Mechanical Properties Of Acrylic Dielectric Elastomer And Azobenzene Liquid Crystal Elastomer

Soft matter covers a large variety of systems, including liquid crystal, polymers, colloids, biological matter and so on. All of these materials are composed of macro molecules or related molecular groups and whose states are between perfect fluid and solid. Dielectric elastomers and liquid crystal elastomers are widely studied. They possess the property of reversible shape chage under related stimulus (light, electrical field etc.), and can be used to design actuators, sensors, artificial muscle etc.. In this dissertation, the mechanical properties of dielectric elastomer (VHBTM9473) under uniaxial stretching are studied and a theoretical photoelectrical conversion device designed with azobenzene liquid crystal elastomer (LCE) is analyzed by photoelectrical coupling mathematical model.Experimental results show that the elastic/viscoelastic recovery of rectangle VHBTM9473film is significant when its stretch reaches500%under uniaxial tensile test. When the stretching rate is high, the max stretching force decreases as the sample height increases. However, almost the same value remains when the stretching rate is slow.For the cases of crack propagation, the driving force for crack propagation and the crack propagating velocity are influenced by the followings:sample height, pre-cut length and stretching rate. For a certain type of samples, the vertical strains when crack starts to propagate are independent of the stretching rates, their values are almost the same. In addition, FEM analysis under quasi-static displacement loading shows that the verticle strains at the crack tips when crack starts to propagate are very close, with values falling in the interval4.21to4.55.For the photoelectrical conversion device, theoretical analysis demonstrated that the induced charge on ferroelectrets is proportional to the intensity of the incident UV light. Moreover, the photoelectrical coupling coefficient is determined by the internal radius p1, external radius p2, height H and thickness p2-p1of the device model, piezoelectric coefficient d’33of ferroelectrets, and the related material parameters of azobenzene LCE.