Article
Materials Science, Multidisciplinary
Huan He, Zhaoxian Liu, Lixin Zhang, Wenzhen Zhao, Ao Fu, Xiaoyang Yi
Summary: The joining of aluminum alloy and Ti-Ni-Hf shape memory dissimilar metals was achieved by cold metal transfer (CMT) welding-brazing with an Al-based filler. The relationship between heat input, microstructures, and joint strength was investigated. The joint consisted of three regions: the Al/SMA brazing interface, weld metal zone, and Al-weld metal zone. The interfacial intermetallic compound (IMC) with a strip or needle-like morphology was identified as TiAl3. The IMC exhibited an inhomogeneous morphology along the brazing interface. The Ti-Ni-Hf SMA adjacent to the interface retained reversible martensitic transformation and its phase transition temperature slightly increased with distance from the interface. Increasing heat input led to an increase in IMC thickness and a decrease in joint strength. The maximum tensile strength achieved was 122 MPa at a heat input of 553.6 J/mm. Fracture initiation occurred at the interface between the IMC and Ti-Ni-Hf and propagated along the interface.
JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T
(2023)
Article
Biochemistry & Molecular Biology
Yang Feng, Zhuguang Nie, Panhong Deng, Liping Luo, Xingman Hu, Jie Su, Haiming Li, Xiaodong Fan, Shuhua Qi
Summary: An effective method of using polydopamine coating to improve the interfacial interaction between Mutiwalled carbon nanotubes (MWCNTs) and epoxy matrix has been developed. This method enhances the performance of the epoxy vitrimer in terms of thermal conductivity, strength, shape memory, repairing, and recycling.
INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES
(2022)
Article
Chemistry, Physical
Tomasz Goryczka, Karol Gryn, Adrian Barylski, Barbara Szaraniec
Summary: Joining NiTi wires with shape memory effect and pseudoelasticity is challenging due to unwanted phase interactions, but a basic laser welding technique can be used to overcome this issue. By optimizing the laser power, high-quality welds with good reversible martensitic transformation and pseudoelasticity can be obtained.
Article
Materials Science, Characterization & Testing
Hong Li, Yi Gao, Shuangliang Zhao, Wei Gao, Xiangning He, Riyao Cong, Xiaoying Xie, Jianju Luo, Chuwang Su
Summary: Shape Memory Polymer (SMP) is a smart material that can respond to changes in the external environment. The synthesized polymer in this study has a wide transition temperature range and exhibits excellent thermally induced shape memory performance, showing great potential for applications.
Article
Materials Science, Characterization & Testing
Yingyu Wang, Feilong Zhu, Qiong Rao, Xiongqi Peng
Summary: This paper presents a 3D finite strain viscoelastic model to characterize the thermomechanical behaviors of amorphous shape memory polymers, with uncoupled structural and stress relaxations. The temperature- and rate-dependent viscoelastic behaviors and stress relaxation are described using molecular mechanism models. The model accuracy is further improved by introducing a modified weight function similar to frozen fraction in phase transition theory. The developed model shows good consistency with experimental data in simulating shape recovery experiments of amorphous SMPs under different conditions.
Article
Materials Science, Multidisciplinary
Yu Zhong, Jilin Xie, Yuhua Chen, Limeng Yin, Peng He, Weiwei Lu
Summary: The micro laser lap welding method was used to form a lap joint between NiTiNb shape memory alloys and Ti6Al4V alloy with a Ni interlayer, resulting in the formation of the brittle intermetallic compound Ti2Ni. Despite the addition of the Ni interlayer, the lap joint still fractured in the fusion zone on the Ti6Al4V alloy side, with a maximum shear load of 122N.
Article
Materials Science, Multidisciplinary
Daniel M. Krajovic, Mitchell Anthamatten
Summary: The study demonstrates a novel shape-memory polymer material that is melt-recyclable, prepared using catalyst-free isocyanate chemistry, with high processability and minimal performance loss. Compared to traditional poly(caprolactone) homopolymers, the new material shows better elastic performance and stress relaxation characteristics. Furthermore, the shape-memory properties of the material remain excellent even after multiple recycling processes.
