Meaning
Polymer degradation modes include the separation of adjacent film layers caused by solvent penetration or swelling stresses. The presence of aggressive active ingredients or cleaning chemicals weakens the bond at the polymer interface, causing structural unbonding without mechanical peeling forces. In multi-layer packaging structures, chemical delamination alters barrier properties when volatile fluids migrate into tie layer interfaces.
The boundary of this mechanism excludes mechanical shear failure occurring during conversion, remaining confined to chemical dissolution or plasticization of the bond interface.
Solvent Attack
Liquid permeation through outer polyolefin layers initiates stress cracking along adhesive boundaries. When polar solvents contact low-density polyethylene, localized swelling alters internal stress distributions across the laminate. This swelling generates mechanical forces that break hydrogen bonds between polyurethane adhesives and substrate films.
Unchecked fluid migration quickly compromises package integrity.
Layer Separation
Adhesive dissolution proceeds rapidly once fluid concentration reaches critical saturation levels at the interface. Blistering forms along the contact zone, expanding into visible channels across the web width. In flexible barrier packaging, chemical delamination transforms bonded structures into unbonded layers, allowing oxygen ingress.
Blisters undermine product protection long before structural tearing occurs.
Interfacial Resistance
Verification of chemical resistance relies on exposure testing using target chemical formulations under elevated temperature profiles. Data sheets record bond retention ratios, comparing pre-exposure peel strength against post-exposure values after immersion. Virgin resin structures exhibit higher resistance than regrind formulations containing residual contaminants.
