Comparative Study of Polyimides Containing Oxadiazole and Ether Groups

2009 ◽  
Vol 21 (5) ◽  
pp. 522-534 ◽  
Author(s):  
Maria Bruma ◽  
Mariana Dana Damaceanu ◽  
Peter Muller
Keyword(s):  
Mechanical Properties ◽  
Thermal Stability ◽  
High Temperature ◽  
Comparative Study ◽  
Aromatic Diamine ◽  
Polycondensation Reaction ◽  
Free Standing ◽  
Aromatic Polyimides ◽  
Film Forming ◽  
As Solubility

An aromatic diamine with a preformed oxadiazole ring and various dianhydrides with ether and other flexible or bulky groups, such as isopropylidene, hexafluoroisopropylidene, cyclohexylidene or fluorenylidene, were used in a polycondensation reaction at high temperature to produce poly(oxadiazole-ether-imide)s. The properties of these polymers such as solubility, film-forming ability, thermal stability and photoluminescence were studied and compared with those of related conventional aromatic polyimides. The mechanical properties of the free-standing films obtained from these polyimides were also investigated.

Microstructure, mechanical properties, and thermal stability of γ-Nb5Si3 under high temperature and high pressure

2021 ◽  
Vol 130 (13) ◽  
pp. 135104
Author(s):  
Juwei Wang ◽  
Haihua Chen ◽  
Zhengang Zhang ◽  
Bin Wang ◽  
Hongtao Ma ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Thermal Stability ◽  
High Pressure ◽  
High Temperature ◽  
Thermal Stability Of

scholarly journals Enhanced High-Temperature Mechanical Properties of Al–Cu–Li Alloy through T1 Coarsening Inhibition and Ce-Containing Intermetallic Refinement

Materials ◽  
2019 ◽  
Vol 12 (9) ◽  
pp. 1521 ◽  
Author(s):  
Xinxiang Yu ◽  
Zhiguo Zhao ◽  
Dandan Shi ◽  
Han Dai ◽  
Jie Sun ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Thermal Stability ◽  
High Temperature ◽  
Tensile Elongation ◽  
Intermetallic Phase ◽  
Phase Interface ◽  
Thermal Exposure ◽  
Main Element ◽  
Temperature Deformation ◽  
High Temperature Mechanical Properties

The effects of the addition of 0.29 wt% Ce on the high-temperature mechanical properties of an Al–Cu–Li alloy were investigated. Ce addition contributes to T1 (Al2CuLi) phase coarsening inhibition and Ce-containing intermetallic refinement which greatly improved the thermal stability and high-temperature deformation uniformity of this alloy. On the one hand, small Ce in solid solution and segregation at phase interface can effectively prevent the diffusion and convergence of the main element Cu on T1 phase during thermal exposure. Therefore, the thermal stability of Ce-containing alloy substantiality improves during thermal exposure at the medium-high-temperature stage (170 °C to 270 °C). On the other hand, the increment of the tensile elongation in Ce-containing alloy is much greater than that in Ce-free alloy at high temperatures tensile test, because the refined Al8Cu4Ce intermetallic phase with high-temperature stability are mainly located in the fracture area with plastic fracture characteristics. This work provides a new method for enhancing high-temperature mechanical properties of Al–Cu–Li alloy which could be used as a construction material for high-temperature structural components.

Synthesis and properties of polyimides derived from bis(4-aminophenyl)isohexides

2016 ◽  
Vol 29 (2) ◽  
pp. 197-204 ◽  
Author(s):  
Xiaodong Ji ◽  
Jingling Yan ◽  
Xiuju Liu ◽  
Zikun Wang ◽  
Zhen Wang
Keyword(s):  
Mechanical Properties ◽  
Thermal Stability ◽  
Glass Transition ◽  
Physical And Mechanical Properties ◽  
Amic Acid ◽  
Systematic Investigation ◽  
Structure Property ◽  
Free Standing ◽  
Structure Property Relationship ◽  
Relationship Of

Several partially bio-based polyimides have been successfully synthesized by polycondensation between bis(4-aminophenyl)isohexides with various commercial dianhydrides. Flexible and free-standing films were readily obtained from their poly(amic acid) or polyimide solutions. A systematic investigation of the structure–property relationship of polyimides highlights the significant impact of the isohexides moieties on their physical and mechanical properties (glass transition temperature, inherent viscosity, thermal stability, solubility, and mechanical properties). The results revealed that these polyimides exhibited comparable thermal stability and mechanical properties to those of petrochemical-based ones.

Nafion – Azole Composite Membranes for High Temperature PEMFC

2014 ◽  
Vol 783-786 ◽  
pp. 1692-1697
Author(s):  
Je Deok Kim ◽  
Mun Suk Jun
Keyword(s):  
Mechanical Properties ◽  
Thermal Stability ◽  
High Temperature ◽  
Proton Conductivity ◽  
Composite Membrane ◽  
Room Temperature ◽  
Composite Membranes ◽  
Thermal And Mechanical Properties ◽  
High Proton Conductivity ◽  
High Proton

Nafion-azole (benzimidazole, 1,2,4-triazole, 1,2,3-triazole) composite membranes were prepared by room temperature and autoclave solution processing for high temperature (above 100 °C) PEMFC. Among the various Nafion – azole composite membranes, Nafion – 1,2,3-triazole membrane showed excellent flexibility, thermal stability, and homogeneous structure. Nafion – 1,2,4-triazole composite membrane had high thermal and mechanical properties, and also showed high proton conductivity of 0.02 S/cm at the temperature of 160 °C under dry (N2) condition.

scholarly journals Optically Active Polyurethane/Silica Aerogel Coated Cotton Fabrics for Thermal Protection

2021 ◽  
Vol 8 ◽  
Author(s):  
Ling Lin ◽  
Ziyin Li ◽  
Haiyan Mao ◽  
Wenyao Li ◽  
Chaoxia Wang
Keyword(s):  
Mechanical Properties ◽  
Thermal Stability ◽  
Thermal Protection ◽  
Cotton Fabrics ◽  
Retention Performance ◽  
Thermal Insulating ◽  
Film Forming ◽  
Warmth Retention ◽  
Coated Fabrics ◽  
Coated Cotton

Application of SiO2 aerogel in thermal protective clothing has been limited due to its brittle nature, ordinary mechanical properties, and poor film forming performance. This work is aimed to develop thermal protective cotton fabrics by coating blended OPU/SiO2 aerogel with enhanced mechanical properties and thermal protection performance. The OPU/SiO2 aerogel composites with different ratio were applied onto cotton fabrics by knife-coating. The morphology, chemical component, crystalline structure, thermal stability and compression strength were characterized by scanning electron microscopy (SEM), Fourier transfer Infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TG) and compression test, respectively. Besides, the warmth retention performance and heat protection performance together with air and moisture permeability of the coated fabrics were studied. The results showed that OPU/SiO2 aerogel were successfully coated onto cotton fabrics with enhanced mechanical properties and thermal stability together with better film forming capacity. The heat transfer coefficient of the coated cotton fabrics was distinctly dropped due to the synergistic effect of OPU and SiO2 aerogel, which resulted in higher warmth retention. The OPU/SiO2 aerogel coated fabrics exhibited obvious heat insulation performance with its surface temperate almost 4°C than the uncoated fabrics. This work demonstrates a new strategy of fabricating stronger thermal insulating textiles using OPU/SiO2 aerogel composites.

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