Tunable shape recovery progress of thermoplastic polyurethane by solvents

2018 ◽  
Vol 47 (1) ◽  
pp. 7-13 ◽  
Author(s):  
Changchun Wang ◽  
Bo Kou ◽  
Zusheng Hang ◽  
Xuejuan Zhao ◽  
Tianxuan Lu ◽  
...  
Keyword(s):  
Shape Memory ◽  
Internal Stress ◽  
Recovery Time ◽  
Shape Recovery ◽  
Thermoplastic Polyurethane ◽  
Recovery Process ◽  
Solubility Parameters ◽  
Content Type ◽  
Shape Memory Properties ◽  
Residual Strains

Purpose This study aims to present that the chemo-responsive shape recovery of thermoplastic polyurethane (TPU) is tunable by solvents with different solubility parameters, and it is generic for chemo-responsive shape-memory polymer and its composites. Design/methodology/approach Two kinds of commercial TPU samples with different thicknesses were prepared by panel vulcanizer and injection molding (an industrial manner) to investigate their chemo-responsive shape memory properties in acetic ether and acetone. Findings Results showed that all of TPU films with different thicknesses can fully recover their original shapes weather they recover in acetic ether or acetone. But the recovery time of TPU films in acetone is greatly reduced, especially for the twisting samples. The residual strains of recovery TPU samples after extension reduce obviously. Research limitations/implications The great decrement of recovery time is related to two factors. One is due to the bigger solubility parameter of acetone with higher dipole moment compared with those of acetic ether, and the other is the remained internal stress of TPU films after preparation. The internal stress is identified to have an effect on the shape-memory properties by comparing the recovery process of samples with/without annealing. The reduced residual strains of recovery TPU samples after extension is due to the increasing mobility of polymer segments after molecules of acetic ether penetrates into the polymeric chains. Originality/value This is a universal strategy to control the recovery process of shape-memory materials or composites. The underlying mechanism is generic and should be applicable to chemo-responsive shape-memory polymers or their composites.

Shape Recovery Characteristics of 3D Printed Soft Polymers and Their Composites

2016 ◽  
Author(s):  
Wenbo Liu ◽  
Nan Wu ◽  
Kishore Pochiraju
Keyword(s):  
High Resolution ◽  
Shape Memory ◽  
Recovery Time ◽  
Shape Recovery ◽  
Recovery Process ◽  
Hot Water ◽  
Recovery Ratio ◽  
3D Printed ◽  
Term Creep

Shape memory polymers can be triggered to assume memorized shapes from temporarily deformed forms using thermal stimuli. This paper focuses on the characterization of the shape memory behaviors observed in selected 3D printable photo-cured polymer parts and filament with specified fillers. The shape recovery ratio and recovery time were analyzed using 3D printed specimens with 90° bends. Parts with the mixture of selected commercially available polymers — a rigid polymer (RP) and two digitally mixed polymer blends (DB-A and DB-B) were 3D-printed on a multi-material 3D printer capable of producing digital materials with variable mix ratios. The recovery ratios were determined after thermal triggering and after long-term creep (self-recovery) without thermal triggering. The 3D printed parts were heated to above their glass transaction temperature to train temporary shapes and the recovery of original shapes after a thermal trigger was monitored using a high-resolution camera. Long-term self-recovery (non-triggered) was also studied by observing the parts after temporary shape has been trained, as the try to regain their original shape over several days of slow recovery. The recovery of bending angles was quantitatively recorded from the images taken during the shape recovery process. The recovery due to thermal triggers was monitored under a high resolution microscope by reheating with hot water at 90°C. Experiments of long-term self-recovery at room temperature included monitoring of several parts by taking periodic images of the specimens using a resolution camera. The effect of inclusion of fillers on the shape recovery characteristics was also investigated. Silicon Carbide (SiC) with different weight fractions were mixed into PLA powders. Continuous filaments were extruded using a single screw extruder. The recovery time of thermal activation recovery was then characterized to determine the effect of addition of the fillers. The effect of material-mix ratio, initial printed orientation, filler type on the recovery ratio and recovery time are described in this paper.

Investigate of Electrical Conductivity of Shape-Memory Polymer Filled with Carbon Black

2008 ◽  
Vol 47-50 ◽  
pp. 714-717 ◽  
Author(s):  
Xin Lan ◽  
Jin Song Leng ◽  
Yan Ju Liu ◽  
Shan Yi Du
Keyword(s):  
Electrical Conductivity ◽  
Carbon Black ◽  
Shape Memory ◽  
Shape Recovery ◽  
Volume Fraction ◽  
Shape Memory Polymer ◽  
Recovery Process ◽  
Thermomechanical Properties ◽  
Electrically Conductive ◽  
New System

A new system of thermoset styrene-based shape-memory polymer (SMP) filled with carbon black (CB) is investigated. To realize the electroactive stimuli of SMP, the electrical conductivity of SMP filled with various amounts of CB is characterized. The percolation threshold of electrically conductive SMP filled with CB is about 3% (volume fraction of CB), which is much lower than many other electrically conductive polymers. When applying a voltage of 30V, the shape recovery process of SMP/CB(10 vol%) can be realized in about 100s. In addition, the thermomechanical properties are also characterized by differential scanning calorimetery (DSC).

