Multi-shape memory effect in shape memory polymer composites

2012 ◽  
Vol 74 ◽  
pp. 220-222 ◽  
Author(s):  
Abdul Basit ◽  
Gildas L'Hostis ◽  
Bernard Durand
2010 ◽  
Vol 638-642 ◽  
pp. 2189-2194 ◽  
Author(s):  
Hisaaki Tobushi ◽  
Shunichi Hayashi ◽  
Y. Sugimoto ◽  
K. Date

The shape memory composite (SMC) with shape memory alloy (SMA) and shape memory polymer (SMP) was fabricated, and the two-way bending deformation and recovery force were investigated. The results obtained can be summarized as follows. (1) Two kinds of SMA tapes which show the shape memory effect and superelasticity were heat-treated to memorize the round shape, respectively. The shape-memorized round SMA tapes were sandwiched between the SMP sheets, and the SMC belt was fabricated. (2) The two-way bending deformation with an angle of 56 degrees is observed during heating and cooling. (3) If the SMC belt is heated and cooled by keeping the form, recovery force increases during heating and decreases during cooling.


2020 ◽  
Vol 1010 ◽  
pp. 142-147
Author(s):  
Nur Athirah Rasli @ Rosli ◽  
Syazana Ahmad Zubir

Various polyurethane-based shape memory polymer was synthesized using polycaprolactone (PCL) as soft segment and, hexamethylene diisocyanate (HMDI) and isophorone diisocyanate (IPDI) as the hard segments. Palm kernel oil-based polyol was used to replace part of the petroleum-based polyol due to the increasing demand on renewable resources as a result of environmental awareness. The synthesis has been carried out using two step polymerization method. The effects of varying the molar ratio of IPDI/HMDI on material properties such as crystallinity, transition temperature, morphology, shape memory effect and tensile strength were investigated by using Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM), shape memory test and tensile test. A high IPDI content in SMPU results in better shape memory effect, whereas increasing HMDI content leads to a better chain flexibility. In this work, the incorporation of IPDI contributes to the formation of phase separation which enhance the formation of crystalline soft segment structure while the incorporation of HMDI as isocyanate tend to promote phase mixing which enhance the chain flexibility of the SMPU backbone.


2008 ◽  
Vol 47-50 ◽  
pp. 690-693 ◽  
Author(s):  
Da Wei Zhang ◽  
Jin Song Leng ◽  
Yan Ju Liu

This paper is concerned about the synthesis of shape memory styrene copolymer and the investigation of the influence of radialization dosage on its shape memory effect. As one of novel actuators in smart materials, shape memory polymers (SMPs) have been investigated intensively. Styrene copolymer with proper cross-linking degree can exhibit shape memory effect (SME). In this paper, the influence of radialization on shape memory effect of styrene copolymer was investigated through altering the dosage of radialization. The radialization dosage of styrene copolymer was determined by changed radicalization time. The glass transition temperature (Tg) of styrene copolymerwas measured by Dynamic Mechanical Analysis (DMA). The shape memory performance of styrene copolymer with different radiated dosage was also evaluated. Results indicated that the shape memory polymer (SMP) was synthesized successfully. The Tg increased from 60°C to 65°C followed by increasing the radialization dosage. Moreover, the SMP experienced good SME and the largest reversible strain of the SMP reached as high as 150%. When heating above Tg+30°C (different copolymers performed different Tg), the shape recovery speed of the copolymers increased with increasing the radialization dosage. However, the recovery speed decreased with increasing the radialization dosage at the same temperature of 95°C.


2005 ◽  
Vol 872 ◽  
Author(s):  
Emily A. Snyder ◽  
Tat H. Tong

AbstractThe basic principle for the operation of a thermally stimulated shape memory polymer (SMP) is a drastic change in elastic modulus above the glass transition temperature (Tg). This change from glassy modulus to rubbery modulus allows the material to be deformed above the Tg and retain the deformed shape when cooled below the Tg. The material will recover its original shape when heated above the Tg again. However, thermal activation is not the only possibility for a polymer to exhibit this shape memory effect or change of modulus. This paper discusses results of an alternative approach to SMP activation.It is well known that the Tg of a thermosetting polymer is proportional to its crosslinking density. It is possible for the crosslinking density of a room temperature elastomer to be modified through photo-crosslinking special photo-reactive monomer groups incorporated into the material system in order to increase its Tg. Correspondingly, the modulus will be increased from the rubbery state to the glassy state. As a result, the material is transformed from an elastomer to a rigid glassy photoset, depending on the crosslinking density achieved during exposure to the proper wavelength of light. This crosslinking process is reversible by irradiation with a different wavelength, thus making it possible to produce light-activated SMP materials that could be deformed at room temperature, held in deformed shape by photo-irradiation using one wavelength, and recovered to the original shape by irradiation with a different wavelength.In this work, monomers which contain photo-crosslinkable groups in addition to the primary polymerizable groups were synthesized. These monomers were formulated and cured with other monomers to form photo-responsive polymers. The mechanical properties of these materials, the kinetics, and the reversibility of the photo-activated shape memory effect were studied to demonstrate the effectiveness of using photo-irradiation to effect change in modulus (and thus shape memory effect).


2011 ◽  
Vol 179-180 ◽  
pp. 325-328 ◽  
Author(s):  
Bo Zhou ◽  
Xue Lian Wu ◽  
Yan Ju Liu ◽  
Jin Song Leng

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.


2020 ◽  
Vol 31 (18) ◽  
pp. 2152-2164
Author(s):  
Xue-Jiao Zhang ◽  
Qing-Sheng Yang ◽  
Jin-Song Leng

Poly( l-lactide-co-ε-caprolactone) is an environment-friendly shape memory polymer. Molecular dynamics method was used to study the shape memory effect and mechanical properties of graphene oxide–reinforced poly( l-lactide-co-ε-caprolactone) to understand the microscopic mechanism. Two models containing dispersed graphene oxide were constructed. It is shown that the addition of graphene oxide causes the glass transition temperature of material to rise because of limitation on polymer activity. The uniaxial tensile properties of the composites were studied. The results exhibited that strength of composites depend on the interface state of the polymer and graphene oxide. The strength of the composite with covalent bond is much higher than that of another without the covalent bond between graphene oxide and poly( l-lactide-co-ε-caprolactone) generated. Stress softening effect was observed in the cross-linked composite in the glass state. Their uniaxial tension thermodynamic cycles were carried out to consider the shape memory effect of the composites. It is shown that graphene oxide–reinforced composites with different interactions exhibit fair shape memory effect in the direction of paralleling graphene oxide surface. In terms of the direction perpendicular to graphene oxide sheet, the fixed ratios of the composites decrease slightly about 1.64%–3.63%, and the recovery ratios of the composites with the covalent bond are higher than others about 3.22%–12.93%.


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