Structure And Properties Of BPDA-PDA Polyimide From Its Poly(Amic Acid) Precursor Complexed With An Aminoalkyl Methacrylate

1991 ◽  
Vol 227 ◽  
Author(s):  
Moonhor Ree ◽  
Thomas L. Nunes ◽  
K.-J. Rex Chen ◽  
George Czornyj
Keyword(s):  
Residual Stress ◽  
Stress Relaxation ◽  
Strain Analysis ◽  
Polyimide Film ◽  
Amic Acid ◽  
Structure And Properties ◽  
Structure Property ◽  
Induced Stress ◽  
History Of ◽  
Acid Precursor

ABSTRACTBPDA-PDA poly(amic acid) precursor was functionalized through its carboxylic acid groups being linked with a crosslinkable aminoalkyl methacrylate, 2-(dimethylamino)ethyl methacrylate (DMAEM), by acid/base complexation. BPDA-PDA polyimide films, which were thermally imidized from the precursors complexed with various amounts of DMAEM, were characterized by means of wide angle x-ray diffraction, stress-strain analysis, and residual stress analysis. The structure and properties of the BPDA-PDA polyimide film were dependent upon the history of the precursor, that is, the complexation of the poly(amic acid) precursor with DMAEM. The molecular packing order was enhanced with the history of DMAEM loading while the molecular order along the chain axis was disrupted. Overall, physical properties, such as mechanical properties and residual stress, were degraded with DMAEM loading. The moisture induced stress relaxation behavior was sensitive to the history of DMAEM loading, whereas the creep induced stress relaxation was varied little due to its high Tg. These properties are understood in terms of structure/property relationships, as well as microvoids, which were possibly generated by outgassing the bulky DMAEM pendent groups during thermal imidization.

The Effect of Photoreactive Substituents on the Morphological Structure and Properties of BPDA-PPD Based Polyimides

1992 ◽  
Vol 264 ◽  
Author(s):  
John C. Coburn ◽  
M. T. Pottiger ◽  
A. E. Nader ◽  
C. A. Pryde
Keyword(s):  
Crystal Structure ◽  
Morphological Structure ◽  
Amic Acid ◽  
Structure And Properties ◽  
Crystalline Morphology ◽  
Crystallite Orientation ◽  
Covalently Bonded ◽  
Out Of Plane ◽  
Order Of Magnitude ◽  
Acid Precursor

AbstractAdding photoreactive substituents onto a biphenyldianhydride (BPDA) and p-phenylene diamine (PPD) poly(amic acid) precursor influences the onset of imidization and the development of anisotropy and crystalline morphology during processing and the resulting morphology and properties of the fully cured films. Amine salts shift the imidization to lower temperatures while the covalently bonded esters shift the imidization to slightly higher temperatures. Anisotropy of the photosensitive polyimides develops at higher cure temperatures compared to the poly(amic acid). The photoreactive substituents do not affect the crystal structure, but do influence the crystallite orientation and morphology. Out-of-plane coefficients of thermal expansion (CTEs), calculated from the volume expansivities of these systems, are an order of magnitude larger than the in-plane CTEs.

Surface Integrity - an Inherent Load Sensor

2013 ◽  
Vol 797 ◽  
pp. 679-684 ◽  
Author(s):  
Berend Denkena ◽  
Jens Köhler ◽  
Bernd Breidenstein ◽  
Tobias Mörke
Keyword(s):  
Heat Treatment ◽  
Residual Stress ◽  
Stress Relaxation ◽  
Surface Integrity ◽  
Mechanical Load ◽  
Stress Sensitivity ◽  
Load History ◽  
Initial Residual Stress ◽  
Load Sensor ◽  
History Of

The presented approach evaluates the application of the surface integrity of machined components as load sensors. Residual stress relaxation due to mechanical load is utilized to retrieve information on the load history of a component. The critical load stress, the sensitivity and the relaxation gradient are quantified and analyzed for AISI 1060 steel. More specifically, the influence of heat treatment and therefore of the materials ultimate strength has been evaluated. The results show that the knowledge on the error determining the residual stress is crucial for the accuracy of the approach. Furthermore, a sufficient relaxation gradient has to be provided by low residual stress sensitivity and high initial residual stress magnitude. Both properties can be influenced by heat treatment and machining.

Synthesis of 1,4-Bis(3-amino-5-trifluoromethylphenoxy)Benzene and Properties of the Polyimide Film Therefrom

2012 ◽  
Vol 581-582 ◽  
pp. 297-300
Author(s):  
Yun Hua Lu ◽  
Bing Wang ◽  
Guo Yong Xiao ◽  
Zhi Zhi Hu
Keyword(s):  
Catalytic Reduction ◽  
Visible Region ◽  
Optical Transmittance ◽  
Polyimide Film ◽  
Amic Acid ◽  
Decomposition Temperature ◽  
Structure And Properties ◽  
Thermal Decomposition Temperature ◽  
Fluorinated Polyimides ◽  
Thermal Imidization

