摘要 |
<p>This invention is directed to the use of microencapsulated blowing agents in the bulk polymerization of cycloolefin monomers by ring-opening polymerization. These microencapsulated blowing agents aid in filling molds during reaction injection molding procedures such that both surfaces of the article being molded remain in contact with their respective mold surfaces eliminating sink marks in these surfaces. In addition, the microencapsulants may be introduced at higher levels which provide structural foams with the polymers from cycloolefin monomers.</p> |