scholarly journals Closed-Cell Rigid Polyimide Foams for High-Temperature Applications: The Effect of Structure on Combined Properties

Polymers ◽  
2021 ◽  
Vol 13 (24) ◽  
pp. 4434
Author(s):  
Yawei Shi ◽  
Aijun Hu ◽  
Zhiyuan Wang ◽  
Kedi Li ◽  
Shiyong Yang
Keyword(s):  
Thermal Stability ◽  
Decomposition Temperature ◽  
Precursor Powder ◽  
Diethyl Ester ◽  
Aromatic Diamine ◽  
Excellent Thermal Stability ◽  
Compression Creep ◽  
Closed Cell ◽  
End Capping ◽  
Tetracarboxylic Dianhydride

Closed-cell rigid polyimide foams with excellent thermal stability and combined properties were prepared by thermal foaming of a reactive end-capped polyimide precursor powder in a closed mold. The precursor powder was obtained by thermal treatment of a polyester-amine salt (PEAS) solution derived from the reaction of the diethyl ester of 2,3,3′,4′-biphenyl tetracarboxylic dianhydride (α-BPDE) with an aromatic diamine mixture of p-phenylenediamine (PDA) and 2-(4-aminophenyl)-5-aminobenzimidazole (BIA) in the presence of an end-capping agent (mono-ethyl ester of nadic acid anhydride, NE) in an aliphatic alcohol. The effect of polymer mainchain structures on the foaming processability and combined properties of the closed-cell rigid polyimide foams were systematically investigated. The polyimide foams (100–300 kg/m3) with closed-cell rates of 91–95% show an outstanding thermal stability with an initial thermal decomposition temperature of ≥490 °C and a glass transition temperature of 395 °C. Polyimide foams with density of 250 kg/m3 exhibited compression creep deformation as low as 1.6% after thermal aging at 320 °C/0.4 MPa for 2 h.

Research on Preparation, Properties and UV Curing Behaviors of Novel Myrcene-Based Vinyl Ester Resin

2013 ◽  
Vol 807-809 ◽  
pp. 2826-2830 ◽  
Author(s):  
Xue Juan Yang ◽  
Shou Hai Li ◽  
Xiao Dong Tang ◽  
Jian Ling Xia
Keyword(s):  
Thermal Stability ◽  
Vinyl Ester ◽  
Impact Resistance ◽  
Uv Curing ◽  
High Hardness ◽  
Decomposition Temperature ◽  
Ftir Analysis ◽  
Vinyl Ester Resin ◽  
Initial Decomposition Temperature ◽  
Excellent Thermal Stability

Myrcene-based vinyl ester resin (VER) monomer was prepared via simple Diels-Alder reaction and ring-opening esterification. The molecular structure and UV curing behaviors of prepared VER monomer were characterized using FTIR analysis method. Moreover, the mechanical properties, thermal stability and hardness of its UV cured product were also investigated. FTIR analysis results demonstrated that the target myrcene-based VER monomer has been successfully synthesized. UV curing behaviors analysis showed that prepared myrcene-based VER monomer could reach ultimate cured level within 50 s. Physical properties study showed that the UV cured product has certain tensile, flexural, impact resistance properties and high hardness. TGA indicated the UV cured product had excellent thermal stability, as it showed high thermal initial decomposition temperature at 359.6 °C .

scholarly journals Development of Interfacial Adhesive Property by Novel Anti-Stripping Composite between Acidic Aggregate and Asphalt

Polymers ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 473
Author(s):  
Guohong Zhang ◽  
Jianhui Qiu ◽  
Jingzhuo Zhao ◽  
Dingbang Wei ◽  
Hui Wang
Keyword(s):  
Thermal Stability ◽  
Interfacial Adhesion ◽  
Moisture Damage ◽  
Decomposition Temperature ◽  
Social Significance ◽  
Excellent Thermal Stability ◽  
Adhesion Properties ◽  
Stability Performance ◽  
The Poor ◽  
Damage Process

