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Polymerization of lactide

  • US 5,235,031 A
  • Filed: 03/13/1992
  • Issued: 08/10/1993
  • Est. Priority Date: 03/13/1992
  • Status: Expired due to Fees
First Claim
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1. A process for polymerizing lactide comprising melting at 100°

  • to 220°

    C. a lactide and up to 20 mole percent of another lactone of the formula ##STR5## where n is 4 or 5, h, i, k and m are independently 1 or 2, each R is independently selected from H or hydrocarbyl containing up to 12 carbon atoms or substituted hydrocarbyl containing up to 12 carbon atoms with a catalyst of the formula MZ3, wherein M is yttrium or a rare earth metal and one Z is --OCR'"'"'3 where R'"'"' is independently hydrogen, hydrocarbyl or substituted hydrocarbyl, the remaining two Zs are fluoride, chloride, bromide, iodide, carboxylate, tetrasubstituted porphyrinato (-2), betadiketone anions, beta keto ester anions, cyclopentadienide, phenoxide or pentamethylcyclopentadienide, and cooling the resulting polymer.

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