ACS APPLIED POLYMER MATERIALS
(2021)
Article
Chemistry, Physical
Elisa Fracchia, Jana Bidulska, Robert Bidulsky, Marco Actis Grande
Summary: In this study, AA1070 aluminium alloy sheets were prepared with three different cutting processes and joined using TIG and MIG welding. The mechanical properties and micro-hardness of the sheets were evaluated, and the effects of edge preparation on the tensile properties were analyzed through surface fracture observations.
Article
Materials Science, Characterization & Testing
Yunlong Shi, Hairong Chen, Xiaoyu Guan
Summary: Research on shape memory-based materials, including SMPU electrospun nanofiber-based yarn and coil, has been increasing due to their shape programming and recovery attributes. The novel method of preparing these materials using a twisting process has shown improved shape recovery properties compared to traditional SMPU fiber. Interlayer friction between nanofibers also enhances the shape recovery performance of the yarns and coils.
Article
Materials Science, Composites
Xuweilai Ni, Long Chen, Yuan Si, Xiaoyu Chen, Chunping Zhou, Pingping Niu
Summary: The preparation and performance of directional shape memory magnetic carbon nanotubes/epoxy resin composites were studied. The results showed that when the mass fraction of magnetic carbon nanotubes was 1.5 wt%, the dispersion was 77.5% and the orientation rate was 80%, leading to significantly improved thermal mechanical properties. The temperature rise of the composites increased by 38.7%, the shape recovery rate increased by 1.01%, and the shape recovery rate reached 360% of the raw material.
COMPOSITES SCIENCE AND TECHNOLOGY
(2023)
Article
Polymer Science
Hengheng Zhao, Xuefeng Wei, Yue Fang, Ke Gao, Tongkui Yue, Liqun Zhang, Venkat Ganesan, Fanlong Meng, Jun Liu
Summary: This study utilizes coarse-grained molecular dynamics simulations to investigate the effect of bond swap energy barrier (Delta E-sw) on the mechanical properties of vitrimers. The results show that Delta E-sw plays a critical role in the dynamics of linear chains and reactive beads. The study also demonstrates that an intermediate value of Delta E-sw can achieve the best mechanical performance characteristics. Additionally, the study explores the impact of Delta E-sw on stress relaxation, self-healing capability, and extrusion rate of polymer vitrimers.
Article
Polymer Science
Takuya Ohzono, Hiroyuki Minamikawa, Emiko Koyama, Yasuo Norikane
Summary: Crystallite formation in cross-linked polymeric networks can enhance mechanical properties, driving by an increasing content of alkyl chain segments that results in a higher modulus and hysteresis stress-strain response. The entropic elasticity recovers in isotropic states at higher temperatures.
Article
Chemistry, Multidisciplinary
Guoxian Zhang, Qing Zhang, Zijian Guo, Chunmei Li, Feijie Ge, Qiuyu Zhang
Summary: A convenient and facile strategy using a disulfide-containing diamine solution is developed to achieve patterned secondary crosslinking in an optical shape-memory polymer network, enabling shape reconfiguration, welding, reprogramming, and complex shape transformation. The material allows for the assembly and photothermal control of a gripper for object manipulation.
Article
Polymer Science
Xiaodong Wang, Zhenghong Li
Summary: The study investigates the effect of local vibration and structural rearrangement of macromolecular chains on the shape memory behavior of SMPs using the extended free volume theory. The dependences of glass transition, thermomechanical behavior, and triple-shape recovery behavior of SMPs on thermal history are discussed by introducing the phase transition theory. The accumulation of remote free volume upon heating is identified as the driving force for the shape memory effect in SMPs.
Review
Construction & Building Technology
Iman Abavisani, Omid Rezaifar, Ali Kheyroddin
Summary: Shape memory materials (SMMs) are widely used in civil engineering due to their unique ability to memorize their original shape and return to it under stimuli. These materials, including shape memory alloys, magnetic shape memory alloys, shape memory polymers, and shape memory ceramics, have multifunctional properties and can be applied in various systems.
