Properties of poly(urea‐formaldheyde) microcapsules containing an epoxy resin

Abstract

Physical properties of urea-formaldehyde microcapsules containing an epoxy resin are presented and discussed. Microcapsules were prepared by in situ polymerization of monomers in an oil-in-water emulsion. Differential scanning calorimetry, thermogravimetric analysis, and scanning electronic microscopy were applied to investigate thermal and morphological microcapsule properties. Microencapsulation was detected by means of FTIR and Raman techniques. It was found that the amount of encapsulated epoxy resin as well as the extent of urea-formaldehyde polymerization depends on the reaction temperature and the stirring speed

Microcapsules filled with reactive solutions for self-healing materials

“…The microencapsulation of active materials including epoxy resins [5,6], hardeners [7][8][9], and solvents [10,11] is of particular interest for capsular adhesives [8], protection of catalysts [12], and self-healing materials [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28]. Microcapsules release their contents in response to a stimulus such as mechanical damage or through a controlled release process.…”

Full Recovery of Fracture Toughness Using a Nontoxic Solvent‐Based Self‐Healing System

“…Several groups have reported the success and ease of making microcapsules containing epoxy resins. [21][22][23][24] We selected the epoxide functionality as a coencapsulant to test our mechanistic hypothesis that solvents swell the epoxy matrix and transport the residual amines in the matrix sol, making them available for further curing. As reported below, an improvement in the healing efficiencies (ca.…”

Preparation of capsules containing rejuvenators for their use in asphalt concrete

“…Arshady [15] defines the microcapsules as "particles, spherical or irregular, in the size range of about 50 nm to 2000 m or larger, and composed of an excipient polymer matrix (shell or wall) and an incipient active polymer (core substance)". Encapsulation of active substances as epoxy resins [16,17], hardeners [18] or solvents [19] is of particular interest for self-healing materials [20][21][22][23][24], coatings [25] and many other industrial applications such as capsular adhesives [18] and protection of catalysis [26]. The capsules developed for this paper can break due to constant fatigue loads as well as increasing stiffness of the binder during oxidization: traffic loads will result in higher stresses on the shell of the capsule due to the increased stiffness.…”

“…Before writing this paper, urea-formaldehyde [17] and melamine-formaldehyde [27] microcapsules containing rejuvenators with an average diameter of 15 m were made and mixed in asphalt concrete. During the mixing process it became clear that these capsules were not strong enough and therefore preliminary released the rejuvenator into the asphalt concrete mixture.…”