Two-part, cyanoacrylate/free radically curable adhesive systems

A two-part curable composition comprising:

• (a) a first part comprising a cyanoacrylate component and an acidic component;
• and
• (b) a second part comprising a free radical curable component and a peroxy acetal and/or ketal,
• wherein the peroxy acetal and/or ketal is present in an amount from about 0.05 to about 5 percent by weight of the composition and is embraced by
• wherein here R1, R2, R3 and R4 are each independently selected from hydrogen, C1-6 alkyl, C5-7 cycloalkyl, alkoxy, C1-6 peroxy alkyl, C5-7 aryl, and C6-10 alkaryl, and R1 and R4 taken together form a cyclic ring with at least two peroxy linkages as part of the ring, wherein the peroxy acetal and/or ketal is one or more of:
• A. wherein R1 and R4 are each tert-butyl and R2 and R3 are each hydrogen or cyclohexane;
• B. wherein R1 is tert-butyl, R2 and R3 are each cyclohexane, and R4 is methoxy;
• C. wherein R1 and R4 are each tert-butyl, R2 is ethyl, and R3 is methyl;
• D. wherein R1 and R4 are each tert-butyl, R2 is phenyl, and R3 is ethyl;
• E. wherein R1 and R4 are each tert-butyl, R2 is phenyl, and R3 is 1-phenyl methyl;
• and
• F. wherein R1 and R4 are each tert-butyl, R2 is hydrogen, and R3 is 1-phenyl methyl.