Firstly, 1,4-bis(3-nitro-5-trifluoromethylphenoxy)benzene(I) was synthesized through the nucleophilic substitution reaction of 3,5-dinitrobenzotrifluoride and 1,4-dihydroxybenzene in the presence of potassium carbonate. Then, the diamine monomer 1,4-bis(3-amino-5-trifluoromethylphenoxy)benzene (II) was obtained through the catalytic reduction with hydrazine and Pd/C. These fluorinated polyimides (PI) were synthesized from the fluorinated diamine II with four kinds of dianhydrides, including pyromellitic dianhydride (PMDA), 3,3’,4,4’-biphenyltetracarboxylic acid dianhydride (BPDA), 3,3’,4,4’-oxydiphthalic anhydride (ODPA) and 3,3’,4,4’-benzophenonetetracarboxylicdianhydride (BTDA) respectively, via thermal imidization of poly(amic acid) (PAA). The structure and properties of these obtained fluorinated PIs were characterized. These experimental results showed that these fluorinated PI films exhibited excellent optical transmittance in the visible region and thermal resistance. The PI derived from ODPA showed the best optical transparency with the transmittance higher than 85.38 % at 450 nm. These PIs also exhibited good thermal properties with 5 wt% thermal decomposition temperature above 533 °C.

Comparative study of the effective parameters on residual stress relaxation in welded aluminum plates under cyclic loading

2020 ◽  
Vol 21 (5) ◽  
pp. 505
Author(s):  
Yousef Ghaderi Dehkordi ◽  
Ali Pourkamali Anaraki ◽  
Amir Reza Shahani
Keyword(s):  
Residual Stress ◽  
Cyclic Loading ◽  
Stress Relaxation ◽  
Stress Amplitude ◽  
Cyclic Plasticity ◽  
Mean Stress ◽  
Effective Parameters ◽  
Perfect Plasticity ◽  
Residual Stress Relaxation ◽  
Aluminum Plates

The prediction of residual stress relaxation is essential to assess the safety of welded components. This paper aims to study the influence of various effective parameters on residual stress relaxation under cyclic loading. In this regard, a 3D finite element modeling is performed to determine the residual stress in welded aluminum plates. The accuracy of this analysis is verified through experiment. To study the plasticity effect on stress relaxation, two plasticity models are implemented: perfect plasticity and combined isotropic-kinematic hardening. Hence, cyclic plasticity characterization of the material is specified by low cycle fatigue tests. It is found that the perfect plasticity leads to greater stress relaxation. In order to propose an accurate model to compute the residual stress relaxation, the Taguchi L18 array with four 3-level factors and one 6-level is employed. Using statistical analysis, the order of factors based on their effect on stress relaxation is determined as mean stress, stress amplitude, initial residual stress, and number of cycles. In addition, the stress relaxation increases with an increase in mean stress and stress amplitude.

Irradiation-induced stress relaxation of Eurofer97 steel

2011 ◽  
Vol 417 (1-3) ◽  
pp. 104-107 ◽  
Author(s):  
N.V. Luzginova ◽  
M. Jong ◽  
J.W. Rensman ◽  
J.B.J. Hegeman ◽  
J.G. van der Laan
Keyword(s):  
Stress Relaxation ◽  
Induced Stress

Structure–property relationships of aromatic polyamides and polythioamides: comparative consideration with those of analogous polyesters, polythioesters and polydithioesters

RSC Advances ◽  
2015 ◽  
Vol 5 (117) ◽  
pp. 96611-96622 ◽  
Author(s):  
Masayuki Nagasawa ◽  
Tatsuya Ishii ◽  
Daisuke Abe ◽  
Yuji Sasanuma
Keyword(s):  
Structure And Properties ◽  
Structure Property ◽  
Aromatic Polyamides ◽  
Structure Property Relationships

The structure and properties of aromatic polyamides and polythioamides were investigated and compared with those of analogous polyesters, polythioesters, and polydithioesters.

scholarly journals Prediction of Residual Stress Relaxation of Shot Peened 2024-T351 Aluminum Alloy: Part 1

2011 ◽  
Vol 462-463 ◽  
pp. 1355-1360
Author(s):  
Omar Suliman Zaroog ◽  
Aidy Ali ◽  
Sahari B. Barkawi
Keyword(s):  
Residual Stress ◽  
Stress Relaxation ◽  
Shot Peening ◽  
Applied Load ◽  
Cold Work ◽  
Cyclic Tests ◽  
Initial State ◽  
Loading Cycle ◽  
Residual Stress Relaxation ◽  
Alloy Part

It is important to account for residual stress relaxation phenomenon in the design of the component. Specimens of 2024-T351 aluminium alloy were used in this study. The specimens were shot peened under three different shot peening intensities. Cyclic tests for two load magnitudes were performed for 1, 2, 10, 1000 and 10000 cycles. Residual stresses, microhardness and the cold work percentage were measured at initial state and after each loading cycle for the three shot peening intensities and for the two loads. The study revealed that most of the drop in the residual stress, microhardness and cold work happened in the first cycle are dependent on the applied load.

Sign in / Sign up

Export Citation Format

Share Document