2021 Volume 57 Issue 1 Pages 12-18
Crosslinked poly（n-butyl acrylate-acrylic acid）（ A） and crosslinked poly（2-ethylhexyl acrylate-acrylic acid） random copolymers（ B） were analyzed by a dynamic mechanical analysis（ DMA） and 1H pulse nuclear magnetic resonance（ pulse NMR） spectroscopy. From DMA, the storage modulus（ G'） at rubbery plateau region was A > B and dependent on the crosslinking agent content. The G' shows the molecular mobility of polymer chain. In the pulse NMR analysis, the temperature which relaxation starts was dependent on the glass transition temperature（ Tg）, namely the intermolecular force. It was independent on the crosslinking agent content. The temperature dependence of tack for A and B was measured by a probe tack test. The tack measured above 0 ℃ was influenced by a contact time and a crosslinking agent content. It was B > A. It was explained by the better wettability for B than A caused by the difference of molecular mobility shown by G". The rising of tack begins below 0 ℃ was more gradual for B than A. This tendency was good accordance with the relaxation starting around Tg measured by pulse NMR. Using of both data for the DMA and the pulse NMR was useful to the analysis of the tack properties.
