Achieving multimodal locomotion by a crosslinked poly(ethylene-co-vinyl acetate)-based two-way shape memory polymer

2021 ◽  
Author(s):  
Yao Zhao ◽  
Kaiyuan Peng ◽  
Jiaxin Xi ◽  
Shima Shahab ◽  
Reza Mirzaeifar
Keyword(s):  
Shape Memory ◽  
Vinyl Acetate ◽  
Smart Materials ◽  
Shape Memory Polymer ◽  
Soft Actuator ◽  
Output Force ◽  
Poly Ethylene ◽  
Underlying Mechanisms ◽  
Soft Actuators ◽  
Hot Surface

Abstract Locomotion is a critically important topic for soft actuators and robotics, however, the locomotion applications based on two-way shape memory polymers have not been well explored so far. In this work, a crosslinked poly(ethylene-co-vinyl acetate) (cPEVA)-based two-way shape memory polymer is synthesized using dicumyl peroxide (DCP) as the crosslinker. The influence of the DCP concentration on the mechanical properties and the two-way shape memory properties is systematically studied. A Venus flytrap-inspired soft actuator is made by cPEVA, and it is shown that the actuator can efficiently perform gripping movements, indicating that the resultant cPEVA SMP is capable of producing large output force and recovering from large deformations. This polymer is also utilized to make a self-rolling pentagon-shaped device. It is shown that the structure will efficiently roll on a hot surface, proving the applicability of the material in making sophisticated actuators. With introducing an energy barrier, jumping can be accomplished when the stored energy is fast released. Finite element simulations are also conducted to further understand the underlying mechanisms in the complex behavior of actuators based on cPEVA SMP. This work provides critical insights in designing smart materials with external stimulus responsive programmable function for soft actuator applications.

Torsional Fiber Actuators from Shape-memory Polymer

MRS Advances ◽  
2018 ◽  
Vol 3 (63) ◽  
pp. 3861-3868 ◽  
Author(s):  
Muhammad Farhan ◽  
Tobias Rudolph ◽  
Karl Kratz ◽  
Andreas Lendlein
Keyword(s):  
Vinyl Acetate ◽  
Shape Memory Polymer ◽  
Circular Cross Section ◽  
Humanoid Robots ◽  
Melting Transition ◽  
Heating And Cooling ◽  
Rotary Motors ◽  
Temperature Ranges ◽  
Poly Ethylene ◽  
Soft Actuators

ABSTRACT:Humanoid robots, prosthetic limbs and exoskeletons require soft actuators to perform their primary function, which is controlled movement. In this work, we explored whether crosslinked poly[ethylene-co-(vinyl acetate)] (cPEVA) fibers, with different vinyl acetate (VA) content can serve as torsional fiber actuators, exhibiting temperature controlled reversible rotational changes. Broad melting transitions ranging from 50 to 90 °C for cPEVA18-165 or from 40 to 80 °C for cPEVA28-165 fibers in combination with complete crystallization at temperatures around 10 °C make them suitable actuating materials with adjustable actuation temperature ranges between 10 and 70 °C during repetitive cooling and heating. The obtained fibers exhibited a circular cross section with diameters around 0.4±0.1 mm, while a length of 4 cm was employed for the investigation of reversible rotational actuation after programming by twist insertion using 30 complete rotations at a temperature above melting transition. Repetitive heating and cooling between 10 to 60 °C or 70 °C of one-end-tethered programmed fibers revealed reversible rotations and torsional force. During cooling 3±1 complete rotations (Δθr = + 1080±360°) in twisting direction were observed, while 4±1 turns in the opposite direction (Δθr = - 1440±360°) were found during heating. Such torsional fiber actuators, which are capable of approximately one rotation per cm fiber length, can serve as miniaturized rotary motors to provide rotational actuation in futuristic humanoid robots.

