Meaning
Chemical degradation mechanisms describe the pyrolytic breakdown of primary fatty acid amide slip additives in polyolefin formulations subjected to elevated thermal processing conditions. Exposure to processing temperatures above two hundred and forty degrees Celsius initiates erucamide thermal cracking, yielding volatile amine species and lower molecular weight carbonyl compounds. These degradation products alter the surface energetics of extruded films, generating smoke and unpleasant odours in processing halls.
The chemical reaction alters functional slip behavior, rendering coefficient of friction targets unpredictable across converted film rolls. Standard analytical testing tracks these breakdown products via gas chromatography coupled with mass spectrometry.
Amide Cleavage
Thermal energy inside the extruder barrel cleaves the unsaturated carbon-carbon double bond and the primary amide group along the cis-13-docosenamide chain. Secondary oxidation reactions accelerate when dissolved oxygen is present in the feed throat of the processing machine. The occurrence of erucamide thermal cracking reduces the concentration of intact slip additive available to diffuse to the film surface during cooling.
Breakdown fragments like octanal and acrolein migrate rapidly to the surface, causing severe die buildup and plate-out on downstream chill rolls.
Surface Migration
Fatty acid amides must remain intact during melt extrusion to migrate to the polymer surface and lower the coefficient of friction. When thermal degradation occurs inside the melt stream, the resulting short-chain molecules aggregate unpredictably, disrupting the formation of a uniform lubricant monolayer. Film surface tension increases, resulting in poor slip performance and optical haze.
Extrusion Boundary
Processing window limits dictate that polyolefin melt temperatures should be maintained below threshold cleavage points during long residence times. High shear zones near mixing elements amplify degradation, causing severe yellowing in clear packaging films. Once thermal cleavage occurs, post-extrusion addition of slip additives cannot restore optical clarity or target surface lubricity.
