Obtaining the glass transition temperature by measuring the crack healing process of glassformers

2008 ◽  
Vol 92 (13) ◽  
pp. 131906 ◽  
Author(s):  
J. L. Zhang ◽  
W. H. Wu ◽  
H. W. Zhou ◽  
X. Z. Guo ◽  
Y. N. Huang
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Healing Process ◽  
Crack Healing

Effects of Programming Temperature on the Efficiency of Self-Healing Polymers

2012 ◽  
Author(s):  
Yves Quentin Yougoubare ◽  
Ifeanyi Janarus Okoro ◽  
Su-Seng Pang
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Shape Recovery ◽  
Strength Properties ◽  
Self Healing ◽  
Test Results ◽  
Crack Healing ◽  
Micro Cracks ◽  
Intrinsic Correlation

Self-healing shape memory polymers possess the ability to heal macro and micro cracks by autonomic processes or when subjected to a suitable external stimulus. Recent advancements in the field have shown that the healing capabilities of self-healing polymers can be improved, thus yielding to high healing efficiencies. Depending on the application, the efficiency may refer to shape fixity, shape recovery ratio, dimensions recovery, strength regain, crack healing, etc. Based on test results, it is established that there is an intrinsic correlation between pre-strain levels, shape fixing and free shape recovery of samples programmed above the glass transition temperature (Tg). For samples programmed at multiple temperatures (above and below the glass transition temperature), the absence of lateral and 3D confinements lead to poor to no crack healing. Better compressive strength properties were, however, achieved by samples programmed at higher temperatures above Tg.

A Novel Poly(Ionic Liquid) as the Thermal Insulating Material

2020 ◽  
Vol 13 (3) ◽  
pp. 241-247
Author(s):  
Wenxin Wei ◽  
Guifeng Ma ◽  
Hongtao Wang ◽  
Jun Li
Keyword(s):  
Thermal Conductivity ◽  
Ionic Liquid ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Flame Resistance ◽  
Insulating Material ◽  
Low Thermal Conductivity ◽  
Thermal Insulating ◽  
Poly Ionic Liquid

Objective: A new poly(ionic liquid)(PIL), poly(p-vinylbenzyltriphenylphosphine hexafluorophosphate) (P[VBTPP][PF6]), was synthesized by quaternization, anion exchange reaction, and free radical polymerization. Then a series of the PIL were synthesized at different conditions. Methods: The specific heat capacity, glass-transition temperature and melting temperature of the synthesized PILs were measured by differential scanning calorimeter. The thermal conductivities of the PILs were measured by the laser flash analysis method. Results: Results showed that, under optimized synthesis conditions, P[VBTPP][PF6] as the thermal insulator had a high glass-transition temperature of 210.1°C, high melting point of 421.6°C, and a low thermal conductivity of 0.0920 W m-1 K-1 at 40.0°C (it was 0.105 W m-1 K-1 even at 180.0°C). The foamed sample exhibited much low thermal conductivity λ=0.0340 W m-1 K-1 at room temperature, which was comparable to a commercial polyurethane thermal insulating material although the latter had a much lower density. Conclusion: In addition, mixing the P[VBTPP][PF6] sample into polypropylene could obviously increase the Oxygen Index, revealing its efficient flame resistance. Therefore, P[VBTPP][PF6] is a potential thermal insulating material.

High-temperature carbon plastics based on thermoreactive polyimide binder

2020 ◽  
pp. 89-102
Author(s):  
M. I. Valueva ◽  
I. V. Zelenina ◽  
M. A. Zharinov ◽  
M. A. Khaskov
Keyword(s):  
Glass Transition ◽  
High Temperature ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Strength Properties ◽  
High Glass Transition Temperature ◽  
Reinforced Plastics ◽  
Carbon Plastics ◽  
Fundamental Possibility ◽  
Fiber Reinforced Plastics

The article presents results of studies of experimental carbon plastics based on thermosetting PMRpolyimide binder. Сarbon fiber reinforced plastics (CFRPs) are made from prepregs prepared by melt and mortar technologies, so the rheological properties of the polyimide binder were investigated. The heat resistance of carbon plastics was researched and its elastic-strength characteristics were determined at temperatures up to 320°С. The fundamental possibility of manufacturing carbon fiber from prepregs based on polyimide binder, obtained both by melt and mortar technologies, is shown. CFRPs made from two types of prepregs have a high glass transition temperature: 364°C (melt) and 367°C (solution), with this temperature remaining at the 97% level after boiling, and also at approximately the same (86–97%) level of conservation of elastic strength properties at temperature 300°С.

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