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Liao S.-H.,National Tsing Hua University | Weng C.-C.,National Tsing Hua University | Yen C.-Y.,National Tsing Hua University | Hsiao M.-C.,National Tsing Hua University | And 6 more authors.
Journal of Power Sources | Year: 2010

Multiwalled carbon nanotubes (MWCNTs) are covalently modified with different molecular weights 400 and 2000 poly(oxyalkylene)-amine bearing the diglycidyl ether of bisphenol A (DGEBA) epoxy (POA400-DGEBA and POA2000-DGEBA) oligomers. The oxidized MWCNTs (MWCNTs-COOH) are converted to the acid chloride-functionalized MWCNTs, followed by the reaction with POA-DGEBAs to prepare the MWCNTs/POA400-DGEBA and MWCNTs/POA2000-DGEBA. FTIR, thermogravimetric analysis (TGA) and high resolution X-ray photoelectron spectra (XPS) reveal that the POA-DGEBAs are covalently attached to the surface of MWCNTs. The morphology of MWCNTs/POA-DGEBA is observed by TEM. The POA400-DGEBA coated on the MWCNTs is thicker and more uniform. However, the coating of POA2000-DGEBA on the MWCNTs shows a worm-like bulk substance and the MWCNT surface is bare. In addition, the flexural strength and the bulk electrical conductivity of the MWCNTs/polypropylene nanocomposite bipolar plates are measured 59% and 505% higher than those of the original composite bipolar plates by adding 8 phr of MWCNTs/POA400-DGEBA. The maximum current density and power density of the single cell test for the nanocomposite bipolar plate with 4 phr MWCNTs/POA400-DGEBA are 1.32 A cm -2 and 0.533 W cm -2, respectively. The overall performance confirms the functionalized MWCNTs/polypropylene nanocomposite bipolar plates prepared in this study are suitable for PEMFC application. © 2009.

Li J.H.,Plastics Industry Development Center
Annual Technical Conference - ANTEC, Conference Proceedings | Year: 2012

In this study, the aliphatic or aromatic isocyanates and poly-alcohols was used to synthesize polyurethane with shape memory function, which the polyol was derived from the biomass polylactic acid (PLA). The recycled PLA was degraded into the low molecular weight PLA (Mw 1,000) and the chain extension agent (1,4-butanediol, BDO) reaction was added to form biomass polyol. The analysis of Fourier transform infrared spectroscopy (FTIR) and Gel permeation chromatography (GPC) were proved the synthesis of polyol. The recovery ratio of shape memory and mechanical properties of polyurethane were improved significantly due to the urea structure, the biomass polyurethane with shape memory could be increased up to 95% of recovery ratio. Different isocyanate (hexamethylene diisocyanate, HDI, or 4,4-diphenylmethene diisocyanate, MDI) were compared and found that the functional group of aromatic was better than that of aliphatic in the synthesis of polyurethane with shape memory behavior.

Hsiao M.-C.,National Tsing Hua University | Liao S.-H.,National Tsing Hua University | Yen M.-Y.,National Tsing Hua University | Ma C.-C.M.,National Tsing Hua University | And 5 more authors.
Journal of Power Sources | Year: 2010

This study prepares novel metal mesh hybrid polymer composite bipolar plates for proton exchange membrane fuel cells (PEMFCs) via inserting a copper or aluminum mesh in polymer composites. The composition of polymer composites consists of 70 wt% graphite powder and 0-2 wt% modified multi-walled carbon nanotubes (m-MWCNTs). Results indicate that the in-plane electrical conductivity of m-MWCNTs/polymer composite bipolar plates increased from 156 S cm-1 (0 wt% MWCNT) to 643 S cm-1 (with 1 wt% MWCNT) (D.O.E. target >100 S cm-1). The bulk thermal conductivities of the copper and aluminum mesh hybrid polymer composite bipolar plates (abbreviated to Cu-HPBP and Al-HPBP) increase from 27.2 W m-1 K-1 to 30.0 W m-1 K-1 and 30.4 W m-1 K-1, respectively. The through-plane conductivities decrease from 37.8 S cm-1 to 36.7 S cm-1 for Cu-HPBP and 22.9 S cm-1 for Al-HPBP. Furthermore, the current and power densities of a single fuel cell using copper or aluminum mesh hybrid polymer composite bipolar plates are more stable than that of using neat polymer composite bipolar plates, especially in the ohmic overpotential region of the polarization curves of single fuel cell tests. The overall performance confirms that the metal mesh hybrid polymer composite bipolar plates prepared in this study are promising for PEMFC application. © 2009.

