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.

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.

Reliability of Low Glass Transition Temperature COTS PEM’s for Space Applications

2003 ◽  
Author(s):  
M. Sandor ◽  
S. Agarwal ◽  
D. Peters ◽  
M. S. Cooper
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Flame Retardants ◽  
Measurement Techniques ◽  
Test Results ◽  
Space Applications ◽  
Molding Compound ◽  
Different Temperatures ◽  
Compound Materials

Microcircuit manufacturers of Plastic Encapsulated Microcircuits (PEM’s) have made changes in epoxy molding compound materials and chemistry, which lower Glass Transition Temperature (Tg). PEM users in harsh environments have concerns if either the part in its application, or in evaluation or assembly, is used close to, or above, the Tg. Various Tg measurement techniques are available and discussed. Test results from one technique is reviewed. The implications of the Tg results on usage of these parts in space applications will be presented. Burn-in/ reliability test results of samples with low Tg PEM’s will be presented. The reliability experiments include testing under different temperatures. The issue being addressed is whether outgassing of molding compounds occurs when the temperature of the molding compound exceeds the Tg. This is a caution noted by many vendors. As an example outgassing of flame retardants can degrade parametric performance and wire bond integrity. This would be the case when PEMS are being qualified for Space applications using burn-in or in storage environments. JPL’s past experience has shown that COTS PEMS parametrics can degrade significantly even when the burn-in temperature is well below the Tg. Two different microcircuits exhibiting low Tg were evaluated. Assessment of final electrical test measurements and yield are shown.

scholarly journals PROPERTIES OF EPOXY COMPOSITES CURED BY A COMPLEX OF ORGANIC TIN HALIDE WITH AN AMINOPHENOL HARDENER

2020 ◽  
Vol 5 (11) ◽  
pp. 89-101
Author(s):  
Y. Kochergin ◽  
A. Nosova ◽  
T. Kravchuk ◽  
T. Grigorenko ◽  
V. Zolotareva
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Water Environment ◽  
Strength Properties ◽  
Epoxy Composites ◽  
Antifouling Coatings ◽  
Hydraulic Equipment ◽  
Deformation Ability ◽  
Low Exposure

A method for the synthesis of a complex based on an organic tin halide – dibutylol dibromide – and a aminophenol hardener of the UP-583 brand has been developed. It is found that samples cured with a complex hardener at room temperature are characterized by lower values of tensile strength, elastic modulus and glass transition temperature compared to samples cured with the original hardener UP-583. The values of strain at break are approximately the same for both hardeners. After heat treatment, the strength and modulus values for samples containing the complex sharply increase, as a result of which they are superior to samples based on UP-583. The deformation capacity does not change much, the glass transition temperature increases after heating, but remains significantly lower than for samples cured with the original UP-583. The observed change in the deformation and strength properties of samples during their exposure in a liquid medium is explained by the superposition of the effects of plasticization and re-hardening of epoxy polymers. At low exposure times, the action of the sorbed moisture is mainly aimed at weakening the intermolecular interaction in the sample. In result, its strength decreases and deformability increases. At large values of exposure times, when the amount of sorbed water becomes sufficiently large and a fairly intense molecular mobility develops, pre-hardening processes prevail, leading to an increase in the cross-linking density and, to a decrease in the deformation ability and an increase in the strength index. It is shown that epoxy composites containing a complex hardener are characterized by good performance in the water environment, increased resistance to the development of fungi and mold, as well as better fire resistance. The studied polymers are promising for obtaining antifouling coatings based on them for hydraulic equipment, sea and river vessels.

scholarly journals Influence of the Glass Transition Temperature and the Density of Crosslinking Groups on the Reversibility of Diels-Alder Polymer Networks

Polymers ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1189
Author(s):  
Merlina Thiessen ◽  
Volker Abetz
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Radical Polymerization ◽  
Polymer Networks ◽  
Alder Reaction ◽  
Diels Alder ◽  
Self Healing ◽  
Scanning Calorimetry ◽  
Diels Alder Reaction

The interest in self-healing, recyclable, and adaptable polymers is growing. This work addresses the reversibility of crosslink formation based on Diels-Alder reaction in copolymer networks containing furfuryl and maleimide groups, which represent the “diene” and the “dienophile,” respectively. The copolymers are synthesized by atom transfer radical polymerization (ATRP) and free radical polymerization. The diene bearing copolymers are crosslinked either with a small molecule containing two dienophiles or with a dienophile bearing copolymer. The influence of the crosslinking temperature on the Diels-Alder reaction is analyzed. Furthermore, the influence of the glass transition temperature and the influence of the density of crosslinking groups on the thermo-reversibility of crosslinking are investigated by temperature dependent infrared spectroscopy and differential scanning calorimetry. It is shown that the reversibility of crosslinking is strongly influenced by the glass transition temperature of the system.

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

scholarly journals Influence of Material Properties on the Damage-Reporting and Self-Healing Performance of a Mechanically Active Dynamic Network Polymer in Coating Applications

Molecules ◽  
2021 ◽  
Vol 26 (9) ◽  
pp. 2468
Author(s):  
Da Hae Son ◽  
Gi Young Kim ◽  
Ji-Eun Jeong ◽  
Sang-Ho Lee ◽  
Young Il Park ◽  
...  
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Material Properties ◽  
Substrate Surface ◽  
Polymer Network ◽  
Polymer Networks ◽  
Indentation Hardness ◽  
Indentation Modulus ◽  
Self Healing

We conducted a detailed investigation of the influence of the material properties of dynamic polymer network coatings on their self-healing and damage-reporting performance. A series of reversible polyacrylate urethane networks containing the damage-reporting diarylbibenzofuranone unit were synthesized, and their material properties (e.g., indentation modulus, hardness modulus, and glass-transition temperature) were measured conducting nanoindentation and differential scanning calorimetry experiments. The damage-reporting and self-healing performances of the dynamic polymer network coatings exhibited opposite tendencies with respect to the material properties of the polymer network coatings. Soft polymer network coatings with low glass-transition temperature (~10 °C) and indentation hardness (20 MPa) exhibited better self-healing performance (almost 100%) but two times worse damage-reporting properties than hard polymer network coatings with high glass-transition temperature (35~50 °C) and indentation hardness (150~200 MPa). These features of the dynamic polymer network coatings are unique; they are not observed in elastomers, films, and hydrogels, whereby the polymer networks are bound to the substrate surface. Evidence indicates that controlling the polymer’s physical properties is a key factor in designing high-performance self-healing and damage-reporting polymer coatings based on mechanophores.

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