Contact Angle Goniometry Protocols for Polyolefin Lamination Adhesion Verification
Sessile contact angle goniometry isolates polar and dispersive surface energy to verify polyolefin corona treatment and prevent lamination delamination.
Polypropylene
Thermal Resistance
A thermoplastic polymer with a high melting temperature and rigidity provides strong barrier properties for high-performance packaging. Extensively used as a coating and film, polypropylene can withstand the heat of microwave ovens and hot-fill processes that would melt other plastics. This characteristic makes it the preferred material for microwaveable food trays and heat-resistant barrier laminates.
Mechanical Toughness
This plastic is known for its high tensile strength and resistance to fatigue, which allows it to function as a durable living hinge on molded caps and closures. It also offers excellent resistance to grease and chemical solvents, protecting paperboard boxes from oily food stains. Its higher stiffness compared to polyethylene allows packaging designers to use thinner coatings without sacrificing the package’s overall strength.
Extrusion Requirement
Processing this resin on extrusion coating lines requires higher extruder temperatures and different chill-roll settings than those used for lower melting polymers. These demanding processing conditions are necessary to achieve optimal adhesion to the paperboard surface and to prevent delamination. Because the material is prone to shrinking during cooling, converters must manage the cooling rate to avoid causing curl or warpage in the laminated board, ensuring that the sheets remain flat for subsequent die-cutting and folding operations.