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.

Body temperature-responsive two-way and moisture-responsive one-way shape memory behaviors of poly(ethylene glycol)-based networks

2017 ◽  
Vol 8 (25) ◽  
pp. 3833-3840 ◽  
Author(s):  
Guang Yang ◽  
Xueyang Liu ◽  
Alfred Iing Yoong Tok ◽  
Vitali Lipik
Keyword(s):  
Free Radical ◽  
Ethylene Glycol ◽  
Shape Memory ◽  
Shape Memory Polymer ◽  
Polymer Networks ◽  
Poly Ethylene Glycol ◽  
Thermally Induced ◽  
Temperature Responsive ◽  
Shape Memory Effects ◽  
Poly Ethylene

In this work, crosslinked shape-memory polymer networks were prepared by thermally induced free-radical polymerizations of methacrylate-terminated poly(ethylene glycol) (PEG) and n-butyl acrylate (BA), which integrate thermal-responsive two-way and moisture-responsive one-way shape memory effects (SME).

scholarly journals Mono–Material 4D Printing of Digital Shape–Memory Components

Polymers ◽  
2021 ◽  
Vol 13 (21) ◽  
pp. 3767
Author(s):  
Dalia Niazy ◽  
Ahmed Elsabbagh ◽  
Mostafa R. Ismail
Keyword(s):  
Energy Consumption ◽  
Built Environment ◽  
Shape Memory ◽  
Shape Change ◽  
Shape Memory Polymer ◽  
Interactive Systems ◽  
Scanning Calorimetry ◽  
Total Recovery ◽  
Temperature Range ◽  
Environment Temperature

Dynamic shading systems in buildings help reduce solar gain. Actuated systems, which depend on renewable energy with reduced mechanical parts, further reduce building energy consumption compared to traditional interactive systems. This paper investigates stimuli-responsive polymer application in architectural products for sustainable energy consumption, complying with sustainable development goals (SDGs). The proposed research method posits that, by varying the infill percentage in a pre-determined manner inside a 3D-printed mono-material component, directionally controlled shape change can be detected due to thermal stimuli application. Thus, motion behavior can be engineered into a material. In this study, PLA+, PETG, TPU and PA 6 printed components are investigated under a thermal cycle test to identify a thermally responsive shape-memory polymer candidate that actuates within the built environment temperature range. A differential scanning calorimetry (DSC) test is carried out on TPU 95A and PA 6 to interpret the material shape response in terms of transitional temperatures. All materials tested show an anisotropic shape-change reaction in a pre-programmed manner, complying with the behavior engineered into the matter. Four-dimensional (4D)-printed PA6 shows shape-shifting behavior and total recovery to initial position within the built environment temperature range.

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.

A novel shape memory polymer based on conetworks

e-Polymers ◽  
2009 ◽  
Vol 9 (1) ◽  
Author(s):  
Zonghui Li ◽  
Yi Pan ◽  
Peng Zhang ◽  
Zhaohui Zheng ◽  
Xiaobin Ding ◽  
...  
Keyword(s):  
Glass Transition ◽  
Shape Memory ◽  
Shape Memory Polymer ◽  
Recovery Ratio ◽  
Modulus Ratio ◽  
Poly Ethylene Glycol ◽  
Shape Memory Properties ◽  
Shape Memory Effects ◽  
Shape Memory Materials ◽  
Poly Ethylene

AbstractA novel shape memory polymer based on conetworks (CNs) was synthesized. These conetworks consisting of poly(methyl methacrylate) and poly (ethylene glycol) diacrylates showed excellent shape-memory properties with a recovery ratio of nearly 100%. Moreover, different shape memory effects were discovered in different mediums due to their amphiphilic properties. In addition, a large storage modulus ratio above and below the glass transition temperature(Eratio), which probably means excellent shape memory effect, were obtained due to the designed CN structure whether crystallization existed or not. It is quite different from the traditional methods to achieve large Eratio values. The versatility of shapememory conetworks potentially provides us a new route to prepare shape memory materials.

Cross-linked ethylene-vinyl acetate – poly(urethane) temperature-memory composite actuator

2020 ◽  
Vol 54 (28) ◽  
pp. 4441-4455
Author(s):  
JE Rodriguez ◽  
DH Giraldo ◽  
JC Restrepo ◽  
HA Colorado
Keyword(s):  
Shape Memory ◽  
Vinyl Acetate ◽  
Shape Memory Polymer ◽  
Ethylene Vinyl Acetate ◽  
Mechanical Analysis ◽  
Scanning Calorimetry ◽  
Polymeric Systems ◽  
Responsive Polymers ◽  
The Matrix ◽  
The Relationship

Semicrystalline polymeric systems are a type of Shape Memory Polymer (SMP), which are more straightforward to synthesize in comparison with other class of stimulus-responsive polymers. On these systems, the shape memory is triggered by temperature and partially driven by crystallization-induced elongation, heating-induced contraction, and elastic entropy. However, a stable temporary and permanent shape through cycling is not easy to achieve. For that reason, a laminar composite made based in the encapsulation of ethylene vinyl acetate (EVA) inside a PU matrix was developed, with the aim of obtaining an actuator with a preferred deformation direction and stable change of shape. In this study, chemically cross-linked ethylene vinyl acetate copolymer (cEVA) as SMP was synthesized and functionalized as a reinforcing strip. A temperature-memory actuator composite was manufactured by the encapsulation of a shape memory programmed strip in an elastomer matrix. The shape memory properties and thermocycling assessment were evaluated using differential scanning calorimetry and dynamic mechanical analysis. Results show the ability of the actuator to bend and unbend, following multiple consecutive heating-cooling cycles. The relationship between the strip, the matrix, and the interface is critical in the bending and shape memory maintenance.

