ISSN:
0021-9304
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Medicine
,
Technology
Notes:
A near infrared (NIR) method using the 5200 cm-1 absorption of water has been employed to examine water absorbed in photopolymerized dental resins and composites in the form of 0.01-cm-to 0.15-cm-thick specimens. The concentration, c [mol L-1], of absorbed water in specimens of thickness t [cm] was calculated by means of Beer's law, A = ∊ct. A is the NIR absorbance and ∊ is the absorptivity of absorbed water. ∊ depends on the environment of the water molecule and it is necessary to estimate ∊ for water in each material. Water sorption was determined gravimetrically and correlated to the absorbance in the NIR spectrum. Once the relationship between ∊ and water content was known for a material, water sorption was determined rapidly on very thin specimens for faster equilibration. Where dissolution of the specimen occurred, the solubility behavior of the specimen was evaluated from a comparison of NIR and gravimetric measurements. The NIR absorptivity, ∊, of water absorbed in a polymeric medium was found to be inversely related to the degree of hydrophilicity and hydrogen bonding capability of the polymer. The presence of water clusters in a polyethylene oxide methacrylate polymer was inferred from convex-up curvature in the plot of ∊ vs. water content.
Additional Material:
13 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/jbm.820251005
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