scholarly journals Characterization of polydimethylsiloxane rubber upon photochemical, thermal, salt-fog ageings and exposure to acid vapours

e-Polymers ◽  
2006 ◽  
Vol 6 (1) ◽  
Author(s):  
F. Delor-Jestin ◽  
N. S. Tomer ◽  
R.P. Singh ◽  
J. Lacoste
Keyword(s):  
Ir Spectroscopy ◽  
Chemical Structure ◽  
Mesh Size ◽  
Cross Linking ◽  
Scanning Calorimetry ◽  
New Knowledge ◽  
Salt Fog ◽  
Complementary Analysis ◽  
Thermal Stability Of

AbstractThe changes in the chemical structure and the physical properties of a filled crosslinked polydimethylsiloxane rubber were monitored as a function of various ageing factors. The variables included photochemical, thermal, salt-fog ageings and exposure to acid vapours. Unaged and aged samples were studied by IR spectroscopy, hardness measurements, Differential Scanning Calorimetry (DSC) and thermogravimetric analysis (TGA) coupled with IR spectroscopy. No significant oxidation was detected after all ageings, except for nitric acid treatment. The presence of aluminium trihydrate was clearly identified as responsible for the observed chemical changes. Then an important vulnerability of this filled silicone rubber towards the cross-linking reactions provoked by usual ageings was also detected. The DSC-thermoporosimetry measurements of the mesh size distribution gave a comparison of cross-linking densities for each ageing. The complementary analysis with TGAIR allowed us to differenciate the thermal stability of the formulation after various ageings and to acquire new knowledge about thermal decomposition.

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.

Synthesis and characterization of diaminomaleonitrile-functionalized polystyrene grafts for application in pervaporation separation

2008 ◽  
Vol 62 (4) ◽  
Author(s):  
Hamada Abdel-Razik
Keyword(s):  
Chemical Structure ◽  
Thermal Characteristics ◽  
Gravimetric Analysis ◽  
Thermal Gravimetric ◽  
Optimum Conditions ◽  
Scanning Calorimetry ◽  
Phenol Water ◽  
Pervaporation Separation ◽  
Thermal Stability Of

AbstractSynthesis, characterization and application of diaminomaleonitrile (DAMN)-functionalized polystyrene grafts were studied. Dibenzoyle peroxide (BP) was used as an initiator. Optimum conditions for grafting were found to be c(DAMN) = 0.5 M, c(BP) = 0.016 M, θ = 85 °C and t = 4 h. Water uptake of the polystyrene graft membranes was found to increase with the increase of the grafting yield. The chemical structure, thermal characteristics and thermal stability of the obtained membranes were investigated by means of FTIR spectroscopy, differential scanning calorimetry, and thermal gravimetric analysis. Polystyrene graft membrane with the degree of grafting of up to 96 % was found to be useful for the pervaporation separation of phenol/water mixtures.

Synthesis and Characterization of Conjugated-Polymer/Graphene/Nanodiamond Nanocomposite for Electrochemical Energy Storage

2015 ◽  
Author(s):  
Danny Illera Perozo ◽  
Humberto Gómez Vega ◽  
Julian Yepes Martínez
Keyword(s):  
Conjugated Polymer ◽  
Synthesis And Characterization ◽  
Cross Linking ◽  
Scanning Calorimetry ◽  
Polymer Shell ◽  
Host Materials ◽  
The Matrix ◽  
Thermal Stability Of

The synthesis and characterization of Polyaniline/Graphene/ Nanodiamond Nanocomposite is reported. The resulting materials were synthetized following a polymerization in situ scheme and characterized by Fourier Transform Infrared Spectroscopy (FTIR), Thermogravimetry (TGA), Differential Scanning Calorimetry (DSC), Scanning Electron Microscopy (SEM) and Cyclic Voltammetry (CV). The effect of different loads of graphene and nanodiamond on the resulting nanocomposite was studied. Despite the presence of the host materials, the formation of Polyaniline polymer is successfully accomplished for all samples. The microstructure of the resulting materials is core-shell type with the additives being covered (core) by layers of the conjugated polymer (shell). The thermal stability of the nanocomposites is improved as confirmed by measuring an increase on the Temperature of Decomposition and the Cross-Linking Temperature compared to bare polymer. Electrochemical characterization reveals that the presence of the additives does not affect the electroactive behaviour of the matrix polymer allowing it to reversely shift from different oxidation stages. The effect of additive content on the charge transfer kinetics is discussed.

