CHAIN EXTENSION OF POLYESTERS PET AND PBT WITH 2 NEW DIIMIDODIEPOXIDES .2.

Two new diglycidyl ester compounds containing preformed imide rings fo r better thermal stability were prepared to be used as chain extenders for PET and PET. The preparation of these compounds was carried out i n two steps. In the first step, diimidodiacids were prepared from pyro mellitic anhydride and 3-aminopropanoic acid or 4-(aminomethyl)benzoic acid. From these diimidoacids, in a second step, diimidodiepoxides we re obtained by reaction with epichlorohydrin. The aforementioned diimi dodiepoxides were used as chain extenders for poly(ethylene terephthal ate) (PET) and poly(butylene terephthalate) (PET) with satisfactory re sults. The polyester samples obtained from various residence times in the reactor, were characterized by solution viscosity measurements, ca rboxyl, and hydroxyl end-group determination. Starting from a PET havi ng intrinsic viscosity ([eta]) of 0.60 dL/g and carboxyl content (CC) of 42 equiv/10(6) g, one could obtain PET with [eta] of 1.16 and CC be low 5 equiv/10(6) g. The typical reaction condition for the coupling o f PET was its heating with the chain extender under argon atmosphere a bove its melting temperature (280 degrees C) for several minutes. Anal ogous results were obtained for PET. The hydroxyl content in all cases was increased. (C) 1996 John Wiley & Sons, Inc.