Structure, thermal stability, electrochemical behaviors, and mechanical properties of organosoluble polyimide with pyrimidine ring in the main chain

2016 ◽  
Vol 133 (28) ◽  
Author(s):  
Baoming Li ◽  
Zhiyin Wu ◽  
Li Lin
Keyword(s):  
Mechanical Properties ◽  
Thermal Stability ◽  
Main Chain ◽  
Pyrimidine Ring ◽  
Electrochemical Behaviors

A Study of the Nitrogen-Containing Heterocycles on Copolyimide Properties for Proton Exchange Membranes

2013 ◽  
Vol 401-403 ◽  
pp. 563-566 ◽  
Author(s):  
Yu Han Li ◽  
Wei Jian Wang ◽  
Yu Fei Chen ◽  
Lei Wang
Keyword(s):  
Mechanical Properties ◽  
Thermal Stability ◽  
Proton Conductivity ◽  
Water Uptake ◽  
Main Chain ◽  
Proton Exchange Membranes ◽  
Proton Exchange ◽  
Membrane Properties ◽  
Dimensional Changes ◽  
Sulfonated Polyimide

Containing pyrimidine and pyridine monomers were incorporated respectively into the main chain of a sulfonated polyimide in order to investigate the effect of nitrogen-containing heterocycles on membrane properties such as water uptake and proton conductivity. With increasing content of the nitrogen-containing heterocycles, water uptake of membranes and dimensional changes remarkable decrease. The copolymer showed higher thermal stability (desulfonation temperature up to 330 °C) and reasonable good mechanical properties. These membranes also showed higher proton conductivity, which was comparable or even higher than Nafion 117.

Synthesis and Properties of a Novel Polymeric Phosphate Flame Retardant

2013 ◽  
Vol 750-752 ◽  
pp. 785-788
Author(s):  
Li Yan
Keyword(s):  
Mechanical Properties ◽  
Thermal Stability ◽  
Flame Retardant ◽  
Sulfur Content ◽  
Main Chain ◽  
Decomposition Temperature ◽  
Pendant Group ◽  
Bisphenol S ◽  
Considerable Decrease ◽  
Polymer Systems

A novel polymeric phosphate flame retardant (PFR-P) was synthesized from 1-oxo-4-hydroxymethyl-2,6,7-trioxa-1-phosphbicyclo [2.2.octane (pentaerythritol phosphate, PEPA), POCl3and bisphenol S. Phosphorus was bonded both in the main chain and in the pendant group of flame-retardant polymer molecule, reached a content of 13.1%. And sulfur content was 6.75%. The thermal stability was investigated by TGA, and the results showed that the initiative decomposition temperature was 334°C with 41.1% charring residue at 500°C under air. The high phosphorus and sulfur content contributes an excellent flame retardancy to PC/ABS without a considerable decrease of mechanical properties. It is a potential flame retardant for other polymer systems.

scholarly journals Enhanced electrical conductivity and mechanical properties in thermally stable fine-grained copper wire

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Qingzhong Mao ◽  
Yusheng Zhang ◽  
Yazhou Guo ◽  
Yonghao Zhao
Keyword(s):  
Mechanical Properties ◽  
Thermal Stability ◽  
Electrical Conductivity ◽  
Yield Strength ◽  
High Speed ◽  
Copper Wire ◽  
Rapid Development ◽  
Dislocation Slip ◽  
Ultrafine Grains ◽  
The Wire

AbstractThe rapid development of high-speed rail requires copper contact wire that simultaneously possesses excellent electrical conductivity, thermal stability and mechanical properties. Unfortunately, these are generally mutually exclusive properties. Here, we demonstrate directional optimization of microstructure and overcome the strength-conductivity tradeoff in copper wire. We use rotary swaging to prepare copper wire with a fiber texture and long ultrafine grains aligned along the wire axis. The wire exhibits a high electrical conductivity of 97% of the international annealed copper standard (IACS), a yield strength of over 450 MPa, high impact and wear resistances, and thermal stability of up to 573 K for 1 h. Subsequent annealing enhances the conductivity to 103 % of IACS while maintaining a yield strength above 380 MPa. The long grains provide a channel for free electrons, while the low-angle grain boundaries between ultrafine grains block dislocation slip and crack propagation, and lower the ability for boundary migration.

