Cramer Structural Classification Tiers for Non-Intentionally Added Substances
Assigning non-intentionally added substances to Cramer tiers determines analytical screening limits, where Class III migrants require migration caps under 90 ppb.
Epoxy Degradation Products
Meaning
Chemical compounds generated during the thermal, oxidative, or hydrolytic breakdown of cured epoxy resins constitute the primary indicators of polymer network failure. These epoxy degradation products usually consist of bisphenols, alkyl phenols, and low molecular weight amine fragments. Understanding their formation is essential for determining the service life of thermoset matrix composites in harsh environments.
When the resin starts to break down, these chemical species migrate out of the polymer matrix.
Chemical Leaching
Leaching of the breakdown products occurs when the composite comes into contact with hot solvents or high-pressure steam. Since many epoxy degradation products are soluble in polar organic liquids, they leave behind microscopic voids that accelerate further moisture ingress. This phenomenon degrades the barrier properties of the protective polymer coating.
Structural Degradation
Loss of cross-link density directly diminishes the glass transition temperature of the epoxy system. As epoxy degradation products build up, the polymer network becomes less rigid and more susceptible to deformation under mechanical load. This breakdown leads to delamination of the composite laminate.
Process Hazard
Workers in compounding and recycling facilities encounter exposure risks when handling aged epoxy composite parts. High temperatures during pyrolysis or mechanical grinding release epoxy degradation products into the working environment. Adequate ventilation systems must be maintained to capture these volatile emissions during processing.