المؤلفون: Hiroyuki FUKUTOMI, 福冨 広幸

المصدر: 非破壊検査 / Journal of The Japanese Society for Non-Destructive Inspection. 2023, 72(12):554

المؤلفون: Sangjun Hong, Na-young Park, Sanghyeon Ju, Ajeong Lee, Youngeun Shin, Jung Soo Kim, Moon-Kwang Um, Jin Woo Yi, Han Gi Chae, Teahoon Park

المصدر: Polymer Testing, Vol 124, Iss , Pp 108086- (2023)

مصطلحات موضوعية: Life estimation, Segmented polyurethane, Glycolysis, Accelerated aging, Depolymerization, Polymers and polymer manufacture, TP1080-1185

الوصف: Polyurethane (PU) has numerous applications in daily life, such as coating, cushions, and insulation materials. It is also used as an encapsulation material for sensors. In the case of PU used as an encapsulant, PU elastomer containing an ether-based polyol is generally used and has a long lifespan in a general environment. However, it is challenging to predict its lifespan when used as an encapsulation material for sonar sensors because PU is exposed to the filling liquid. It is required to accurately predict the encapsulation material's lifespan to ensure the sensor's safety. For the exact estimation of PU lifespan, an accelerated aging experiment was conducted on PU elastomer in a filling solution at various temperatures. Fourier transform infrared spectroscopy was used to track the chemical changes in the PU elastomer, and it was observed that both urethane and urea bonds were degraded. Modulated differential scanning calorimetry and thermogravimetric analysis were also used to study changes in the structure of PU elastomer by heat aging. The tensile strength, elongation, and hardness of the heat-aged elastomer at various temperatures were obtained, and the Arrhenius plots were constructed. Finally, the lifespan was considered when the tensile strength was 70% of the initial state by using the ASTM D2000 standard. Thus, the lifespan of PU at 25 °C was calculated to be 12.2 years.

وصف الملف: electronic resource

العلاقة: http://www.sciencedirect.com/science/article/pii/S0142941823001666Test; https://doaj.org/toc/0142-9418Test

الوصول الحر: https://doaj.org/article/82a35ffbb11d4f36b3049e84866ca58dTest

المؤلفون: Hamid Reza Heydarnezhad (10230155), Naser Mohammadi (4255666), Angel Alegria (2891732)

مصطلحات موضوعية: Biophysics, Biochemistry, Medicine, Biotechnology, Ecology, Space Science, Biological Sciences not elsewhere classified, Chemical Sciences not elsewhere classified, nanoparticle-induced viscosity redu., C 60 nanofiller, C 60 content, microphase-mixed PUs, NPU, viscosity reduction, matrix, terminal rheological properties, wt, block copolymer-based nanocomposites, C 60 nanoparticles, length, Segmented Polyurethane Nanocomposites, HS, shear rheological behavior, SS, eff, η 0 values

الوصف: To provide a fundamental understanding regarding the potential of nanoparticle-induced viscosity reduction in segmented block copolymer-based nanocomposites, the shear rheological behavior of segmented polyurethane/C 60 nanocomposites (NPUs) was studied up to 2 wt % C 60 , and the results were complemented by several dynamic and structural probes. The same microstructural features and dynamical relaxations were revealed for each matrix (PU) and its corresponding NPUs in the absence of deformation, representing the lack of difference in their dynamical behaviors at all studied C 60 content. Under shear, however, interesting changes in the terminal rheological properties of PUs were observed in the presence of a C 60 nanofiller. An anomalous terminal shear viscosity (η 0 ) reduction was found for microphase-mixed PUs at a low C 60 content of up to 0.5 wt %. However, the microphase-mixed NPUs containing a higher C 60 content as well as the microphase-separated NPUs showed a higher η 0 than their matrices. Slippage at the polymer/C 60 interfaces was suggested as a possible mechanism behind the viscosity reduction, which appeared controllable by the degree of microphase separation, the ratio of slip length to the nanoparticle size, and the stiffness of segments. Accordingly, an effective slip length, b eff , was considered as the key factor in controlling the observed noncontinuum effects regarding the nanoparticle-induced viscosity reduction in the microphase-mixed PUs. When most C 60 nanoparticles of radius r are positioned on the hard segments (HSs) of microphase-mixed PUs, b eff / r > 1 can lead to viscosity reduction, while the localization of C 60 in the vicinity of soft segments (SSs) increased the matrix’s η 0 . A semiuniversal curve was also found to roughly estimate the η 0 values of various NPUs.

