Fatty Acid Amide Additive Selection for Polyolefin Films
Select erucamide for thermal stability and predictable migration, balancing inorganic antiblock surface adsorption to maintain stable film friction below 0.25.
Kinetic Friction
Meaning
Dynamic resistance forces govern the movement of polymer surfaces when they slide past each other at constant velocity. Extruded plastic packaging films require a low coefficient of kinetic friction to run smoothly through high-speed bagging machines and form-fill-seal equipment. This material property determines the pulling force required to keep the web moving after sliding has already commenced.
It is typically measured using standard ASTM test methods that pull a weighted sled across the film surface.
Process Slippage
Low surface resistance prevents the web from sticking or jamming against the metal collar of the packaging machine. High kinetic friction causes film stretching, tension spikes and inconsistent bag lengths. Molders also monitor this value to ensure molded parts release cleanly from the steel core during high-speed ejection cycles.
Additive Migration
Slip agents like erucamide migrate to the surface of the plastic part after extrusion to create a lubricating layer. This active migration controls the kinetic friction of the polymer film during its shelf life. Process technicians must adjust the concentration of these internal lubricants to balance slip performance against heat seal strength.
Defect Consequence
Excessively low resistance values cause telescoping rolls that slide apart during shipment. Conversely, high resistance leads to surface scratching on the molded part. Monitoring the friction behavior prevents costly downtime during the converting step.