scholarly journals Thermal Stability and Monomer Elution of Bulk Fill Composite Resins Cured from Different Irradiation Distances

2021 ◽  
Author(s):  
Elmira Jafari Navimipour ◽  
Fatemeh Pournaghi Azar ◽  
Sajjad Keshipour ◽  
Saba Nadervand
Keyword(s):  
Thermal Stability ◽  
Gas Chromatography ◽  
Weight Loss ◽  
Thermogravimetric Analysis ◽  
Composite Resins ◽  
Degree Of Conversion ◽  
Light Curing ◽  
Base Composite ◽  
Post Hoc ◽  
Thermal Stability Of

Objectives: This study aimed to evaluate the thermal stability and monomer elution of bulk fill composite resins cured at different irradiation distances. Materials and Methods: Forty cylindrical-shaped (3×4mm) specimens were fabricated from two composite resins (X-tra fil, X-tra base) and cured from 0 and 7mm distances. In 9 specimens, the degree of conversion was determined by the release of monomers. For this purpose, after curing of composites, they were immersed in 5 mL of 99.9% methanol and stored at 37°C for 24h. The eluted monomer was then analyzed by gas chromatography (GC). Also, thermal stability of one sample from each group was assessed by thermogravimetric analysis (TGA) at a rate of 10°C/min. Data were analyzed using two-way ANOVA and Tukey’s post-hoc test (P<0.05). Results: X-tra fil had significantly higher degree of conversion than X-tra base (P=0.001). Specimens cured at 7mm distance had significantly lower degree of conversion compared with those cured at 0 mm distance (P=0.001). The interaction effect of composite type and distance of light curing unit from the surface of samples was statistically significant (P=0.001). Regarding the TGA results, the lowest and the highest percentages of weight loss were detected in X-tra fil cured at 0 mm distance and X-tra base cured at 7mm distance, respectively. Conclusion: X-tra fil composite cured at 0mm distance had the highest degree of conversion and thermal stability, and X-tra base composite cured at 7mm distance had the lowest values.

Study of Thermal Behaviour of EPDM/SBR Blends and Carbon Nanocoatings Deposited by Sputtering

2021 ◽  
Vol 875 ◽  
pp. 116-120
Author(s):  
Muhammad Alamgir ◽  
Faizan Ali Ghauri ◽  
Waheed Qamar Khan ◽  
Sajawal Rasheed ◽  
Muhammad Sarfraz Nawaz ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Weight Loss ◽  
Thermogravimetric Analysis ◽  
Thermal Behavior ◽  
Thermal Behaviour ◽  
X Ray Diffraction ◽  
X Ray ◽  
Thermal Stability Of

In this study, the effect of SBR concentration (10 Phr, 20 Phr & 30 Phr ) on the thermal behavior of EPDM/SBR blends was studied. Thermogravimetric analysis (TGA) was used to check weight loss of samples as function of temperature by heating upto 600°C. X-ray diffraction (XRD) was performed to determine quality and % crystallinity of the elastomer blends. It was seen that % crystallinity improved with an increase in the content of SBR in EPDM/SBR blends. TGA revealed that the thermal stability of EPDM/SBR blends has improved by 17% than neat EPDM. Carbon nano-coatings produced by sputtering have no beneficial influence on thermal behaviour of elastomers.

Thermal Stability of N-Heterocycle-Stabilized Iodanes – A Systematic Investigation

2019 ◽  
Author(s):  
Andreas Boelke ◽  
Yulia A. Vlasenko ◽  
Mekhman S. Yusubov ◽  
Boris Nachtsheim ◽  
Pavel Postnikov
Keyword(s):  
Thermal Stability ◽  
Differential Scanning Calorimetry ◽  
Thermogravimetric Analysis ◽  
Systematic Investigation ◽  
Scanning Calorimetry ◽  
Thermal Stability Of

<p>The thermal stability of pseudocyclic and cyclic <i>N</i>-heterocycle-stabilized (hydroxy)aryl- and mesityl(aryl)-l<sup>3</sup>-iodanes (NHIs) through thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) is investigated. NHIs bearing <i>N</i>-heterocycles with a high N/C-ratio such as triazoles show among the lowest descomposition temperatures and the highest decomposition energies. A comparison of NHIs with known (pseudo)cyclic benziodoxolones is made and we further correlated their thermal stability with reactivity in a model oxygenation. </p>

scholarly journals Study on Thermal Decomposition Behaviors of Terpolymers of Carbon Dioxide, Propylene Oxide, and Cyclohexene Oxide

