scholarly journals Mechanical properties of NiTi-TiC shape-memory composites

1997 ◽  
Author(s):  
D.C. Dunand ◽  
K.L. Fukami-Ushiro ◽  
D. Mari ◽  
J.A. Roberts ◽  
M.A. Bourke
Polymers ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 807 ◽  
Author(s):  
Lin Xia ◽  
Han Gao ◽  
Weina Bi ◽  
Wenxin Fu ◽  
Guixue Qiu ◽  
...  

Shape memory composites of trans-1,4-polyisoprene (TPI) and low-density polyethylene (LDPE) with easily achievable transition temperatures were prepared by a simple physical blending method. Carbon black (CB) was introduced to improve the mechanical properties of the TPI/LDPE composites. The mechanical, cure, thermal and shape memory properties of the TPI/LDPE/CB composites were investigated in this study. In these composites, the crosslinked network generated in both the TPI and LDPE portions acted as a fixed domain, while the crystalline regions of the TPI and LDPE portions acted as a reversible domain in shape memory behavior. We found the mechanical properties of composites were promoted significantly with an increase of CB content, accompanied with the deterioration of shape memory properties of composites. When CB dosage was 5 parts per hundred of rubber composites (phr), best shape memory property of composites was obtained with a shape fixity ratio of 95.1% and a shape recovery ratio of 95.0%.


2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Yongkun Wang ◽  
Yuting Zhang ◽  
Jinhua Zhang ◽  
Junjue Ye ◽  
Wenchao Tian

Purpose The purpose of this paper is to study the influence of calcium sulfate whiskers (CSWs) on the thermodynamic properties and shape memory properties of epoxy/cyanate ester shape memory composites. Design/methodology/approach To improve the mechanical properties of shape memory cyanate ester (CE)/epoxy polymer (EP) resin, high performance CSWs were used to reinforce the thermo-induced shape memory CE/EP composites and the shape memory CSW/CE/EP composites were prepared by molding. The effect of CSW on the mechanical properties and shape memory behavior of shape memory CE/EP composites was investigated. Findings After CSW filled the shape memory CE/EP composites, the bending strength of the composites is greatly improved. When the content of CSW is 5 Wt.%, the bending strength of the composite is 107 MPa and the bending strength is increased by 29 per cent compared with bulk CE/EP resin. The glass transition temperature and storage modulus of the composites were improved in CE/EP resin curing system. However, when the content of CSW is more than 10 Wt.%, clusters are easily formed between whiskers and the voids between whiskers and matrix increase, which will lead to the decrease of mechanical properties of composites. The results of shape memory test show that the shape memory recovery time of the composites decreases with the decrease of CSW content at the same temperature. In addition, the shape recovery ratio of the composites decreased slightly with the increase of the number of thermo-induced shape memory cycles. Research limitations/implications A simple way for fabricating thermo-activated SMP composites has been developed by using CSW. Originality/value The outcome of this study will help to fabricate the SMP composites with high mechanical properties and the shape memory CSW/CE/EP composites are expected to be used in space deployable structures.


Polymers ◽  
2021 ◽  
Vol 13 (20) ◽  
pp. 3479
Author(s):  
Lin Xia ◽  
Jiafeng Meng ◽  
Yuan Ma ◽  
Ping Zhao

We processed a series of shape memory Eucommia rubber (ER) composites with both carbon–carbon and ionic cross-linking networks via a chemical cross-linking method. The influence of the carbon–carbon cross-linking and ion cross-linking degree of ER composites on curing, mechanical, thermal, and shape memory properties were studied by DSC, DMA, and other analytical techniques. Dicumyl peroxide (DCP) and zinc dimethacrylate (ZDMA) played a key role in preparing ER composites with a double cross-linking structure, where DCP initiated polymerization of ZDMA, and grafted ZDMA onto polymer molecular chains and cross-linked rubber molecular chains. Meanwhile, ZDMA combined with rubber macromolecules to build ionic cross-linking bonds in composites under the action of DCP and reinforced the ER composites. The result showed that the coexistence of these two cross-linking networks provide a sufficient restoring force for deformation of shape memory composites. The addition of ZDMA not only improved the mechanical properties of materials, but also significantly enhanced shape memory performance of composites. In particular, Eucommia rubber composites exhibited outstanding mechanical properties and shape memory performance when DCP content was 0.2 phr.


1996 ◽  
Vol 459 ◽  
Author(s):  
D. C. Dunand ◽  
K. L. Fukami-Ushiro ◽  
D. Mari ◽  
J. A. Roberts ◽  
M. A. Bourke

ABSTRACTThis paper reviews recent work on the mechanical behavior of martensitic NiTi composites reinforced with 10–20 vol.% TiC particulates. The behavior of the composites is compared to that of unreinforced NiTi, so as to elucidate the effect of mismatch due to matrix transformation, thermal expansion, twinning or slip, in the presence of purely elastic particles. The twinning and subsequent thermal recovery of deformed composites, measured both macroscopically (by compressive testing and by dilatometry) and microscopically (by neutron diffraction), are summarized.


Author(s):  
Christina N. Yarborough ◽  
Emily M. Childress ◽  
Richard K. Kunz

As the need for deployable space structures continues to increase, a deeper understanding of the mechanical properties and the responses of shape memory composites will be needed. Past research efforts have been focused on woven (0/90) carbon fiber composites which limit the shape memory capabilities due to the brittle nature of this fiber. The current work not only utilizes a synthetic fiber which allowed for a greater versatility in the composite, but also investigates the effects of angle plies and fiber volume fraction on the attainable bend ratio of the laminates. Four types of laminates were made to test the effects of laminate thickness, angle-plies, and fiber volume fraction. The specimens from these laminates were placed in both bending and tensile tests to investigate the effect of the fiber reinforcement on the polymer’s stiffness, strength and recovery. Testing revealed that the thicker specimens demonstrated improved recovery over the thinner samples, and that the angle-ply specimens recovered better than the (0/90) specimens. The recovery of the (0/90) specimens was improved by increasing the fiber volume fraction. Most significantly, the specimens were able to achieve smaller bend ratios than in previous studies without fiber microbuckling or fiber breakage. The tensile test data revealed that the bending cycles had little to no affect on the material properties of the composite. Only the modulus of the 5-ply (0/90) was seen to slightly decrease as the bending ratio decreased.


2021 ◽  
Vol 419 ◽  
pp. 129437
Author(s):  
Chen Yang ◽  
Rui Zheng ◽  
Muhammad Rizwan Younis ◽  
Jundong Shao ◽  
Lian-Hua Fu ◽  
...  

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