العلاقة: https://figshare.com/articles/journal_contribution/Non-Einstein_Rheology_in_Segmented_Polyurethane_Nanocomposites/14160614Test

الإتاحة: https://doi.org/10.1021/acs.macromol.0c02503.s001Test

المؤلفون: Zhe Shi, Cong Zhang, Xin-Gang Chen, Ang Li, Yang-Fei Zhang

المصدر: Nanomaterials; Volume 11; Issue 5; Pages: 1289

مصطلحات موضوعية: carbon fiber fabric, graphene, segmented polyurethane, composites, thermal properties, mechanical properties, electrical properties, thermal interface material

الوصف: Thermal conductive materials with reliable and high performances such as thermal interface materials are crucial for rapid heat transferring in thermal management. In this work, carbon fiber fabric and graphene reinforced segmented polyurethane composites (CFF-G/SPU) were proposed and prepared to obtain superior thermal, mechanical and electrical properties using the hot-pressing method. The composites exhibit excellent tensile strength and can withstand a tensile force of at least 350 N without breaking. The results show that, comparing with the SPU material, the thermal conductivity is increased by 28% for the CFF-G/SPU composite, while the in-plane electrical conductivity is increased by 8 orders of magnitude to 175 S·m−1. The application of CFF-G/SPU composite as a winding thermal interface material with electric-driven self-heating effect presents good performances of fluidity and interface wettability. The composite has great advantages in phase transition and filling the interfacial gap in the short time of few seconds under the condition of electrical field, with the interface temperature difference between two layers significantly reduced.

وصف الملف: application/pdf

العلاقة: Nanocomposite Materials; https://dx.doi.org/10.3390/nano11051289Test

الإتاحة: https://doi.org/10.3390/nano11051289Test

المؤلفون: Kejiao Li, Yuhong Qi, Yingju Zhou, Xiaoyu Sun, Zhanping Zhang

المصدر: Polymers; Volume 13; Issue 4; Pages: 573

مصطلحات موضوعية: poly(ethylene glycol)-segmented polyurethane coating, seawater immersion, microstructure, properties

الوصف: Polyurethane has a microphase separation structure, while polyethylene glycol (PEG) can form a hydrated layer to resist protein adsorption. In this paper, PEG was introduced to polyurethane to improve the antifouling properties of the polyurethane, providing a new method and idea for the preparation of new antifouling polyurethane materials. The mechanical properties, hydrophilicity, swelling degree, microphase separation and antifouling performance of the coatings were evaluated. The response characteristics of the polyurethane coatings in a seawater environment were studied, and the performance changes of coatings in seawater were tested. The results showed that the crystallized PEG soft segments increased, promoting microphase separation. The stress at 100% and the elasticity modulus of the polyurethane material also markedly increased, in addition to increases in the swelling degree in seawater, the water contact angle decreased. A total of 25% of PEG incorporated into a soft segment can markedly improve the antibacterial properties of the coatings, but adding more PEG has little significant effect. After immersion in seawater, the coatings became softer and more elastic. This is because water molecules formed hydrogen bonding with the amino NH, which resulted in a weakening effect being exerted on the carbonyl C=O hydrogen bonding and ether oxygen group crystallization.

