Strength Properties of Epoxy Compounds

Achieving good adhesion not only depends on selecting the right adhesive, but also on implementing the best surface preparation techniques. Regardless of the substrate, proper surface preparation always plays an essential role in achieving strong bonds. This white paper explores the various techniques including degreasing, abrasion, chemical treatments and physical methods.

Master Bond employs advanced, state of the art testing methods to ensure accurate, repeatable, and reproducible strength measurements. Strict adherence to material and process specifications is integral for meeting high quality standards. Master Bond mechanical testing equipment is frequently used for performing tensile and shear tests.To illustrate, below you can see the curves that were obtained from the tensile testing of Master Bond epoxy EP42HT-2MED. This tensile test is based on ASTM D638 - 14 Standard Test Method for Tensile Properties of Plastics.Graph 1: Force vs. DisplacementGraph 2: Tensile Stress vs. StrainIn a tensile test, the material by itself is clamped on both ends and pulled apart at a fixed speed. The force that the specimen must support, or the reaction force, is then measured and plotted as a result of the displacement. This force as a function of displacement is shown in the first graph. These values are then converted into the stress-strain curve shown in the second graph. This one represents the stress that the material must withstand when it is subject to a specific amount of strain.Strength information like this can help engineers decide which products would be the best candidates to evaluate. However, testing would ultimately have to be performed in the context of an application, to gauge feasibility and ensure precise suitability. Factors such as the substrates being bonded, mechanical forces involved, and operating conditions such as temperatures, thermal cycling, and chemical exposure will have an impact on the results. It is important to note that processing of the adhesive plays an essential role in optimizing adhesion and product functionality. Optimal performance can be achieved by following the appropriate procedures for surface preparation, application of the adhesive, and curing. To perform such tensile testing, Master Bond employs the Instron Model 3367 Dual-Column Universal Testing System in conjunction with Bluehill LE Software. Many Master Bond epoxies and other chemistries exhibit outstanding physical strength properties for high performance bonding, sealing, coating, potting, and encapsulation. This equipment enables Master Bond the ability to quantitatively assess those strength properties.Instron 3367 Universal Testing SystemDisclaimer: The findings in this article are not meant to be used for specification purposes.References: Instron testing systems: https://www.instron.com/en/products/testing-systems/universal-testing-systems

Because of its outstanding strength and other physical properties, Master Bond Supreme 10HT has been selected for use in several published research studies in the aerospace, electronics, OEM, materials science and more.

The graphs below display the lap shear strength of eight distinct Master Bond epoxy adhesives for dissimilar metal bonding. They show the bonding of aluminum to stainless steel, aluminum to titanium, and nickel to titanium. In every experiment, the 4 x 1 x 1/16 inch metal coupons were roughened and cleaned with acetone prior to bonding.Supreme 10HT consistently displayed the highest lap shear strength among the products tested. However, when choosing an adhesive for dissimilar metal bonding, the processing and operating conditions play a large role as well. For example, if thermal conductivity is required, Supreme 10AOHT or Supreme 18TC may be better options. If a room temperature cure is needed, Supreme 11HT or EP21ND-LP may be desired. For more information on Master Bond high strength epoxy adhesives, please contact our technical advisors.Disclaimer: The findings in this article are not meant to be used for specification purposes.

In many applications, proper surface preparation is essential to optimize bond strength for long term performance and durability. How to achieve optimal bond strength with proper surface preparation of your metal? We’ll demonstrate how in this captivating video.

Master Bond EP15 is a one-component, thermally-curing epoxy with a tensile strength in excess of 12,000 psi (82.7 MPa) due to the formation of rigid, dimensionally stable bonds upon curing. This bulk tensile strength makes it ideal for testing the adhesive and cohesive strengths of various thermal spray coatings according to ASTM C633, which requires the use of a high tensile strength adhesive that does not fail until after the coating.