Effect of C12-14 Alcohols on the Thermomechanical Properties of Epoxy Shape-Memory Polymer

2014 ◽  
Vol 787 ◽  
pp. 275-280
Author(s):  
Li Min Zhao ◽  
Xue Feng ◽  
Xu Jun Mi ◽  
Yan Feng Li ◽  
Hao Feng Xie ◽  
...  
Keyword(s):  
Transition Temperature ◽  
Shape Memory ◽  
Room Temperature ◽  
Aliphatic Alcohol ◽  
Shape Memory Polymer ◽  
Mechanical Analysis ◽  
Thermomechanical Properties ◽  
Epoxy System ◽  
Scanning Calorimetry ◽  
Epoxy Polymers

A critical parameter for a shape memory polymer (SMP) lies in its shape memory transition temperature. For an amorphous SMP polymer, it is highly desirable to develop methods to tailor its Tg, which corresponds to its shape memory transition temperature. Starting with an amine cured aromatic epoxy system, epoxy polymers were synthesized by introducing flexible aliphatic alcohol. The thermal and thermomechanical properties of these epoxy polymers were characterized by differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). All the crosslinked epoxy polymers with Tg’s above room temperature were found to possess shape memory properties.

scholarly journals The Effect of Surface Treatment with Isocyanate and Aromatic Carbodiimide of Thermally Expanded Vermiculite Used as a Functional Filler for Polylactide-Based Composites

Polymers ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 890
Author(s):  
Mateusz Barczewski ◽  
Olga Mysiukiewicz ◽  
Aleksander Hejna ◽  
Radosław Biskup ◽  
Joanna Szulc ◽  
...  
Keyword(s):  
Impact Strength ◽  
Mechanical Stability ◽  
Thermomechanical Analysis ◽  
Thermomechanical Properties ◽  
Phenyl Isocyanate ◽  
Sem Analysis ◽  
Scanning Calorimetry ◽  
Melt Mixing ◽  
Expanded Vermiculite ◽  
Chain Extenders

In this work, thermally expanded vermiculite (TE-VMT) was surface modified and used as a filler for composites with a polylactide (PLA) matrix. Modification of vermiculite was realized by simultaneous ball milling with the presence of two PLA chain extenders, aromatic carbodiimide (KI), and 4,4’-methylenebis(phenyl isocyanate) (MDI). In addition to analyzing the particle size of the filler subjected to processing, the efficiency of mechanochemical modification was evaluated by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The composites of PLA with three vermiculite types were prepared by melt mixing and subjected to mechanical, thermomechanical, thermal, and structural evaluation. The structure of composites containing a constant amount of the filler (20 wt%) was assessed using FTIR spectroscopy and SEM analysis supplemented by evaluating the final injection-molded samples’ physicochemical properties. Mechanical behavior of the composites was assessed by static tensile test and impact strength hardness measurements. Heat deflection temperature (HDT) test and dynamic thermomechanical analysis (DMTA) were applied to evaluate the influence of the filler addition and its functionalization on thermomechanical properties of PLA-based composites. Thermal properties were assessed by differential scanning calorimetry (DSC), pyrolysis combustion flow calorimetry (PCFC), and thermogravimetric analysis (TGA). The use of filler-reactive chain extenders (CE) made it possible to change the vermiculite structure and obtain an improvement in interfacial adhesion and more favorable filler dispersions in the matrix. This translated into an improvement in impact strength and an increase in thermo-mechanical stability and heat release capacity of composites containing modified vermiculites.

scholarly journals Harnessing reversible dry adhesion using shape memory polymer microparticles

RSC Advances ◽  
2021 ◽  
Vol 11 (32) ◽  
pp. 19616-19622
Author(s):  
Wenbing Li ◽  
Junhao Liu ◽  
Wanting Wei ◽  
Kun Qian
Keyword(s):  
Shape Memory ◽  
Shape Memory Polymer ◽  
Shape Memory Polymers ◽  
Memory Effects ◽  
Reversible Adhesion ◽  
Dry Adhesion ◽  
Bonding Property ◽  
Shape Memory Effects ◽  
Polymer Microparticles

Shape memory polymers can provide excellent bonding property because of their shape memory effects. This paper proposes an adhesive unit that is capable of repeatable smart adhesion and exhibits reversible adhesion under heating.

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