Method for mitigating cure shrinkage in high temperature-processed thermosetting adhesives and SMC

1. A thermosetting polymer composite comprising a thermosetting polymer matrix material, a filler selected from the group consisting of particulate fillers, fiber, and combinations thereof, and from about 0.1 to about 5 weight percent of reduced-volume hollow shape-memory alloy particles having a maximum length of from about 1 micrometer to about 100 micrometers, wherein the reduced-volume hollow shape-memory alloy particles undergo irreversible volume expansion during a thermal process to compensate for a volume loss of the cured thermosetting polymer matrix material and the reduced-volume hollow shape-memory alloy particles have a trained shape selected from the group consisting of hollow microspheres, hollow micro-ellipsoids, hollow micro-tubes, and combinations thereof.

2. The thermosetting polymer composite according to claim 1 , wherein the thermosetting polymer composite is a sheet molding compound composition.

3. A method of making a cured, thermoset polymer composite, comprising:

providing the thermosetting polymer composite according to claim 1 ; and

curing the thermosetting polymer composite at least in part at a temperature above a transformation temperature of the reduced-volume hollow shape-memory alloy particles so that the reduced-volume hollow shape-memory alloy particles undergo irreversible volume expansion to compensate for volume loss resulting from shrinkage of the thermosetting polymer matrix material after the curing.

4. The method according to claim 3 , wherein the thermosetting polymer composite has minimal or no volume change after the curing of the thermosetting polymer matrix material.

5. The method according to claim 3 , wherein the thermosetting polymer composite is cured in a compression mold.

6. A thermosetting adhesive composition comprising a thermosetting polymer and crosslinker or curing agent system and from about 0.1 to about 5 weight percent of reduced-volume hollow shape-memory alloy particles having a maximum length of from about 1 micrometer to about 100 micrometers, wherein the reduced-volume hollow shape-memory alloy particles undergo irreversible volume expansion during a thermal process to compensate for a volume loss of the cured thermosetting polymer and the reduced-volume hollow shape-memory alloy particles have a trained shape selected from the group consisting of hollow microspheres, hollow micro-ellipsoids, hollow micro-tubes, and combinations thereof.

7. A method of bonding two articles together by applying the thermosetting adhesive composition according to claim 6 between adjoining surfaces of the two articles and curing the thermosetting adhesive composition to bond the two surfaces together, wherein the cure temperature is at least in part at a temperature around the transformation temperature of the reduced-volume hollow shape-memory alloy particles.

8. The method according to claim 7 , wherein the thermosetting adhesive composition has minimal or no volume change after the curing of the thermosetting adhesive.

9. The method according to claim 7 , wherein at least one of the two articles comprises an SMC article, wherein the reduced-volume hollow shape-memory alloy particles expand such that bond line read-out is not visible.

10. A bonded SMC assembly prepared according to the method of claim 9 .

11. An automotive vehicle comprising the bonded SMC assembly according to claim 10 .