Waxd Study of Low TCE Polyimide Films Formed from Polyamic Acid Blends and Copolymers.

1992 ◽  
Vol 264 ◽  
Author(s):  
Thomas L. Nunes ◽  
Krishna G. Sachdev
Keyword(s):  
Molecular Structure ◽  
Tensile Strength ◽  
Crystallinity Index ◽  
Moisture Uptake ◽  
Chain Segment ◽  
Polyimide Films ◽  
Flexible Chain ◽  
Polyamic Acid ◽  
Out Of Plane ◽  
Molecular Anisotropy

AbstractLow TCE polyimides, typically BPDA-PDA and related materials are well known for their special properties which include low in-plane TCE, up to 3X higher elastic modulus and ultimate tensile strength, and lower moisture uptake relative to the commonly known flexible chain polyimides [1]. These differences are due to the rod-like orientation and highly organized molecular structure of the polyimides that are derived from linear-planar precursors resulting in more anisotropic properties such as the X-Y vs Z-direction TCE [2], and optical as well as dielectric properties.In the present study, we have measured the WAXD patterns of polyimide films formed from BPDA-PDA and BTDA-PDA polyamic acid mixtures and BPDA-BTDA-PDA random copolyamic acids. In order to examine the effect of a highly flexible chain segment on the molecular anisotropy of rod-like polyimides, preliminary WAXD patterns were recorded for films of BPDA-BDAF and a BPDA-PDA-BDAF copolyimide.An in-plane and an out-of-plane crystallinity index, measures of molecular order within the polyimide films studied were estimated from the WAXD patterns. The data are correlated with the various blends and copolymer compositions and discussed in terms of structural implications.

Low TCE Polyimides from Polyamic Acid Blends and Copolymers: Preparation and Characterization Studies

1992 ◽  
Vol 264 ◽  
Author(s):  
Krishna G. Sachdev ◽  
Sandra Graham-Ode ◽  
Thomas L. Nunes ◽  
Paul S. Ho
Keyword(s):  
Experimental Data ◽  
Mechanical Properties ◽  
Residual Stress ◽  
Thermal Expansion ◽  
Silicon Wafers ◽  
Chain Segment ◽  
Flexible Chain ◽  
Polyamic Acid ◽  
Characterization Studies

AbstractA series of polyimides prepared from BPDA-PDA and BTDA-PDA polyamic acid blends and the corresponding (BPDA-PDA)x-(BTDA-PDA)y copolymers have been investigated for the mechanical properties, the thermal expansion, and the residual stress in films cured on silicon wafers. To determine the effect of inclusion of a highly flexible chain segment into BPDA-PDA structure, a BPDA-PDA/BDAF copolyimide has also been characterized. The experimental data are correlated with the chemistry and the composition of the blends and the copolyimides.

Effect Of Moisture On The Physical Properties Of Polyimide Films

1991 ◽  
Vol 227 ◽  
Author(s):  
Rajeevi Subramanian ◽  
Michael T. Pottiger ◽  
Jacqueline H. Morris ◽  
Joseph P. Curilla
Keyword(s):  
Dielectric Constant ◽  
Steady State ◽  
Electrical Properties ◽  
Relative Humidity ◽  
Quartz Crystal ◽  
Moisture Absorption ◽  
Relative Dielectric Constant ◽  
Moisture Uptake ◽  
Polyimide Films ◽  
Effect Of Moisture

ABSTRACTMoisture absorption and its effect on electrical properties were measured for several polyimides. A Quartz Crystal Microbalance (QCM) was used to investigate the moisture absorption in BPDA/PPD, PMDA/ODA, and BTDA//ODA/MPD polyimides. The steady-state moisture uptake in polyimides as a function of relative humidity (RH) was determined by exposing film samples to successively higher RH values ranging from 10 to 85% at 25°C. The isothermal moisture absorption as a function of percent RH was found to be nearly linear for all of the polyimides studied. The effect of moisture on the electrical properties of a BPDA/PPD polyimide was also investigated. The relative dielectric constant at 25 °C was found to be a linear function of the moisture absorbed.

Effects of geometry and specimen size on out-of-plane tensile strength of aligned CFRP determined by direct tensile method

2010 ◽  
Vol 41 (10) ◽  
pp. 1425-1433 ◽  
Author(s):  
Eiichi Hara ◽  
Tomohiro Yokozeki ◽  
Hiroshi Hatta ◽  
Takashi Ishikawa ◽  
Yutaka Iwahori
Keyword(s):  
Tensile Strength ◽  
Specimen Size ◽  
Out Of Plane ◽  
Direct Tensile

scholarly journals The out of plane behaviour of masonry infilled frames

2021 ◽  
Vol 2090 (1) ◽  
pp. 012148
Author(s):  
G Frunzio ◽  
L Di Gennaro
Keyword(s):  
Tensile Strength ◽  
Constitutive Model ◽  
Experimental Tests ◽  
Seismic Resistance ◽  
Review Of The Literature ◽  
Framed Structures ◽  
Seismic Modelling ◽  
Masonry Infills ◽  
Out Of Plane ◽  
The Subject

Abstract The great interest about out of plane behavior of masonry infill walls has recently increased since it is a key point in the seismic modelling of framed structures. Their contribute to the whole seismic resistance of a framed building cannot be skipped. After a review of the literature on the subject, this paper presents a trilinear constitutive model for the out of plane behavior of masonry infills based on the tensile strength of the constituents. Comparisons with literature model are provided and the identification of the model is based on experimental tests.

