scholarly journals Preparation and Properties of Inherently Black Polyimide Films with Extremely Low Coefficients of Thermal Expansion and Potential Applications for Black Flexible Copper Clad Laminates

Polymers ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 576 ◽  
Author(s):  
Yao-yao Tan ◽  
Yan Zhang ◽  
Gang-lan Jiang ◽  
Xin-xin Zhi ◽  
Xiao Xiao ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Dimensional Stability ◽  
Elevated Temperatures ◽  
Coefficient Of Thermal Expansion ◽  
Optical Transmittance ◽  
Molecular Structures ◽  
Molar Ratio ◽  
Optical Parameters ◽  
Aromatic Diamines ◽  
Potential Applications

In the current work, a series of black polyimide (PI) films with excellent thermal and dimensional stability at elevated temperatures were successfully developed. For this purpose, two aromatic diamines including 4,4′-iminodianline (NDA) and 2-(4-aminophenyl)-5- aminobenzimidazole (APBI) were copolymerized with pyromellitic dianhydride (PMDA) to afford PIs containing imino groups (–NH–) in the molecular structures. The referenced PI film, PI-ref, was simultaneously prepared from PMDA and 4,4′-oxydianiline (ODA). The introduction of imino groups endowed the PI films with excellent blackness and opaqueness with the optical transmittance lower than 2% at the wavelength of 600 nm at a thickness of 25 μm and lightness (L*) below 10 for the CIE (Commission International Eclairage) Lab optical parameters. Meanwhile, the introduction of rigid benzimidazole units apparently improved the thermal and dimensional stability of the PI films. The PI-d film based on PMDA and mixed diamines (NDA:APBI = 70:30, molar ratio) showed a glass transition temperature (Tg) of 445.5 °C and a coefficient of thermal expansion (CTE) of 8.9 × 10−6/K in the temperature range of 50 to 250 °C, respectively. It is obviously superior to those of the PI-a (PMDA-NDA, Tg = 431.6 °C; CTE = 18.8 × 10−6/K) and PI-ref (PMDA-ODA, Tg = 418.8 °C; CTE: 29.5 × 10−6/K) films.

Thermal Expansion of Polyether Ether Ketone Bearing Components

2019 ◽  
Vol 64 (4) ◽  
pp. 1-5 ◽  
Author(s):  
Bryan D. Allison ◽  
Connor M. Vanderwiel
Keyword(s):  
Thermal Expansion ◽  
Elevated Temperatures ◽  
Coefficient Of Thermal Expansion ◽  
Aerospace Applications ◽  
Polyether Ether Ketone ◽  
Molded Parts ◽  
Injection Molded ◽  
Ether Ketone ◽  
Bearing Design ◽  
Strong Candidate

Carbon fiber–reinforced polyether ether ketone (PEEK) is a strong candidate for aerospace bearing cages due to its low density and good mechanical properties. However, there are still concerns regarding its performance at the elevated temperatures seen in aerospace applications. In particular, an accurate measurement of PEEK's coefficient of thermal expansion (CTE) is critical to proper bearing design. In this paper, the CTE of as-manufactured PEEK cages was measured to determine the range of CTE that can be expected for production parts. A range of cage sizes and designs were considered in this study. Components that were manufactured from stock shapes through subtractive methods were studied in addition to components made via injection molding. The CTE of machined PEEK was found to be significantly higher than that of injection-molded PEEK and also varied significantly from part to part. In contrast, the CTE of molded PEEK cages was found to be fairly consistent between parts. Finally, the CTE of PEEK was found to increase above the glass transition temperature of 143 °C, but it was demonstrated that this increase is relatively small for injection-molded parts.