scholarly journals Shape-Memory-Recovery Characteristics of Microcellular Foamed Thermoplastic Polyurethane

Polymers ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 351
Author(s):  
Chang-Seok Yun ◽  
Joo Seong Sohn ◽  
Sung Woon Cha
Keyword(s):  
Shape Memory ◽  
Cell Density ◽  
Shape Recovery ◽  
Structural Changes ◽  
Thermoplastic Polyurethane ◽  
Testing Machine ◽  
Base Material ◽  
Memory Mechanism ◽  
Foaming Process ◽  
Dog Bone

We investigated the shape-recovery characteristics of thermoplastic polyurethane (TPU) with a microcellular foaming process (MCP). Additionally, we investigated the correlation between changes in the microstructure and the shape-recovery characteristics of the polymers. TPU was selected as the base material, and the shape-recovery characteristics were confirmed using a universal testing machine, by manufacturing dog-bone-type injection-molded specimens. TPUs are reticular polymers with both soft and hard segments. In this study, we investigated the shape-memory mechanism of foamed polymers by maximizing the shape-memory properties of these polymers through a physical foaming process. Toward this end, TPU specimens were prepared by varying the gas pressure, foaming temperature, and type of foaming gas in the batch MCP. The effects of internal structural changes were investigated. These experimental variables affected the microstructure and shape-recovery characteristics of the foamed polymer. The generated cell density changed, which affected the shape-recovery characteristics. In general, a higher cell density corresponded to a higher shape-recovery ratio.

Additive manufacturing of shape memory polymers: effects of print orientation and infill percentage on shape memory recovery properties

2020 ◽  
Vol 26 (9) ◽  
pp. 1593-1602
Author(s):  
Jorge Villacres ◽  
David Nobes ◽  
Cagri Ayranci
Keyword(s):  
Additive Manufacturing ◽  
Shape Memory ◽  
Shape Recovery ◽  
Fused Deposition Modeling ◽  
Large Strain ◽  
Shape Memory Polymers ◽  
Polymeric Materials ◽  
Content Type ◽  
Fused Deposition ◽  
Memory Recovery

Purpose The purpose of this paper is to study the shape memory properties of SMP samples produced through a MEAM process. Fused deposition modeling or, as it will be referred to in this paper, material extrusion additive manufacturing (MEAM) is a technique in which polymeric materials are extruded though a nozzle creating parts via accumulation and joining of different layers. These layers are fused together to build three-dimensional objects. Shape memory polymers (SMP) are stimulus responsive materials, which have the ability to recover their pre-programmed form after being exposed to a large strain. To induce its shape memory recovery movement, an external stimulus such as heat needs to be applied. Design/methodology/approach This project investigates and characterizes the influence of print orientation and infill percentage on shape recovery properties. The analyzed shape recovery properties are shape recovery force, shape recovery speed and time elapsed before activation. To determine whether the analyzed factors produce a significant variation on shape recovery properties, t-tests were performed with a 95% confidence factor between each analyzed level. Findings Results proved that print angle and infill percentage do have a significant impact on recovery properties of the manufactured specimens. Originality/value The manufacturing of SMP objects through a MEAM process has a vast potential for different applications; however, the shape recovery properties of these objects need to be analyzed before any practical use can be developed. These have not been studied as a function of print parameters, which is the focus of this study.

Shape memory effects of EVM-GMA/PVC blends

2020 ◽  
pp. 009524432095358
Author(s):  
Yanlu Chen ◽  
Zhengwei Lin ◽  
Haotian Zhao ◽  
Xingxing Ji ◽  
Xinyan Shi
Keyword(s):  
Shape Memory ◽  
Glycidyl Methacrylate ◽  
Shape Recovery ◽  
Physical And Mechanical Properties ◽  
Ethylene Vinyl Acetate ◽  
Recovery Efficiency ◽  
Restoring Force ◽  
Shape Memory Properties ◽  
Shape Memory Effects ◽  
Two Phases

In this paper, polyvinyl chloride (PVC) masterbatch, prepared using ethylene-vinyl acetate-glycidyl methacrylate terpolymer (EVM-GMA) as a polymer plasticizer replacing traditional harmful ester, was blended with EVM-GMA in melt and then cured by peroxide in a compression mold to prepare EVM-GMA/PVC blends. The results showed that with the increase of PVC, physical and mechanical properties have improved significantly. Two phases in blends formed a “sea-island” structure and the interface was blurred. Blends riched in EVM-GMA all had excellent dual shape memory properties. After removing applied force, there was only a slight recovery of the instantaneous elastic deformation and blends still retained the original temporary shape (the shape fixation was more than 99%). The shape recovery efficiency of specimen (EVM-GMA/PVC = 90/10) was the highest, which evidenced that entropy elastic effect of molecular chains and elastic restoring force provided by crosslinked structure achieved a balance at this point.