Studies on control of and preventive measures against asphalt pavement moisture damage have important economic and social significance due to the multiple damage and repair of pavements, the reasons for which include the poor interfacial adhesive ability between acidic aggregates and asphalts. Anti-stripping agent is used in order to improve the poor adhesion, and decomposition temperature is regarded as being important for lots of anti-stripping products, because they always decompose and lose their abilities under the high temperature in the mixing plant before application to the pavement. A novel anti-stripping composite, montmorillonoid/Polyamide (OMMT/PAR), which possesses excellent thermal stability performance and is effective in preventing moisture damage, especially for acidic aggregates, was prepared. Moreover, the modification mechanisms and pavement properties were also investigated with reference to the composites. The results show that OMMT/PAR was prepared successfully, improving the interfacial adhesion between the acidic aggregate and the modified asphalt. Due to the nanostructure of OMMT/PAR, the thermal stability was enhanced dramatically and the interfacial adhesion properties were also improved. Furthermore, asphalts modified with OMMT/PAR and their mixtures showed excellent properties. Finally, the moisture damage process and the mechanisms by which OMMT/PAR improves the interfacial adhesion properties are explained through adhesion mechanism analyses.

Preparation and thermal stability of heat-resistant phenolic resin system constructed by multiple heat-resistant compositions containing boron and silicon

2016 ◽  
Vol 29 (4) ◽  
pp. 493-498 ◽  
Author(s):  
Fengyi Wang ◽  
Zhixiong Huang ◽  
Guangwu Zhang ◽  
Yunxia Li
Keyword(s):  
Thermal Stability ◽  
Phenol Formaldehyde ◽  
Interlayer Spacing ◽  
Decomposition Temperature ◽  
Char Yield ◽  
X Ray Diffraction ◽  
Excellent Thermal Stability ◽  
Heat Resistant ◽  
Graphite Structure ◽  
Thermal Stability Of

This work reports a boron- and silicon-containing phenolic-formaldehyde (PF) resin exhibiting an extremely high thermal decomposition temperature and char yield and formed by copolymerizing phenol, formaldehyde, boric acid (BA), and phenyltriethoxysilane (PTES). The structure of BA and PTES-modified PF (BSPF) resin was characterized by Fourier transform infrared spectroscopy. Thermal stability of the investigated composites was estimated by means of thermogravimetric analysis (TGA). The results of TGA indicated that the modified resin exhibited excellent thermal stability. Specifically, the thermoset had a char yield of 77.0% when the boron and silicon contents were only 1.27 wt% and 1.7 wt%, respectively. Compared with the unmodified resin (PF), the temperature at the maximum decomposing rate of the BSPF increased by 84°C and its charring yield was enhanced by 15.0%. The cured products of PF and BSPF were further investigated by X-ray diffraction and Raman spectroscopy, respectively. The incorporation of boron and silicon into the carbon lattice results in a decrease of interlayer spacing, and Raman ID/ IG values for PF and BSPF (2.63 and 1.32) show that the rearrangement of crystalline structure leads to an increase in graphite structure and a decrease in disordered structure upon the modification processes.

Research on the preparation of heat-resistant epoxy resin cured by o-carborane-based diamine

2017 ◽  
Vol 30 (9) ◽  
pp. 1094-1100 ◽  
Author(s):  
Zhao Juan ◽  
Qing Ning ◽  
Jiang Shaohua ◽  
Wu Suping
Keyword(s):  
Thermal Stability ◽  
Differential Scanning Calorimetry ◽  
Thermogravimetric Analysis ◽  
Epoxy Resin ◽  
Decomposition Temperature ◽  
Scanning Calorimetry ◽  
Initial Decomposition Temperature ◽  
Excellent Thermal Stability ◽  
Thermal Oxidative Stability ◽  
Air Atmosphere

A novel carborane-containing epoxy resin was prepared via the curing reaction between epoxy resin (E51) and 1,2-bis(4-aminophthalimide)dimethyl-1,2-dicarba-closododecaborane (4-AP CBR). According to the nonisothermal differential scanning calorimetry method and the T-β extrapolation method, the curing temperatures of the 4-AP CBR/E51 system were theoretically determined. The cured carboranyl epoxy resin was analyzed by thermogravimetric analysis (TGA), which revealed that the resin had excellent thermal stability and thermal oxidative stability. The results of TGA indicated that the initial decomposition temperature of the resin was exceeding 400°C and the char yield at 800°C was around 60% both under nitrogen and in air atmosphere.

