Synthesis and Thermal Properties of Azobenzene Core Polyester Dendrimers with Trityl Groups at the Periphery

2018 ◽  
Vol 762 ◽  
pp. 171-175 ◽  
Author(s):  
Lauma Laipniece ◽  
Valdis Kampars
Keyword(s):  
Glass Transition ◽  
Thermal Properties ◽  
Growth Strategy ◽  
Transition Temperatures ◽  
Glass Transition Temperatures ◽  
The Core ◽  
Azobenzene Chromophore

We have synthesized polyester type dendrimers containing azobenzene chromophore in the core and trityl groups at the periphery using divergent growth strategy up to 3rdgeneration. We analyzed dendrimer samples using NMR, HPLC, TG, DSC and UV-Vis techniques. We found out that functionalization of dendrimer periphery is not complete. Dendrimers with trityl groups at the periphery have glass transition temperatures in the range 73-87 °C.

The Preparation and Properties of A New Family of Amorphous Fluoropolymers: Teflon® Af

1989 ◽  
Vol 167 ◽  
Author(s):  
Paul R. Resnick
Keyword(s):  
Thin Films ◽  
Glass Transition ◽  
Thermal Properties ◽  
Physical Properties ◽  
Chemical Resistance ◽  
Transition Temperatures ◽  
Glass Transition Temperatures ◽  
New Family ◽  
The Family ◽  
Solution Cast

AbstractTeflon® AF is a family of amorphous fluoropolymers with glass transition temperatures as high as 300° based on bis-2,2-trfluoromethyl-4,5-difluoro-1,3-dioxole, (I), which has unusual properties [1–3] (Figure 1). The family retains the superior electrical, chemical resistance and thermal properties associated with fluoropolymers. In addition the polymers have high optical clarity, limited solubility in some commercially available perfluorinated ethers such as Fluorinert® FC-75 and improved physical properties below their glass transition temperatures (Figure 2). Teflon® AF polymers may be either solution cast into clear micron thin films or melt processed into a variety of forms.

Synthesis of novel allylamine-fluorene based benzoxazine and its copolymerization with typical benzoxazine: curing behavior and thermal properties

2020 ◽  
Vol 44 (43) ◽  
pp. 18917-18928
Author(s):  
Ting Wang ◽  
Zhi-cheng Wang ◽  
Zhong-cheng Pan ◽  
Abdul Qadeer Dayo ◽  
Wen-bin Liu ◽  
...  
Keyword(s):  
Glass Transition ◽  
Thermal Properties ◽  
Transition Temperatures ◽  
Glass Transition Temperatures ◽  
Curing Behavior

Poly(t-BF-sa-a) showed much better thermal properties and glass transition temperatures than traditional fluorene-based benzoxazine monomers.

Influence of water absorption on mechanical properties and glass transition temperatures of polyamide6/hexagonal boron nitride composites

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Kawaljit Singh Randhawa ◽  
Ashwin Patel
Keyword(s):  
Glass Transition ◽  
Thermal Properties ◽  
Hexagonal Boron Nitride ◽  
Water Molecules ◽  
Mechanical And Thermal Properties ◽  
Transition Temperatures ◽  
Glass Transition Temperatures ◽  
Content Type ◽  
Environmental Humidity ◽  
Influence Of Water

PurposeThe absorption of moisture/water can affect the mechanical and thermal properties of polymers and polymer composites as many polymers, mainly polyamide thermoplastics, are sensitive to environmental humidity and can absorb a large amount of moisture. This paper investigates the effect of water molecules' absorption on mechanical and thermal properties of polyamide6/hexagonal boron nitride (PA6/h-BN) composites.Design/methodology/approachThe PA6/h-BN composites were exposed to an open environment and water for 15 days to analyse the effect of humidity/water molecules' absorption on mechanical and thermal properties. The tensile strength, hardness and impact strength of materials were measured and compared. The scanning electron microscopy (SEM), x-ray diffraction (XRD) and differential scanning calorimetry (DSC) analyses were utilized to see the influence of water absorption on microstructure, crystallinity and glass transition temperatures.FindingsAfter exposing materials to an open environment and water, the tensile strength and hardness were found to decline, while improvement in impact strength was noticed. SEM characterization revealed the formation of voids/pockets in water-immersed materials. DSC analysis revealed the loss in glass transition temperatures, and XRD analysis revealed the loss in crystallinity of water-immersed materials.Originality/valueEnvironmental conditions vary according to the geographical areas, and it varies in many countries throughout the year. Polyamides are sensitive to the environmental humidity and can absorb a large amount of moisture from the environment. It becomes necessary to test these materials in their original working conditions, and sometimes it is mandatory to see the effects of extreme environmental conditions on a component. In this article, efforts have been made to investigate the influence of extreme humidity/water conditions on thermo-mechanical properties of PA6/h-BN composites.

