Thermal Stability of Polyurethane Coating Prepared by Using Diphenylolpropane

2021 ◽  
Vol 899 ◽  
pp. 739-744
Author(s):  
Indira N. Bakirova ◽  
Svetlana E. Mitrofanova
Keyword(s):  
Thermal Stability ◽  
Temperature Region ◽  
Polymer Structure ◽  
Phenolic Hydroxyl ◽  
Polyurethane Coating ◽  
Thermooxidative Degradation ◽  
Stabilizing Effect ◽  
Varnish Coating ◽  
Higher Temperature ◽  
Thermal Stability Of

Thermal stability on air of polyurethane varnish coating prepared from diphenylolpropane, polyetherpolyol and polyisocyanate was assessed. The presence of urethane groups, formed by phenolic hydroxyl of diphenylolpropane, in the polymer structure was shown to decrease its thermooxidative degradation onset temperature. At the same time, deceleration of thermooxidative processes due to stabilizing effect of diphenylolpropane released at the beginning of thermal decay of polyurethane is observed in the higher temperature region.

scholarly journals Thermal stability of polyurethane coating prepared by using diphenylolpropane

2020 ◽  
Vol 62 (4) ◽  
pp. 81-87
Author(s):  
Indira N. Bakirova ◽  
Keyword(s):  
Thermal Stability ◽  
Thermal Decomposition ◽  
Weight Loss ◽  
Elevated Temperatures ◽  
Onset Temperature ◽  
Phenolic Hydroxyl ◽  
Hydroxyl Groups ◽  
Polyurethane Coating ◽  
Urethane Group ◽  
Thermal Stability Of

Thermal stability of polyurethane varnish coating prepared by using diphenylolpropane, polyetherpolyol and polyisocyanate with an equimolar ratio of isocyanate and hydroxyl groups was assessed in the air. The polyurethane weight loss thermogram shows three temperature regions: I – (217-275)°С, II – (275-380)°С, and III – above 380°С. For interpreting thermogram of the polyurethane under study the model substances simulating the urethane groups of a polymer were synthesized. The substance containing the urethane group formed by phenolic hydroxyl of diphenylolpropane was shown to demonstrate relatively low thermal stability and gets broken down into isocyanate and bisphenol. Decomposition of the substance containing the urethane group formed by alcoholic hydroxyl occurs at the higher temperature. The data obtained allow interpreting the occurrence of thermal decomposition step I in TGA curve by structural changes in the blocks formed by diphenylolpropane and polyisocyanate being the least stable when exposed to elevated temperatures. The next step can be attributed to decomposition of more thermostable urethane groups formed by functional groups of oligooxypropylenetriol and polyisocyanate. Transition to the step III accompanied by severe sample weight loss due to decomposition of urethane groups is explained by thermal oxidation of oligoether units of polymer. Based on the data obtained the conclusion was made that the presence of urethane groups formed by phenolic hydroxyl of diphenylolpropane in polymer structure results in the decreased thermooxidative decomposition onset temperature of polymer. At the same time, a deceleration of thermooxidative processes due to the stabilizing effect of diphenylolpropane released at the beginning of thermal decomposition of polyurethane is observed in a high-temperature region. The proposed polyurethane coating is inferior to commercial counterparts in thermal decomposition onset temperature but superior to them in the temperature corresponding to a 50% polymer weight loss.

Systematic Characterization of Different Quaternary Ammonium Salts to be Used in Organoclays

2012 ◽  
Vol 727-728 ◽  
pp. 1552-1556
Author(s):  
Renata Barbosa ◽  
Dayanne Diniz Souza ◽  
Edcleide Maria Araújo ◽  
Tomás Jefférson Alves de Mélo
Keyword(s):  
Thermal Stability ◽  
Quaternary Ammonium ◽  
Chemical Structure ◽  
Quaternary Ammonium Salts ◽  
Ammonium Salts ◽  
Degradation Mechanisms ◽  
Scanning Calorimetry ◽  
Higher Temperature ◽  
Thermal Stability Of