Synthesis and Characterization of Processable Polyimide Titania Nanohybrids

2011 ◽  
Vol 326 ◽  
pp. 88-96 ◽  
Author(s):  
Malik Adnan Saeed ◽  
Zulfiqar H. Lodhi ◽  
Aziz Ullah Khan ◽  
Wasim Asghar
Keyword(s):  
Thermal Stability ◽  
Absorption Band ◽  
Sol Gel ◽  
High Yield ◽  
Commercial Application ◽  
Aromatic Diamine ◽  
Polyamic Acid ◽  
Excellent Thermal Stability ◽  
Result Show ◽  
Thermal Stability Of

A new aromatic diamine monomer {4-amino [4-(diphenylamino) phenyl] anilino} phenyl amine (DPA -4) were synthesized in high yield and purity. {4-amino [4-(diphenylamino) phenyl] anilino} phenyl amine (DPA -4) monomer were reacted with Tetra carboxylic dianhydride (BT) leading to the formation of polyamic acid, followed by the preparation of polyimide/Titania hybrid films through non-hydrolytic sol-gel method. The synthesized polyimide were considered as blank & compared with the nano-hybrids derived from polyimides/Titania blends of different TiO2content. Synthesized polyimide showed excellent solubility in aprotic solvents like DMF, DMSO, NMP, and DMAC proving best processibility in various applications. Polyimide exhibited excellent thermal stability and its glass transition temperature was 450°C & 5% weight loss is in the range of 500°C~600°C. The thermal stability of Polyimide/Titania composites decreased slightly with increase of TiO2content. Result show decrease in thermal stability of nano-hybrids caused by the decomposition of catalytic activity of Titania & incomplete imidizations of polyamic acid. The absorption band of PI-O-Ti bonds in FTIR spectra of hybrids films revealed the formation of hybrid inorganic network between polyimide and TiO2.Scanning electron microscopy results indicated that the nanometer-scaled inorganic domains were homogeneously dispersed in polyimides matrix due to the introduction of TiO2.The studies on the optical properties of hybrids films indicated the red-shift to the absorption band increased with increasing TiO2content, while all the hybrids films maintained their transparencies. This kind of hybrid materials has potential commercial application in the field of opto-electronics appliances.

Olefin Metathesis–Based Chemically Recyclable Polymers Enabled by a Fused-Ring Monomer

2020 ◽  
Author(s):  
Junpeng Wang ◽  
Devavrat Sathe ◽  
Junfeng Zhou ◽  
Hanlin Chen ◽  
Hsin-Wei Su ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Thermal Stability ◽  
Ring Opening ◽  
Strain Energy ◽  
Decomposition Temperature ◽  
Excellent Thermal Stability ◽  
Fused Ring ◽  
Promising Solution ◽  
Sustainable Materials ◽  
Tunable Mechanical Properties

Abstract A promising solution to address the challenges in plastics sustainability is to replace current polymers with chemically recyclable ones that can depolymerise into their constituent monomers for circular use of materials. Despite the progress, few depolymerisable polymers exhibit the excellent thermal stability and strong mechanical properties of traditional polymers. Here we report a series of chemically recyclable polymers that show excellent thermal stability (decomposition temperature > 370 ºC) and tunable mechanical properties. The polymers are formed via ring-opening metathesis polymerisation of cyclooctene with a trans-cyclobutane installed at the 5,6-positions. The additional ring converts the non-depolymerisable polycyclooctene into a depolymerisable polymer by reducing the ring strain energy in the monomer (from 8.2 kcal/mol in unsubstituted cyclooctene to 4.9 kcal/mol in the fused ring). The fused-ring monomer enables a broad scope of functionalities to be incorporated, providing access to chemically recyclable elastomers and plastics that show promise as next-generation sustainable materials.

