scholarly journals Brazilian gutta-percha points. Part II: thermal properties

2007 ◽  
Vol 21 (1) ◽  
pp. 29-34 ◽  
Author(s):  
Cláudio Maniglia-Ferreira ◽  
Eduardo Diogo Gurgel-Filho ◽  
João Batista Araújo Silva Jr ◽  
Regina Célia Monteiro de Paula ◽  
Judith Pessoa Andrade Feitosa ◽  
...  
Keyword(s):  
Differential Scanning Calorimetry ◽  
Thermal Properties ◽  
Physical Properties ◽  
Ambient Temperature ◽  
Amorphous Phase ◽  
Thermal Behaviour ◽  
Chemical Structure ◽  
Scanning Calorimetry ◽  
Gutta Percha ◽  
Thermal Manipulation

This study was undertaken to explore the effect of heating on gutta-percha, analyzing the occurrence of endothermic peaks corresponding to the transformation that occurs in the crystalline structure of the polymer during thermal manipulation. This study also seeked to determine the temperature at which these peaks occur, causing a transformation from the beta- to the alpha-form, and from the alpha- to the amorphous phase. Eight nonstandardized gutta-percha points commercially available in Brazil (Konne, Tanari, Endopoint, Odous, Dentsply 0.04, Dentsply 0.06, Dentsply TP, Dentsply FM) and pure gutta-percha (control) were analysed using differential scanning calorimetry (DSC) and thermogravimetry analysis (TGA). The transition temperatures were determined and analysed. With the exception of Dentsply 0.04 and Dentsply 0.06, the majority of the products showed thermal behaviour typical of beta-gutta-percha, with two endothermic peaks, exhibiting two crystalline transformations upon heating from ambient temperature to 130°. Upon cooling and reheating, few samples presented two endothermic peaks. It was concluded that heating dental gutta-percha to 130°C causes changes to its chemical structure which permanently alter its physical properties.

scholarly journals Improved Processing and Properties for Polyphenylene Oxide Modified by Diallyl Orthophthalate Prepolymer

Polymers ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 2016
Author(s):  
Honghua Wang ◽  
Qilin Mei ◽  
Yujie Ding ◽  
Zhixiong Huang ◽  
Minxian Shi
Keyword(s):  
Differential Scanning Calorimetry ◽  
Thermal Properties ◽  
Phase Separation ◽  
Dilution Effect ◽  
Gradual Decrease ◽  
Gel Point ◽  
Dynamic Mode ◽  
Curing Process ◽  
Scanning Calorimetry ◽  
Polyphenylene Oxide

Diallyl orthophthalate (DAOP) prepolymer was investigated as a reactive plasticizer to improve the processability of thermoplastics. The rheology of blends of DAOP prepolymer initiated by 2,3-dimethyl-2,3-diphenylbutane (DMDPB) and polyphenylene oxide (PPO) was monitored during the curing process, and their thermal properties and morphology in separated phases were also studied. Differential scanning calorimetry (DSC) results showed that the cure degree of the reactively plasticized DAOP prepolymer was reduced with increasing PPO due to the dilution effect. The increasing amount of the DAOP prepolymer led to a gradual decrease in the viscosity of the blends and the rheology behavior was consistent with the chemical gelation of DAOP prepolymer in blends. This indicated that the addition of the DAOP prepolymer effectively improved processability. The phase separation occurring during curing of the blend and the transition from the static to dynamic mode significantly influences the development of the morphology of the blend corresponding to limited evolution of the conversion around the gel point.

scholarly journals Synthesis and mesomorphic properties of calamitic malonates and cyanoacetates tethered to 4-cyanobiphenyls

2012 ◽  
Vol 8 ◽  
pp. 371-378 ◽  
Author(s):  
Katharina C Kress ◽  
Martin Kaller ◽  
Kirill V Axenov ◽  
Stefan Tussetschläger ◽  
Sabine Laschat
Keyword(s):  
Differential Scanning Calorimetry ◽  
Ambient Temperature ◽  
Liquid Crystalline ◽  
X Ray Diffraction ◽  
Cyanoacetic Acid ◽  
Scanning Calorimetry ◽  
Isotropic Liquid ◽  
X Ray ◽  
Nematic Phases ◽  
Mesomorphic Properties

4-Cyano-1,1'-biphenyl derivatives bearing ω-hydroxyalkyl substituents were reacted with methyl 3-chloro-3-oxopropionate or cyanoacetic acid, giving liquid-crystalline linear malonates and cyanoacetates. These compounds formed monotropic nematic phases at 62 °C down to ambient temperature upon cooling from the isotropic liquid. The mesomorphic properties were investigated by differential scanning calorimetry, polarizing optical microscopy and X-ray diffraction (WAXS).

scholarly journals Processing of (Co)Poly(2-oxazoline)s by Electrospinning and Extrusion from Melt and the Postprocessing Properties of the (Co)Polymers

Polymers ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 295 ◽  
Author(s):  
Wojciech Wałach ◽  
Natalia Oleszko-Torbus ◽  
Alicja Utrata-Wesołek ◽  
Marcelina Bochenek ◽  
Ewa Kijeńska-Gawrońska ◽  
...  
Keyword(s):  
Differential Scanning Calorimetry ◽  
Thermal Properties ◽  
Molar Mass ◽  
Three Dimensional ◽  
Fused Deposition Modelling ◽  
Processing Conditions ◽  
Structure And Properties ◽  
Scanning Calorimetry ◽  
Gradient Copolymers ◽  
Fused Deposition

