scholarly journals CURING OF DIGLYCIDAL ESTERS OF BISPHENOLS WITH AMINE HARDENERS

World Science ◽  
2021 ◽  
Author(s):  
Givi Papava ◽  
Ketevan Ebralidze ◽  
Eter Gavashelidze ◽  
Marina Gurgenishvili ◽  
Shalva Papava ◽  
...  
Keyword(s):  
Thermal Properties ◽  
Heat Resistance ◽  
Chemical Structure ◽  
High Heat ◽  
Thermal Parameters ◽  
High Heat Resistance ◽  
Aromatic Diamines ◽  
Temperature Range ◽  
Epoxy Polymers

The effect of hardeners on the properties of cured epoxy polymers is studied. For the purpose of synthesis of polymers with increased thermal properties. Theglycide esters of polycyclic bisphenols synthesized by us were used as a diol component. Since the thermal and heat resistance of polymers, in addition to the chemical structure of bisphenols, also depend on the structure of the hardener used, amine hardeners of different chemical structure are used to improve the thermal parameters of polymers, both heat resistance and heat resistance. The influence of the chemical structure of these hardeners on the properties of epoxy polymers is studied. Cured epoxy polymers are characterized by high heat resistance. High heat resistance results are obtained by 4,4′-diaminodiphenylsulfone, benzidine, 4,4′-diaminodiphenyloxide and other aromatic diamines. Polymers obtained by curing with these hardeners are deformed in the temperature range of 220-245°C. The use of the above hardeners gives high results in terms of heat resistance. In all cases, the polymers obtained on the basis of these hardeners decrease in weight by 10% in the temperature range of 340-400°C.

scholarly journals CURING OF DIGLYCIDAL ESTERS OF BISPHENOLS WITH ACID HARDENERS

World Science ◽  
2021 ◽  
Author(s):  
Givi Papava ◽  
Nora Dokhturishvili ◽  
Nazi Gelashvili ◽  
Ia Chtrekashvili ◽  
Ketevan Papava ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Heat Resistance ◽  
Chemical Structure ◽  
Modern Technology ◽  
Temperature Range ◽  
Epoxy Polymers

The unique properties of epoxy polymers have led to their wide application in various fields of modern technology. The influence of the structure of bisphenols on the properties of epoxy polymers, especially thermal ones, is known. However, the chemical structure of the hardener also affects the properties of cured epoxy polymers. As hardeners, we used acid hardeners of various structures: anhydrides of maleic, phthalic, pyromellite, methyltetrahydrophthalic and other acids. The following hardeners give high results in heat resistance: pyromellite and methyltetrahydrophthalic anhydrides. Polymers obtained by curing with these hardeners are deformed in the temperature range of 220-245°C. The use of these hardeners gives high results in terms of thermal stability. These polymers are formed by curing these components. It is known that the properties of epoxy polymers depend on the chemical structure of the glycide ether. There was some interest in investigating the influence on the properties of epoxy polymers as a chemical structure, as well as the nature of hardeners. For this purpose, diglycidal esters based on bisphenols were synthesized.

scholarly journals Preparation and Characterization of Semi-Alicyclic Polyimides Containing Trifluoromethyl Groups for Optoelectronic Application

Polymers ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 1532
Author(s):  
Mei Zhang ◽  
Weili Liu ◽  
Xia Gao ◽  
Peng Cui ◽  
Tao Zou ◽  
...  
Keyword(s):  
Heat Resistance ◽  
High Heat ◽  
Dielectric Constants ◽  
Dielectric Anisotropy ◽  
Good Mechanical Property ◽  
Cutoff Wavelength ◽  
High Heat Resistance ◽  
Aromatic Diamines ◽  
Yellowness Index ◽  
Trifluoromethyl Groups

Transparent polyimides (PI) films with outstanding overall performance are attractive for next generation optoelectronic and microelectronic applications. Semi-alicyclic PIs derived from alicyclic dianhydrides and aromatic diamines have proved effective to prepare transparent PIs with high transmittance. To optimize the combined properties of semi-alicyclic PIs, incorporating bulky trifluoromethyl groups into the backbones is regarded as a powerful tool. However, the lack of fundamental understanding of structure–property relationships of fluorinated semi-alicyclic PIs constrains the design and engineering of advanced films for such challenging applications. Herein, a series of semi-alicyclic PIs derived from alicyclic dianhydrides and trifluoromethyl-containing aromatic diamines was synthesized by solution polycondensation at high temperature. The effects of alicyclic structures and bulky trifluoromethyl groups on thermal, dielectric and optical properties of PIs were investigated systematically. These PI films had excellent solubility, low water absorption and good mechanical property. They showed high heat resistance with Tg in the range of 294–390 °C. It is noted that tensile strength and thermal stability were greatly affected by the rigid linkages and alicyclic moieties, respectively. These films exhibited obviously low refractive indices and significantly reduced dielectric constants from 2.61 to 2.76, together with low optical birefringence and dielectric anisotropy. Highly transparent films exhibited cutoff wavelength even as low as 298 nm and transmittance at 500 nm over 85%, displaying almost colorless appearance with yellowness index (b*) below 4.2. The remarkable optical improvement should be mainly ascribed to both weak electron-accepting alicyclic units and bulky electron-withdrawing trifluoromethyl or sulfone groups. The present work provides an effective strategy to design molecular structures of optically transparent PIs for a trade-off between solution-processability, low water uptake, good toughness, high heat resistance, low dielectric constant and excellent optical transparency.