High Transparency and Thermal Stability of Alicyclic Polyimide with Crosslinking Structure by Triallylamine

2011 ◽  
Vol 287-290 ◽  
pp. 1388-1396 ◽  
Author(s):  
Juo Chen Chen ◽  
Wen Yen Tseng ◽  
I Hsiang Tseng ◽  
Mei Hui Tsai
Keyword(s):  
Coefficient Of Thermal Expansion ◽  
Radical Reaction ◽  
Covalent Bond ◽  
Decomposition Temperature ◽  
Aromatic Diamine ◽  
Ultraviolet Region ◽  
Free Radical Reaction ◽  
Near Ultraviolet ◽  
Different Content ◽  
Tetracarboxylic Dianhydride

Colorless alicyclic polyimides (ALPIs) were synthesized from an alicyclic dianhydride, bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride (BCDA) and an aromatic diamine, 3,4'-oxydianiline (3,4'-ODA). For comparison, a series of crosslinkable ALPI membranes with different content of crosslinkable reagents were prepared. The crosslinkable PI reacts with the crosslinkers and forms covalent bond to create the crosslink structure between PI backbones by free radical reaction. Almost of the crosslinkable PIs exhibit excellent dimensional stability and higher transparency because of the crosslink structure and non-conjugate alicyclic chain. All of the crosslink ALPIs could be coated into flexible and tough films. They had a UV-Vis cut-off at 297 nm and a transmittance of higher than 80% in near ultraviolet region. These PIs show low coefficient of thermal expansion ranging from 57.36 to 47.53 ppm/°C, the glass transition temperature in the range of 336.2-333.0 °C, the decomposition temperature in the range of 433.7-440.0 °C. The crosslinkable ALPIs show excellent optical properties with the excited wavelength ranging from 340 to 328 nm and stronger emission intensity than linear PI, the haze lower than 0.7, the refractive index about 1.6 and the abbe numbers over 165.

Microstructure studies of tungsten silicide schottky contacts on Gaas

1987 ◽  
Vol 45 ◽  
pp. 328-329
Author(s):  
Yih-Cheng Shih ◽  
E. L. Wilkie
Keyword(s):  
Thermal Stability ◽  
Field Effect Transistors ◽  
Schottky Contact ◽  
Schottky Contacts ◽  
Excellent Thermal Stability ◽  
Barrier Heights ◽  
Gaas Substrates ◽  
Film Adhesion ◽  
Threshold Voltages ◽  
Thermal Stability Of

Tungsten silicides (WSix) have been successfully used as the gate materials in self-aligned GaAs metal-semiconductor-field- effect transistors (MESFET). Thermal stability of the WSix/GaAs Schottky contact is of major concern since the n+ implanted source/drain regions must be annealed at high temperatures (∼ 800°C). WSi0.6 was considered the best composition to achieve good device performance due to its low stress and excellent thermal stability of the WSix/GaAs interface. The film adhesion and the uniformity in barrier heights and ideality factors of the WSi0.6 films have been improved by depositing a thin layer of pure W as the first layer on GaAs prior to WSi0.6 deposition. Recently WSi0.1 has been used successfully as the gate material in 1x10 μm GaAs FET's on the GaAs substrates which were sputter-cleaned prior to deposition. These GaAs FET's exhibited uniform threshold voltages across a 51 mm wafer with good film adhesion after annealing at 800°C for 10 min.

scholarly journals Boosted piezoelectricity with excellent thermal stability in tetragonal NaNbO3-based ceramics

2020 ◽  
Author(s):  
Lu Wang ◽  
Shengdong Sun ◽  
Huajie Luo ◽  
Yang Ren ◽  
Hui Liu ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Temperature Stability ◽  
Lead Free ◽  
Excellent Thermal Stability ◽  
Lead Free Ceramics ◽  
Piezoelectric Performance

The realization of high piezoelectric performance and excellent temperature stability simultaneously in lead-free ceramics is the key for replacing Pb-containing perovskites in industry. In this study, large piezoelectric performance (d33...

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