How to enhance moisture resistance of adhesives?

There are several reasons: 

• Degradation of the adhesive bond: Water molecules can disrupt the interactions between the adhesive and the adherends (the materials being bonded). This can lead to a loss of adhesion strength and potential failure of the bond.
• Hydrolysis: Moisture can make adhesives more susceptible to hydrolysis which can significantly weaken the bond and lead to cracking or peeling over time.
• Swelling and expansion: Moisture absorption can make certain adhesives swell or expand. This can lead to debonding or warping of the adhered materials.
• Growth of microorganisms: Moisture may create a favorable environment for the growth of mold or mildew on the adhesive surface.

At the resin selection stage, it is key to opt for polymers with:

1. Less water absorption: Such polymers will absorb less water when exposed to moisture. This reduces the effect on bulk properties such as strength, flexibility, and adhesion to the bonded materials. This is much needed in construction applications such as flooring (tile adhesives).
2. Low diffusion coefficient: This is critical for packaging applications. It can be measured via an ASTM procedure D 1653. The method describes variables and how the rate of transmission can be measured.

Demand for moisture-resistant flooring adhesives is on the rise
Credits: Spectra Contract Flooring²