Studies of degradation have verified that the decomposition of some quaternary ammonium salts can begin to be significant at the temperature of about 180 ° C and like most thermoplastics are processed at least around this temperature, the thermal stability of the salt in clay should always be considered. Some salts are more stable than others, being necessary to study the degradation mechanisms of each case. In this work, four quaternary ammonium salts were characterized by differential scanning calorimetry (DSC) and thermogravimetry (TG). The results of DSC and TG showed that the salts based chloride (Cl-) anion begin to degrade at similar temperatures, while the salt based bromide (Br-) anion degrades at higher temperature. Subsequently, a quaternary ammonium salt was chosen to be used in organoclays, depending on its chemical structure and its thermal behavior.

scholarly journals Effect of High Temperature on the Electrochemical and Optical Properties of Emeraldine Salt Doped with DBSA and Sulfuric Acid

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Salma Gul ◽  
Anwar-ul-Haq Ali Shah ◽  
Salma Bilal
Keyword(s):  
Thermal Stability ◽  
Cyclic Voltammetry ◽  
Sulfuric Acid ◽  
Effect Of Temperature ◽  
Visible Spectroscopy ◽  
Emeraldine Salt ◽  
Higher Temperature ◽  
Stability Effect ◽  
Thermal Stability Of ◽  
Comprehensive Study

A comprehensive study of thermally treated polyaniline in its emeraldine salt form is presented here. It offers an understanding of the thermal stability of the polymer. Emeraldine salt was prepared by a novel emulsion polymerization pathway using dodecylbenzene sulfonic acid and sulfuric acid together as dopants. The effect of temperature and heating rate on the degradation of this emeraldine salt was studied via thermogravimetric analysis. The thermally analyzed sample was collected at various temperatures, that is, 250, 490, 500, and 1000°C. The gradual changes in the structure of the emeraldine salt were followed through cyclic voltammetry, Fourier transform infrared spectroscopy, and ultraviolet-visible spectroscopy. Results demonstrate that emeraldine salt shows high thermal stability up to 500°C. This is much higher working temperature for the use of emeraldine salt in higher temperature applications. Further heat treatment seems to induce deprotonation in emeraldine salt. Cyclic voltammetry and ultraviolet-visible spectroscopy revealed that complete deprotonation takes place at 1000°C where it loses its electrical conductivity. It is interesting to note that after the elimination of the dopants, the basic backbone of emeraldine salt was not destroyed. The results reveal that the dopants employed have a stability effect on the skeleton of emeraldine salt.

Thermal stability of carbon nitride thin films

2001 ◽  
Vol 16 (11) ◽  
pp. 3188-3201 ◽  
Author(s):  
Niklas Hellgren ◽  
Nian Lin ◽  
Esteban Broitman ◽  
Virginie Serin ◽  
Stefano E. Grillo ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Thermal Stability ◽  
Photoelectron Spectroscopy ◽  
Carbon Nitride ◽  
Amorphous Structure ◽  
X Ray ◽  
Bonding Structure ◽  
Higher Temperature ◽  
Electron Energy Loss ◽  
Thermal Stability Of

The thermal stability of carbon nitride films, deposited by reactive direct current magnetron sputtering in N2 discharge, was studied for postdeposition annealing temperatures TA up to 1000 °C. Films were grown at temperatures of 100 °C (amorphous structure) and 350 and 550 °C (fullerenelike structure) and were analyzed with respect to thickness, composition, microstructure, bonding structure, and mechanical properties as a function of TA and annealing time. All properties investigated were found to be stable for annealing up to 300 °C for long times (>48 h). For higher TA, nitrogen is lost from the films and graphitization takes place. At TA = 500 °C the graphitization process takes up to 48 h while at TA = 900 °C it takes less than 2 min. A comparison on the evolution of x-ray photoelectron spectroscopy, electron energy loss spectroscopy and Raman spectra during annealing shows that for TA > 800 °C, preferentially pyridinelike N and –C≡N is lost from the films, mainly in the form of molecular N2 and C2N2, while N substituted in graphite is preserved the longest in the structure. Films deposited at the higher temperature exhibit better thermal stability, but annealing at temperatures a few hundred degrees Celsius above the deposition temperature for long times is always detrimental for the mechanical properties of the films.

scholarly journals Anionic surfactant sulfate dodecyl sodium (SDS)-induced thermodynamics and conformational changes of collagen by ultrasensitive microcalorimetry

