Modeling Hydrophobic Decay and Additive Migration Dynamics in Treated Polyolefin Extrusions
Polyolefin surface treatment decays via polar group reorientation and slip agent bloom, requiring controlled additive specifications and inline bump corona.
Dyne Testing
Surface Measurement
Standardized procedures for determining the surface energy of non-porous substrates provide a quantifiable metric for liquid wettability. During dyne testing, a series of liquid solutions with known surface tensions are applied to a material to observe their behavior. Precision matters.
The result identifies the highest energy level at which a liquid will wet the surface without reticulation or bead formation. This measurement is expressed in millinewtons per meter or dynes per centimeter.
Chemical Interaction
Specific interactions between the test fluid and the polymer surface reveal the presence of functional groups created during treatment. As the fluid is wiped across the sample, the dyne testing process tracks how long the liquid film remains continuous before breaking into droplets. A surface that maintains a solid film for at least two seconds indicates that its energy matches or exceeds that of the solution.
If the fluid beads up immediately, the surface energy is lower than the value of the test ink.
Operational Threshold
Print quality and adhesive performance rely on maintaining surface energy above specific levels required for the chosen ink or coating system. For most water based inks and laminating adhesives, dyne testing must show a value of at least 38 to 40 units to ensure adequate wetting and long term bonding. High performance coatings often require even higher levels to prevent defects like pinholes or crawling.
Consistent monitoring allows converters to detect when corona or flame treatments have decayed over time. Proper storage of test pens or fluids is necessary to prevent contamination that could skew the results and lead to incorrect process adjustments on the production line.