Mechanical and thermal characterization of grafted PP-NCC nanocomposites

2019 ◽  
pp. 089270571987822
Author(s):  
Saud Aldajah ◽  
Mohammad Y Al-Haik ◽  
Waseem Siddique ◽  
Mohammad M Kabir ◽  
Yousef Haik
Keyword(s):  
Thermal Properties ◽  
Interfacial Adhesion ◽  
Thermal Characterization ◽  
Mechanical And Thermal Properties ◽  
Screw Extruder ◽  
Scanning Calorimetry ◽  
Three Point Bending ◽  
Twin Screw ◽  
Thermal Stability Of

This study reveals the enhancement of mechanical and thermal properties of maleic anhydride-grafted polypropylene (PP- g-MA) with the addition of nanocrystalline cellulose (NCC). A nanocomposite was manufactured by blending various percentages of PP, MA, and NCC nanoparticles by means of a twin-screw extruder. The influence of varying the percentages of NCC on the mechanical and thermal behavior of the nanocomposite was studied by performing three-point bending, nanoindentation, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and Fourier-transform infrared (FTIR) spectroscopy tests. The novelty of this study stems on the NCC nanoparticles and their ability to enhance the mechanical and thermal properties of PP. Three-point bending and nanoindentation tests revealed improvement in the mechanical properties in terms of strength, modulus, and hardness of the PP- g-MA nanocomposites as the addition of NCC increased. SEM showed homogeneity between the mixtures which proved the presence of interfacial adhesion between the PP- g-MA incorporated with NCC nanoparticles that was confirmed by the FTIR results. DSC and TGA measurements showed that the thermal stability of the nanocomposites was not compromised due to the addition of the coupling agent and reinforced nanoparticles.

scholarly journals Preparation and Characterization of Spherical Submicron CL-20 by Siphon Spray Refinement

2020 ◽  
Vol 2020 ◽  
pp. 1-9 ◽  
Author(s):  
Jiangtao Xing ◽  
Weili Wang ◽  
Wenzheng Xu ◽  
Tianle Yao ◽  
Jun Dong ◽  
...  
Keyword(s):  
Impact Sensitivity ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Crystal Forms ◽  
Refined Method ◽  
Diffraction Angle ◽  
Ultrasonic Assisted ◽  
The Impact ◽  
Thermal Stability Of

In order to improve the safety of hexanitrohexaazaisowurtzitane (CL-20), submicron CL-20 particles were prepared by a siphon ultrasonic-assisted spray refining experimental device. The samples were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and differential scanning calorimetry (DSC), and the impact sensitivity of the samples was tested. The results show that the particle size of siphon-refined CL-20 is about 800 nm~1 μm, which is more smooth, mellow, and dense than that of CL-20 prepared by a traditional pressure-refined method. The peak diffraction angle of pressure- and siphon-refined CL-20 is basically the same as that of raw CL-20, and their crystal forms are ε type. The peak strength of pressure- and siphon-refined CL-20 decreased obviously. The apparent activation energy of pressure-refined CL-20 and siphon-refined CL-20 is 13.3 kJ/mol and 11.95 kJ/mol higher than that of raw CL-20, respectively. The thermal stability of CL-20 is improved. The activation enthalpy (ΔH#) is significantly higher than that of raw CL-20, and the characteristic drop is 70.4% and 82.7% higher than that of raw CL-20. The impact sensitivity of siphon-refined CL-20 is lower than that of pressure-refined CL-20, so the safety performance of an explosive is improved obviously.

scholarly journals Characterization of the Interface Between the Bulk Glass Forming Alloy Zr41Ti14Cu12Ni10Be23 with Pure Metals and Ceramics

2000 ◽  
Vol 15 (7) ◽  
pp. 1617-1621 ◽  
Author(s):  
Jan Schroers ◽  
Konrad Samwer ◽  
Frigyes Szuecs ◽  
William L. Johnson
Keyword(s):  
Sessile Drop ◽  
Bulk Glass ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Glass Forming ◽  
Processing Times ◽  
Thermal Stability Of

The reaction of the bulk glass forming alloy Zr41Ti14Cu12Ni10Be23 (Vit 1) with W, Ta, Mo, AlN, Al2O3, Si, graphite, and amorphous carbon was investigated. Vit 1 samples were melted and subsequently solidified after different processing times on discs of the different materials. Sessile drop examinations of the macroscopic wetting of Vit 1 on the discs as a function of temperature were carried out in situ with a digital optical camera. The reactions at the interfaces between the Vit 1 sample and the different disc materials were investigated with an electron microprobe. The structure and thermal stability of the processed Vit 1 samples were examined by x-ray diffraction and differential scanning calorimetry. The results are discussed in terms of possible applications for composite materials.

The Synthesis and Characterization of the Graphene Oxide Covalent Modified Phenolic Resin Nanocomposites

2011 ◽  
Vol 327 ◽  
pp. 115-119 ◽  
Author(s):  
Duo Wang ◽  
Jie Gao ◽  
Wei Fang Xu ◽  
Feng Bao ◽  
Rui Ma ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Phenolic Resin ◽  
Synthesis And Characterization ◽  
Infrared Spectrometry ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Hummers Method ◽  
Modified Hummers Method ◽  
Thermal Stability Of

Graphene oxide (GO) was made by a modified Hummers method. Graphene oxide modified phenolic resin nanocomposites (GO/PF) were prepared by Steglich esterification, catalyzed by dicyclohexyl carbodiimide and 4-dimethylaminopyridine. The composites were characterized by Fourier transform infrared spectrometry, differential scanning calorimetry, X-ray powder diffraction, and scanning electron microscopy. The result revealed that the graphene oxide was absolutely exfoliated and covalent linked GO/PF composite was obtained. The thermal stability of PF is remarkably improved by modification with GO.