2021 ◽  
Vol 3 (1) ◽  
Author(s):  
Jie Zhang ◽  
Chunhua Wang ◽  
Fengteng Zhang ◽  
Wei Lin
Keyword(s):  
Thermal Stability ◽  
Conformational Changes ◽  
Triple Helix ◽  
Striking Difference ◽  
Thermal Transition ◽  
Scanning Calorimetry ◽  
Helix Structure ◽  
Stabilizing Effect ◽  
Collagen Molecules ◽  
Thermal Stability Of

Abstract In this communication, sulfate dodecyl sodium (SDS)-induced thermodynamics and conformational changes of collagen were studied. We used ultrasensitive differential scanning calorimetry (US-DSC) to directly monitor the thermal transition of collagen in the presence of SDS. The results show that SDS affects the conformation and thermal stability of collagen very differently depending on its concentrations. At CSDS ≤ 0.05 mM, the enhanced thermal stability of collagen indicates the stabilizing effect by SDS. However, a further increase of SDS leads to the denaturation of collagen, verifying the well-known ability of SDS to unfold proteins. This striking difference in thermodynamics and conformational changes of collagen caused by SDS concentrations can be explained in terms of their interactions. With increasing SDS, the binding of SDS to collagen can be dominated by electrostatic interaction shifting to hydrophobic interaction, and the latter plays a key role in loosening and unfolding the triple-helix structure of collagen. The important finding in the present study is the stabilizing effect of SDS on collagen molecules at extreme low concentration. Graphical abstract

Photo-Cross-Linking-Assisted Thermal Stability of DNA Origami Structures and Its Application for Higher-Temperature Self-Assembly

2011 ◽  
Vol 133 (37) ◽  
pp. 14488-14491 ◽  
Author(s):  
Arivazhagan Rajendran ◽  
Masayuki Endo ◽  
Yousuke Katsuda ◽  
Kumi Hidaka ◽  
Hiroshi Sugiyama
Keyword(s):  
Thermal Stability ◽  
Self Assembly ◽  
Dna Origami ◽  
Cross Linking ◽  
Higher Temperature ◽  
Thermal Stability Of

Sonochemically Synthesis of Antimonite Nanoparticles and Its Influence on the Thermal Stability of the ABS Terpolymer

2013 ◽  
Vol 32 (4) ◽  
pp. 339-343 ◽  
Author(s):  
Siyamak Bagheriyan
Keyword(s):  
Thermal Stability ◽  
Acrylonitrile Butadiene Styrene ◽  
X Ray Diffraction ◽  
Limiting Oxygen Index ◽  
X Ray ◽  
Sonochemical Reaction ◽  
Ft Ir ◽  
Higher Temperature ◽  
Thermal Stability Of ◽  
Butadiene Styrene

AbstractSb2S3 nanoparticles were synthesized via a simple sonochemical reaction between SbCl3 and thioacetamide. The effect of different parameters such as power and time of pulsation on the morphology of the product has been investigated. The Sb2 S3 nanostructures were then added to acrylonitrile-butadiene-styrene terpolymer. The effect of Sb2 S3 nanostructures on the thermal stability of the polymeric matrix has been examined. The thermal decomposition of the nanocomposite shifts towards higher temperature in the presence of the Sb2 S3 . Nanostructures were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR), photoluminescence (PL) spectroscopy, thermogravimetric analysis (TGA), UL-94 and limiting oxygen index (LOI) analysis.

scholarly journals Improved Self-Supporting and Ceramifiable Properties of Ceramifiable EPDM Composites by Adding Aramid Fiber

Polymers ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 1523
Author(s):  
Dong Zhao ◽  
Wei Liu ◽  
Yucai Shen ◽  
Guodong Jiang ◽  
Tingwei Wang
Keyword(s):  
Thermal Stability ◽  
Aramid Fiber ◽  
Thermal Shrinkage ◽  
Network Structures ◽  
Ethylene Propylene Diene Monomer ◽  
Solvent Resistance ◽  
Fiber Network ◽  
Higher Temperature ◽  
Thermal Stability Of ◽  
Scanning Electron

