Effect of pre-imidization on the aggregation structure and properties of polyimide films

Polymer ◽  
2012 ◽  
Vol 53 (19) ◽  
pp. 4157-4163 ◽  
Author(s):  
Ying Wang ◽  
Yang Yang ◽  
Zhenxing Jia ◽  
Jiaqiang Qin ◽  
Yi Gu
Keyword(s):  
Structure And Properties ◽  
Polyimide Films ◽  
Aggregation Structure

Preparation, structure and properties of porous polyimide films via PAA/PU alloy

2007 ◽  
Vol 2 (1) ◽  
pp. 13-16
Author(s):  
Jiugui Liu ◽  
Lizhong Jiang ◽  
Jiayu Zhan ◽  
Dezhen Wu ◽  
Riguang Jin
Keyword(s):  
Structure And Properties ◽  
Polyimide Films

Organo-soluble segmented rigid-rod polyimide films. Part 4.—Anisotropic structure and properties

1993 ◽  
Vol 3 (4) ◽  
pp. 353-360 ◽  
Author(s):  
Fred E. Arnold ◽  
Dexing Shen ◽  
Chul Joo Lee ◽  
Frank W. Harris ◽  
Stephen Z. D. Cheng ◽  
...  
Keyword(s):  
Anisotropic Structure ◽  
Structure And Properties ◽  
Polyimide Films ◽  
Rigid Rod

Alteration of Structure and Properties of Thin Polyimide Films and Coatings by Plasma and Thermal Treatment

2004 ◽  
Vol 38 (2) ◽  
pp. 124-128 ◽  
Author(s):  
O. A. Agapov ◽  
P. G. Babaevskii ◽  
A. A. Zhukov ◽  
G. A. Korneeva ◽  
I. Yu. Korovina ◽  
...  
Keyword(s):  
Thermal Treatment ◽  
Structure And Properties ◽  
Polyimide Films

Structure Development in Polyimide Films

1993 ◽  
Vol 308 ◽  
Author(s):  
John C. Coburn ◽  
Michael T. Pottiger ◽  
Coralie A. Pryde
Keyword(s):  
Glass Transition ◽  
Coefficient Of Thermal Expansion ◽  
Rapid Heating ◽  
Biaxial Stress ◽  
Slow Heating ◽  
Structure And Properties ◽  
Polyimide Films ◽  
Axis Orientation ◽  
Chain Axis ◽  
Out Of Plane

ABSTRACTThe influence of processing conditions on the structure and properties in spin coated polyimide films prepared from flexible, semi-rigid and rigid chemistries was investigated. While the relationship between processing, structure and properties is different for each chemistry, some general trends were observed. Curing above the glass transition in the flexible polyimide BTDA//ODA/MPD, that is incapable of crystallizing and has very little in-plane orientation, has virtually no effect on the structure or properties compared to curing below the glass transition. Curing at temperatures above the glass transition in cry stall izable stiff polyimides such as BPDA//PPD and PMDA//ODA results in an increase in birefringence, in-plane CTE and biaxial stress. In BPDA//PPD, the increase in birefringence is attributed to an increase in polarizability and possibly, an increase in the overall in-plane alignment of the imide ring as evidenced by IR analysis. The increase in in-plane CTE is attributed to a loss in chain axis orientation caused by relaxation effects. The increase in stress is attributed to the increase in the in-plane CTE and also from shrinkage forces arising from crystallization. Rapid heating during cure in the flexible amorphous BTDA//ODA/MPD has essentially no effect on structure or properties compared to slow heating. In the semi-crystalline polyimides, rapid heating during cure leads to higher levels of crystallinity and significantly higher stresses. The increase in stresses is attributed to a loss in chain axis orientation in the plane of the film and shrinkage forces arising from additional crystallization. The directional dependence of the coefficient of thermal expansion, an important functional property, is extremely sensitive to molecular anisotropy. BTDA//ODA/MPD, which is almost isotropic, has an out-of-plane CTE that is approximately 20 percent higher than the in-plane CTE. In contrast, the out-of-plane CTE for the most anisotropic polyimide in this study, BPDA//PPD, is 25 times larger than the in-plane CTE. This sensitivity of the CTE to molecular orientation must be taken into account when modeling stress in, or designing, electronic devices.

Research on Structure and Properties of Lotus Fibers

2012 ◽  
Vol 476-478 ◽  
pp. 1948-1954
Author(s):  
Dong Sheng Chen ◽  
Ying Jin Gan ◽  
Xiao Hong Yuan
Keyword(s):  
Morphological Structure ◽  
High Strength ◽  
Chemical Components ◽  
Structure And Properties ◽  
X Ray Diffraction ◽  
Cross Sectional ◽  
Initial Modulus ◽  
Aggregation Structure ◽  
Cross Striation ◽  
Fiber Fabric

In order to understand the structure and properties of lotus fibers to provide theoretical basis for developing lotus fiber fabric, the research on chemical components, morphological structure, aggregation structure and mechanical properties of nature lotus fiber is implemented by chemical quantitative analysis, scanning electron microscope, infrared spectra, X-ray diffraction analysis and so on. The result is shown. First, lotus fiber is consist of cellulose, hemicellulose, fat waxy, lignin, ash, pectin, hydrotrope, amino acids and so on, where cellulose is the main ingredient. The lotus fiber, showing ribbon spiral revolving structure vertically, has clearly imperceptible cross striation, and is bundle fiber composed of many monofils. Then, the cross-sectional of lotus monofil is circular or similar to circular. Lotus fiber is typical cellulose I structure with 48% crystallinity and 60% orientation. The density, fineness and moisture regain of lotus fiber is respectively 1.1848 g/cm3, 1.55 dtex, 12.32%. Lotus fiber is high strength and low stretch fiber with initial modulus 146.81 cN/dtex, breaking strength 3.44 cN/dtex and breaking elongation 2.75%.

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