Preparation of solution-processable colorless polyamide-imides with extremely low thermal expansion coefficients through an in-situ silylation method for potential space optical applications

e-Polymers ◽  
2016 ◽  
Vol 16 (5) ◽  
pp. 395-402 ◽  
Author(s):  
Song Wang ◽  
Guangjie Yang ◽  
Shibin Wu ◽  
Ge Ren ◽  
Wei Yang ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Coefficient Of Thermal Expansion ◽  
Linear Chain ◽  
Tensile Modulus ◽  
Optical Homogeneity ◽  
One Pot ◽  
System Architectures ◽  
Thermal Expansion Coefficients ◽  
Low Thermal Expansion

AbstractSeveral tough and flexible fluorinated polyamide-imide films were prepared from trimellitic anhydride chloride and 2,2′-bis(trifluoromethyl)benzidine through a facile one-pot in-situ silylation method. By incorporating fluorinated side groups, the solubility of the prepared polyamide-imide was greatly enhanced. Meanwhile, due to their linear chain configuration and the existence of hydrogen bonding, the prepared polyamide-imide films revealed high tensile strength, high tensile modulus, high glass transition temperature (Tg) and most interestingly, very low coefficient of thermal expansion (CTE) of 11 ppm/°C. Copolymerization with pyromellitic dianhydride (PMDA) led to an extremely low CTE of 4 ppm/°C which should be among the lowest values available for soluble polyamide-imides. The optical homogeneity and stress homogeneity of the obtained polyamide-imide films were also tested. After non-contact with substance and thermal treatment at 300°C, they revealed a better optical homogeneity and stress homogeneity than that of the commercially available Kapton polyimide (PI) films, with a PV value of 0.915 λ and RMS value of 0.163 λ. Thus, these colorless and soluble polyamide-imide films simultaneously possessing promising optical imaging performance are good candidates as novel diffractive membrane optical system architectures.

Highly transparent and flexible silica/cellulose films with a low coefficient of thermal expansion

RSC Advances ◽  
2014 ◽  
Vol 4 (94) ◽  
pp. 52349-52356 ◽  
Author(s):  
Yuehan Wu ◽  
Xingzhong Zhang ◽  
Bin Li ◽  
Shilin Liu
Keyword(s):  
Thermal Expansion ◽  
Coefficient Of Thermal Expansion ◽  
Cellulose Films ◽  
Thermal Expansion Coefficients ◽  
Low Thermal Expansion ◽  
Expansion Coefficients

Highly transparent and flexible silica/cellulose films with low thermal expansion coefficients have been prepared by the in situ synthesis of silica in cellulose scaffolds using Na2SiO3 as a precursor.

Bilayer graded Al/B4C/rice husk ash composite: Wettability behavior, thermo-mechanical, and electrical properties

2018 ◽  
Vol 52 (27) ◽  
pp. 3745-3758 ◽  
Author(s):  
Amin Bahrami ◽  
Niloofar Soltani ◽  
Martin I Pech-Canul ◽  
Shaghayegh Soltani ◽  
Luis A González ◽  
...  
Keyword(s):  
Electrical Resistivity ◽  
Thermal Expansion ◽  
Aluminum Alloys ◽  
Rice Husk ◽  
Rice Husk Ash ◽  
Material Selection ◽  
Coefficient Of Thermal Expansion ◽  
Thermal Expansion Coefficients ◽  
One Step ◽  
The Difference

In this study, wettability behavior of B4C substrate as well as B4C/crystalline rice husk ash and B4C/amorphous rice husk ash substrates with two aluminum alloys were studied. The electrical resistivity, thermal expansion coefficients, and thermal diffusivity of bilayer Al/B4C/rice husk ash composite fabricated by one-step pressureless infiltration were measured and the obtained data were systemically analyzed using the Taguchi method and analysis of variance. Boron carbide substrates after addition of amorphous or crystalline rice husk ash display good wettability with molten aluminum alloys. The results show that, electrical resistivity of Al/B4C/rice husk ash composites is mainly influenced by initial preform porosity, while the coefficient of thermal expansion of composites is determined by the chemical composition of infiltrated alloys. The measured values for coefficient of thermal expansion (10.5 × 10−6/℃) and electrical resistivity (0.60 × 10−5 Ω.m) of Al/B4C/rice husk ash composites, fabricated according to analysis of variance's optimal conditions are in good agreement with those of the projected values (11.02 × 10−6/℃ and 0.65 × 10−5 Ω.m, respectively). The difference between the corresponding values obtained from verification tests and projected values, for electrical resistivity and coefficient of thermal expansion are less than 5%. Finally, as a material selection approach, the strengths and weaknesses of the composites have been graphed in the form of radar diagrams.

