Poly (2,2'bis (3,4-dicarboxyphenoxy) phenylpropane)-2 phenylendiimide (ULTEM) was subjected to photo aging in the attempt to find evidence on the structure of the species formed in the oxidative degrdn. The oxidative process was followed as a function of the exposure time by MALDI and SEC/MALDI techniques. The SEC curves showed extensive degrdn., with the formation of low molar mass oligomers having different end groups. Highly valuable structural information on the photoxidized ULTEM species was extd. from the MALDI spectra of the photoxidized ULTEM samples.These showed the presence of polymer chains contg. acetophenone, Ph acetic acid, phenols, benzoic acid, phthalic anhydride and phthalic acid end groups. The mechanisms accounting for the formation of photoxidn. products of Ultem involve the operation of several simultaneous reactions: i) photo-cleavage of Me groups of the N-Me phthalimide terminal units; ii) photoxidative degrdn. of the isopropylidene bridge of BPA units; iii) photoxidn. of phthalimide units to phthalic anhydride end groups: iiii) hydrolysis of phthalic anhydride end groups. The kinetic behavior of all the species detected is in agreement with the predictions of the reaction mechanisms hypothesized.
Photooxidation mechanisms of polyetherimide Ultem investigated by MALDI-TOF-MS
SCarroccio
2003
Abstract
Poly (2,2'bis (3,4-dicarboxyphenoxy) phenylpropane)-2 phenylendiimide (ULTEM) was subjected to photo aging in the attempt to find evidence on the structure of the species formed in the oxidative degrdn. The oxidative process was followed as a function of the exposure time by MALDI and SEC/MALDI techniques. The SEC curves showed extensive degrdn., with the formation of low molar mass oligomers having different end groups. Highly valuable structural information on the photoxidized ULTEM species was extd. from the MALDI spectra of the photoxidized ULTEM samples.These showed the presence of polymer chains contg. acetophenone, Ph acetic acid, phenols, benzoic acid, phthalic anhydride and phthalic acid end groups. The mechanisms accounting for the formation of photoxidn. products of Ultem involve the operation of several simultaneous reactions: i) photo-cleavage of Me groups of the N-Me phthalimide terminal units; ii) photoxidative degrdn. of the isopropylidene bridge of BPA units; iii) photoxidn. of phthalimide units to phthalic anhydride end groups: iiii) hydrolysis of phthalic anhydride end groups. The kinetic behavior of all the species detected is in agreement with the predictions of the reaction mechanisms hypothesized.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