Thermomechanical Characterization of a Series of Crosslinked Poly[ethylene-co-(vinyl acetate)] (PEVA) Copolymers

2015 ◽  
Vol 1718 ◽  
pp. 123-130 ◽  
Author(s):  
Matthias Heuchel ◽  
Laith Al-Qaisi ◽  
Karl Kratz ◽  
Ulrich Nöchel ◽  
Marc Behl ◽  
...  
Keyword(s):  
Shape Memory ◽  
Vinyl Acetate ◽  
Mechanical Stability ◽  
Shape Memory Polymer ◽  
Thermomechanical Properties ◽  
Scanning Calorimetry ◽  
Temperature Range ◽  
Shape Memory Effects ◽  
Cross Links ◽  
Poly Ethylene

ABSTRACTCrosslinked poly[ethylene-co-(vinyl acetate)] (cPEVA) has been recently introduced as a polymer material, which can be functionalized with various shape-memory effects by solely altering the thermomechanical treatment called programming.In this study two series of cPEVAs with different vinyl acetate contents of 18 wt% (cPEVA18) and 28 wt% (cPEVA28) comprising different crosslink densities were investigated by differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA) in the temperature range of -130 °C to 120 °C. DMTA tests were performed in torsion mode, because such movements are highly relevant in the context of complex shape changes in shape-memory polymer based devices. Finally, the obtained DMTA results were compared with DMTA conducted in tension mode. Swelling experiments revealed a gel content in the range from 81% to 90% for cPEVA18 samples while for cPEVA28s a complete conversion was observed. The degree of swelling was found to decrease substantially with increasing crosslink density for both cPEVA series.The influence of VA content and extent of crosslinking on the appearance of the respective melting (Tm) and glass transition (Tg) as well as the thermomechanical properties of cPEVA systems could be demonstrated by discussing both DSC and DMTA results. The temperature range of mechanical stability correlates with the VA content and is determined by decreasing Tm values. The cross links do barely alter the stiffness of a PEVA up to the Tm rang, but lead to constant mechanical rigidity in the rubbery range above Tm.

scholarly journals Fully-Printable Soft Actuator with Variable Stiffness by Phase Transition and Hydraulic Regulations

Actuators ◽  
2021 ◽  
Vol 10 (10) ◽  
pp. 269
Author(s):  
Tingchen Liao ◽  
Manivannan Sivaperuman Kalairaj ◽  
Catherine Jiayi Cai ◽  
Zion Tsz Ho Tse ◽  
Hongliang Ren
Keyword(s):  
Transition Period ◽  
Shape Memory Polymer ◽  
Variable Stiffness ◽  
Pressure Variation ◽  
Soft Actuator ◽  
Output Force ◽  
Load Carrying ◽  
Force Variation ◽  
Stiffness Variation ◽  
Short Transition

Actuators with variable stiffness have vast potential in the field of compliant robotics. Morphological shape changes in the actuators are possible, while they retain their structural strength. They can shift between a rigid load-carrying state and a soft flexible state in a short transition period. This work presents a hydraulically actuated soft actuator fabricated by a fully 3D printing of shape memory polymer (SMP). The actuator shows a stiffness of 519 mN/mm at 20 ∘C and 45 mN/mm at 50 ∘C at the same pressure (0.2 MPa). This actuator demonstrates a high stiffness variation of 474 mN/mm (10 times the baseline stiffness) for a temperature change of 30 ∘C and a large variation (≈1150%) in average stiffness. A combined variation of both temperature (20–50 ∘C) and pressure (0–0.2 MPa) displays a stiffness variation of 501 mN/mm. The pressure variation (0–0.2 MPa) in the actuator also shows a large variation in the output force (1.46 N) at 50 ∘C compared to the output force variation (0.16 N) at 20 ∘C. The pressure variation is further utilized for bending the actuator. Varying the pressure (0–0.2 MPa) at 20 ∘C displayed no bending in the actuator. In contrast, the same variation of pressure at 50 ∘C displayed a bending angle of 80∘. A combined variation of both temperature (20–50 ∘C) and pressure (0–0.2 MPa) shows the ability to bend 80∘. At the same time, an additional weight (300 g) suspended to the actuator could increase its bending capability to 160∘. We demonstrated a soft robotic gripper varying its stiffness to carry objects (≈100 g) using two individual actuators.