Highly transparent polyhydroxyimide/TiO2 and ZrO2 hybrid films with high glass transition temperature (Tg) and low coefficient of thermal expansion (CTE) for optoelectronic application

2017 ◽  
Vol 5 (33) ◽  
pp. 8444-8453 ◽  
Author(s):  
Shun-Wen Cheng ◽  
Tzu-Tien Huang ◽  
Chia-Liang Tsai ◽  
Guey-Sheng Liou
Keyword(s):  
Thermal Expansion ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Thermal Expansion Coefficient ◽  
Coefficient Of Thermal Expansion ◽  
High Glass Transition Temperature ◽  
Hybrid Films ◽  
Optoelectronic Application ◽  
Low Thermal Expansion

Highly transparent polyhydroxyimide/TiO2 and ZrO2 hybrids films with high glass transition temperature and low thermal expansion coefficient for optoelectronic application.

scholarly journals In-situ alloying of AlSi10Mg+Si using Selective Laser Melting to control the coefficient of thermal expansion

2019 ◽  
Vol 795 ◽  
pp. 8-18 ◽  
Author(s):  
Theresa Hanemann ◽  
Luke N. Carter ◽  
Moritz Habschied ◽  
Nicholas J.E. Adkins ◽  
Moataz M. Attallah ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Selective Laser Melting ◽  
Coefficient Of Thermal Expansion ◽  
Laser Melting

Thermal Expansion of SrZr4-xTix(PO4)6 Ceramics

2018 ◽  
Vol 281 ◽  
pp. 169-174
Author(s):  
Yang Wang ◽  
Yuan Yuan Song ◽  
Yuan Yuan Zhou ◽  
Lu Ping Yang ◽  
Fu Tian Liu
Keyword(s):  
Thermal Expansion ◽  
Relative Density ◽  
Thermophysical Properties ◽  
Sintering Temperature ◽  
Temperature Range ◽  
Thermal Expansion Coefficients ◽  
High Relative Density ◽  
Low Thermal Expansion ◽  
Expansion Coefficients

Low thermal expansion ceramics have been widely applied in multiple fields. In this paper, a series of low thermal expansion ceramics SrZr4-xTix(PO4)6 was prepared and characterized. The SrZr4-xTix(PO4)6 ceramics could be well sintered in the temperature range of 1400~1500 °C. The effect of the addition of Ti substituting Zr and the sintering temperature was studied. The Ceramic with x =0.1 sintered at 1450 °C, the SrZr4-xTix(PO4)6 had a high relative density. The thermal expansion coefficients were about 3.301×10-6 °C-1. It was demonstrated that the microstructure of the SrZr4-xTix(PO4)6 could be altered by adding varying amount of Ti to tailor the thermophysical properties of the material.

Some recent developments in high-strength glasses and ceramics

1964 ◽  
Vol 282 (1388) ◽  
pp. 52-56
Keyword(s):  
Thermal Expansion ◽  
Bending Strength ◽  
Glass Ceramics ◽  
High Strength ◽  
Fine Grained ◽  
Thermal Expansion Coefficients ◽  
Low Thermal Expansion ◽  
Recent Developments ◽  
Expansion Coefficients ◽  
Mechanical Strengths

Two areas of development in the field of glasses and ceramics have produced new materials with unusual combinations of properties. Glass-ceramics are melted and formed as glasses by conventional glass-forming techniques, but by a subsequent heat treatment, they are converted to fine-grained crystalline structures with new and useful combinations of properties. Products with thermal expansion coefficients approaching zero and flexural strengths ranging from 10 000 to 50 000 Lb./in. 2 have been made though not all combinations of low thermal expansion coefficients and high mechanical strengths are possible. The second area of development is in so-called Chemcor glasses. Such glass products can be preferentially pre-stressed by chemical means so as to produce an outer layer with high compressive stress and a bending strength in the finished product up to 100 000 Lb/in. 2 .

Fabrication and Characterization of Low Thermal Expansion Cordierite/Spodumene/Mullite Composite Ceramic for Cookware

2018 ◽  
Vol 766 ◽  
pp. 276-281
Author(s):  
Pranee Junlar ◽  
Thanakorn Wasanapiarnpong ◽  
Lada Punsukmtana ◽  
Noppasint Jiraborvornpongsa
Keyword(s):  
Thermal Expansion ◽  
Water Absorption ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Coefficient Of Thermal Expansion ◽  
Slip Casting ◽  
Ceramic Composites ◽  
Modulus Of Rupture ◽  
Mullite Phase ◽  
Low Thermal Expansion

Ceramic cookware can be taken a direct flame or stove top for the duration without damage. The selected materials must have low thermal expansion coefficient, high strength, low water absorption and high thermal shock resistance, reasonable in cost and easy to be produced. Cordierite and spodumene composite has been interested for ceramic cookware due to their fitted properties. In previous work, study in the cordierite-spodumene composite with low thermal expansion coefficient of 2.60 x 10-6 /°C when sintered at 1250 oC with a ratio of spodumene 60 wt% and cordierite 40 wt% can withstand the pot shape samples. However, the sample showed relatively high water absorption and low strength which was not appropriate for using in this application. In this research, mullite is added in the formula to improve strength and densification of ceramic composites. Spodumene, ball clay, calcined talc and calcined alumina are used as starting raw materials and formed by slip casting. All samples are sintered in a temperature range from 1250-1275 °C in an electric furnace. Water absorption and bulk density were tested by Archimedes method, modulus of rupture was tested by the three-point bending method, microstructure were investigated by SEM and the coefficient of thermal expansion was measured by dilatometer. It was found that the mullite phase was investigated when adding mullite more than 30 wt% in cordierite-spodumene composite.

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