Material Resilience
Environmental stress testing evaluates the structural durability of composite materials under varying humidity and temperature conditions. Subjecting packaging to hygrothermal cycling reveals how laminations and adhesives respond to the stresses of real-world transit across different climate zones. High humidity swells paperboard fibers.
Subsequent heat dries them out and causes them to shrink.
Thermal Interaction
Internal stresses develop at the interfaces between different materials because polymers and cellulose fibers expand and contract at different rates. These differential dimensional changes can break the bonds created by adhesive systems, leading to localized peeling or delamination. The test cycles simulate several years of outdoor exposure in a fraction of the time, allowing manufacturers to optimize their barrier coating formulations.
Damage Assessment
Evaluating the tested samples involves inspecting them for delamination or loss of tensile strength. In flexible laminations, the adhesive layer is monitored to see if it remains flexible and intact after exposure to repeated cycles of hot-humid and cold-dry air. High resistance to these changes is necessary for packaging designed to protect electronics or medical devices that cannot tolerate moisture ingress during long transit and storage periods.
When the adhesive degrades, the protective barrier of the foil or polymer is compromised, exposing the enclosed product to atmospheric contaminants.