2018 ◽  
Vol 19 (12) ◽  
pp. 3723 ◽  
Author(s):  
Shaoyun Chen ◽  
Min Xiao ◽  
Luyi Sun ◽  
Yuezhong Meng
Keyword(s):  
Carbon Dioxide ◽  
Thermal Stability ◽  
Thermal Decomposition ◽  
Thermogravimetric Analysis ◽  
Propylene Carbonate ◽  
Cyclohexene Oxide ◽  
Block Polymers ◽  
Rate Method ◽  
Poly Propylene ◽  
Thermal Stability Of

The terpolymerization of carbon dioxide (CO2), propylene oxide (PO), and cyclohexene oxide (CHO) were performed by both random polymerization and block polymerization to synthesize the random poly (propylene cyclohexene carbonate) (PPCHC), di-block polymers of poly (propylene carbonate–cyclohexyl carbonate) (PPC-PCHC), and tri-block polymers of poly (cyclohexyl carbonate–propylene carbonate–cyclohexyl carbonate) (PCHC-PPC-PCHC). The kinetics of the thermal degradation of the terpolymers was investigated by the multiple heating rate method (Kissinger-Akahira-Sunose (KAS) method), the single heating rate method (Coats-Redfern method), and the Isoconversional kinetic analysis method proposed by Vyazovkin with the data from thermogravimetric analysis under dynamic conditions. The values of ln k vs. T−1 for the thermal decomposition of four polymers demonstrate the thermal stability of PPC and PPC-PCHC are poorer than PPCHC and PCHC-PPC-PCHC. In addition, for PPCHC and PCHC-PPC-PCHC, there is an intersection between the two rate constant lines, which means that, for thermal stability of PPCHC, it is more stable than PCHC-PPC-PCHC at the temperature less than 309 °C and less stable when the decomposed temperature is more than 309 °C. Pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) and thermogravimetric analysis/infrared spectrometry (TG/FTIR) techniques were applied to investigate the thermal degradation behavior of the polymers. The results showed that unzipping was the main degradation mechanism of all polymers so the final pyrolysates were cyclic propylene carbonate and cyclic cyclohexene carbonate. For the block copolymers, the main chain scission reaction first occurs at PC-PC linkages initiating an unzipping reaction of PPC chain and then, at CHC–CHC linkages, initiating an unzipping reaction of the PCHC chain. That is why the T−5% of di-block and tri-block polymers were not much higher than that of PPC while two maximum decomposition temperatures were observed for both the block copolymer and the second one were much higher than that of PPC. For PPCHC, the random arranged bulky cyclohexane groups in the polymer chain can effectively suppress the backbiting process and retard the unzipping reaction. Thus, it exhibited much higher T−5% than that of PPC and block copolymers.

scholarly journals Synergistic Effect of 2-Acrylamido-2-methyl-1-propanesulfonic Acid on the Enhanced Conductivity for Fuel Cell at Low Temperature

Membranes ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 426
Author(s):  
Murli Manohar ◽  
Dukjoon Kim
Keyword(s):  
Thermal Stability ◽  
Weight Loss ◽  
Fuel Cell ◽  
Membrane Structure ◽  
Polymer Electrolyte Membranes ◽  
Aliphatic Chain ◽  
Electrolyte Membranes ◽  
Ft Ir ◽  
Enhanced Conductivity ◽  
Thermal Stability Of

This present work focused on the aromatic polymer (poly (1,4-phenylene ether-ether-sulfone); SPEES) interconnected/ cross-linked with the aliphatic monomer (2-acrylamido-2-methyl-1-propanesulfonic; AMPS) with the sulfonic group to enhance the conductivity and make it flexible with aliphatic chain of AMPS. Surprisingly, it produced higher conductivity than that of other reported work after the chemical stability was measured. It allows optimizing the synthesis of polymer electrolyte membranes with tailor-made combinations of conductivity and stability. Membrane structure is characterized by 1H NMR and FT-IR. Weight loss of the membrane in Fenton’s reagent is not too high during the oxidative stability test. The thermal stability of the membrane is characterized by TGA and its morphology by SEM and SAXS. The prepared membranes improved proton conductivity up to 0.125 Scm−1 which is much higher than that of Nafion N115 which is 0.059 Scm−1. Therefore, the SPEES-AM membranes are adequate for fuel cell at 50 °C with reduced relative humidity (RH).

scholarly journals The Use of POSS-Based Nanoadditives for Cable-Grade PVC: Effects on its Thermal Stability