Synthesis, structure and tunable shape memory properties of polytriazoles: dual-trigger temperature and repeatable shape recovery

2015 ◽  
Vol 3 (21) ◽  
pp. 11596-11606 ◽  
Author(s):  
M. Ragin Ramdas ◽  
K. S. Santhosh Kumar ◽  
C. P. Reghunadhan Nair
Keyword(s):  
Shape Memory ◽  
Shape Recovery ◽  
Shape Memory Polymers ◽  
Shape Memory Properties

Click assisted synthesis resulted in low, high and dual trigger temperature shape memory polymers. They exhibit high shape recovery and repeatability in shape memory properties.

scholarly journals The Influence of Shape Changing Behaviors from 4D Printing through Material Extrusion Print Patterns and Infill Densities

Materials ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 3754
Author(s):  
Seokwoo Nam ◽  
Eujin Pei
Keyword(s):  
Shape Memory ◽  
Recovery Time ◽  
Shape Recovery ◽  
Shape Memory Polymer ◽  
Material Extrusion ◽  
Concentric Pattern ◽  
Dimensional Printing ◽  
Recovery Result ◽  
Am Processes ◽  
Recovery Temperature

Four-dimensional printing (4DP) is an approach of using Shape Memory Materials (SMMs) with additive manufacturing (AM) processes to produce printed parts that can deform over a determined amount of time. This research examines how Polylactic Acid (PLA), as a Shape Memory Polymer (SMP), can be programmed by manipulating the build parameters of material extrusion. In this research, a water bath experiment was used to show the results of the shape-recovery of bending and shape-recovery speed of the printed parts, according to the influence of the print pattern, infill density and recovery temperature (Tr). In terms of the influence of the print pattern, the ‘Quarter-cubic’ pattern with a 100% infill density showed the best recovery result; and the ‘Line’ pattern with a 20% infill density showed the worst recovery result. The ‘Cubic-subdivision’ pattern with a 20% infill density demonstrated the shortest recovery time; and the ‘Concentric’ pattern with a 100% infill density demonstrated the longest recovery time. The results also showed that a high temperature and high infill density provided better recovery, and a low temperature and low infill density resulted in poor recovery.

scholarly journals Mechanical, Thermal, and Shape Memory Properties of Three-Dimensional Printing Biomass Composites

Polymers ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 1234 ◽  
Author(s):  
Hongjie Bi ◽  
Min Xu ◽  
Gaoyuan Ye ◽  
Rui Guo ◽  
Liping Cai ◽  
...  
Keyword(s):  
Shape Memory ◽  
Wood Flour ◽  
Memory Performance ◽  
Thermoplastic Polyurethane ◽  
Tensile Elongation ◽  
Three Dimensional ◽  
Mechanical Analysis ◽  
Shape Memory Properties ◽  
Shape Memory Composites ◽  
Recovery Angle

In this study, a series of heat-induced shape memory composites was prepared by the hot-melt extrusion and three-dimensional (3D) printing of thermoplastic polyurethane (TPU) using wood flour (WF) with different contents of EPDM-g-MAH. The mechanical properties, microtopography, thermal property analysis, and heat-induced shape memory properties of the composites were examined. The results showed that, when the EPDM-g-MAH content was 4%, the tensile elongation and tensile strength of the composites reached the maximum value. The scanning electron microscopy and dynamic mechanical analysis results revealed a good interface bonding between TPU and WF when the EPDM-g-MAH content was 4%. The thermogravimetric analysis indicated that the thermal stability of TPU/WF composites was enhanced by the addition of 4% EPDM-g-MAH. Heat-induced shape memory test results showed that the shape memory performance of composites with 4% EPDM-g-MAH was better than that of unmodified-composites. The composites’ shape recovery performance at a temperature of 60 °C was higher than that of the composites at ambient temperature. It was also found that, when the filling angle of the specimen was 45°, the recovery angle of the composites was larger.

Shape Memory Properties of Ultrafine-Grained Austenitic Stainless Steel

2013 ◽  
Vol 738-739 ◽  
pp. 496-500 ◽  
Author(s):  
Karine Andrea Käfer ◽  
Heide Heloise Bernardi ◽  
Leonardo Kenji Fudo Naito ◽  
Nelson Batista de Lima ◽  
Jorge Otubo
Keyword(s):  
Shape Memory ◽  
Shape Recovery ◽  
Equal Channel Angular Extrusion ◽  
Ti Alloy ◽  
Compression Tests ◽  
Austenitic Matrix ◽  
Ultrafine Grained ◽  
Shape Memory Properties ◽  
Intermetallic Precipitates ◽  
Different Temperatures

In this work the effect of grain refinement on the shape memory properties of a Fe-Mn-Si-Cr-Ni-Co-Ti alloy was evaluated using compression tests. In order to refine the microstructure, the samples were heavily deformed by equal channel angular extrusion (ECAE) and then annealed at different temperatures ranging from 450°C to 1050°C. These treatments resulted in the formation of intermetallic precipitates and strengthening of austenitic matrix. The results of compression testes show that the higher degrees of shape recovery (56 % for 4% strain) were achieved by the samples with smaller grain size (12 µm).

Sign in / Sign up

Export Citation Format

Share Document