JOURNAL OF BUILDING ENGINEERING
(2021)
Article
Chemistry, Multidisciplinary
Tomoya Higashihara, Mao-Chun Fu, Kouji Hatakeyama, Shinji Ando, Ryosuke Takahashi, Mitsuru Ueda
Summary: The design, synthesis, and optical characterization of refractive-index-contrast (RIC) triazine-based poly(phenylene sulfide)s (PPSs) were investigated, leading to the successful synthesis of novel PPSs with two different pendant groups. PPS-2CA exhibited high refractive index values and increased delta n values by deprotecting PPS-2E.
Article
Polymer Science
Eisuke Fujiwara, Ryohei Ishige, Daniel Alonso Cerron-Infantes, Michael Josef Taublaender, Miriam M. Unterlass, Shinji Ando
Summary: Increasing the weight density of the lattice enhances lattice deformation in rigid-rod aromatic polyimide, caused by suppression of lattice deformation due to misfit strain induced by mismatch of interchain distances between crystalline and noncrystalline domains.
Article
Chemistry, Multidisciplinary
Saranyoo Sornkamnerd, Shuhei Sasaki, Tetsu Mitsumata, Kenji Takada, Tomohiro Okada, Shinji Ando, Tatsuo Kaneko
Summary: By synthesizing bio-polyimides using renewable materials, transparent films with high heat resistance and good electrical resistance were prepared, suitable for applications in the field of electric insulators.
Article
Materials Science, Textiles
Ayumi Isaka, Takako Ohashi, Fumika Koizumi, Eisuke Fujiwara, Shinji Ando, Akio Kuzuhara
Summary: This study developed a novel spectroscopic method using ATR-FT/IR spectroscopy to quantitatively analyze oil- and protein-based soil components adhering to cotton fibres, without the need for extraction. The method was also used to examine the effect of washing time and mechanical action on detergent performance, providing new insights into detergent evaluation.
JOURNAL OF FIBER SCIENCE AND TECHNOLOGY
(2021)
Article
Materials Science, Multidisciplinary
Naiqiang Liang, Eisuke Fujiwara, Mayuko Nara, Ryohei Ishige, Shinji Ando
Summary: A series of semi-aliphatic polyimide copolymers were synthesized by controlling the molar ratio of PHDA units, resulting in a continuous change in fluorescence color from pink to yellow. By doping a small amount of sulfuric acid into the CoPI films, the absorption and emission from anions were suppressed, leading to the formation of colorless and transparent films with large Stokes-shifted orange fluorescence, which show potential for solar spectral conversion applications.
ACS APPLIED POLYMER MATERIALS
(2021)
Article
Engineering, Environmental
Artjima Ounkaew, Pornnapa Kasemsiri, Uraiwan Pongsa, Salim Hiziroglu, Patimakorn Pasuwan, Yuwasiri Boonlai, Somnuk Theerakulpisut
Summary: The study found that by incorporating substances such as glycerol, citric acid and zinc oxide into poly(vinyl alcohol)/starch films, it can enhance antibacterial activity and improve moisture barrier properties, maintaining the quality of fresh food and extending shelf life.
JOURNAL OF POLYMERS AND THE ENVIRONMENT
(2022)
Article
Polymer Science
Atsuko Tabuchi, Teruaki Hayakawa, Shigeki Kuwata, Ryohei Ishige, Shinji Ando
Summary: By synthesizing N-cyclohexylphthalimide-substituted compounds, bright yellow fluorescence was observed in solution and crystalline states. Through substitution strategies, the resulting PI films displayed bright white fluorescence with a 1.7-fold increase in quantum yield.
Article
Chemistry, Multidisciplinary
Naiqiang Liang, Shigeki Kuwata, Ryohei Ishige, Shinji Ando
Summary: A novel imide compound and polyimides with multiple intramolecular hydrogen bonds were synthesised to investigate the effects of distinct H-bond structures on photoluminescence properties, revealing excited-state intramolecular proton transfer as the main luminescence mechanism. These compounds show promise for solar spectral conversion applications.
