Static and Dynamic Mechanical Properties of Cross-Linked Poly (Tripropyleneglycoldiacrylate)/Liquid Crystal Blends

This investigation reports on static and dynamic mechanical properties of cross-linked Poly(tripropyleneglycoldiacrylate) (Poly-TPGDA) networks, elaborated via radical polymerization processes induced by Ultraviolet (UV) radiation. The presence of low molecular weight liquid crystal (LC) molecules in the polymer matrix modifies the dynamic and static mechanical behavior of the obtained composite materials. The storage modulus decreases with increasing LC content in the temperature range from T=25°C to -15°C, due to the plasticizing effect induced by the presence of low molecular weight LC in the polymer matrix. In the case of polymer/LC blends with more than 30 weight (wt.)-% LC and for temperatures lower than -15°C, a reinforcement effect could be seen, leading to a change of the shape of the decreasing curves. This phenomenon interferes with the plasticizing effect which himself governs the whole mechanical behavior of the cured polymer/LC system. A sort of competition takes place especially for temperatures lower than -75°C, so that the storage modulus increases or remains constant between 20 and 60 wt.-% LC