scholarly journals p-Xylylenediamine and Its New Polyimides

2016 ◽  
Vol 6 (1) ◽  
pp. 45 ◽  
Author(s):  
Bulat A. Zhubanov ◽  
Valentina D. Kravtsova ◽  
Kair A. Zhubanov ◽  
Tleutay S. Abildin ◽  
Nagima B. Bizhanova
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Terephthalic Acid ◽  
Breaking Strength ◽  
Isonicotinic Acid ◽  
High Yield ◽  
Temperature Range ◽  
One Step ◽  
Dielectric Permitivity

<p><em>p</em>-Xylylenediamine was synthesized with high yield through a hydrogenization of dinitrile of terephthalic acid. The effect of catalyst and solvent on the yield of the product was studied. The hydrogenization was carried out on skeletal catalysts based on alloy of Reney nickel Ni:Al (1:1) in aliphatic alcohols (C<sub>1</sub>-C<sub>4</sub>) at 4.0 MPa and 60 <sup>o</sup>C. New alkanearomatic polyimides were synthesized by one-step polycondensation of <em>p</em>-xylylenediamine and dianhydride of tricyclodecentetracarboxylic acid in the presence of isonicotinic acid as a catalyst in nonpolar amide solvents at 110-120 <sup>o</sup>C. The films based on the synthesized polyalkanimides are stable with 70-80 MPa breaking strength and 30-40% elongation. The glass transition temperature of the polymers is within 265-280 <sup>o</sup>C temperature range, the temperature of decomposition is above 340 <sup>o</sup>C. The tangent of dielectic loss of the films at 1 kHz and 25 <sup>o</sup>C is 0.002-0.004, the dielectric permitivity is about 3.22-3.35.</p>

Study on the Crystallization Activation Energy of Poly (L-lactic acid) Nucleated with P-tert-butylcalix[8]arene

2018 ◽  
Vol 26 (2) ◽  
pp. 169-175
Author(s):  
Yaoqi Shi ◽  
Liang Wen ◽  
Zhong Xin
Keyword(s):  
Activation Energy ◽  
Lactic Acid ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Crystallization Temperature ◽  
Nucleating Agent ◽  
Crystallization Activation Energy ◽  
Temperature Range ◽  
Chain Mobility

The crystallization activation energy (Δ E) of a polymer comprises the nucleation activation energy Δ F and the transport activation energy Δ E*. In this paper, the Δ E of poly (L-lactic acid) (PLLA) nucleated with nucleating agent p- tert-butylcalix[8]arene (tBC8) was calculated. The results showed that the Δ E of nucleated PLLA was 165.97 kJ/mol, which is higher than that of pure PLLA. The reason why Δ E of PLLA increased when incorporating nucleating agent was studied. The increment of glass transition temperature ( Tg) for nucleated PLLA revealed that the polymer chain mobility was restricted by tBC8, which was considered as the reason for the increase of Δ E*. Further, polyethylene glycol (PEG) was added to improve the chain mobility, thus eliminated the variation of the transport activation energy Δ E* caused by tBC8. Then the effect of the increment of crystallization temperature range on the increase of Δ F was also taken into consideration. It was concluded that both decreasing the mobility of chain segments and increasing the crystallization temperature range caused an increase of Δ E for PLLA/tBC8.

Effect of Glass Transition Temperature Range on the Caking Behavior of Freeze-dried Carbohydrate Blend Powders

2020 ◽  
Author(s):  
Alex Eduardo Alvino Granados ◽  
Takumi Mochizuki ◽  
Kiyoshi Kawai
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Temperature Range ◽  
Freeze Dried

The Effect of Thermal History on Porcelain Expansion Behavior

1989 ◽  
Vol 68 (9) ◽  
pp. 1313-1315 ◽  
Author(s):  
C.W. Fairhurst ◽  
D.T. Hashinger ◽  
S.W. Twiggs
Keyword(s):  
Thermal Expansion ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Heating Rate ◽  
Room Temperature ◽  
Heating Rates ◽  
Thermal Expansion Data ◽  
Temperature Range ◽  
Expansion Behavior

