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OBSERVATION OF HETEROGENEOUS TRACE (0.4-PERCENT W/W) WATER-UPTAKE IN BISPHENOL A POLYCARBONATE BY NMR IMAGING

TitleOBSERVATION OF HETEROGENEOUS TRACE (0.4-PERCENT W/W) WATER-UPTAKE IN BISPHENOL A POLYCARBONATE BY NMR IMAGING
Publication TypeJournal Article
Year of Publication1992
AuthorsFyfe, CA, Randall, LH, Burlinson, NE
JournalChemistry of Materials
Volume4
Pagination267-271
Date PublishedMar-Apr
Type of ArticleArticle
ISBN Number0897-4756
KeywordsDIFFUSION, mobility, NUCLEAR MAGNETIC-RESONANCE, POLYMERS
Abstract

The uptake of water by injection-molded bars of bisphenol A polycarbonate (Lexan 121 resin) has been monitored by a combination of one-dimensional proton NMR spectroscopy, relaxation time (T1 and T2) measurements, and microscopic imaging techniques. The bulk of the water absorbed in the initial stages (20-24 h) of 100-degrees-C water exposure is uniformly distributed throughout the polymer with a trace amount of the water found in clusters of 200-300-mu-m in size. The water that has aggregated to form these clusters is more mobile, having a T2 relaxation time 20 times longer than that found for the uniformly distributed water. At longer exposure times (30-40 days) the number of clusters is observed to increase. Although the total amount of water adsorbed is considerably less than 1 % w/w, good-quality images are obtained, demonstrating that the NMR microimaging technique can successfully monitor even trace levels of solvent if the molecules are relatively mobile.

URL<Go to ISI>://A1992HL70200010