Many factors can contribute to adhesive failure, including surface preparation, substrate composition, and time. To improve the chances of successful application, it is essential to understand these factors and the various ways they can be altered. Following are some of the most important considerations to ensure adhesive success.
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Surface preparation
The successful bonding of an adhesive depends on the adhesion between the substrate and the adhesive. In addition to the type of adhesive, surface preparation also affects the durability and lifespan of the bond. Different surface conditions call for different adhesives and surface preparation methods. Some surfaces are easily prepared with a light dusting, while others require intensive processes to ensure a consistent surface for bonding.
One of the factors affecting adhesion is the roughness of the surface. The better the surface is prepared, the more it can hold adhesive. A smooth surface is easier to bond, but a rough surface will require more effort. Changing the surface profile by sanding and buffing will result in more surface area and more adhesive contact areas. To ensure you will get the best one, check the Bostik website, which Bostik provides adhesive technologies across a wide range of sectors.
Composition of the substrate
When determining the strength of an adhesive bond, it’s essential to know how the composition of the substrate affects its performance. Surface characteristics such as absorbency and porosity can prevent the bonding of certain materials. Non-porous and glossy substrates may not allow the adhesive to bond properly, while excessively warm substrates can cause the adhesive to fail to set. To overcome these problems, adding pressure can increase the surface area available for bonding and aid the adhesive to move into the substrate’s pores.
As with any adhesive, the composition of the substrate has an impact on the strength of the bond. Fast-curing adhesives can overcome this problem by being blended with a standard adhesive to achieve the desired bond strength. Other joining methods can also reduce stress peaks using a hybrid adhesive process.
Time
One large home gaming console manufacturer recently experienced a setback when they decided to launch a new product just before the holidays. Testing for adhesive bonding materials was delayed until too late, causing the company to miss the holiday buying rush. Adhesive testing is essential for new products, and a knowledgeable converter can help you make the right choice. Choosing the wrong adhesive can have ramifications for the entire product development process, from the early stages to long-term success. It’s not always easy to identify if an adhesive has failed, but it’s usually apparent when it doesn’t bond well to surfaces.
Adhesive failure is typically caused by one of three reasons. Inadequate surface preparation, improper curing methods, and incompatibility with the substrate are all factors that can lead to poor bonding. If these factors are present, a failure will be more likely. Poor bonding may be prevented by following guidelines. However, there are always exceptions. So, when choosing an adhesive, read the product data-sheet before making the purchase.
Temperature
The application temperature range of adhesive systems is critical for achieving the desired bond strength, and it also dictates pot life and the amount of dwell time required to wet the surface. A wide temperature range is possible for most adhesive systems.
The ambient temperature affects bonding because different materials have varying coefficients of thermal expansion. The change in length caused by temperature changes results in stresses in bonded joints. These stresses are present in the unloaded joint after a cure at 150 degC and after the parts have been cooled down to room temperature. Further operations occur at lower temperatures, which lead to even more stress. Moreover, lower temperatures decrease the strength and stiffness of the adhesive, whereas higher temperatures increase the risk of cracking.
The temperature dependence of adhesive strength was shown in a gecko spatula experiment despite the differences between natural and synthetic systems. For example, the surface water on hydrophilic glass surfaces decreased adhesion at room temperature. In addition, gecko toes could expel thin layers of water on a hydrophilic sapphire prism at room temperature. Both experiments supported the hypothesis that water particles bind together by rearrangement of surface chemical groups in the water.
