High-viscous 2,2-bis[4-(2-hydroxymethacryloyoxypropoxy)phenyl]propane (I) or 1,6-bis(methacryloyloxy-2-ethoxy-carbonylamino)-2,4,4-trimethylhexane (II) and a low-viscous diluent, triethylene glycol dimethacrylate (III), were blended 0-100% (at 10% steps) and photopolymerized (1 mW/cm(2), 366 nm) at 20-70 degrees C (at 10 degrees steps) with 0.2% of 2,2-dimethoxy-2-phenylacetophenone as photoinitiator., The rate, final deg. of double-bond conversion, and activation energy were detd. The most reactive compns. (50-70% of III), related to initial viscosity, had the lowest polymn. activation energy. The rate rose with temp. up to 60 degrees C, then fell. The viscosity activation energies were ca. 120 and ca. 90 kJ/mol for I and II, resp.