Chiang M.-F.,National Chung Hsing University | Chu M.-Z.,National Chung Hsing University | Chu M.-Z.,Plastics Industry Development Center | Wu T.-M.,National Chung Hsing University
Polymer Degradation and Stability | Year: 2011

This study elucidates the thermal degradation behavior of biodegradable poly(l-lactide) (PLLA)/layered double hydroxide (LDH) nanocomposites was explored using thermogravimetric analysis (TGA) and pyrolysis-gas chromatography/mass spectroscopy (Py-GC/MS) in an inert atmosphere. PLLA/LDH nanocomposites were fabricated using PLLA and organically-modified magnesium/aluminum layered double hydroxide (P-LDH) in tetrahydrofuran solution. According to the TGA results, the thermal stability of PLLA/P-LDH nanocomposites was significantly lower than that of pure PLLA matrix, perhaps because P-LDH provides thermal acceleration of the degradation of the underlying polymer from the heat source. The identification of the thermal degradation products by Py-GC/MS evidently shows that introducing P-LDH into PLLA leads to a remarkable change during the thermal degradation process. The main reaction route of neat PLLA was through inter- and intra-transesterification to generate lactides and oligomer. The primary volatile products obtained from PLLA/P-LDH nanocomposites were lactides regardless of the temperature of degradation. These results suggest that the thermal degradation behavior of PLLA/P-LDH nanocomposites is governed by the preferential formation of lactide by the unzipping depolymerization reaction, which is catalyzed by Mg and Al components in P-LDH. © 2010 Elsevier Ltd. All rights reserved.

Yu Y.-H.,National Ilan University | Huang C.-H.,Chung Yuan Christian University | Huang C.-H.,Plastics Industry Development Center | Yeh J.-M.,Chung Yuan Christian University | Huang P.-T.,Fu Jen Catholic University
Organic Electronics: physics, materials, applications | Year: 2011

A series of N-diaryl-anthracene-9,10-diamine derivatives with methyl substituents at meta or para position of N-diaryl rings were synthesized and used as dopants for Organic Light-Emitting Devices (OLED). The effects of substituted methyl substituents have been compared based on both materials and solid device evaluation. The performance of solid state devices in the configuration of ITO/N,N′-bis(naphthalene-1-yl)-N,N′-bis(phenyl) benzidine (NPB) (40 nm)/3% dopant: 9,10-di(2-naphthyl)anthracene (AND) (40 nm)/tris(8-hydroxyquinoline)aluminum (Alq3) (20 nm)/LiF (1.5 nm)/Al (200 nm) have been studied. As compared to the non-substituted dopant N,N,N′,N′-tetraphenyl-anthracene-9,10-diamine, current efficiency was promoted to approximately 2.9, 6.33, and 7.94 cd/A, and power efficiency was improved by 0.74, 2.26 and 3.02 lm/W, for dopants with the substituted methyl groups at meta, para and both meta/para positions, respectively. The device, prepared by using the dimethyl-substituted dopant at meta/para position, showed the best performance when the luminance of the device reached 24,991 cd/m 2 with CIE (x, y) = (0.38, 0.59), and the efficiency of the device reached 24.99 cd/A and 7.48 lm/W at a driving current of 100 mA/cm2. As compared with a device made of a coumarin (C545T)/Alq3-based emitting layer, the dimethyl-substituted dopant/ADN-based device developed in this study, exhibited great improvement in device performance. © 2011 Elsevier B.V. All rights reserved.

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