Poly(2-oxazoline) (POx) matrices in the form of non-woven fibrous mats and three-dimensional moulds were obtained by electrospinning and fused deposition modelling (FDM), respectively. To obtain these materials, poly(2-isopropyl-2-oxazoline) (PiPrOx) and gradient copolymers of 2-isopropyl- with 2-n-propyl-2-oxazoline (P(iPrOx-nPrOx)), with relatively low molar masses and low dispersity values, were processed. The conditions for the electrospinning of POx were optimised for both water and the organic solvent. Also, the FDM conditions for the fabrication of POx multi-layer moulds of cylindrical or cubical shape were optimised. The properties of the POx after electrospinning and extrusion from melt were determined. The molar mass of all (co)poly(2-oxazoline)s did not change after electrospinning. Also, FDM did not influence the molar masses of the (co)polymers; however, the long processing of the material caused degradation and an increase in molar mass dispersity. The thermal properties changed significantly after processing of POx what was monitored by increase in enthalpy of exo- and endothermic peaks in differential scanning calorimetry (DSC) curve. The influence of the processing conditions on the structure and properties of the final material were evaluated having in a mind their potential application as scaffolds.

Study of thermal properties of Ga0.5In1.5Se3 by differential scanning calorimetry

2021 ◽  
pp. 2150407
Author(s):  
S. I. Ibrahimova
Keyword(s):  
Crystal Structure ◽  
Differential Scanning Calorimetry ◽  
Thermal Properties ◽  
Thermal Effects ◽  
Room Temperature ◽  
Structural Studies ◽  
X Ray Diffraction ◽  
Hexagonal Symmetry ◽  
Scanning Calorimetry ◽  
X Ray

The crystal structure and thermal properties of the [Formula: see text] compound have been investigated. Structural studies were performed by X-ray diffraction at room temperature. The crystal structure of this compound was found to correspond to the hexagonal symmetry of the space group P61. Thermal properties were studied using a differential scanning calorimetry (DSC). It was found in the temperature range [Formula: see text] that thermal effects occur at temperatures [Formula: see text] and [Formula: see text]. The thermodynamic parameters of these effects are calculated.

A Deep Blue Organic Light Emitting Diodes Characteristic of Isomerically-Featured Phosphine Oxides Containing N-Phenyl Benzimidazole

2020 ◽  
Vol 20 (8) ◽  
pp. 4657-4660
Author(s):  
Kyeong Hyeon Kim ◽  
Jae Hyeok Lee ◽  
Dong-Eun Kim ◽  
Hoon-Kyu Shin ◽  
Burm-Jong Lee
Keyword(s):  
Differential Scanning Calorimetry ◽  
Thermal Properties ◽  
Thermogravimetric Analysis ◽  
Light Emitting Diodes ◽  
Organic Light Emitting Diodes ◽  
Phosphine Oxides ◽  
Scanning Calorimetry ◽  
Light Emitting ◽  
Deep Blue ◽  
Organic Light

An isomeric series of phosphine oxides with N-phenyl benzimidazole such as 2-DPPI, 3-DPPI and 4-DPPI were synthesized for organic light emitting diodes (OLED). The thermal properties of DPPI isomers were determined by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). OLED devices using DPPI isomers as the emitting material were fabricated, which configuration was ITO/MoOx [30 nm]/NPB [500 nm]/DPPI [300 nm]/Alq3 [200 nm]/Liq[10 nm]/Al [120 nm]. The emitting colors of the devices were respectively a deep-blue (430 nm, 4-DPPI) and greenish-yellows (510–580 nm, 3-DPPI and 530 nm, 2-DPPI). In particular, the emitting color of 4-DPPI device was not changed during the alteration of applied voltages (6.5–11.5 V), and the CIE coordinate was a satisfactory deep-blue (0.161, 0.101).

Thermal properties of cowpea flour: A study by differential scanning calorimetry

Nahrung/Food ◽  
2003 ◽  
Vol 47 (3) ◽  
pp. 161-165 ◽  
Author(s):  
Folake O. Henshaw ◽  
Kay H. McWatters ◽  
John O. Akingbala ◽  
Manjeet S. Chinnan
Keyword(s):  
Differential Scanning Calorimetry ◽  
Thermal Properties ◽  
Scanning Calorimetry ◽  
Cowpea Flour

Synergistic Antioxidation Properties of Tin Dialkyldithiocarbamate With Dialkyldiphenylalmine

2009 ◽  
Author(s):  
Jian-Qiang Hu ◽  
Ke-Yi Gao ◽  
Da-Wei Liu
Keyword(s):  
Thin Film ◽  
Differential Scanning Calorimetry ◽  
Fourier Transform ◽  
Chemical Structure ◽  
Ftir Analysis ◽  
Synthetic Lubricant ◽  
Scanning Calorimetry ◽  
Oxidation Induction Time ◽  
Pentaerythritol Ester ◽  
Carbonyl Peak

Differential scanning calorimetry (DSC) and thin film micro oxidation test (TMOT) were employed to evaluate the antioxidation properties of tin dialkyldithiocarbamate (SnDDC) with p,p′dioctyldiphenylamine (DODPA) antioxidant in pentaerythritol ester (PE) or polyalphaolefin synthetic lubricant (PAO), and their chemical structure were identified by fourier transform infrared spectroscopy (FTIR) analysis. DSC test shows that incipient oxidation temperature and oxidation induction time of DODPA-containing PE were improved significantly by SnDDC addition, SnDDC shows a good oxidative synergism with DODPA antioxidant. TMOT results indicates that the combination of SnDDC and DODPA in polyalphaolefin can also effectively reduce the weight lost, carbonyl peak square index and diposits of oxidized oils, which confirm that the combination of SnDDC and DODPA exhibit good synergistic antioxidation properties and deposits inhibition.

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