Porcelain-fused-to-metal restorations are fired several hundred degrees above the glass-transition temperature and cooled rapidly through the glass-transition temperature range. Thermal expansion data from room temperature to above the glass-transition temperature range are important for the thermal expansion of the porcelain to be matched to the alloy. The effect of heating rate during measurement of thermal expansion was determined for NBS SRM 710 glass and four commercial opaque and body porcelain products. Thermal expansion data were obtained at heating rates of from 3 to 30°C/min after the porcelain was cooled at the same rate. By use of the Moynihan equation (where Tg systematically increases in temperature with an increase in cooling/heating rate), the glass-transition temperatures (Tg) derived from these data were shown to be related to the heating rate.

Deformation and ultimate properties of poly(butyl methacrylate) under uniaxial stretching over a broad temperature range around the glass-transition temperature

1987 ◽  
Vol 29 (8) ◽  
pp. 1872-1880 ◽  
Author(s):  
G.V. Vinogradov ◽  
V.Ye. Dreval ◽  
M.K. Kurbanaliyev ◽  
Ye.K. Borisenkova ◽  
M.P. Zabugina ◽  
...  
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Broad Temperature Range ◽  
Butyl Methacrylate ◽  
Uniaxial Stretching ◽  
Temperature Range ◽  
Ultimate Properties

Glass Transition Temperature Improvement for Polychloroprene by One-Step ATRP Reaction

2013 ◽  
Vol 18 (7) ◽  
pp. 488-494
Author(s):  
E. Rusen ◽  
A. Mocanu ◽  
C. Damian ◽  
A. Diacon
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
One Step

A Rapid Heating and Cooling Rate Dilatometer for Measuring Thermal Expansion in Dental Porcelain

1989 ◽  
Vol 68 (9) ◽  
pp. 1316-1318 ◽  
Author(s):  
S.W. Twiggs ◽  
J.R. Searle ◽  
R.D. Ringle ◽  
C.W. Fairhurst
Keyword(s):  
Thermal Expansion ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Rapid Heating ◽  
Optical Pyrometer ◽  
Thermal Expansion Data ◽  
Dental Porcelain ◽  
Temperature Range ◽  
Heating And Cooling

Herein we describe a dilatometer that consists of a low-mass infrared furnace for rapid heating or cooling, an optical pyrometer, and a laser interferometer. The dilatometer facilitates observations of thermal expansion at rates comparable with those in dental laboratory practice over the temperature range necessary for comparison of thermal expansion of dental porcelain and alloy. Examples of thermal expansion data obtained at a 600°Clmin heating rate on NIST SRM 710 glass and dental porcelain are reported. To a limited extent, thermal expansion data above the glass-transition temperature range of dental porcelain were obtained. A shift of the glass-transition temperature range to higher temperatures was observed for both materials, compared with data obtained at 20°Clmin.

scholarly journals Microstructure and Damping Property of Polyurethane Composites Hybridized with Ultraviolet Absorbents

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Jiang Chang ◽  
Bing Tian ◽  
Li Li ◽  
Yufeng Zheng
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Crystalline State ◽  
Interfacial Bonding ◽  
Damping Factor ◽  
Damping Property ◽  
Temperature Range ◽  
The Matrix ◽  
Polyurethane Composites

This article investigated the microstructure and damping property of TPU composites with different contents of ultraviolet absorbents. It can be found that the ultraviolet absorbents formed fiber-shaped precipitations in the TPU matrix. The UV-328 was randomly distributed in the matrix and exhibited a weak interfacial bonding with the matrix. In comparison, the UV-329 was well embedded in the matrix and formed a relatively better interfacial bonding and compatibility with the TPU matrix. The damping factor tanδ of both 328-composites and 329-composites had been reduced gradually with increasing content of ultraviolet absorbents at the glass transition temperature range due to the fact that the ultraviolet absorbents were in the crystalline state which decreased the volume content of the viscoelastic TPU matrix. But the tanδ increased at the temperature range of higher than the glass transition temperature, which should be related to the dominance of interfacial frictions between the ultraviolet absorbents and the matrix on the energy absorption.

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