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End capping technology

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End capping of polyester oligomers. which may used as plasticizer for PVC, used as nucleating agent in Polyester synthesis etc..

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End capping technology

  1. 1. End capping Technology We can do endcappingof both –OH groupsand –COOH Groups: -OH Group endcapping For –OH groups of MEG can be endcappedby usingthe followingchemicals. 1) Napthalinicacid 2) Benzoicacid 3) StearicAcid 4) Or any monocarboxylic Acidcompound _COOH group end capping… COOH groups can end capped by usingthe following  Ethylene or propylene carbonate  phenylene-bis-oxazoline (2,2'-1, 3- phenylene-bis(2-oxazoline)  Dicyclohexyl carbodiimide  Sodium methoxide or sodiummethylate  Alkylacetylacetonate( Ex. Methyl acetylacetonate)  N-Benzoyl-E-Caprolactam  1-morpholino-1-cyclohexene  1-methyl imidazole  Monocyclic imino ether compound  Epoxy compounds Polyesterendcapping -OH groupendcappingwill be usedforthe stoppingpolymerizationatrequiredIV. Why because,inpolycondensationreaction ethylene glycol endgrouponlyreacttoincrease the MW (not–COOH groups) Eventhoughwe endcap –COOH group, polymerization will continue throughthe ethylene glycol endgroups. If we endcap bothside of -OHgroup,there is no chance to undergo furtherpolymerization. – OH endcappedpolymercanadd at any stage of reactionbecause itwasalreadyblockedboth side –OH groups;it won’treact farther;it will workas a plasticizerandnucleatingagent. AfterPC,there are veryfew –COOH endgroups(<35 meg/ton). It may create hydrolyticdegradation or oxidative degradation.For avoidingsuchdegradationgenerally – cooh groupswill be endcapped. evenif we added_COOH endcapped polymeratthe endof EI or PC againit will reactthroughethyleneglycol end groupand increase the IV. It won’t workas a nucleatingagent.
  2. 2. AfterEsterification,the followingpolymerchainsare inreactor 1) Both side Hydroxyl groupterminatedoligomers(min90%) 2) One side Hydroxyl groupterminatedandotherside –COOHterminatedoligomer(max 10%) 3) Both side –COOHterminatedoligomer(veryfew,notmore than1%) Esterificationwascarriedout@ 240 to 250 deg C undervacuum. The above condition -COOHgroupsof PTA react withMEG to form BHET, but undervacuum –COOH cannot react with –OH groupof MEG. (undervacuumMEG will be removedveryquicklysothat MEG has no time toreact with –COOH groups) At the endpolycondenzation: The resincontains 1) Both side Hydroxyl groupterminatedpolymerchain(more than95%) 2) One side Hydroxyl groupterminatedandotherside –COOHterminatedpolymerchain(veryfew, lessthan3%) Polycondenzationwascarriedout@280 to 290 degC underveryfine vacuum In polycondenzationreaction,polymerizationwashappedasfollows Hydroxyl groupterminatedpolymerchainscanonlyinvolvedinthe polycondenzationreactionandgive MEG as by product. –COOH terminatedpolymerchaincannotmore reactive inpolycondenzation reaction

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