N2, O2, and CO2 in Acrylic Syrup

Poly methyl-methacrylate (PMMA) is used in the production of high-grade acrylic sheets for skylights, spas, and bath tubs. Crucial to the process is the removal of dissolved atmospheric gases in the pre-polymerization syrup - excess gas can cause trapped bubbles, discoloration, or localized opaque spots.

Removal of the gases is accomplished by holding the syrup under vacuum for an optimum length of time, determined by quick analysis with a PDD. The upper chromatogram is before the degassing process; the lower one, after.

impurities in acrylic syrup

Courtesy of Aristech Chemical Corp., Benku Thomas, Senior Research Engineer

Run conditions
Sample Poly methyl-methacrylate syrup (before and after degassing)
Sample volume 1 µl, splitless
Injector temp 250°C
Detector mode Helium photoionization
Discharge gas Helium @ 30 ml/min
Dopant gas None
Detector temp 180°C
Column 2 m x 1/16" OD HayeSep micro packed column
Column temp 25°C for 5 min, to 250°C at 20°C/min
Attenuation 1 x 10-1