scholarly journals Molecular Simulation of Improved Mechanical Properties and Thermal Stability of Insulation Paper Cellulose by Modification with Silane-Coupling-Agent-Grafted Nano-SiO2

Processes ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 766
Author(s):  
Zhengxiang Zhang ◽  
Haibin Zhou ◽  
Wentao Li ◽  
Chao Tang
Keyword(s):  
Mechanical Properties ◽  
Thermal Stability ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Mechanical Parameters ◽  
Nano Sio2 ◽  
Silane Coupling ◽  
Thermal Stability Of ◽  
Trimethoxy Silane

Cellulose is an important part of transformer insulation paper. Thermal aging of cellulose occurs in long-term operation of transformers, which deteriorates the mechanical properties and thermal stability of cellulose, resulting in a decrease in the transformer life. Therefore, improvement of the mechanical properties and thermal stability of cellulose has become a research hotspot. In this study, the effects of different silane coupling agents on the mechanical properties and thermal stability of modified cellulose were studied. The simulation results showed that the mechanical parameters of cellulose are only slightly improved by KH560 (γ-glycidyl ether oxypropyl trimethoxysilane) and KH570 (γ-methylacrylloxy propyl trimethoxy silane) modified nano-SiO2, while the mechanical parameters of cellulose are greatly improved by KH550 (γ-aminopropyl triethoxy silane) and KH792 (N-(2-aminoethyl)-3-amino propyl trimethoxy silane) modified nano-SiO2. The glass-transition temperature of the composite model is 24 K higher than that of the unmodified model. The mechanism of the change of the glass-transition temperature was analyzed from the point of view of free-volume theory. The main reason for the change of the glass-transition temperature is that the free volume abruptly changes, which increases the space for movement of the cellulose chain and accelerates the whole movement of the molecular chain. Therefore, modifying cellulose with KH792-modified nano-SiO2 can significantly enhance the thermal stability of cellulose.

Nanocomposite Epoxy Resin for SiC Module

2011 ◽  
Vol 2011 (HITEN) ◽  
pp. 000196-000200 ◽  
Author(s):  
Kenji Okamoto ◽  
Yuji Takematsu ◽  
Miyako Hitomi ◽  
Yoshinari Ikeda ◽  
Yoshikazu Takahashi
Keyword(s):  
Thermal Stability ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Epoxy Resin ◽  
Molecular Motion ◽  
Experimental Results ◽  
Power Module ◽  
Operation Temperature ◽  
Thermal Stability Of

There is a demand to improve the thermal stability of epoxy molding resins used in the power module of SiC power chips operating at temperatures of 200°C or more. This paper describes a technique for increasing the thermal stability of the resin by decreasing molecular motion through the addition of nanofiller. The experimental results showed that the glass transition temperature (Tg) of the epoxy resin increased by approximately 30°C when the silica nanofiller was added. The epoxy resin added nanofiller was investigated in order to achieve the operation temperature 200°C of power module.

Thermal Properties of Acrylic Resin Denture Base Material Containing Silver Nanoparticle Synthesized from Aqueous Extract of Boesenbergia rotunda

2018 ◽  
Vol 777 ◽  
pp. 173-177
Author(s):  
Panjaporn Wongwitthayakool ◽  
Matsayapan Pudla
Keyword(s):  
Thermal Stability ◽  
Glass Transition ◽  
Thermal Properties ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Base Material ◽  
Acrylic Resin ◽  
Denture Base ◽  
Acrylic Resins ◽  
Thermal Stability Of