Synthesis and properties of low coefficient of thermal expansion copolyimides derived from biphenyltetracarboxylic dianhydride with p-phenylenediamine and 4,4′-oxydialinine

e-Polymers ◽  
2016 ◽  
Vol 16 (4) ◽  
pp. 295-302 ◽  
Author(s):  
Yonglin Lei ◽  
Yuanjie Shu ◽  
Jinhua Peng ◽  
Yongjian Tang ◽  
Jichuan Huo
Keyword(s):  
Thermal Stability ◽  
Thermal Expansion ◽  
Coefficient Of Thermal Expansion ◽  
Thermomechanical Analysis ◽  
Amic Acid ◽  
Molar Ratio ◽  
Structure And Property ◽  
Property Relations ◽  
Ft Ir ◽  
Biphenyltetracarboxylic Dianhydride

AbstractA series of copolyimides were prepared by thermal imidization of poly(amic acid)s (PAAs) derived from 3,3′,4,4′-biphenyltetracarboxylic dianhydride (s-BPDA), 2,3′,3,4′-biphenyltetracarboxylic dianhydride (a-BPDA), p-phenylenediamine (PDA) and 4,4′-oxydialinine (4,4′-ODA) commonly used for the production of commercial polyimides. The flexible copolyimide films were obtained from that the molar ratio of s-BPDA, a-BPDA, PDA and 4,4′-ODA was 9:1:8:2 (Co-PIs-3), 8:2:9:1 (Co-PIs-5) and 8:2:8:2 (Co-PIs-6). These obtained copolyimide films were characterized by Fourier transform-infrared spectroscopy(FT-IR), wide angle X-ray (WAXD), Thermogravimetric (TG), dynamic mechanical thermal analysis (DMA), thermomechanical analysis (TMA), field-emission scanning electron microscopy (FE-SEM) and mechanical properties measurement. The results showed that three copolyimides remained semi-crystalline and exhibited high glass transition temperature (Tg), high thermal stability, great ultimate tensile strength and low coefficient of thermal expansion (CTE). The Co-PIs-5 had lower crystallinity, lower CTE, greater elongation at break, higher Tg and thermal stability and the greater dense extent, compared with Co-PIs-3 and Co-PIs-6. Structure and property relations of the prepared polyimides were also briefly discussed. The results revealed that the copolymerization of s-BPDA/PDA with a small number of 4,4′-ODA/a-BPDA was a useful means for enhancing flexibility without sacrificing low CTE.

Thermal Shrinkage Behavior of Battery Separator

2018 ◽  
Author(s):  
Shutian Yan ◽  
Jie Deng ◽  
Chulheung Bae ◽  
Xinran Xiao
Keyword(s):  
Thermal Expansion ◽  
Elevated Temperatures ◽  
Coefficient Of Thermal Expansion ◽  
Porous Membrane ◽  
Thermal Shrinkage ◽  
Dynamic Mechanical Analyzer ◽  
Free Standing ◽  
Dynamic Mechanical ◽  
Battery Separator ◽  
Shrinkage Behavior

Battery separators are thin, porous membrane of 20∼30 microns thickness. Polymer separators display a significant amount of shrinkage at elevated temperatures. It is difficult to quantitatively characterize the large shrinkage behavior with a free standing separator sample. This paper examines the use of a dynamic mechanical analyzer under tensile mode in measuring the coefficient of thermal expansion (CTE) of three commonly used separators.

Effect of aggregate type on linear thermal expansion of self-consolidating concrete at elevated temperatures

2012 ◽  
Vol 19 (3) ◽  
pp. 259-269 ◽  
Author(s):  
Tayfun Uygunoğlu ◽  
İlker Bekir Topçu
Keyword(s):  
Thermal Expansion ◽  
Thermal Properties ◽  
Elevated Temperatures ◽  
Coefficient Of Thermal Expansion ◽  
Linear Thermal Expansion ◽  
Thermal Tests ◽  
Linear Change ◽  
Volcanic Tuff ◽  
Self Consolidating Concrete ◽  
Cement Ratio

AbstractIn this study, the effects of aggregate type on the coefficient of thermal expansion of self-consolidating concrete (SCC) produced with normal and lightweight (porous) aggregate (SCLC) were investigated. In experiments, three aggregate types, gravel, volcanic tuff, and diatomite, were used. Different combinations of water/cement ratio and superplasticizer dosage levels were prepared for the SCC and SCLC mixtures. Thermal tests were performed to accurately characterize the coefficient of thermal expansion (CTE) of SCC and SCLC aged 28 days using the dilatometer. The CTEs of SCC and SCLC were defined by measuring the linear change in length of concrete specimens subjected to a range of temperatures from 20°C to 1000°C. The results, in general, showed that SCLC has a lower CTE than that of SCC above 100°C. Moreover, CTE values of SCC and SCLC were decreased with increase in porous structure. The aggregate type has significant influence on the thermal properties of SCC.