Polymers ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 1105 ◽  
Author(s):  
Palin ◽  
Rombolà ◽  
Milanesio ◽  
Boccaleri
Keyword(s):  
Mechanical Properties ◽  
Thermal Stability ◽  
Thermogravimetric Analysis ◽  
Thermal Degradation ◽  
Additive Effects ◽  
Poly Vinyl Chloride ◽  
The Family ◽  
Mechanical Performances ◽  
Oligomeric Silsesquioxane ◽  
Thermal Stability Of

Plasticized–Poly(vinyl chloride) (P-PVC) for cables and insulation requires performances related to outdoor, indoor and submarine contexts and reduction of noxious release of HCl-containing fumes in case of thermal degradation or fire. Introducing suitable nanomaterials in polymer-based nanocomposites can be an answer to this clue. In this work, an industry-compliant cable-grade P-PVC formulation was added with nanostructured materials belonging to the family of Polyhedral Oligomeric Silsesquioxane (POSS). The effects of the nanomaterials, alone and in synergy with HCl scavenging agents as zeolites and hydrotalcites, on the thermal stability and HCl evolution of P-PVC were deeply investigated by thermogravimetric analysis and reference ASTM methods. Moreover, hardness and mechanical properties were studied in order to highlight the effects of these additives in the perspective of final industrial uses. The data demonstrated relevant improvements in the thermal stability of the samples added with nanomaterials, already with concentrations of POSS down to 0.31 phr and interesting additive effects of POSS with zeolites and hydrotalcites for HCl release reduction without losing mechanical performances.

PS-TiO2 Nanocomposites: Thermal Investigations

2011 ◽  
Vol 1312 ◽  
Author(s):  
Rafael Villegas ◽  
Yun Zhai ◽  
Hailan Xu ◽  
Dorina Magdalena Chipara ◽  
David Hui ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Thermal Analysis ◽  
Thermogravimetric Analysis ◽  
Mass Loss ◽  
Correlation Coefficient ◽  
Analysis Data ◽  
First Derivative ◽  
Thermal Investigations ◽  
Thermal Stability Of ◽  
Gaussian Line

ABSTRACTNanocomposites of polystyrene loaded with various amounts of anatase (ranging between 0 % wt. and 20 % wt.) have been synthesized and investigated by thermal analysis. The research was focused on the simulation of Thermogravimetric Analysis data, aiming to a refined understanding of the interactions between of polystyrene and TiO2 nanoparticles. The dependence of the first derivative of residual mass on temperature has been used to determine more accurately the temperature at which the mass loss is maxim. Several functions have been used to simulate the dependence of the first derivative of mass loss on the temperature of the sample. The highest correlation coefficient was obtained for the asymmetric Gaussian combination, which connects two halves of a Gaussian line with different linewidth. An increase of the thermal stability of the polymeric matrix upon loading with TiO2 is reported.

Intumescent Flame Retardant Epoxy Resins Based on Condensation Polymers of P-Phenylenediamine and Bispirocyclic Pentaerythritol Diphosphate

2012 ◽  
Vol 482-484 ◽  
pp. 1863-1868 ◽  
Author(s):  
Ya Wen Huang ◽  
Jia Jun Ma ◽  
Jun Xiao Yang
Keyword(s):  
Thermal Stability ◽  
Thermogravimetric Analysis ◽  
Epoxy Resin ◽  
Flame Retardancy ◽  
Epoxy Resins ◽  
Char Residue ◽  
Retarding Effect ◽  
Condensation Polymers ◽  
Thermal Stability Of ◽  
Sem Investigation

Copolymer of p-phenylenediamine and bispirocyclic pentaerythritol diphosphate was synthesized and characterized by FTIR and 1H NMR. This polymer was used to prepare epoxy resin/SPDA composites. Thermal stability of SPDA and epoxy/SPDA composites were investigated by thermogravimetric analysis (TGA), and their flammability were investigated by the LOI test. TGA results showed that the addition of SPDA improved the char residue of epoxy resin. SEM investigation showed that the residual chars have a honeycomb-like structure, indicating an intumescent flame retarding effect of SPDA in composites. In addition, all of above results confirmed that accelerate carbonization play a key role in improving flame retardancy of epoxy resin.

Determination of thermal stability of oils by pyrolytic gas chromatography

1983 ◽  
Vol 19 (8) ◽  
pp. 412-414
Author(s):  
N. A. Kudryavtseva ◽  
I. A. Mikhailov ◽  
E. M. Nikonorov ◽  
L. A. Rakova
Keyword(s):  
Thermal Stability ◽  
Gas Chromatography ◽  
Thermal Stability Of
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