Browsing by Author "Yu, Hsin-Pei"

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An in situ fabrication process for highly electrical conductive polyimide/MWCNT composite films using 2,6-diaminoanthraquinone
(2013-10-18)
Huang, Yi-Chia
;
Lin, June-Hua
;
Tseng, I-Hsiang
;
Lo, An-Ya
;
Lo, Teng-Yuan
We present a valuable in situ fabrication process for synthesizing high electrical conductive polyimide/multiwalled carbon nanotube (PI/MWCNT) composite films. The success of this process was achieved the addition of 2,6-diaminoanthraquinone (DAAQ). The DAAQ is not only an excellent dispersion agent to stably disperse pristine MWCNTs in solvent but also a monomer to directly synthesize PI. The strong interaction between DAAQ with MWCNT was verified by FTIR, UV-Vis, Raman, and fluorescence spectra. The highest value of electrical conductivity of 55.6 S/cm are achieved by the PI composite containing 40 wt.% of MWCNT. Moreover, the electrical conductivity of this film further enhanced to 106 S/cm after the thermal compression process. The MWCNT content at the percolation threshold of conductivity is 0.50 wt.% (or 0.32 vol.%) and the critical exponent is equal to 2.52. The developed in situ fabrication process through DAAQ-derived molecules can also be applied to synthesize other polymers requiring diamine structure. (C) 2013 Published by Elsevier Ltd.
Enhancement of adhesion between copper foil and polyimide film containing thermally decomposable polystyrene particles
(2012-11-25)
Tsai, Mei-Hui
;
Huang, Yi-Chia
;
Tseng, I-Hsiang
;
Yu, Hsin-Pei
;
Lin, Yin-Kai
A facile method was developed to synthesize porous polyimide (PI) films with enhanced adhesion to Cu foil. Various amounts (0.14 wt %) of polystyrene (PS) spheres with the diameter of 250 nm were mixed with the PI precursor synthesized from pyromellitic dianhydride (PMDA) and 4,4'-oxydianiline in N,N'-dimethylacetamide. PS was decomposed during thermal imidization process to create the porous PI structure. The increase in surface area and surface roughness was observed from the obtained porous PI films and was a function of the PS content up to 4 wt %. A significant improvement in the adhesion strength between porous PI film and Cu foil, which was determined by 90 degrees peel test, was achieved. The adhesion strength of PI containing 4 wt % PS to Cu was 1.53 kgf/cm compared with pure PI of 1.08 kgf/cm. Meanwhile, the synthesized porous PI films exhibit sufficient mechanical strength and thermal stability for practical applications. (c) 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Thermal and mechanical properties of polyimide/nano-silica hybrid films
(2011-05-31)
Tsai, Mei-Hui
;
Huang, Yi-Chia
;
Tseng, I-Hsiang
;
Yu, Hsin-Pei
;
Lin, Yin-Kai
A novel route to synthesize polyimide (PI)/silica hybrid films with improved thermal and mechanical properties was developed. Low-molecular-weight poly(amic acid) (PAA), which is the precursor of PI, was successfully synthesized by controlling the molar ratio of monomers, [4,4'-(4,4'-isopropylidenediphenoxy) bis(phthalic anhydride)] (IDPA) and 2,2'-bis(4-(4-aminophenoxy)phenyl)propane (BAPP). The PM with its low-molecule-weight feature showed good compatibility with silica-sol and dispersed well within the network of silica-sol. Silica nanoparticles with an average size of 20 nm were obtained without adding coupling agents and dispersed homogenously within the resulting PI/silica hybrid films due to the hydrogen bonding between Si-OH groups and C=O in imide rings of polyimide. The improvement in the storage modulus and the coefficient of thermal expansion (CTE) by hybrid films was revealed. With the presence of 50 wt.% silica in hybrid films, the storage modulus was 5857 MPa and the CTE was 18.1 ppm/degrees C. compared with 1620 MPa and 76.5 ppm/degrees C for pure PI. Most importantly, the transmission at 550 nm was 81.4% for the hybrid film with 50 wt.% silica, which is close to 87.5% for pure PI. The CTE of the hybrid film dropped to the level comparable with that of copper without sacrificing its transparency, which was associated with the well-dispersed silica nanoparticles and the semi-interpenetrating polymer network (semi-IPN) structure within the PI matrix. Crown Copyright (C) 2011 Published by Elsevier B.V. All rights reserved.