Silver nanoparticles (AgNPs) were synthesized by bioreduction method using aqueous extracts of Boesenbergia rotunda as reducing and stabilizing agents. Ultraviolet-Visible (UV-Vis) spectrophotometer was utilized to monitor the qualitative formation of AgNPs. The UV-Vis spectrum showed that the spherical AgNPs with diameter of 20-40 nm were formed. The antifugal activity of synthesized AgNPs was investigated using Candida albicans, which was found that the synthesized AgNPs could be used as effective growth inhibitors. The influence of the incorporation of prepared AgNPs on thermal properties of the acrylic denture base material was investigated. Glass transition temperature of filled acrylic resins was studied using the dynamic mechanical analyzer (DMA). The temperature sweeps were performed with tension mode. Thermogravimetry analysis (TGA) was used to examine effect of AgNP concentration and thermocycling (1250, 2500, 5000, and 10000 cycles) on thermal stability of AgNP filled acrylic resin denture base materials. Glass transition temperature (Tg) of the acrylic resins slightly increase with increasing AgNP contents. TGA results indicated that AgNP retarded thermal degradation of acrylic resin denture material, and thermocycling did not affect thermal stability of AgNP filled acrylic resin denture material.

Isothermal Crystallization of Zr55Al10Ni5Cu30 Bulk Amorphous Alloy Near the Glass Transition Temperature

2004 ◽  
Vol 449-452 ◽  
pp. 933-936 ◽  
Author(s):  
Zhuang Qi Hu ◽  
Q.S. Zhang ◽  
Hai Feng Zhang ◽  
B.Z. Ding ◽  
Z.M. Rao
Keyword(s):  
Thermal Stability ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Amorphous Alloy ◽  
Amorphous Phase ◽  
Isothermal Crystallization ◽  
Metastable Phases ◽  
Bulk Amorphous Alloy ◽  
Thermal Stability Of

Isothermal crystallization of Zr55Al10Ni5Cu30bulk amorphous alloy near the glass transition temperature has been investigated. The microstructures and thermal stability of the annealed amorphous alloy were examined by HRTEM, XRD and DSC. The amorphous phase in the Zr55Al10Ni5Cu30bulk amorphous alloy crystallized at 420°C through the following processes of amorphous →amorphous with clusters + metastable phases→metastable phases.

Effects of graphene on thermal properties and thermal stability of polycarbonate/graphene nanocomposite

2021 ◽  
pp. 089270572199788
Author(s):  
Md Amir Sohel ◽  
Abhijit Mondal ◽  
P Mohammad Arif ◽  
Sabu Thomas ◽  
Asmita SenGupta
Keyword(s):  
Thermal Stability ◽  
Thermal Decomposition ◽  
Glass Transition ◽  
Thermal Properties ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Multilayer Graphene ◽  
Melt Mixing ◽  
Graphene Nanocomposite ◽  
Thermal Stability Of

Polycarbonate (PC) /graphene nanocomposite was prepared using multilayer graphene (MLG) with loadings of 0.5, 1, and 3 wt% via melt mixing process. Morphological, structural, and thermal properties of the PC/MLG nanocomposites are investigated to look into the influence of MLG on the nanocomposite. A significant increase (∼6.4°C) in glass transition temperature is observed upon the addition of 3 wt% of MLG into the polycarbonate matrix. This increase in glass transition temperature may be due to the interaction between the MLG and polycarbonate polymer matrix. The specific heat capacity of pure PC and PC/MLG nanocomposites varies linearly with temperature below their glass transition. Upon the addition of MLGs, the overall thermal stability of PC/MLG nanocomposites increases with MLG loadings. A maximum increase about 29.23°C in T onset of thermal decomposition is observed in PC/MLG nanocomposite having 3 wt% of MLG loading. The activation energy ( Ea) of thermal decomposition is also calculated by kinetic analysis of thermal decomposition of the PC/MLG nanocomposites using Horowitz–Metzger and Broido’s methods.

scholarly journals Synthesis of Fe75Si20-xB5Mx (M=Ti, Ta or Zr) Powders by Wet Mechanical Milling

2015 ◽  
Vol 13 ◽  
pp. 54-58
Author(s):  
Horea Florin Chicinaş ◽  
Bogdan Viorel Neamţu ◽  
Traian Florin Marinca ◽  
Ionel Chicinaş
Keyword(s):  
Thermal Stability ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Transition Metals ◽  
Mechanical Alloying ◽  
Crystallization Temperature ◽  
Mechanical Milling ◽  
Thermal Stability Of

Amorphous Fe75Si20-xB5Mxpowders with M= Ti, Ta or Zr andx= 0 and 5 were synthesized by wet mechanical alloying, using benzene as a surfactant. The thermal stability of the Fe-Si-B alloy increases by introducing transition metals. The replacement of 5% Si with Ti, Ta or Zr leads to an increase of the crystallization temperature. It was found that the replacement of 5% Si with Zr increases the crystallization temperature with 115 °C, and also reveals a glass transition temperature around 580 °C.

