properties of polyurethane (PU) reinforced urea–formaldehyde (UF) shells are characterized. It was found that shell thickness is both a function of PU content in the core phase and of the microcapsule diameter. Furthermore, a saturation thickness was found for high PU contents or high capsule diameters and this phenomenon had direct implications on the bursting force under compression of single microcapsules. With help of an analytical model, the Young's modulus of the hybrid PU/UF was determined and in general, PU-reinforced shells had a lower modulus but higher ductility in terms of elongation at break, leading to more resistant microcapsules overall. [Copyright &y& Elsevier]
Copyright of Materials Chemistry & Physics is the property of Elsevier B.V. and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
Database: Engineering Source
Description
Abstract:Abstract: Encapsulation of liquid phases is a crucial step in many self-healing material systems where a healing agent has to be protected during processing and then released during a damage event. In this work, the mechanical properties of polyurethane (PU) reinforced urea–formaldehyde (UF) shells are characterized. It was found that shell thickness is both a function of PU content in the core phase and of the microcapsule diameter. Furthermore, a saturation thickness was found for high PU contents or high capsule diameters and this phenomenon had direct implications on the bursting force under compression of single microcapsules. With help of an analytical model, the Young's modulus of the hybrid PU/UF was determined and in general, PU-reinforced shells had a lower modulus but higher ductility in terms of elongation at break, leading to more resistant microcapsules overall. [Copyright &y& Elsevier]
ISSN:02540584
DOI:10.1016/j.matchemphys.2013.10.041