scholarly journals CRYSTALLIZATION STRUCTURES AND THERMAL PROPERTIES OF HIGH HEAT-RESISTANCE PLLA/PDLA BLENDS

2013 ◽  
Vol 013 (8) ◽  
pp. 1006-1012 ◽  
Author(s):  
Chen Lu ◽  
Tang Song-chao ◽  
Xia Ji ◽  
Pu Wen-liang ◽  
Li Rui
Keyword(s):  
Thermal Properties ◽  
Heat Resistance ◽  
High Heat ◽  
High Heat Resistance

scholarly journals Clustering rooting for the high heat resistance of some CHNO energetic materials

FirePhysChem ◽  
2021 ◽  
Vol 1 (1) ◽  
pp. 8-20
Author(s):  
Xingyu Huo ◽  
Fanfan Wang ◽  
Liang Liang Niu ◽  
Ruijun Gou ◽  
Chaoyang Zhang
Keyword(s):  
Heat Resistance ◽  
Energetic Materials ◽  
High Heat ◽  
High Heat Resistance

scholarly journals Molecular Physiological Characterization of a High Heat Resistant Spore Forming Bacillus subtilis Food Isolate

2021 ◽  
Vol 9 (3) ◽  
pp. 667
Author(s):  
Zhiwei Tu ◽  
Peter Setlow ◽  
Stanley Brul ◽  
Gertjan Kramer
Keyword(s):  
Bacillus Subtilis ◽  
Heat Resistance ◽  
Dipicolinic Acid ◽  
Laboratory Strain ◽  
High Heat ◽  
High Heat Resistance ◽  
Vegetative Cells ◽  
Heat Resistant ◽  
Food Isolate ◽  
Wet Heat

Bacterial endospores (spores) are among the most resistant living forms on earth. Spores of Bacillus subtilis A163 show extremely high resistance to wet heat compared to spores of laboratory strains. In this study, we found that spores of B. subtilis A163 were indeed very wet heat resistant and released dipicolinic acid (DPA) very slowly during heat treatment. We also determined the proteome of vegetative cells and spores of B. subtilis A163 and the differences in these proteomes from those of the laboratory strain PY79, spores of which are much less heat resistant. This proteomic characterization identified 2011 proteins in spores and 1901 proteins in vegetative cells of B. subtilis A163. Surprisingly, spore morphogenic protein SpoVM had no homologs in B. subtilis A163. Comparing protein expression between these two strains uncovered 108 proteins that were differentially present in spores and 93 proteins differentially present in cells. In addition, five of the seven proteins on an operon in strain A163, which is thought to be primarily responsible for this strain’s spores high heat resistance, were also identified. These findings reveal proteomic differences of the two strains exhibiting different resistance to heat and form a basis for further mechanistic analysis of the high heat resistance of B. subtilis A163 spores.

P-57: A Transparent Plastic Film having Excellent Optical Properties and High Heat Resistance for Flexible Display Substrates

2006 ◽  
Vol 37 (1) ◽  
pp. 418 ◽  
Author(s):  
Yoshiaki Watanabe ◽  
Ken-ichi Makita ◽  
Yasuyoshi Fujii ◽  
Hisanori Okada ◽  
Naoto Obara ◽  
...  
Keyword(s):  
Optical Properties ◽  
Heat Resistance ◽  
High Heat ◽  
Plastic Film ◽  
High Heat Resistance ◽  
Flexible Display ◽  
Transparent Plastic

Palladium-catalyzed silation of adamantanedi- and triol, leading to adamantane–siloxane alternating polymers with high heat resistance

Polymer ◽  
2007 ◽  
Vol 48 (15) ◽  
pp. 4301-4304 ◽  
Author(s):  
Joji Ohshita ◽  
Koichi Hino ◽  
Ko Inata ◽  
Atsutaka Kunai ◽  
Takayuki Maehara
Keyword(s):  
Heat Resistance ◽  
High Heat ◽  
High Heat Resistance ◽  
Palladium Catalyzed

A high heat-resistance bioplastic foam with efficient electromagnetic interference shielding

2017 ◽  
Vol 323 ◽  
pp. 29-36 ◽  
Author(s):  
Cheng-Hua Cui ◽  
Ding-Xiang Yan ◽  
Huan Pang ◽  
Li-Chuan Jia ◽  
Xin Xu ◽  
...  
Keyword(s):  
Heat Resistance ◽  
Electromagnetic Interference ◽  
High Heat ◽  
High Heat Resistance ◽  
Electromagnetic Interference Shielding

scholarly journals Factors Contributing to Heat Resistance of Clostridium perfringens Endospores

2008 ◽  
Vol 74 (11) ◽  
pp. 3328-3335 ◽  
Author(s):  
Benjamin Orsburn ◽  
Stephen B. Melville ◽  
David L. Popham
Keyword(s):  
Cell Wall ◽  
Heat Resistance ◽  
Clostridium Perfringens ◽  
Food Poisoning ◽  
High Heat ◽  
Relative Importance ◽  
High Heat Resistance ◽  
Factors Affecting ◽  
Cooking Process ◽  
Determining Factors

ABSTRACT The endospores formed by strains of type A Clostridium perfringens that produce the C. perfringens enterotoxin (CPE) are known to be more resistant to heat and cold than strains that do not produce this toxin. The high heat resistance of these spores allows them to survive the cooking process, leading to a large number of food-poisoning cases each year. The relative importance of factors contributing to the establishment of heat resistance in this species is currently unknown. The present study examines the spores formed by both CPE+ and CPE− strains for factors known to affect heat resistance in other species. We have found that the concentrations of DPA and metal ions, the size of the spore core, and the protoplast-to-sporoplast ratio are determining factors affecting heat resistance in these strains. While the overall thickness of the spore peptidoglycan was found to be consistent in all strains, the relative amounts of cortex and germ cell wall peptidoglycan also appear to play a role in the heat resistance of these strains.

Sign in / Sign up

Export Citation Format

Share Document