Polymeric Systems Which Expand on Polymerization for Use in High Strength Composites.
Annual rept. 1 Feb 71-31 Jan 72,
MARYLAND UNIV COLLEGE PARK DEPT OF CHEMISTRY
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Ring-opening polymerizations usually involves somewhat less shrinkage than either addition or condensation polymerization because for every new bond that is formed involving a shift from a Van der Waals dis- tance to a covalent distance, another bond is broken involving a shift from a covalent distance to a near Van der Waals distance. If mono-mers were utilized in which two or more bonds were broken for every new bond that is formed in the polymerization process, near zero shrinkage or even expansion would be possible. Among the monomers that give essentially zero contraction or some expansion on polymeriza- tion are the spiro ortho esters, spiro orthocarbonates, and bicyclo ketal lactones. These monomers by undergoing some expansion or polymerization can be utilized in precision castings, high strength adhesives, prestressed construction, and dental fillings. Author, modified-PL
- Polymer Chemistry