Processable Poly(Keto-Imide)s Having Bulky Pendent Ether Groups

1998 ◽  
Vol 10 (1) ◽  
pp. 1-10 ◽  
Author(s):  
S Tamai ◽  
W Yamashita ◽  
A Yamaguchi
Keyword(s):  
Glass Transition ◽  
Thermal Properties ◽  
Melting Point ◽  
Ambient Temperature ◽  
Organic Solvents ◽  
Pyromellitic Dianhydride ◽  
Transition Temperatures ◽  
Glass Transition Temperatures ◽  
Chemical Structures ◽  
Tetracarboxylic Dianhydride

1, 3-Bis(3-aminobenzoyl)benzene (BAB), 1, 3-bis(3-amino-4-phenoxybenzoyl)benzene (BAPB) and 1, 3-bis(3-amino-4-biphenoxybenzoyl)benzene (BABB) were synthesized from 1, 3-bis(3-nitro-4-chlorobenzoyl)benzene. By using these three diamines and commercially available tetracarboxylic dianhydrides such as 3, 3′, 4, 4′-benzophenone tetracarboxylic dianhydride (BTDA) and pyromellitic dianhydride (PMDA), several kinds of poly(keto-imide)s were synthesized. Thermal properties and processability such as melt-flowability and solubility in organic solvents of the obtained poly(keto-imide)s were investigated by focusing on the chemical structures of their repeating structure units. Inherent viscosities of poly(keto-imide)s ranged from 0.54 to 0.75 dl g−1. These poly(keto-imide)s displayed glass transition temperatures ( Tg) between 219 and 256 °C, and only the poly(keto-imide) prepared from BAB and PMDA showed a melting point ( Tm)at 451 °C. Melt-flowabilities of these poly(keto-imide)s except for BAB/PMDA poly(keto-imide) were observed between 285 and 330 °C. The poly(keto-imide)s having bulky pendent ether groups were soluble in chloroform, 1, 1, 2-trichloroethane, N, N-dimethylacetamide and m-cresol at ambient temperature.

Synthesis and Hole-Transporting Properties of Various Bicarbazyl Derivatives

2008 ◽  
Vol 8 (9) ◽  
pp. 4797-4802 ◽  
Author(s):  
Yoon-Mi Lee ◽  
Soo-Kang Kim ◽  
Chang-Jun Lee ◽  
Ji-Hoon Lee ◽  
Jong-Wook Park
Keyword(s):  
Glass Transition ◽  
Thermal Properties ◽  
Transition Temperatures ◽  
Glass Transition Temperatures ◽  
Hole Transporting ◽  
Luminance Efficiency

This paper reports a new HTL material that has high glass-transition temperatures (Tg) and excellent thermal properties. The synthesized material was N,N-diethyl-3,3′-bicarbazyl (DEBC), N,N-diphenyl-3,3′-bicarbazyl (DPBC) and N,N-dinaphthyl-3,3′-bicarbazyl (DNBC). The device that used DPBC as HTL showed the highest efficiency of 4.95 cd/A and 2.22 lm/W at 10 mA/cm2. This is an improvement by more than 10% from the luminance efficiency of NPB, a commercialized material.

Influence of moisture/water absorption on mechanical and thermal properties of polyamide6/boric oxide composites

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Kawaljit Singh Randhawa ◽  
Ashwin Patel
Keyword(s):  
Tensile Strength ◽  
Glass Transition ◽  
Thermal Properties ◽  
Water Immersion ◽  
Boric Oxide ◽  
Mechanical And Thermal Properties ◽  
Transition Temperatures ◽  
Glass Transition Temperatures ◽  
Content Type ◽  
Oxide Composites

Purpose This paper aims to investigate the mechanical and thermal behavior, i.e. tensile strength, hardness, impact strength and glass transition temperatures of water-treated polyamide6/boric oxide (PA) composites. Design/methodology/approach The PA6 and PA6/boric oxide composites were exposed to an open environment and immersed in water for 15 days to analyze the effect of environmental humidity and frequent water immersion conditions on the composite’s mechanical and thermal properties. The tensile strength, elastic modulus, hardness and impact strength of materials were measured to identify the mechanical properties. The scanning electron microscopy (SEM), X-ray diffraction (XRD) and differential scanning calorimetry (DSC) characterizations were used to see the effect of humidity/water absorption on microstructure, crystallinity and glass transition temperatures. Findings The testing results revealed the loss in strength, elastic modulus and hardness, while the impact resistance was improved after exposure of materials to humidity/water. SEM images clearly show the formation of voids and XRD graphs revealed the loss in crystallinity after water immersion. The DSC plots of water immersed materials revealed the loss of glass transition temperatures up to 15°C. Originality/value The mechanical and thermal behavior of PA composites varies according to the surrounding atmosphere. Experiments were performed to investigate the influence of water treatment on the PA6/B2O3 composite’s mechanical and thermal properties. Water treatment resulted in the bonding between PA and water molecules, which generated voids in the materials. These voids generations are found the main reason for the low strength and hardness of water-treated materials.

Degradability, thermal stability, and high thermal properties in spiro polycycloacetals partially derived from lignin

2021 ◽  
Author(s):  
Minjie Shen ◽  
Srikanth Vijjamarri ◽  
Hongda Cao ◽  
Karla Solis ◽  
Megan L. Robertson
Keyword(s):  
Thermal Stability ◽  
Glass Transition ◽  
Thermal Properties ◽  
High Performance ◽  
Transition Temperatures ◽  
Thermal Stabilities ◽  
Glass Transition Temperatures ◽  
Acidic Solutions

Spiro polycycloacetals were synthesized from vanillin and syringaldehyde, along with high-performance co-monomers, exhibiting high glass transition temperatures and thermal stabilities, and rapid rates of hydrolysis in acidic solutions.

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