Adhesives: Test Method, Group Assignment, and Categorization Guide for High-Loading-Rate Applications  Preparation and Testing of Single Lap Joints (Ver. 2.2, Unlimited)

Jensen, Robert E.; DeSchepper, Daniel; Flanagan, David; Chaney, Gerard; Pergantis, Charles

doi:10.21236/ad1008131

“…This theory has led to the use of surface patterning and surface roughening via grit blasting , as ways of increasing adhesive strength. Grit blasting of aluminum is common in Army applications and was therefore adopted in this work. It is important to note, however, that mechanical interlocking is only effective if the substrate is effectively wet by the adhesive and can cause air voids at the adhesive/adherend interface if wetting is poor.…”

Section: Resultsmentioning

confidence: 99%

“…The aluminum 2024-T3 substrates were prepared according to the guidelines published previously . Oil, grease, dirt, and heavy surface oxidation were removed using acetone (>99.5%, Sigma-Aldrich) and an abrasion pad, Scotch-Brite 048011-65530.…”

Section: Methodsmentioning

confidence: 99%

“…The aluminum 2024-T3 substrates were prepared according to the guidelines published previously. 33 Oil, grease, dirt, and heavy surface oxidation were removed using acetone (>99.5%, Sigma-Aldrich) and an abrasion pad, Scotch-Brite 048011-65530. Grit blasting was performed using virgin 60-grit aluminum oxide abrasive blasting media (Grainger) and a grit blaster (Econoline).…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

“…A minimum of 10 single-lap joint specimens were performed for each experiment. Previously published guidelines 33 were used to prepare single-lap samples to be in accordance with ASTM D1002. Tooling fixtures included shim plates and 3 stacking steel plates (5.4 kg) to control bondline thickness (0.381 mm).…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

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Polydopamine and Polydopamine–Silane Hybrid Surface Treatments in Structural Adhesive Applications

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¹

,

Flanagan

²

,

Orlicki

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et al. 2018

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Numerous studies have focused on the remarkable adhesive properties of polydopamine, which can bind to substrates with a wide range of surface energies, even under aqueous conditions. This behavior suggests that polydopamine may be an attractive option as a surface treatment in structural bonding applications, where good bond durability is required. Here, we assessed polydopamine as a surface treatment for bonding aluminum plates with an epoxy resin. A model epoxy adhesive consisting of diglycidyl ether of bisphenol A (DGEBA) and Jeffamine D230 polyetheramine was employed, and lap shear measurements (ASTM D1002 10) were made (i) under dry conditions to examine initial bond strength and (ii) after exposure to hot/wet (63 °C in water for 14 days) conditions to assess bond durability. Surprisingly, our results showed that polydopamine alone as a surface treatment provided no benefit beyond that obtained by exposing the substrates to an alkaline solution of tris buffer used for the deposition of polydopamine. This implies that polydopamine has a potential Achilles' heel, namely, the formation of a weak boundary layer that was identified using X-ray photoelectron spectroscopy (XPS) of the fractured surfaces. In fact, for longer deposition times (2.5 and 18 h), the tris buffer-treated surface outperformed the polydopamine surface treatments, suggesting that tris buffer plays a unique role in improving adhesive performance even in the absence of polydopamine. We further showed that the use of polydopamine-3-aminopropyltriethoxysilane (APTES) hybrid surface treatments provided significant improvements in bond durability at extended deposition times relative to both polydopamine and an untreated control.

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Bioinspired Design Provides High‐Strength Benzoxazine Structural Adhesives

Higginson

¹

,

Malollari

²

,

Xu

³

et al. 2019

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A synthetic strategy to incorporate catechol functional groups into benzoxazine thermoset monomers was developed, leading to a family of bioinspired small‐molecule resins and main‐chain polybenzoxazines derived from biologically available phenols. Lap‐shear adhesive testing revealed a polybenzoxazine derivative with greater than 5 times improved shear strength on aluminum substrates compared to a widely studied commercial benzoxazine resin. Derivative synthesis identified the catechol moiety as an important design feature in the adhesive performance and curing behavior of this bioinspired thermoset. Favorable mechanical properties comparable to commercial resin were maintained, and glass transition temperature and char yield under nitrogen were improved. Blending of monomers with bioinspired main‐chain polybenzoxazine derivatives provided formulations with enhanced shear adhesive strengths up to 16 MPa, while alloying with commercial core–shell particle‐toughened epoxy resins led to shear strengths exceeding 20 MPa. These results highlight the utility of bioinspired design and the use of biomolecules in the preparation of high‐performance thermoset resins and adhesives with potential utility in transportation and aerospace industries and applications in advanced composites synthesis.

show abstract

Bioinspired Design Provides High‐Strength Benzoxazine Structural Adhesives

Higginson

¹

,

Malollari

²

,

Xu

³

et al. 2019

View full text Add to dashboard Cite

A synthetic strategy to incorporate catechol functional groups into benzoxazine thermoset monomers was developed, leading to a family of bioinspired small‐molecule resins and main‐chain polybenzoxazines derived from biologically available phenols. Lap‐shear adhesive testing revealed a polybenzoxazine derivative with greater than 5 times improved shear strength on aluminum substrates compared to a widely studied commercial benzoxazine resin. Derivative synthesis identified the catechol moiety as an important design feature in the adhesive performance and curing behavior of this bioinspired thermoset. Favorable mechanical properties comparable to commercial resin were maintained, and glass transition temperature and char yield under nitrogen were improved. Blending of monomers with bioinspired main‐chain polybenzoxazine derivatives provided formulations with enhanced shear adhesive strengths up to 16 MPa, while alloying with commercial core–shell particle‐toughened epoxy resins led to shear strengths exceeding 20 MPa. These results highlight the utility of bioinspired design and the use of biomolecules in the preparation of high‐performance thermoset resins and adhesives with potential utility in transportation and aerospace industries and applications in advanced composites synthesis.

show abstract

Adhesives: Test Method, Group Assignment, and Categorization Guide for High-Loading-Rate Applications Preparation and Testing of Single Lap Joints (Ver. 2.2, Unlimited)

Cited by 4 publications

References 0 publications

Polydopamine and Polydopamine–Silane Hybrid Surface Treatments in Structural Adhesive Applications

Polydopamine and Polydopamine–Silane Hybrid Surface Treatments in Structural Adhesive Applications

Bioinspired Design Provides High‐Strength Benzoxazine Structural Adhesives

Bioinspired Design Provides High‐Strength Benzoxazine Structural Adhesives

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