وصف الملف: application/pdf

العلاقة: Polymer Applications; https://dx.doi.org/10.3390/polym13040573Test

الإتاحة: https://doi.org/10.3390/polym13040573Test

المؤلفون: Cong Zhang, Zhe Shi, An Li, Yang-Fei Zhang

المصدر: Polymers; Volume 12; Issue 12; Pages: 3004

مصطلحات موضوعية: reduced graphene oxide, segmented polyurethane, composites, solid–solid phase change, thermal interface material, thermal conductivity, interfacial wettability

الوصف: Thermal interface material (TIM) is crucial for heat transfer from a heat source to a heat sink. A high-performance thermal interface material with solid–solid phase change properties was prepared to improve both thermal conductivity and interfacial wettability by using reduced graphene oxide (rGO)-coated polyurethane (PU) foam as a filler, and segmented polyurethane (SPU) as a matrix. The rGO-coated foam (rGOF) was fabricated by a self-assembling method and the SPU was synthesized by an in situ polymerization method. The pure SPU and rGOF/SPU composite exhibited obvious solid–solid phase change properties with proper phase change temperature, high latent heat, good wettability, and no leakage. It was found that the SPU had better heat transfer performance than the PU without phase change properties in a practical application as a TIM, while the thermal conductivity of the rGOF/SPU composite was 63% higher than that of the pure SPU at an ultra-low rGO content of 0.8 wt.%, showing great potential for thermal management.

وصف الملف: application/pdf

العلاقة: Polymer Composites and Nanocomposites; https://dx.doi.org/10.3390/polym12123004Test

الإتاحة: https://doi.org/10.3390/polym12123004Test

المؤلفون: Francolini I, Silvestro I, Di Lisio V, Martinelli A, Piozzi A

المساهمون: Francolini, I, Silvestro, I, Di Lisio, V, Martinelli, A, Piozzi, A

مصطلحات موضوعية: segmented polyurethane, polyethylene glycol, microbial biofilm, antifouling material, medical device-related infection, wound dressings

الوصف: Despite advances in material sciences and clinical procedures for surgical hygiene, medical device implantation still exposes patients to the risk of developing local or systemic infections. The development of efficacious antimicrobial/antifouling materials may help with addressing such an issue. In this framework, polyethylene glycol (PEG)-grafted segmented polyurethanes were synthesized, physico-chemically characterized, and evaluated with respect to their bacterial fouling-resistance properties. PEG grafting significantly altered the polymer bulk and surface properties. Specifically, the PEG-grafted polyurethanes possessed a more pronounced hard/soft phase segregated microstructure, which contributed to improving the mechanical resistance of the polymers. The better flexibility of the soft phase in the PEG-functionalized polyurethanes compared to the pristine polyurethane (PU) was presumably also responsible for the higher ability of the polymer to uptake water. Additionally, dynamic contact angle measurements evidenced phenomena of surface reorganization of the PEG-functionalized polyurethanes, presumably involving the exposition of the polar PEG chains towards water. As a consequence, Staphylococcus epidermidis initial adhesion onto the surface of the PEG-functionalized PU was essentially inhibited. That was not true for the pristine PU. Biofilm formation was also strongly reduced

العلاقة: info:eu-repo/semantics/altIdentifier/pmid/30823606; info:eu-repo/semantics/altIdentifier/wos/WOS:000460805400209; volume:20; numberofpages:16; journal:INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES; http://hdl.handle.net/11573/1280176Test; info:eu-repo/semantics/altIdentifier/scopus/2-s2.0-85064176772

الإتاحة: https://doi.org/10.3390/ijms20041001Test
http://hdl.handle.net/11573/1280176Test

المؤلفون: Umaprasana Ojha, Saurabh Kr Tiwary, Suman Debnath

المصدر: ACS Applied Polymer Materials. 3:2166-2177

مصطلحات موضوعية: chemistry.chemical_classification, Materials science, Polymers and Plastics, Process Chemistry and Technology, Organic Chemistry, Polymer, Linkage (mechanical), Shape-memory alloy, law.invention, chemistry.chemical_compound, chemistry, Vitrimers, Creep, law, Carboxylate, Composite material, Segmented polyurethane, Polyurethane

الوصف: Though conventional polyurethane foams are among the most widely used polymer materials currently, the lack of reprocessability and creep resistance ability restricts their further commercial growt...

