scholarly journals Carborane-Containing Aromatic Polyimide Films with Ultrahigh Thermo-Oxidative Stability

Polymers ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 1930
Author(s):  
Fulin Liu ◽  
Guangqiang Fang ◽  
Haixia Yang ◽  
Shiyong Yang ◽  
Xuezhong Zhang ◽  
...  
Keyword(s):  
Oxidative Stability ◽  
Elevated Temperatures ◽  
Oxidative Degradation ◽  
Film Surface ◽  
Amic Acid ◽  
Skin Layer ◽  
Polymer Materials ◽  
Aromatic Diamine ◽  
Self Healing ◽  
Aromatic Polyimide

Carborane-containing aromatic polyimide (CPI) films with ultrahigh thermo-oxidative stability at 700 °C have been prepared by casting poly(amic acid) (PAA) resin solution on a glass surface, followed by thermal imidization at elevated temperatures. The PAA solution was prepared by copolymerization of an aromatic dianhydride and an aromatic diamine mixture, including carborane-containing aromatic diamine in an aprotic solvent. The CPI films showed excellent thermo-oxidative stability at 700 °C due to the multilayered protection layers formed on the film surface by thermal conversion of the carborane group into boron oxides. The boron oxide layer enhanced the degradation activation energy and suppressed the direct contact of inner polymer materials with oxygen molecules in a high-temperature environment, acting as a “self-healing” skin layer on the polyimide materials. The CPI-50 film was still flexible and maintained 50% retention of mechanical strength even after thermo-oxidative aging at 700 °C/5 min. The mechanism of thermo-oxidative degradation was proposed.

scholarly journals Preparation and Thermal Evaluation of Novel Polyimide Protective Coatings for Quartz Capillary Chromatographic Columns Operated over 320 °C for High-Temperature Gas Chromatography Analysis

Polymers ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 946 ◽  
Author(s):  
Meng-ge Huangfu ◽  
Yan Zhang ◽  
Xin-ling Zhang ◽  
Jin-gang Liu ◽  
Ying-cong Liu ◽  
...  
Keyword(s):  
Gas Chromatography ◽  
High Temperature ◽  
Elevated Temperatures ◽  
Protective Coatings ◽  
Linear Thermal Expansion ◽  
Amic Acid ◽  
Aromatic Diamine ◽  
Thermal Shock Test ◽  
Chromatographic Columns ◽  
Quartz Capillary

Protection of intrinsically brittle quartz chromatographic columns (CCs) from breakage or property deterioration in gas chromatography (GC) analysis has become an important research topic regarding high-temperature GC techniques. Polyimide (PI) has proved to be the most suitable protective coating for quartz CCs. In the current research, a series of novel high-temperature-resistant PI coatings for quartz CCs operated over 320 °C have been successfully prepared. For this purpose, the aromatic diamine with a rigid skeleton structure 2-(4-aminophenyl)-5-aminobenzimidazole (APBI) was copolymerized with two aromatic dianhydrides—3,3’,4,4’-benzophenotetracarboxylic acid dianhydride (BTDA) and 4,4’-oxydiphthalic anhydride (ODPA)—and an aromatic diamine with flexible ether linkages—4,4’-oxydianiline (ODA)—by a two-step polymerization procedure via soluble poly(amic acid) (PAA) precursors, followed by thermal imidization at elevated temperatures. The developed PI coatings exhibited good comprehensive properties, including glass transition temperatures (Tg) as high as 346.9 °C, measured by dynamic mechanical analysis (DMA), and coefficients of linear thermal expansion (CTEs) as low as 24.6 × 10−6/K in the range of 50–300 °C. In addition, the PI coatings exhibited good adhesion to the fused quartz capillary columns. No cracking, delamination, warpage, or other failures occurred during the 100-cycle thermal shock test in the range of 25–320 °C.

Structural Performance of Pultruded Composites under Elevated Temperatures

2009 ◽  
Vol 79-82 ◽  
pp. 2223-2226
Author(s):  
Ayman S. Mosallam
Keyword(s):  
Elevated Temperature ◽  
High Temperatures ◽  
Elevated Temperatures ◽  
Oxidative Degradation ◽  
Viscoelastic Behavior ◽  
Structural Performance ◽  
Crystalline Polymers ◽  
Damage To The Material ◽  
Continuous Working ◽  
Pultruded Composites

One of the major limitations for wider use of pultruded fiber reinforced polymeric (PFRP) composites in the civil engineering sector has been their behavior under elevated temperature and ultimately fire. This limitation arises not only due to the reduction in mechanical properties at high temperatures, including increased propensity to creep, but also due to limitations on the continuous working temperature causing permanent damage to the material as a result of thermal and oxidative degradation. Significant gains in property retention at high temperatures with crystalline polymers have been derived from the incorporation of fibrous reinforcement, but the development of new polymer matrices is the key for further elevation of the useful temperature range. This paper presents summary results of a research project focused on characterizing the viscoelastic behavior of commercially-produced, off-the-shelf unidirectional PFRP materials subjected to elevated temperature environments.