scholarly journals Improving Spinnability of Hyper-coal Derived Spinnable Pitch through the Hydrogenation with 1, 2, 3, 4-tetrahydroquinoline

2018 ◽  
Author(s):  
Jianxiao Yang ◽  
Wei Wu ◽  
Xiaxiang Zhang ◽  
Kui Shi ◽  
Xuanke Li ◽  
...  
Keyword(s):  
Molecular Structure ◽  
Heat Treatment ◽  
Tensile Strength ◽  
Carbon Fiber ◽  
Oxygen Content ◽  
Softening Point

The proper hydrogenation of Hyper-coal (HPC) using 1, 2, 3, 4-tetrahydroquinoline (THQ) was able to decrease the oxygen content and adjust the molecular structure of HPC for preparing the spinnable pitch with high softening point (SP). The spinnable pitch prepared from the THQ-soluble (QS) fraction of HPC as a precursor consisted more naphthenic carbon groups than that prepared from the 1-methylnaphthalene (1-MN) soluble (MNS) fraction of HPC. The HPC-QS derived pitch showed excellent spinnability even the SP of 260°C, and the tensile strength of the resultant carbon fiber was up to 1350 MPa with a diameter around 8 µm by only heat treatment at 800°C for 5 min.

Modeling and experimental investigation of out-of-plane deformation on mechanical performance of composites manufactured by ATL

2016 ◽  
Vol 36 (5) ◽  
pp. 347-359 ◽  
Author(s):  
Qiyi Chu ◽  
Yong Li ◽  
Jun Xiao ◽  
Dajun Huan ◽  
Xiaodong Chen
Keyword(s):  
Tensile Strength ◽  
Deformation Rate ◽  
Mechanical Performance ◽  
Plane Deformation ◽  
Experimental Results ◽  
Predicting Model ◽  
Fiber Waviness ◽  
Manufacturing Method ◽  
Four Point Bending ◽  
Out Of Plane

The change of mold normal curvature along the trajectory may result in out-of-plane waviness during the automated laying process, on which the layup speed and temperature would have an effect. A new parameter, deformation rate, was defined by combining the effect of mold curvature change rate and layup speed. A predicting model was proposed based on the fiber waviness and interlaminar sliding model to calculate the relationship between stiffness retention and the layup process parameters, including deformation rate and temperature. An experimental study on the effect of different deformation parameters on the tensile performance of composites was carried out based on a new manufacturing method of plated specimens with different levels of waviness by means of a four-point bending fixture. The experimental results showed that when the deformation temperature increases from 20℃ to 80℃, the tensile strength increases first and then decreases while the tensile module keeps increasing. While the deformation rate decreases from 0.40 to 0.04 mm−1/s, both tensile strength and module showed an increasing trend. The predicting model being validated by experimental results can be utilized to optimize the layup process parameter to satisfy the quality and efficiency requirements.

Polyamic Acid Langmuir-Blodgett (LB) Films Containing A Stable Second-Order NLO Chromophore

1995 ◽  
Vol 413 ◽  
Author(s):  
D. W. Cheong ◽  
J. -I Chen ◽  
J. Kumar ◽  
S. K. Tripathy
Keyword(s):  
Nonlinear Coefficient ◽  
Polarized Light ◽  
Second Order ◽  
Polyimide Films ◽  
Polyamic Acid ◽  
Lb Films ◽  
Langmuir Blodgett ◽  
Number Of Layers ◽  
Absorption Correction ◽  
Nlo Chromophores

ABSTRACTNonlinear optical (NLO) LB films of polyamic acid containing a stable NLO dye were prepared and imidized either chemically or thermally. The optical properties and molecular orientation of these LB films were studied. From the absorption spectra, we infer that the derivative of the pnitroazobenzene chromophore covalently attatched to polyamic acid did not show significant aggregation. Quadratic dependence of SHG on the number of layers in polyamic acid films indicated the noncentrosymmetric organization of polar NLO chromophores. A second-order nonlinear coefficient (d33) of 23.4 pm/V was observed at 1064 nm after absorption correction. In polyimide films, SH intensity was dramatically reduced due to the collapse of the layered structure upon imidization process. In-plane isotropy of the LB films of polyamic acid and polyimide were lost upon irradiation of polarized light.

scholarly journals Improving Spinnability of Hyper-Coal Derived Spinnable Pitch through the Hydrogenation with 1,2,3,4-Tetrahydroquinoline

2018 ◽  
Vol 4 (3) ◽  
pp. 46
Author(s):  
Jianxiao Yang ◽  
Wei Wu ◽  
Xiaxiang Zhang ◽  
Kui Shi ◽  
Xuanke Li ◽  
...  
Keyword(s):  
Molecular Structure ◽  
Tensile Strength ◽  
Carbon Fiber ◽  
Oxygen Content ◽  
Softening Point ◽  
Carbonization Temperature

The proper hydrogenation of Hyper-coal (HPC) using 1,2,3,4-tetrahydroquinoline (THQ) was able to decrease the oxygen content and adjust the molecular structure of HPC for preparing the spinnable pitch with high softening point (SP). The spinnable pitch prepared from the THQ-soluble (QS) fraction of HPC as a precursor consisted of more naphthenic carbon groups than that prepared from the 1-methylnaphthalene (1-MN) soluble (MNS) fraction of HPC. The HPC-QS derived spinnable pitch showed excellent spinning performance even though the SP of 260 °C, and the tensile strength of the resultant carbon fiber was increased to 1350 MPa with a diameter around 8 µm under the only carbonization temperature of at 800 °C for 5 min.

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