Preparation and characterization of phase-change energy storage nonwoven fabric

2021 ◽  
pp. 152808372110417
Author(s):  
Zhou Zhao ◽  
Ningning Tong ◽  
Hong Song ◽  
Yan Guo ◽  
Jinmei Wang
Keyword(s):  
Phase Transition ◽  
Thermal Stability ◽  
Energy Storage ◽  
Phase Change ◽  
Nonwoven Fabric ◽  
Scanning Calorimetry ◽  
Change Material ◽  
Stretching Process ◽  
Thermal Stability Of

In this work, a phase-change energy storage nonwoven fabric was made of polyurethane phase-change material (PUPCM) by a non-woven melt-blown machine. Polyethylene glycol 2000 was used as the phase transition unit and diphenyl-methane-diisocyanate as the hard segment to prepare PUPCM. Thermal stability of the PUPCM was evaluated through thermal stability analysis. The performance of pristine PUPCM was determined by Fourier transform infrared spectroscopy and differential scanning calorimetry to analyze the spinning technology of spinning temperature and the stretching process. Phase-change energy storage nonwoven fabric (413.22 g/m2) was prepared, and the morphology, solid–solid exothermic phase transition, mechanical properties, and the structures were characterized. The enthalpy of solid–solid exothermic phase transition reached 60.17 mJ/mg (peaked at 23.14°C). The enthalpy of solid–solid endothermic phase transition reached 67.09 mJ/mg (peaked at 34.34°C). The strength and elongation of phase-change energy storage nonwoven fabric were found suitable for garments and tent fabrics.

Preparation and Characterization of Degradable Poly(silyl ester) and the Self-Crosslinking Reaction of Poly(silyl ester) without Solvent

2010 ◽  
Vol 129-131 ◽  
pp. 862-866
Author(s):  
De Jie Zhou ◽  
Nian Feng Han ◽  
Xin De Tang
Keyword(s):  
The Self ◽  
Crosslinking Reaction ◽  
Scanning Calorimetry ◽  
Viscous Liquids ◽  
Tert Butyl ◽  
Silyl Ester ◽  
Linear Poly ◽  
Thermal Stability Of ◽  
Better Than

The new poly(silyl ester) has been prepared by the polycondensation reaction of 1,5-dichloro-1,1,5,5-tetramethyl-3,3-diphenyl-trisi1oxane with di-tert-butyl fumarate by the elimination of tert-butyl chloride as a driving force. To investigate the self-crosslinking reaction of the unsaturated poly(silyl ester), poly(1,1,5,5-tetramethyl-3,3-diphenyltrisiloxane) was self- crosslinked in the presence of 2, 2'-azobis(isobutyronitri1e) (AIBN) as a radical initiator without solvent. After the self-crosslinking, the unsaturated poly(silyl ester), which was viscous liquids, turned into solid product. The characterization of the poly(silyl ester) and the self-crosslinked product included 1H-NMR spectroscopy, differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). Comparisons were made between the linear poly(silyl ester) and the self-crosslinked products. It was found that after crosslinking, the important resonance signal for ethenylene (C=C) of the poly(silyl ester) reduced, which show that the crosslinking reaction is carried out. The self-crosslinked product exist the structures of linear isomer and four-membered ring isomer. The glass-transition temperatures of the self-crosslinked poly(silyl ester) was higher than that of the uncrosslinked poly(silyl ester), and the thermal stability of the self-crosslinked poly(silyl ester) was better than that of uncrosslinked poly(silyl ester).

scholarly journals Thermal characterization of novel aliphatic polyesters with ether and thioether linkages

e-Polymers ◽  
2010 ◽  
Vol 10 (1) ◽  
Author(s):  
M. Soccio ◽  
N. Lotti ◽  
L. Finelli ◽  
A. Munari
Keyword(s):  
Thermal Stability ◽  
Molecular Weight ◽  
Chemical Structure ◽  
Room Temperature ◽  
Crystallization Rate ◽  
Thermal Characterization ◽  
Scanning Calorimetry ◽  
Aliphatic Polyesters ◽  
Good Thermal Stability

AbstractSeveral novel ether or thioether linkage containing aliphatic polyesters and poly(alkylene dicarboxylate)s were synthesized for comparison and characterized in terms of chemical structure and molecular weight. The thermal behavior was examined by thermogravimetric analysis and differential scanning calorimetry. All the polymers showed a good thermal stability, even though lower for the ether or thioether linkage-containing polyesters. The decrement of the thermal stability appears to be more relevant in the case of the presence of sulphur atoms. At room temperature the samples appeared semicrystalline, except PTTDG and PDEDG, which were viscous oils; the effect of the introduction of ether or thioether group was an increment of the Tgvalue, a decrement of the melting temperature and a significant decrease of the crystallization rate. The entity of the variations was found to be affected by the kind of group introduced, and the trend observed can be explained on the basis of atom electronegativity and dimensions

Sign in / Sign up

Export Citation Format

Share Document