Tuneable shape-memory properties of composites based on nanoparticulated plant biomass, lignin, and poly(ethylene carbonate)

Soft Matter ◽  
2018 ◽  
Vol 14 (45) ◽  
pp. 9227-9231 ◽  
Author(s):  
Kazuhiro Shikinaka ◽  
Yudai Funatsu ◽  
Yuki Kubota ◽  
Yoichi Tominaga ◽  
Masaya Nakamura ◽  
...  
Keyword(s):  
Shape Memory ◽  
Plant Biomass ◽  
Ethylene Carbonate ◽  
Shape Memory Polymer ◽  
Shape Memory Properties ◽  
Poly Ethylene ◽  
Properties Of Composites

A shape-memory polymer consisting of lignin and poly(ethylene carbonate) was obtained only by kneading without any toxic reagents.

Tunable shape memory behaviors of poly(ethylene vinyl acetate) achieved by adding poly(L-lactide)

2015 ◽  
Vol 24 (12) ◽  
pp. 125002 ◽  
Author(s):  
Zhi-xing Zhang ◽  
Fei Liao ◽  
Zhen-zhen He ◽  
Jing-hui Yang ◽  
Ting Huang ◽  
...  
Keyword(s):  
Shape Memory ◽  
Vinyl Acetate ◽  
Ethylene Vinyl Acetate ◽  
Poly Ethylene

Shape Memory Behavior of Carbon Composites With Functional Interlayer

2018 ◽  
Author(s):  
L. Santo ◽  
L. Iorio ◽  
G. M. Tedde ◽  
F. Quadrini
Keyword(s):  
Carbon Fiber ◽  
Shape Memory ◽  
Polymer Composites ◽  
Polymer Matrix ◽  
Smart Materials ◽  
Shape Memory Polymer ◽  
Shape Memory Polymers ◽  
Carbon Composites ◽  
Three Point Bending ◽  
Functional Behavior

Shape Memory Polymer Composites (SMPCs) are smart materials showing the structural properties of long-fiber polymer-matrix together with the functional behavior of shape memory polymers. In this study, SM carbon fiber reinforced (CFR) composites have been produced by using a SM interlayer between two CFR prepregs. Their SM properties have been evaluated in comparison with traditional structural CFR composites without the SM interlayer by using an especially designed test. Active and frozen forces are measured during a thermo-mechanical cycle in the three-point bending configuration. Experimental results show that SMPCs are able to fix a temporary deformed shape by freezing high stresses.

scholarly journals Shape-Memory Polymeric Artificial Muscles: Mechanisms, Applications and Challenges

Molecules ◽  
2020 ◽  
Vol 25 (18) ◽  
pp. 4246 ◽  
Author(s):  
Yujie Chen ◽  
Chi Chen ◽  
Hafeez Ur Rehman ◽  
Xu Zheng ◽  
Hua Li ◽  
...  
Keyword(s):  
Shape Memory ◽  
Smart Materials ◽  
Recent Progress ◽  
Shape Memory Polymer ◽  
Shape Memory Polymers ◽  
Artificial Muscles ◽  
Linkage Design ◽  
Wide Range ◽  
Liquid Crystal Elastomers ◽  
Made In

Shape-memory materials are smart materials that can remember an original shape and return to their unique state from a deformed secondary shape in the presence of an appropriate stimulus. This property allows these materials to be used as shape-memory artificial muscles, which form a subclass of artificial muscles. The shape-memory artificial muscles are fabricated from shape-memory polymers (SMPs) by twist insertion, shape fixation via Tm or Tg, or by liquid crystal elastomers (LCEs). The prepared SMP artificial muscles can be used in a wide range of applications, from biomimetic and soft robotics to actuators, because they can be operated without sophisticated linkage design and can achieve complex final shapes. Recently, significant achievements have been made in fabrication, modelling, and manipulation of SMP-based artificial muscles. This paper presents a review of the recent progress in shape-memory polymer-based artificial muscles. Here we focus on the mechanisms of SMPs, applications of SMPs as artificial muscles, and the challenges they face concerning actuation. While shape-memory behavior has been demonstrated in several stimulated environments, our focus is on thermal-, photo-, and electrical-actuated SMP artificial muscles.

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