Thermal Oxidative Degradation Behavior of Fluorinated Thermotropic Liquid Crystal Copolyesters

2015 ◽  
Vol 1088 ◽  
pp. 343-347
Author(s):  
Peng Wei ◽  
Shuo Han Huang ◽  
Yan Ping Wang ◽  
Yi Min Wang
Keyword(s):  
Liquid Crystal ◽  
Oxidative Degradation ◽  
Thermal Oxidative Degradation ◽  
Degradation Behavior ◽  
Molar Percentage ◽  
Good Thermal Stability ◽  
Thermotropic Liquid Crystal ◽  
Air Atmosphere ◽  
Degradation Activation Energy ◽  
Bisphenol Af

In this study, the thermal oxidative degradation behavior of thermotropic liquid crystal copolyesters P-BPAFx containing 2.5-10 mol% bisphenol AF unit were evaluated by thermogravimetric analysis (TGA) technique under air atmosphere and the degradation activation energy (E) was obtained from Kissinger and Kissinger-Akahira-Sunose (KAS) method. The degradation behavior of copolyester are strongly dependent on the molar percentage of BPAF unit. Results showed that the E values obtained by the two methods increase first and then decrease slightly with increasing the BPAF unit and follow the order P-BPAF5.0< P-BPAF10<P-BPAF2.5, indicating P-BPAF2.5 has good thermal stability. The reason for this phenomenon was discussed in detail in the text.

Effect of alkylated diphenylamine on thermal-oxidative degradation behavior of poly-α-olefin

2015 ◽  
Vol 69 (7) ◽  
Author(s):  
Mian-Ran Chao ◽  
Wei-Min Li ◽  
Li-Li Zhu ◽  
Hai-Hong Ma ◽  
Xiao-Bo Wang
Keyword(s):  
Activation Energy ◽  
Oxidative Stability ◽  
Oxidative Degradation ◽  
Thermal Oxidative Degradation ◽  
Degradation Behavior ◽  
Thermal Oxidative Stability ◽  
Zinc Dialkyl Dithiophosphate ◽  
Dialkyl Dithiophosphate

AbstractAn oil-soluble antioxidant, alkylated diphenylamine (ADPA), was prepared by alkylation of diphenylamine. The influence of ADPA on the thermal-oxidative stability of poly-α-olefin (PAO8) was evaluated by thermogravimetry (TG). For comparison, the thermal-oxidative stability of PAO8 with zinc dialkyl dithiophosphate (ZDDP) was also investigated. Activation energy (E

Nonisothermal and Isothermal Degradation Kinetics of Thermotropic Liquid Crystal Copolyesters Containing BPA and BPAF Units

2016 ◽  
Vol 848 ◽  
pp. 179-183
Author(s):  
Peng Wei ◽  
Shuo Han Huang ◽  
Yi Min Wang
Keyword(s):  
Liquid Crystal ◽  
Degradation Kinetics ◽  
Degradation Mechanism ◽  
Nitrogen Atmosphere ◽  
High Glass Transition Temperature ◽  
Isothermal Heating ◽  
Thermotropic Liquid Crystal ◽  
Kinetics Of ◽  
Bisphenol Af ◽  
Dynamic Heating

The thermotropic liquid crystal copolyester P-BPA2.5 and P-BPAF2.5 with low melting temperature and high glass transition temperature were obtained by introducing 2.5mol% bisphenol A (BPA), bisphenol AF (BPAF) and terephthalic acid (TA) receptively into the molecular chain of poly (oxybenzoate-co-oxynaphthoate). The isothermal and nonisothermal degradation behavior of the two copolyesters P-BPA2.5 and P-BPAF2.5 were studied by thermo-gravimetry analysis (TGA) under nitrogen atmosphere. The degradation kinetics of the copolyesters under dynamic and isothermal heating conditions was evaluated byKissinger-Akahira-Sunose (KAS) and iso-conversional methodrespectively. Results showed that the activation energy (E) values followed the order P-BPAF2.5>P-BPA2.5 under dynamic heating atmosphere. However, the P-BPA2.5 showed a better thermal stability as compared with P-BPAF2.5 under isothermal heating conditions. The differences of degradation mechanism between the two copolyesters may be a reason for this phenomenon, which was discussed in detail in the text.

The influence of bisphenol AF unit on thermal behavior of thermotropic liquid crystal copolyesters

2014 ◽  
Vol 586 ◽  
pp. 45-51 ◽  
Author(s):  
Peng Wei ◽  
Miko Cakmak ◽  
Yuwei Chen ◽  
Xinhang Wang ◽  
Yanping Wang ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Thermal Behavior ◽  
Thermotropic Liquid Crystal ◽  
Bisphenol Af

scholarly journals THE INVESTIGATION ON THERMAL OXIDATIVE DESTRUCTION AND ASSESSMENT OF RUBBER SERVICE PERIOD BASED ON TRIPLE COPOLYMER OF TETRAFLUOROETHYLENE, VINYLIDENE FLUORIDE AND HEXAFLUOROPROPYLENE

2020 ◽  
pp. 113-117
Author(s):  
I. M. Baev ◽  
T. V. Sclyarova ◽  
S. V. Borisov ◽  
I. M. Gres ◽  
M. A. Vaniev
Keyword(s):  
Vinylidene Fluoride ◽  
Arrhenius Equation ◽  
Oxidative Degradation ◽  
High Heat ◽  
Thermal Oxidative Degradation ◽  
Oxidative Destruction ◽  
High Heat Resistance ◽  
Air Atmosphere ◽  
Service Period ◽  
Thermal Oxidative Destruction

By thermogravimetric analysis it was studied the thermal oxidative degradation of rubber based on a triple copolymer of tetrafluoroethylene, vinylidene fluoride, and hexafluoropropylene. It was found that the object is characterized by a sufficiently high heat resistance, which is proven by the rather high temperature of loss of 5% of the initial mass of the sample (412 ° C). The service life of the tested unloaded material in air atmosphere, according to the Arrhenius equation, is 2084, 450 and 107 days at the temperature of 185, 200 and 215 ° C respectively.

Reversible microscale assembly of nanoparticles driven by the phase transition of a thermotropic liquid crystal

2017 ◽  
Author(s):  
Niamh Mac Fhionnlaoich ◽  
Stephen Schrettl ◽  
Nicholas B. Tito ◽  
Ye Yang ◽  
Malavika Nair ◽  
...  
Keyword(s):  
Phase Transition ◽  
Liquid Crystal ◽  
Self Assembly ◽  
Nematic Phase ◽  
Hierarchical Control ◽  
Building Blocks ◽  
Model System ◽  
Microscopic Level ◽  
Reversible Process ◽  
Thermotropic Liquid Crystal

The arrangement of nanoscale building blocks into patterns with microscale periodicity is challenging to achieve via self-assembly processes. Here, we report on the phase transition-driven collective assembly of gold nanoparticles in a thermotropic liquid crystal. A temperature-induced transition from the isotropic to the nematic phase leads to the assembly of individual nanometre-sized particles into arrays of micrometre-sized aggregates, whose size and characteristic spacing can be tuned by varying the cooling rate. This fully reversible process offers hierarchical control over structural order on the molecular, nanoscopic, and microscopic level and is an interesting model system for the programmable patterning of nanocomposites with access to micrometre-sized periodicities.

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