scholarly journals Reduced Coefficients of Linear Thermal Expansion of Colorless and Transparent Semi-Alicyclic Polyimide Films via Incorporation of Rigid-Rod Amide Moiety: Preparation and Properties

Polymers ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 413
Author(s):  
Gang-lan Jiang ◽  
Dong-yang Wang ◽  
Hao-peng Du ◽  
Xiao Wu ◽  
Yan Zhang ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Thermal Expansion ◽  
Elevated Temperatures ◽  
Linear Thermal Expansion ◽  
Optical Transparency ◽  
Aromatic Diamines ◽  
Good Thermal Stability ◽  
Glass Substrates ◽  
Rigid Rod ◽  
Pyromellitic Anhydride

Semi-alicyclic colorless and transparent polyimide (CPI) films usually suffer from the high linear coefficients of thermal expansion (CTEs) due to the intrinsic thermo-sensitive alicyclic segments in the polymers. A series of semi-alicyclic CPI films containing rigid-rod amide moieties were successfully prepared in the current work in order to reduce the CTEs of the CPI films while maintaining their original optical transparency and solution-processability. For this purpose, two alicyclic dianhydrides, hydrogenated pyromellitic anhydride (HPMDA, I), and hydrogenated 3,3’,4,4’-biphenyltetracarboxylic dianhydride (HBPDA, II) were polymerized with two amide-bridged aromatic diamines, 2-methyl-4,4’-diaminobenzanilide (MeDABA, a) and 2-chloro-4,4’-diaminobenzanilide (ClDABA, b) respectively to afford four CPI resins. The derived CPI resins were all soluble in polar aprotic solvents, including N-methyl-2-pyrrolidone (NMP) and N,N-dimethylacetamide (DMAc). Flexible and tough CPI films were successfully prepared by casing the PI solutions onto glass substrates followed by thermally cured at elevated temperatures from 80 °C to 250 °C. The MeDABA derived PI-Ia (HPMDA-MeDABA) and PI-IIa (HBPDA-MeDABA) exhibited superior optical transparency compared to those derived from ClDABA (PI-Ib and PI-IIb). PI-Ia and PI-IIa showed the optical transmittances of 82.3% and 85.8% at the wavelength of 400 nm with a thickness around 25 μm, respectively. Introduction of rigid-rod amide moiety endowed the HPMDA-PI films good thermal stability at elevated temperatures with the CTE values of 33.4 × 10−6/K for PI-Ia and 27.7 × 10−6/K for PI-Ib in the temperature range of 50–250 °C. Comparatively, the HBPDA-PI films exhibited much higher CTE values. In addition, the HPMDA-PI films exhibited good thermal stability with the 5% weight loss temperatures (T5%) higher than 430 °C and glass transition temperatures (Tg) in the range of 349–351 °C.

Thermal properties of nanocrystalline Al composites reinforced by AlN nanoparticles

2009 ◽  
Vol 24 (1) ◽  
pp. 24-31 ◽  
Author(s):  
Y.Q. Liu ◽  
H.T. Cong ◽  
H.M. Cheng
Keyword(s):  
Thermal Properties ◽  
Room Temperature ◽  
Significant Contribution ◽  
Elevated Temperatures ◽  
Volume Fraction ◽  
Coefficient Of Thermal Expansion ◽  
High Tc ◽  
Percolation Behavior ◽  
Potential Applications ◽  
Electronic Packaging Material

To explore potential applications of nanocomposites for microelectronic packaging, the thermal properties were investigated on newly developed nanocrystalline Al composites reinforced by AlN nanoparticles. It was found that the thermal conductivity (TC) is reduced with increasing AlN volume fraction (Vp), since connectivity of Al matrix is decreased by introduction of the nanoparticles. Although AlN nanoparticles introduce thermal resistance, they still have significant contribution to the TC of the composite as high-TC inclusion. Particularly, a percolation behavior of AlN nanoparticles is thought to occur with the threshold at 23–30%. Measurements at elevated temperatures (∼500 °C) show almost no distinct degradation of TC relative to room temperature. Moreover, the coefficient of thermal expansion (CTE) is remarkably lowered as Vp increases, e.g., from 26 × 10−6 to 13.9 × 10−6 K−1, by raising Vp to 39%. Therefore, the nanocomposites may be applicable as electronic packaging material, due to the combination of acceptable TC and low CTE.

