Tailoring vinylogous urethane chemistry for the cross-linked polybutadiene: Wide freedom design, multiple recycling methods, good shape memory behavior

Polymer ◽  
2018 ◽  
Vol 148 ◽  
pp. 202-210 ◽  
Author(s):  
Zhiyong Liu ◽  
Changxu Zhang ◽  
Zixing Shi ◽  
Jie Yin ◽  
Ming Tian
2013 ◽  
Vol 864-867 ◽  
pp. 588-591 ◽  
Author(s):  
Xiao Li Wei ◽  
Fa Xing Zhang

A series of novel stable and high-solid-content polyurethane were prepared by self-emulsification,use PES and PPG as mixed soft segments.Influence of APAETMS content and mole ratio of PES/PPG on properties of polyurethane dispersions and films were analyzed .Results show that: the cross-linked complex were multivariate distribution in particle size. With an increase of the mass ratio of PES and PPG and content of APAETMS average particles diameter of polyurethane dispersions became bigger , poly-dispersion became wider., solid content of dispersions decrease.. It is also noticed that the high-solid-content dispersions exhibit a pseudo-plastic behavior, when the mass ratio of PES and PPG is 1:3 and content of APAETMS is 1%, the solid content of dispersions is up to 55%. The film also has a good shape memory behavior.


1999 ◽  
Vol 121 (1) ◽  
pp. 2-8 ◽  
Author(s):  
A. Ishida ◽  
S. Miyazaki

The shape memory effect, superelasticity and two-way shape memory effect of Ni-rich Ti-Ni sputter-deposited thin films were evaluated quantitatively. The results indicated that they are almost comparable to those of bulk specimens. On the other hand, Ti-rich Ti-Ni thin films were found to exhibit a good shape memory behavior owing to a peculiar fine microstructure unlike bulk specimens. Addition of Cu or Pd to a Ti-50at.%Ni thin film was also confirmed to improve the shape memory behavior. These results suggest that shape memory thin films are a promising material for microactuators.


2011 ◽  
Vol 266 ◽  
pp. 171-174 ◽  
Author(s):  
Hai Qing Dong ◽  
Li Jian Liu ◽  
Yong Yong Li

Poly(L-lactide) and poly(ε-caprolactone) (PLLA/PCL) blends with various weight ratios were compounded by melt mixing and their shape memory properties were investigated. The thermal properties, surface morphology and dynamic mechanical properties of the blends were characterized. The results demonstrate that the introduction of PCL improves the process of crystallization of PLLA whereas the reverse situation is for PCL. PLLA/PCL blends were found to exhibit an immiscible behavior from the characterizations of surface morphology. DMA tests show the blends with different weight ratios have different transition temperatures. The properties of blends provide the basis of owning shape memory behavior. The strain recovery ratio (Rr) of PLLA/PCL blend with the weight ratio of 1:3 was about 95% within 22s, whereas the Rr of other blends were less than 75% within 23~30s. It was found that lower transition temperature combined with increased crystallization of PLLA with the increasing PCL content contribute to such a good shape memory effect.


2021 ◽  
Vol 11 (4) ◽  
pp. 1802
Author(s):  
Sneha Samal ◽  
Orsolya Molnárová ◽  
Filip Průša ◽  
Jaromír Kopeček ◽  
Luděk Heller ◽  
...  

An analysis of the shape memory effect of a NiTi alloy by using the spark plasma sintering approach has been carried out. Spark plasma sintering of Ti50Ni50 powder (20–63 µm) at a temperature of 900 °C produced specimens showing good shape memory effects. However, the sample showed 2.5% porosity due to a load of 48 MPa. Furthermore, an apparent shape memory effect was recorded and the specimens were characterized by uniformity in chemical composition and shape memory alloys of NiTi showed significant austenite phases with a bending strain recovery of >2.5%.


Author(s):  
Eva Sanchez-Rexach ◽  
Patrick T. Smith ◽  
Alvaro Gomez-Lopez ◽  
Maxence Fernandez ◽  
Aitziber L. Cortajarena ◽  
...  

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2961
Author(s):  
Moein Rezapour ◽  
Mehdi Ghassemieh ◽  
Masoud Motavalli ◽  
Moslem Shahverdi

This study presents a new way to improve masonry wall behavior. Masonry structures comprise a significant part of the world’s structures. These structures are very vulnerable to earthquakes, and their performances need to be improved. One way to enhance the performances of such types of structures is the use of post-tensioning reinforcements. In the current study, the effects of shape memory alloy as post-tensioning reinforcements on originally unreinforced masonry walls were investigated using finite element simulations in Abaqus. The developed models were validated based on experimental results in the literature. Iron-based shape memory alloy strips were installed on masonry walls by three different configurations, namely in cross or vertical forms. Seven macroscopic masonry walls were modeled in Abaqus software and were subjected to cyclic loading protocol. Parameters such as stiffness, strength, durability, and energy dissipation of these models were then compared. According to the results, the Fe-based strips increased the strength, stiffness, and energy dissipation capacity. So that in the vertical-strip walls, the stiffness increases by 98.1%, and in the cross-strip model's position, the stiffness increases by 127.9%. In the vertical-strip model, the maximum resistance is equal to 108 kN, while in the end cycle, this number is reduced by almost half and reaches 40 kN, in the cross-strip model, the maximum resistance is equal to 104 kN, and in the final cycle, this number decreases by only 13.5% and reaches 90 kN. The scattering of Fe-based strips plays an important role in energy dissipation. Based on the observed behaviors, the greater the scattering, the higher the energy dissipation. The increase was more visible in the walls with the configuration of the crossed Fe-based strips.


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