Meaning
The breakdown of a polymer initiated by biological catalysts that are too large to penetrate the material matrix restricts degradation to the outermost layers of the plastic. When a part is subjected to surface enzymatic erosion, enzymes in the environment bind to the surface and cleave the polymer chains. This process results in a progressive reduction in the part’s thickness and mass while the interior of the material remains unaffected.
Biochemical Process
Active sites on the enzyme molecules must align with specific chemical bonds on the polymer surface to trigger the reaction. During surface enzymatic erosion, the hydrophobic nature of many plastics can hinder this contact, meaning that surface treatments or additives are often used to increase the material’s susceptibility to the enzymes. This biochemical breakdown is highly specific, as each enzyme only targets certain types of chemical bonds, which allows for controlled degradation in selected environments.
Structural Integrity
Because the degradation is limited to the surface, the mechanical properties of the remaining part do not decline prematurely. In contrast to bulk degradation, surface enzymatic erosion preserves the internal structure of the polymer, allowing the part to retain its strength relative to its remaining thickness. This makes it an ideal degradation pathway for applications where a gradual, predictable loss of material is required.
Material Lifecycle
Product designers can control the rate of this degradation by modifying the surface area or surface roughness of the moulded parts. Molders can adjust the injection mould texture to create a smoother or rougher surface, which directly affects how quickly the enzymes can attach and begin the breakdown process.