MATERIALS CHEMISTRY FRONTIERS
(2021)
Article
Chemistry, Inorganic & Nuclear
Takuya Harada, Shinji Ando, Shigeki Kuwata
Summary: A ruthenium complex with an o-benzoquinone dioximate dianion was isolated, and the redox chemistry of its ligand was elucidated. The complex underwent ligand exchange and oxidation reactions, and the reduced ligand was regenerated through a catalytic reduction process with the aid of a base.
EUROPEAN JOURNAL OF INORGANIC CHEMISTRY
(2022)
Article
Polymer Science
Ririka Sawada, Shinji Ando
Summary: This study prepared seven types of polyimides (PIs) incorporating a chiral isosorbide (ISS) skeleton in the main chain (ISS-PIs), which exhibited excellent optical transparency, low refractive indices, and low dielectric constants compared to wholly aromatic PIs. The bulky alicyclic ISS structure and the bent and flexible PI main chains with reduced intermolecular interactions contributed to the optical properties of ISS-PIs.
Article
Polymer Science
Jian Lu, Yu Zhang, Jing Li, Meifang Fu, Guoxiang Zou, Shinji Ando, Yongbing Zhuang
Summary: The correlations between the molecular structures of Tro''ger's base-based polyimides (PIs) and physical properties including thermal conductivity and dielectric properties were investigated. The introduction of Tro''ger's base units effectively reduced the chain orientation and increased the fractional free volume, resulting in low dielectric constants and thermal conductivity values for the PI films. The incorporation of Tro''ger's base units also improved the molecular weights, toughness, and glass-transition temperature of the PIs.
Review
Polymer Science
Shinji Ando
Summary: Various in situ measurement techniques were used to investigate changes in the three-dimensional structures and physical properties of polyimides (PIs) generated at high pressures. The changes in the PI chain repeating units and interchain distances were observed with WAXD and compared with optical absorption, fluorescent and phosphorescent emission spectra, infrared absorption spectra, and refractive indexes observed under the same conditions.
Article
Chemistry, Physical
Marina Doi, Ryohei Ishige, Shinji Ando
Summary: Long-lived room-temperature delayed phosphorescence, known as prolonged irradiation-induced delayed luminescence (PIDL), was observed in air for three imide compounds (ICs) dispersed in polymethyl methacrylate under UV irradiation. The PIDL emission continued as an afterglow for several seconds after the irradiation ceased. The induction time of PIDL was linearly proportional to the concentration of ground state triplet molecular oxygen (O-3(2)).
Article
Polymer Science
Han Jia, Ning Xu, Yoshiki Nagai, Marina Doi, Toshiki Sawada, Takeshi Serizawa, Shinji Ando, Satoshi Habuchi, Tsuyoshi Michinobu
Summary: Aggregation-induced emission (AIE) polymers have been extensively studied for their potential applications in developing new polymer nanoparticles or polymer dots (Pdots) with excellent fluorescence properties. We synthesized conjugated copolymers based on carbazole (Cz) and tetraphenylethene (TPE), a common AIEgen, and found that the presence of an ethynylene spacer between Cz and TPE units resulted in aggregation-caused quenching (ACQ) properties. The ethynylene spacer played a critical role in determining the fluorescent properties of the copolymers in solid states.
Article
Materials Science, Multidisciplinary
Chih-Cheng Kuo, Yan-Cheng Lin, Yu-Che Chen, Ping-Han Wu, Shinji Ando, Mitsuru Ueda, Wen-Chang Chen
Summary: This study extensively investigated the relationships between the structure and dielectric properties of polyimides, revealing highly correlated relationships between dielectric constant values and structural parameters such as fluorine content and volume polarizability. Additionally, a strong correlation was found between dissipation factor values and the imide group content. However, there were multiple positive trends in the relationship between dissipation factor values and volume dipole moment, attributed to the challenges in elucidating local molecular motions in the unit structure of polyimides.
ACS APPLIED POLYMER MATERIALS
(2021)