Highly transparent, stretchable, and self‐healing polymers crosslinked by dynamic zinc(II)-poly(amic acid) bonds

2021 ◽  
Author(s):  
Ai-Nhan Au-Duong ◽  
Yu-Ching Hsu ◽  
Marzelino Malintoi ◽  
Afifah Nur Ubaidillah ◽  
Yen-Ting Li ◽  
...  
Keyword(s):  
Amic Acid ◽  
Self Healing

Accelerating Self-Healing Driven by Surface Energy Using Bulky Ester Groups in Polymer Materials

2021 ◽  
Author(s):  
Shanjun Ding ◽  
Zhu Wang ◽  
Guocui Zhu ◽  
Ximing Zhang ◽  
Jun Zhang ◽  
...  
Keyword(s):  
Surface Energy ◽  
Polymer Materials ◽  
Self Healing

Self-healable Functional Polymers based on Diels-Alder ‘Click Chemistry’ Involving Substituted Furan and Triazolinedione Derivatives; A Simple and Very Fast Approach

2021 ◽  
Author(s):  
Prantik Mondal ◽  
Gourhari Jana ◽  
Tuhin Subhra Pal ◽  
Pratim K. Chattaraj ◽  
Nikhil K Singha
Keyword(s):  
Click Chemistry ◽  
Materials Science ◽  
Functional Polymers ◽  
Diels Alder ◽  
Polymer Materials ◽  
Self Healing ◽  
Natural Phenomena ◽  
Science And Engineering ◽  
Fast Approach ◽  
Materials Science And Engineering

Nowadays, the design of functional polymer materials that can mimic natural phenomena, e.g., self-healing of skin cuts, has got a tremendous interest in materials science and engineering. Recently, 1,2,4-triazoline-3,5-dione (TAD)...

Effect of alkylated diphenylamine on thermal-oxidative degradation behavior of poly-α-olefin

2015 ◽  
Vol 69 (7) ◽  
Author(s):  
Mian-Ran Chao ◽  
Wei-Min Li ◽  
Li-Li Zhu ◽  
Hai-Hong Ma ◽  
Xiao-Bo Wang
Keyword(s):  
Activation Energy ◽  
Oxidative Stability ◽  
Oxidative Degradation ◽  
Thermal Oxidative Degradation ◽  
Degradation Behavior ◽  
Thermal Oxidative Stability ◽  
Zinc Dialkyl Dithiophosphate ◽  
Dialkyl Dithiophosphate

AbstractAn oil-soluble antioxidant, alkylated diphenylamine (ADPA), was prepared by alkylation of diphenylamine. The influence of ADPA on the thermal-oxidative stability of poly-α-olefin (PAO8) was evaluated by thermogravimetry (TG). For comparison, the thermal-oxidative stability of PAO8 with zinc dialkyl dithiophosphate (ZDDP) was also investigated. Activation energy (E

scholarly journals Linseed oil: Characterization and study of its oxidative degradation

2020 ◽  
Vol 71 (1) ◽  
pp. 337 ◽  
Author(s):  
B. M. Berto ◽  
R. K.A. Garcia ◽  
G. D. Fernandes ◽  
D. Barrera-Arellano ◽  
G. G. Pereira
Keyword(s):  
Fatty Acid ◽  
Oxidative Stability ◽  
Induction Period ◽  
Room Temperature ◽  
Linseed Oil ◽  
Oxidative Degradation ◽  
Acid Value ◽  
Quality Parameters ◽  
Time Intervals ◽  
Accelerated Oxidation

This paper proposes to characterize and monitor the degradation of linseed oil under two oxidation conditions using some traditional oxidative and quality parameters. The experimental section of this study was divided into 2 stages. In the first one, three commercial linseed oil samples (OL1, OL2, and OL3) were characterized according to oxidative stability (90 °C) and fatty acid composition. In the second stage, the OL1 sample, selected due to its availability, was subjected to the following oxidation procedures: storage at room temperature conditions with exposure to light and air (temperature ranging from 7 to 35 °C) for 140 days and accelerated oxidation at 100 °C for 7h. Samples were collected at different time intervals and analyzed for oxidative stability (90 °C), peroxide value, and acid value. The results showed that all the samples presented a similar fatty acid profile and that the OL3 sample showed a higher induction period (p < 0.05). Regarding the oxidative degradation, the induction period of the OL1 sample reduced from 9.7 to 5.7 and 9.7 to 6.3 during 140 days of storage under room temperature and 7 h of accelerated oxidation, respectively. The end of induction period of the OL1 sample is expected to occur within 229 days according to an exponential mathematical model fitted to the induction period values at different temperatures. In addition, the OL1 sample met the limits proposed by Codex and Brazilian regulations for peroxide and acid values during the oxidation time intervals.

scholarly journals The effect of foaming agent on mechanical and physical properties of Polypropylene

2018 ◽  
Vol 2 (1) ◽  
Author(s):  
SEDEF CAKIR 1 ◽  
MUHAMMED AYCICEK 1 ◽  
EDIZ ALTUN 2 ◽  
Akin Akinci 1
Keyword(s):  
Mechanical Properties ◽  
Cell Density ◽  
Cell Morphology ◽  
Injection Pressure ◽  
Skin Layer ◽  
Polymer Materials ◽  
Cell Diameter ◽  
Melt Temperature ◽  
Foaming Agent ◽  
Foaming Agents

In this study, Polypropylene (PP) foam materials were used with injection parameters such as melting, molding and injection temperatures. To produce foam materials, chemical foaming agents were used, and added to polymer materials as 1wt.%, 1.5wt.%, 2wt.%, 2.5wt.%, 3wt.%. The mechanical properties of foam samples were determined based on the parameters. Cell morphology characterization such as cell diameter, cell count, skin layer thickness and cell density, and mechanical properties such as tensile and impact strength of polymer foams were examined.Generally, the closed-cell foam structure was obtained. The most important parameters affecting the cell morphology have been injection pressure, melt temperature and amount of foaming agent. With increasing the amount of foaming agent, cell density increased, foam density and mechanical properties decreased.

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