Zirconium tungstate reinforced cyanate ester composites with enhanced dimensional stability

2009 ◽  
Vol 24 (7) ◽  
pp. 2235-2242 ◽  
Author(s):  
Prashanth Badrinarayanan ◽  
Ben Mac Murray ◽  
Michael R. Kessler
Keyword(s):  
Thermal Expansion ◽  
Dimensional Stability ◽  
Coefficient Of Thermal Expansion ◽  
Negative Thermal Expansion ◽  
Thermomechanical Analysis ◽  
Dynamic Mechanical Properties ◽  
Filler Loading ◽  
Cyanate Ester ◽  
Scanning Calorimetry ◽  
Zirconium Tungstate

Zirconium tungstate (ZrW2O8) is a unique ceramic material characterized by isotropic negative thermal expansion behavior over a wide temperature range. Incorporation of ZrW2O8 is expected to improve the dimensional stability of polymers by reducing the overall coefficient of thermal expansion (CTE). In this work, the thermal and dynamic mechanical properties of a bisphenol E cyanate ester reinforced with various loadings of ZrW2O8 are examined. Thermomechanical analysis indicates that the incorporation of ZrW2O8 results in a decrease in CTE at temperatures above and below the glass transition temperature (Tg) of the neat resin. The dynamic storage moduli of the composites reinforced with ZrW2O8 are found to increase with increasing filler loading. Furthermore, the various phase behaviors exhibited by ZrW2O8 are also examined by differential scanning calorimetry measurements.

Synthesis and properties of colorless polyamide films with high thermal resistance and dimensional stability

2020 ◽  
Vol 32 (8) ◽  
pp. 945-952
Author(s):  
Guangliang Song ◽  
Xiaoyu Wang ◽  
Chao Chen
Keyword(s):  
Dimensional Stability ◽  
High Performance ◽  
Coefficient Of Thermal Expansion ◽  
Tensile Modulus ◽  
High Heat ◽  
Cutoff Wavelength ◽  
Structure Property ◽  
Aromatic Diamines ◽  
Wide Range ◽  
High Thermal Resistance

Polyamides (PAs) based on terephthaloyl chloride and a series of aromatic diamines were synthesized; PA films were prepared by solution casting without mechanical stretching to produce high-performance films with good optical transparency and dimensional stability. The PA films displayed high heat resistance with glass transition temperatures ( Tg) of 342–399°C. Good mechanical properties were obtained with tensile modulus and strength up to 5.38 GPa and 195.4 MPa, respectively. Coefficient of thermal expansion of the as-cast PA films achieved to an ultralow value of 8.3 ppm °C−1 and could be tailored in a wide range as a function of the macromolecular composition. The series of PA films showed a transparent and colorless feature, with the cutoff wavelength in the range of 355–365 nm. The data were discussed from the perspective of structure–property relationship, may give helpful knowledge for the topic of PA chemistry, and this method could provide an alternative for the production of high-performance colorless polymer films.

Variation of lattice parameter and coefficient of thermal expansion of Mnln2S4 at elevated temperatures

1987 ◽  
Vol 6 (4) ◽  
pp. 489-490 ◽  
Author(s):  
V. Bhaskara Sastry ◽  
B. Appa Rao ◽  
P. V. Mohan Rao ◽  
K. Satyanarayana Murthy
Keyword(s):  
Thermal Expansion ◽  
Elevated Temperatures ◽  
Coefficient Of Thermal Expansion ◽  
Lattice Parameter
Sign in / Sign up

Export Citation Format

Share Document