Chain-extending phenolic end-capped polyimides
AssigneeUniversity of Notre Dame
InventorGaetano Francis D'Alelio
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Abstract
Aromatic polyimides with phenolic end groups are chain-extended (molecular weight increased) by reacting them with formaldehyde, compounds capable of generating formaldehyde under the reaction conditions or hexamethylene tetramine in the presence of a catalytic amount of lime. These polyimides can be shaped and formed prior to the chain-extending. The aromatic polyimides appropriate for chain-extending are formed by the reaction of aromatic dianhydrides, aromatic diamines and phenolic compounds such as aminophenol.
Claims18
A polymeric chain-extending process comprising:
- heating at a temperature in the range of about 150.degree.-450.degree. C. a polyimide having the formula ##STR21## wherein Ar' is a tetravalent aromatic organic radical, the four carbonyl groups being attached directly to separated carbon atoms and each pair of carbonyl groups being attached to adjacent carbon atoms in the Ar' radical, Ar is a divalent aromatic organic radical, R is an aromatic hydrocarbon radical of 6 to 12 carbon atoms, and n is a positive integer of at least one with a chain-extending material selected from the group consisting of formaldehyde, a compound capable of generating formaldehyde under the reaction conditions and hexamethylene tetramine in the presence of about 1-5% by weight, based on the weight of polyimide, of lime, and wherein the amount of formaldehyde present or generated is about 5-25% by weight, based on the weight of polyimide.
A polymeric chain-extending process comprising:
- heating a polyimide at a temperature in the range of about 150.degree.-450.degree. C. with about 5-25% by weight, based on the weight of polyimide, of formaldehyde or paraformaldehyde and about 1-5% by weight, based on the weight of polyimide, of lime, said polyimide of the formula:
- ##STR26## Ar' is selected from the group consisting of ##STR27## and Ar is selected from the group consisting of ##STR28## and multiples thereof connected to each other by R.sup.IV, wherein R.sup.IV is alkylene of 1 to 3 carbon atoms, ##STR29## --O-- , --S-- , --CH.dbd.CH-- , and --SO.sub.2 -- ##STR30## and n is a positive integer of at least 1.
A polymeric chain-extending process comprising:
- heating at a temperature in the range of about 150.degree.-450.degree. C. a polyimide having the formula ##STR35## wherein Ar' is a tetravalent aromatic organic radical, the four carbonyl groups being attached directly to separate carbon atoms and each pair of carbonyl groups being attached to adjacent carbon atoms in the Ar' radical,
- Ar is a divalent aromatic organic radical,
- R is an aromatic hydrocarbon radical of 6 to 12 carbon atoms, and
- n is a positive integer of at least one
- with a chain-extending material selected from the group consisting of formaldehyde, a compound capable of generating formaldehyde under the reaction conditions and hexamethylene tetramine, wherein the amount of formaldehyde present or generated is about 5-25% by weight, based on the weight of polyimide.
Dependencies are inferred from the claim text.