Ceramifiable ethylene propylene diene monomer (EPDM) composites with fiber network structures were prepared by using aramid fiber (AF), ammonium polyphosphate (APP), and silicate glass frits (SGF). The effect of AF on the curing characteristic of the ceramifiable EPDM composites was studied. The morphology of AF in the composites system was observed by optical microscopy (OM) and scanning electron microscope (SEM). The effects of the observed AF network structures on the solvent resistance, mechanical properties, ablative resistance, self-supporting property, and ceramifiable properties of the composites were investigated. Results suggested that the existence of the AF network structure improved the vulcanization properties, solvent resistance, thermal stability, and ablative resistance of the EPDM composites. An excellent self-supporting property of the EPDM composites was obtained by combining the formation of the AF network and the formation of crystalline phases at higher temperature (above 600 °C). The thermal shrinkage performance of AF and the increased thermal stability of the EPDM composites improved the ceramifiable properties of the EPDM composites.

scholarly journals Influence of antioxidants in epoxy-anhydride resin used for HV applications

2018 ◽  
Author(s):  
Chau Hon Ho ◽  
Emmanuel Logakis ◽  
Andrej Krivda
Keyword(s):  
Thermal Stability ◽  
Glass Transition ◽  
Transition Temperature ◽  
Breakdown Voltage ◽  
Degradation Behavior ◽  
Thermooxidative Degradation ◽  
Thermo Gravimetric ◽  
Chemical Structures ◽  
Stabilizing Effect ◽  
Resin Formulation

<p>In this work, various antioxidants with different chemical structures and functionalities were investigated in respect to their influence in the processibility and properties of a standard epoxyanhydride resin formulation used in HV applications. Such antioxidants are mainly used in thermoplastic materials as they are known for their long- and shortterm stabilizing effect against thermal and thermooxidative degradation. They are also used as UV stabilizers against decomposition and discoloration of the polymer and as metal deactivators by catching and eliminating metal ions. Recently, the use of such antioxidants as voltage stabilizers in cross-linked polyethylene has been reported showing a significant increase in breakdown voltage.</p><p>Our investigations show that the processing requires additional mixing steps in order to completely dissolve antioxidants in the epoxy formulation. While little amounts of antioxidants or voltage stabilizers have a large influence in thermoplastics regarding thermal stability and electrical properties, the studied antioxidants in a concentration range of 1-5 weight-% show surprisingly only little impact in breakdown voltage as well as in dielectric properties and also in degradation behavior as detected by thermo-gravimetric analyses. Only the glass transition temperature of the cured epoxy resin is decreased in a few cases where the antioxidants have a plasticizing effect.</p>

Thermal Stability of Al-Cu-Mg Alloys

2014 ◽  
Vol 794-796 ◽  
pp. 691-696 ◽  
Author(s):  
Gaelle Pouget ◽  
Christophe Sigli
Keyword(s):  
Thermal Stability ◽  
Mg Alloys ◽  
Cu Content ◽  
Precipitate Coarsening ◽  
Aerospace Applications ◽  
Higher Temperature ◽  
Coarsening Kinetics ◽  
Areas Of Interest ◽  
Damage Tolerant ◽  
Thermal Stability Of

The Al-Cu-Mg alloys currently used at elevated temperature for aerospace applications, such as 2618 and 2219, were developed in the 1950s. Since then, not only have property requirements evolved significantly with the widespread introduction of damage tolerant design, but also the understanding and modelling capacity of the alloys' property-composition-processing relationships have developed beyond recognition. Moreover there is a renewed need for higher strength/toughness, higher temperature solutions in many aircraft's hot areas.A kinetic model has been developed to predict the strengthening capability and the thermal stability of hardening phases. It is based on a homogeneous nucleation, growth and coarsening model applied to S' (Al2CuMg) and θ' (Al2Cu); the yield strength is then calculated from the precipitates' size distribution. It suggests two areas of interest in the Al-Cu-Mg diagram.Three targeted compositions were then explored inside and outside the areas of interest and their thermal stability assessed up to 250°C. Different behaviours were observed and are explained by the strengthening potential and the coarsening resistance of S' and θ'. The two interesting areas for thermally stability are confirmed. An area of poorer thermal stability was also identified, associated with a high Cu content in solid solution which accelerates precipitate coarsening kinetics.

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