Rare Earth Elements on Glass-Forming Ability and Thermal Stability of Cu-Zr-Al Metallic Glass

2011 ◽  
Vol 688 ◽  
pp. 426-430 ◽  
Author(s):  
Yan Fang Wang ◽  
Li Li ◽  
Chuan Sun ◽  
Qing Long Lu ◽  
Zhi Qiang Shi
Keyword(s):  
Thermal Stability ◽  
Glass Transition ◽  
Rare Earth ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Metallic Glass ◽  
Rare Earth Elements ◽  
Glass Forming Ability ◽  
Glass Forming ◽  
Thermal Stability Of

The rare earth elements (RE= Y, Sm, La, Ce) were used as alloying materials in Cu50Zr45Al5BMG, and their influences on the glass-forming ability and thermal stability were studied in this paper. All the samples remained in full metallic glass state with minor additions of Y, Sm and La. Increasing the amount of RE additions, the Cu10Zr7and Zr2Cu phases precipitated and glass transition temperatureTgand crystallization temperatureTxsignificantly decreased. The reduced glass transition temperature Trg=Tg/Tlranged from 0.592 to 0.611 and the γ parameter ranged from 0.393 to 0.409.

scholarly journals High Thermally Stable and Melt Processable Polyimide Resins Based on Phenylethynyl-Terminated Oligoimides Containing Siloxane Structure

Materials ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 3742
Author(s):  
Xiaozhou Xu ◽  
Yi Liu ◽  
Bangwei Lan ◽  
Song Mo ◽  
Lei Zhai ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Rheological Properties ◽  
Chemical Crosslinking ◽  
Thermally Stable ◽  
Melt Viscosity ◽  
Biphenyltetracarboxylic Dianhydride ◽  
Thermal Stability Of

A series of 4-phenylethnylphthalic anhydride (PEPA)-terminated oligoimides were prepared by co-oligomerizing isomeric dianhydrides, i.e., 2,3,3′,4′-biphenyltetracarboxylic dianhydride (a-BPDA), 2,3,3′,4′-benzophenonetetracarboxylic dianhydride (a-BTDA) or 2,3,3′,4′-diphenylethertetracarboxylic dianhydride (a-ODPA), with diamines mixture of bis(4-aminophenoxy)dimethyl silane (APDS) and 2,2′-bis(trifluoromethyl) benzidine (TFDB). The effects of siloxane content and dianhydride structure on the rheological properties of these oligoimides and thermal stability of the corresponding cured polyimide resins were investigated. The results indicated that the introduction of the siloxane structure improved the melt processability of the oligoimides, while the thermal stability of the cured polyimide resins reduced. The oligoimide derived from a-ODPA revealed better melt processability and melt stability due to the existence of a flexible dianhydride structure. The oligoimide PIS-O10 derived from a-ODPA gave the lowest minimum melt viscosity of 0.09 Pa·s at 333 °C and showed the excellent melt stability at 260 °C for 2 h with the melt viscosity in the range of 0.69–1.63 Pa·s. It is also noted that the thermal stability of these resins can be further enhanced by postcuring at 400–450 °C, which is attributed to the almost complete chemical crosslinking of the phenyethynyl combined with oxidative crosslinking of siloxane. The PIS-T10 and PIS-O10 resins that were based on a-BTDA and a-ODPA, respectively, even showed a glass transition temperature over 550 °C after postcuring at 450 °C for 1 h.

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