Removable foams based on an epoxy resin incorporating reversible Diels–Alder adducts

McElhanon, James R.; Russick, Edward Mark; Wheeler, David R.; Loy, Douglas A.; Aubert, J.

doi:10.1002/app.10753

Cited by 110 publications

(114 citation statements)

References 50 publications

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“…However, it is also necessary for removable encapsulants to have mechanical and processing properties that are typical of an epoxy or polyurethane encapsulant. We have developed new encapsulants for this purpose that have mechanical properties similar to conventional encapsulants, but can be removed with a chemical process that is relatively benign [1,2]. Conventional epoxy or polyurethane encapsulants are difficult to remove due to crosslinking, solvent resistance, and mechanical toughness.…”

Section: Compatibility Of Fluorinerttm Fc-72 With Selected Materialmentioning

confidence: 99%

“…Adducts can be opened by increasing the temperature and the encapsulant can be removed with a combination of elevated temperature and a solvent [3]. FluorinertTM electronic fluid, FC-72, obtained from the 3M company [4], is the physical blowing agent used in removable epoxy foams, REF308 and REF320 [1,2]. The boiling point of FC-72 is 56 "C. [1,2]).…”

Section: Removablementioning

confidence: 99%

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Compatibility of Fluorinert, FC-72, with selected materials.

Aubert¹,

Sawyer²

2006

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Section: Compatibility Of Fluorinerttm Fc-72 With Selected Materialmentioning

confidence: 99%

Section: Removablementioning

confidence: 99%

Compatibility of Fluorinert, FC-72, with selected materials.

Aubert¹,

Sawyer²

2006

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“…The specific heat is assumed to follow Aselage's data up to the glass transition temperature, which is about 70ºC for REF100 [8]. The glass transition temperature is higher for REF200 and REF300; however, the specific heat is assumed to be the same for these two types of foams.…”

Section: Specific Heatmentioning

confidence: 99%

“…Such encapsulants were removed for component maintenance by using aggressive solvents and/or mechanical chiseling, which can easily damage electronic assemblies. McElhanon et al [8] have recently patented a method to make thermally removable epoxies that can be removed from potted assemblies with a mild solvent (e.g., nbutanol) at 90ºC. Removability was achieved by incorporating chemically labile linkages within the crosslinked polymeric network using the reversible Diels-Alder reaction.…”

Section: Introductionmentioning

confidence: 99%

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Response of removable epoxy foam exposed to fire using an element death model.

Hobbs¹

2004

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Response of removable epoxy foam (REF) to high heat fluxes is described using a decomposition chemistry model [1] in conjunction with a finite element heat conduction code [2] that supports chemical kinetics and dynamic radiation enclosures. The chemistry model [1] describes the temporal transformation of virgin foam into carbonaceous residue by considering breakdown of the foam polymer structure, desorption of gases not associated with the foam polymer, mass transport of decomposition products from the reaction site to the bulk gas, and phase equilibrium. The finite element foam response model considers the spatial behavior of the foam by using measured and predicted thermophysical properties in combination with the decomposition chemistry model. Foam elements are removed from the computational domain when the condensed mass fractions of the foam elements are close to zero. Element removal, referred to as element death, creates a space within the metal confinement causing radiation to be the dominant mode of heat transfer between the surface of the remaining foam elements and the interior walls of the confining metal skin. Predictions were compared to front locations extrapolated from radiographs of foam cylinders enclosed in metal containers that were heated with quartz lamps [3,4]. The effects of the maximum temperature of the metal container, density of the foam, the foam orientation, venting of the decomposition products, pressurization of the metal container, and the presence or absence of embedded components are discussed. 4Intentionally left blank 5

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Diels–Alder Polymers

Yoshie¹

2013

Encyclopedia of Polymer Science and Technology

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The Diels–Alder (DA) cycloaddition is extensively used in polymer chemistry. Linear, network, and hyperbranched polymers have been prepared from monomers and prepolymers containing a diene and a dienophile. Because of the simple reaction conditions, high yield, and high selectivity, the DA reaction has recently been rerecognized as a member of the click‐chemistry family. Polymers with unique architectures (e.g., block and graft copolymers, star polymers, telechelic polymers, dendrimers, and dendronized polymers) have been prepared based on this concept. Many DA reactions are thermally reversible. Enthalpically favorable forward cycloaddition reaction proceeds at low temperature, whereas the opposite cycloreversion proceeds at moderate‐to‐high temperature. Among the various options for optimizing DA reactions in polymer synthesis, researchers have focused on the diene–dienophile combination. Ease of reactant preparation, reaction rate of the DA cycloaddition, equilibrium constant of the DA reaction at room temperature, and temperature above which the retro‐DA reaction proceeds are key points in choosing this option. In addition, reversibility has been exploited in developing various functional polymers such as recyclable gels and thermosets, shape‐memory polymers, and crack‐healing polymers. This article surveys DA reactions in polymer synthesis and coupling, including the click‐chemistry approach, and functionality of DA polymers mainly based on the reversibility.

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Removable foams based on an epoxy resin incorporating reversible Diels–Alder adducts

Cited by 110 publications

References 50 publications

Compatibility of Fluorinert, FC-72, with selected materials.

Compatibility of Fluorinert, FC-72, with selected materials.

Response of removable epoxy foam exposed to fire using an element death model.

Diels–Alder Polymers

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