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Crosslinking of unsaturated polyester resins studied by low-resolution 1H-NMR spectroscopy

✍ Scribed by Karin Hietalahti; Andrew Root; Mikael Skrifvars; Franciska Sundholm

Publisher: John Wiley and Sons
Year: 1997
Tongue: English
Weight: 153 KB
Volume: 65
Category: Article
ISSN: 0021-8995
DOI: 10.1002/(sici)1097-4628(19970705)65:1<77::aid-app10>3.0.co;2-w

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✦ Synopsis

The curing behavior of five unsaturated polyester resins with different molar ratios of styrene to the double bonds in the polyester chain (MR) was investigated. The gel time was measured according to a standard method by the Society of the Plastic Industry (SPI) and by low-resolution pulse nuclear magnetic resonance (LRP-NMR). The gel and curing times decreased and the maximum temperature of the reaction increased when the MR was decreased. The proton mobilities and populations were measured by LRP-NMR. Three components could be seen in the crosslinking reaction: styrene (very mobile, T 2 à 3 s), free polyester polymers (less mobile, T 2 à 150 ms), and cured resin (immobile, T 2 à 0.04 ms). The third component, cured resin, could be detected at the gel point. At this point, the proton mobilities of styrene and free polyester polymers were rapidly decreasing and the proton populations of the cured resin started to increase.

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