Papers by Keyword: Shape-Memory Polymer

Abstract: Deployable flexible displays attract a great attention recently. The flexible display used on electronic equipment have been developed, which can deploy to reveal a much larger screen or rolled up. However, one of major problems is its actuation of deployment and fixture. In this paper, a deployable display actuated by the SMP actuator is proposed. The shape memory polymer (SMP) actuator, which is considered to be attached to the back side of a flexible display, is used to deploy and fix the flexible display. A new method of laser-induced actuation of SMP actuator is investigated. By this method, the SMP can be induced by infrared light transmitted through a treated optical fiber embedded in the actuator.

Abstract: In this current study, spandex fiber with high elasticity and high recovery ratio were added into shape memory epoxy resin. Compared with pure shape memory resin, the Young’s modulus increases by 28.2%, tensile stress by 49.7% and fracture strain by 16.4% in samples with 20 vol% spandex fiber, while recover time reduces by 36s in samples with 40 vol% spandex fiber.

Abstract: Thermo-responsive shape-memory polymer (SMP) has been experimentally demonstrated that shape recovery can be induced by plasticizing solvent. Subject to being immersed into solvent, deformed SMP recover from the temporary shape to original shape, leading to shape recovery induced by the molecular interaction. The actuation of styrene-based SMP has been carried out by electrostatic dipole-dipole interaction and physical swelling effect, respectively. The model can be used to predict the effect of prestress, strain, volume change and chemical potential on SMP actuation in the solvent. Finally, it is found that the simulation agrees well with experimental results. The authors show that the chemo-mechanical instability occurs when the Hessian of the free-energy function ceases to the positive definite. Their calculations show that the shape recovery behavior of SMP is driven by the entropy change markedly, agreeing with existing experimental observations.

Abstract: We demonstrate a novel approach to produce micron sized shape-memory beads from polyurethane shape-memory polymer (SMP)-dimethylformamide (DMF) solution by joule heating carbon fibers. The relationship between the geometrical dimensions of the resultant SMP beads and processing condition is obtained, which shows the convenience in dimension/size control in fabrication. The fabrication mechanism is revealed and good shape-memory effect is proved.

Abstract: The SMC belt composed of two kinds of SMAs and SMP was fabricated and the three-way movement and recovery force in bending were investigated. The results obtained can be summarized as follows. (1) The three-way bending movement was achived during heating and cooling based on the characteristics of the SMA tapes and the SMP sheet. (2) The recovery force increased during heating and decreased during cooling. The recovery force was evaluated by the proposed simple model.

Abstract: The mechanical behaviors of epoxy-based shape memory polymer (SMP) with linear monomer at the temperatures of 25oC, 42oC, 56oC and 66oC are respectively investigated through the tension tests. Material parameter equations are supposed to describe the relationships between the material parameters of SMP with linear monomer and temperature. Numerical calculations show that the supposed material parameter equations well predict the relationships between the material parameters of SMP with linear monomer and temperature.

Abstract: The glass transition temperatures of epoxy-based shape memory polymers (SMPs), which contain a flexibilizer at various contents of 0%, 5%, 10% and 15% respectively, are determined through DMA tests. The shape memory effect of such materials is investigated through shape recovery experiments. Experimental results show that the content of flexibilizer has much influence on the shape memory effect of epoxy-based SMP. A shape recovery equation is developed based on the results of shape recovery experiment. Numerical calculations show that the developed shape recovery equation well predicts the shape recovery behaviors of epoxy-based SMP.

Abstract: Shape memory polymer (SMP) is being used in many engineering fields due to its shape memory effect and the advantages of large recoverable strain, excellent manufacturability, light weight, low cost and bio-degradability. Therefore it is of practical interest to investigate its thermo-mechanical behaviors. In this paper, a numerical simulation method is supposed to simulate the thermo-mechanical behaviors of SMP using the finite element software of MSC Marc, which is good at simulating the thermo-mechanical behaviors of viscous elastic material. The comparisons between the numerical results and the experimental results by Tobushi et al. illustrate the supposed numerical simulation method well describes the thermo-mechanical behaviors of SMP during the thermo-mechanical processes realizing shape memory effect.

Abstract: This paper is concerned about the synthesis of shape memory styrene copolymer and the investigation of the influence of cross-linking degree on its shape memory effect. The influence of cross-linking degree on shape memory effect of styrene copolymer was investigated through altering the dosage of cross-linking agent. The Tg increased from 65 to 80.7 with the gel content increase from 35% to 80% which is achieved by increasing the dosage of cross-linking agent from 1% to 4%. Moreover, the SMP experienced good SME and the largest reversible strain of the SMP reached as high as 150%. When the copolymer was heated above Tg+30 (different copolymers performed different Tg), the shape recovery speed of the copolymers increased with the gel content increase.

Abstract: Shape memory polymers own many advantages compared with traditional shape memory alloys or ceramics. In order to improve their shape recovery stress and realize a stable recovery response during the deployable process, the structure of SMP sandwich beam composed of two metallic skin and one SMP core is considered. The recovery behaviors of pure SMP and SMP beams reinforced by one-layer metallic skin are also discussed for comparison. The results confirm that the deployable properties of SMP matrix can be significantly improved by using sandwich structure.