How to improve hydrolysis resistance?
Last update on Jan 14, 2026
Hydrolysis happens when water disrupts the chemical bonds within a polymer, leading to the degradation of plastic. This process results in the breaking of molecular chains, a reduction in molecular weight, and a deterioration of the polymer's properties, particularly its toughness. While hydrolysis progresses slowly at room temperature, it can accelerate significantly at elevated temperatures.
Steam and boiling water both promote hydrolysis in susceptible plastics, but they differ in intensity and the way they affect materials:
| Boiling water (≈ 100°C, liquid phase) | Steam (≥ 100°C, vapor phase under pressure) | |
| Mechanism | Water molecules penetrate the polymer matrix and break hydrolyzable bonds (like esters, amides, carbonates) through chemical reaction. | Accelerates hydrolytic chain scission, especially in polymers with weak hydrolysis resistance. |
| Impact | Gradual reduction in molecular weight, embrittlement, and loss of mechanical properties. | Rapid degradation in materials |
Film failure of a polyurethane coated fabric due to hydrolysis (Image credits: Association for Contract Textiles)
Factors that determine a plastic's resistance to hydrolysis
The choice of polymer is of prime importance when it comes to designing outdoor components. With careful examination of the factors that lead to failure of plastic by hydrolysis, you can make better choices.
- Strong backbone: Strong covalent bonds within the backbone make it more difficult for water molecules to break the chain apart
- Low hygroscopicity: The lesser the hygroscopicity, the less are chances of hydrolysis reactions taking place
- Presence of hydrolysable bonds: Water can attack certain linkages in polymers, such as esters, amides, or urethanes. Polymers lacking these groups & having only carbon–carbon or carbon–hydrogen bonds are much more resistant to hydrolysis
- High crystallinity: The denser packing makes it harder for water molecules to penetrate and initiate hydrolysis