Check the substrate first: oil, mold release and oxide layers are the leading cause. Phosphate esters cannot fix surface contamination.
Check compatibility: amines or basic fillers neutralize the phosphate group and adhesion collapses.
Check dosage: below 0.5% no continuous interphase forms; above 5% hydrophilicity rises and water resistance falls.
Check cure: acidity suppresses amine synergists. If surface cure is poor, add amine or switch to a Norrish type I initiator.
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