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_________::5ef73674cd1f90ba450d709673c9b745Test
https://doi.org/10.1021/acsapm.1c00199Test

المؤلفون: Koichiro Mikami, Hiroshi Ito, Hajime Sugita, Hideyuki Otsuka, Kota Seshimo, Daisuke Aoki, Takuma Watabe, Yuchen Mao, Takashi Kurose, Shotaro Nishitsuji, Hio Sakai, Akira Ishigami

المصدر: Angewandte Chemie. 133:8487-8490

مصطلحات موضوعية: Damage detection, Materials science, 010405 organic chemistry, Radical, Radical polymerization, Diphenylmethane, General Chemistry, General Medicine, 010402 general chemistry, Elastomer, 01 natural sciences, Catalysis, 0104 chemical sciences, law.invention, chemistry.chemical_compound, Chemical engineering, chemistry, law, Side chain, mechanochemistry, molecular probe, radicals, polymers, polymer reactions, Electron paramagnetic resonance, Segmented polyurethane

الوصف: Mechanochromic elastomers that exhibit force-induced cross-linking reactions in the bulk state are introduced. The synthesis of segmented polyurethanes (SPUs) that contain difluorenylsuccinonitrile (DFSN) moieties in the main chain and methacryloyl groups in the side chains was carried out. DFSN was selected as the mechanophore because it dissociates under mechanical stimuli to form pink cyanofluorene (CF) radicals, which can also initiate the radical polymerization of methacrylate monomers. The obtained elastomers generated CF radicals and changed color by compression or extension; they also became insoluble due to the mechanically induced cross-linking reactions. Additionally, an SPU containing diphenylmethane units also exhibited highly sensitive mechanofluorescence. To the best of our knowledge, this is the first report to demonstrate damage detection ability and changes in the mechanical properties of bulk elastomers induced by simple compression or extension.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::19299be21ef8d05078f5b96f76d2837eTest
https://doi.org/10.1002/ange.202015196Test

المؤلفون: Chen Tan, Teija Tirri, Carl-Eric Wilen

المصدر: Polymers; Volume 9; Issue 5; Pages: 184

مصطلحات موضوعية: adhesive, isocyanate-terminated urethane prepolymers, segmented polyurethane, soft and hard segments

الوصف: In this work, a number of chain extended moisture-curable urethane prepolymers were synthesized in order to develop isocyanate terminated urethane prepolymer formulations that would simultaneously display both high adhesive strength and low viscosity. Proton nuclear magnetic resonance spectroscopy (1H-NMR), size exclusion chromatography (SEC), differential scanning calorimetry (DSC), and Brookfield viscometry were utilized for characterizing the prepared urethane prepolymers. In addition, the adhesion strength of the cured prepolymers was determined by tensile shear strength test according to the DIN EN (Deutsches Institut für Normung, the German Institute for Standardization) 1465 standard. Especially, the role of different types of linear (butanediol, pentanediol) and branched chain extenders (dipropyleneglycol (di-PPG), tripropyleneglycol (tri-PPG) and the influence of their dosage on the degree of microphase separation between hard segments (HS) and soft segments (SS) in urethane prepolymers were studied. Furthermore, the benefits of utilizing either a one-step versus a two-step polymerization process were investigated. The results revealed that the extent of phase separation of different urethane prepolymers was dependent on the extent of hydrogen bonding interactions which was extensively studied by attenuated total reflectance infrared spectroscopy (ATR-FTIR). The incorporation of branched chain extenders (di-PPG and tri-PPG) did not result in notable phase separation between hard segments and soft segments, while linear chain extenders (pentanediol and butanediol) readily promoted phase separation. The degree of phase separation was particularly pronounced for butanediol, and when the linear chain extender ratio was higher than or equal to 0.74. Compared with a two-stage process, one-stage process produced more randomly distributed polymer chains with highly dispersed hard segments. Thus, urethane prepolymers exhibiting strong adhesive strength with simultaneously low viscosity were successfully ...

وصف الملف: application/pdf

العلاقة: Polymer Chemistry; https://dx.doi.org/10.3390/polym9050184Test

الإتاحة: https://doi.org/10.3390/polym9050184Test