| 초록 |
The polyurethane/silica nanocomposites were synthesized by a sol-gel reaction using vinyltrimethoxysilane and by UV curing. Silicas were incorporated as crosslink points and the reactions between silica and PU were confirmed by Si CP/MAS NMR. Dynamic mechanical thermal analyzer(DMTA), cyclic tensile test, and hardness(shore A) were employed to characterize the polyurethane nanocomposites. The static/dynamic mechanical properties measured by DMTA and UTM showed that these properties have significantly been improved with the addition and increasing content of silica. It was confirmed that simple addition of silica disturbs the cure reactions and give decreased crosslink density and tensile strength, whereas modified silica provides the composites with crosslinks which are pinned at the surfaces and effectively reinforces the materials mechanically as well as thermally. |