scholarly journals Improved thermally stable oligoetherols from 6-aminouracil, ethylene carbonate and boric acid

2019 ◽  
Vol 17 (1) ◽  
pp. 1080-1086
Author(s):  
Elżbieta Chmiel-Szukiewicz
Keyword(s):  
Thermal Stability ◽  
Thermal Properties ◽  
Boric Acid ◽  
Ethylene Carbonate ◽  
Pyrimidine Ring ◽  
Polyurethane Foams ◽  
High Thermal Stability ◽  
H Nmr ◽  
Maldi Tof ◽  
Instrumental Methods

AbstractSyntheses of oligoetherols with a 1,3-pyrimidine ring and boron atoms using 6-aminouracil, ethylene carbonate and boric acid has been proposed. The structure of the obtained products were determined by instrumental methods (IR, 1H-NMR and MALDI-ToF spectra). The physicochemical and thermal properties of oligoetherols were examined. The products were characterized by high thermal stability. Based on the tests performed, it was found that oligoetherols obtained from 6-aminouracil, boric acid and ethylene carbonate are suitable for the manufacturing of polyurethane foams with improved thermal stability and reduced flammability.

scholarly journals Internal constraints and arrested relaxation in main-chain nematic elastomers

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Takuya Ohzono ◽  
Kaoru Katoh ◽  
Hiroyuki Minamikawa ◽  
Mohand O. Saed ◽  
Eugene M. Terentjev
Keyword(s):  
Mechanical Properties ◽  
Main Chain ◽  
Polymer Networks ◽  
Nematic Order ◽  
Nematic Elastomers ◽  
Nematic Director ◽  
Highly Nonlinear ◽  
Nonlinear Mechanical ◽  
Liquid Crystal Elastomers ◽  
Memory Applications

AbstractNematic liquid crystal elastomers (N-LCE) exhibit intriguing mechanical properties, such as reversible actuation and soft elasticity, which manifests as a wide plateau of low nearly-constant stress upon stretching. N-LCE also have a characteristically slow stress relaxation, which sometimes prevents their shape recovery. To understand how the inherent nematic order retards and arrests the equilibration, here we examine hysteretic stress-strain characteristics in a series of specifically designed main-chain N-LCE, investigating both macroscopic mechanical properties and the microscopic nematic director distribution under applied strains. The hysteretic features are attributed to the dynamics of thermodynamically unfavoured hairpins, the sharp folds on anisotropic polymer strands, the creation and transition of which are restricted by the nematic order. These findings provide a new avenue for tuning the hysteretic nature of N-LCE at both macro- and microscopic levels via different designs of polymer networks, toward materials with highly nonlinear mechanical properties and shape-memory applications.

scholarly journals High modulus polyimide particle-reinforcement of epoxy composites

2021 ◽  
Author(s):  
Johannes Essmeister ◽  
M. Josef Taublaender ◽  
Thomas Koch ◽  
D. Alonso Cerrón-Infantes ◽  
Miriam M. Unterlass ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Thermal Stability ◽  
Composite Materials ◽  
Epoxy Matrix ◽  
Epoxy Composites ◽  
High Modulus ◽  
Particle Reinforcement

A novel class of fully organic composite materials with well-balanced mechanical properties and improved thermal stability was developed by incorporating highly crystalline, hydrothermally synthesized polyimide microparticles into an epoxy matrix.

scholarly journals Enhanced mechanical properties, water resistance, thermal stability, and biodegradation of the starch-sisal fibre composites with various fillers

2021 ◽  
Vol 198 ◽  
pp. 109373
Author(s):  
Maocheng Ji ◽  
Fangyi Li ◽  
Jianyong Li ◽  
Jianfeng Li ◽  
Chuanwei Zhang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Thermal Stability ◽  
Water Resistance ◽  
Sisal Fibre ◽  
Fibre Composites
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