Preparation, characterization and thermal aging behaviors of phenylmethylsiloxane-modified epoxy/ DGBEA hybrids, and Synthesis and characterization of novel liquid zirconium-siloxane hybrid resin

• Main Authors: Hsu, Chia Wen, 許嘉紋
• Other Authors: Tan, Chung Sung
• Format: Others
• Language: zh-TW
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/82347160521371256210

博士 === 國立清華大學 === 化學工程學系 === 103 === The aims of this research are development the silicone-modified epoxy based organic-inorganic transparent hybrids for high performance LED encapsulant applications. The thermal stability and cured network relaxation behaviors of transparent hybrids during thermal aging were investigated. Moreover, a liquid zirconium hybrid resin (Zr–QR) was synthesized through sol-gel reactions in order to increase the reactivity of silicone-modified cycloaliphatic epoxy. The acceleration ability of the Zr–QR and the fabrication of a transparent silicone-modified cycloaliphatic epoxy– zirconium nanocomposite were studied in this research. The first part of this study is to investigate the thermal stability of the diglycidyl ether of bisphenol A (DGEBA)–methylhexahydrophtalic anhydride (MHHPA) modified with phenylmethylsiloxane-modified epoxy (PMSE) and the effects of this hybrid on the performance of light emitting diodes (LEDs). The optical and dynamic mechanical properties of the materials, and the effects of these properties on the light output from the encapsulated LEDs, were studied following long-term thermal ageing at 150℃. The DGEBA–PMSE hybrids were highly transparent and its optical stability was shown in the stable light output of the LED, which was 19% higher than that of LEDs encapsulated by DGEBA–MHHPA after 30 days. The conformation rearrangement occurred in the nanoscale domain of the hybrids after thermal ageing, which caused the dynamic mechanical effect on the LED performance, as demonstrated by TEM. The hybrid modified using 0.2 equivalents of PMSE possessed both optical and dynamic mechanical stability were investigated, and resulted in the most stable LED performance. In the second part of this study, the cured network conformations and structural relaxation behaviours of the diglycidyl ether of bisphenol A (DGEBA)-methylhexahydrophthalic anhydride (MHHPA) modified with phenylmethylsiloxane-modified epoxy (PMSE) at different aging temperatures were studied using dynamic mechanical analysis (DMA) and positron annihilation lifetime spectroscopy (PALS). The DMA results revealed that the cured PMSE network can insert into the cured DGEBA network to form interpenetrating polymer networks (IPNs). The structural relaxation behaviours of DGEBA–PMSE-0.4 prepared using DGEBA, PMSE, and MHHPA at a ratio of 0.6:0.4:1 by equivalent weight were studied using PALS at 150°C and 55°C. The aging-induced free volume relaxation parameters of DGEBA–PMSE-0.4 at 150°C and 55°C were investigated using the double additive exponential model and the Kohlrausch–Williams–Watts exponential model. For double additive exponential model, only one relaxation time (ζ) of 584.5 h was found at 150°C; By contrast, there were two separate relaxation times of 37.4 h (ζ1) and 753.6 h (ζ2) at 55°C. The ζ1 of the IPNs hybrid can be attributed to the network relaxation of PMSE, and the ζ2 can be attributed to the network relaxation of DGEBA at 55°C. The results suggested the double additive exponential model can effectively predict DGEBA–PMSE hybrid relaxation behaviours. In the third part of this study, a liquid zirconium hybrid resin (Zr–QR) was synthesized through sol-gel reactions of zirconium butoxide with silanol-terminated polydimethylsiloxane (DMS-S12) and γ- glycidoxypropyltrimethoxysilane (Z-6040). The sol-gel reactions were monitored using Fourier transform infrared (FT-IR) spectroscopy and proton nuclear magnetic resonance spectroscopy. The Zr–QR morphology was investigated using field emission transmission electron microscopy. The Zr–QR had a well-ordered morphology and the dimension was less than 5nm. These properties were achieved because DMS-S12 was used to separate the zirconium clusters and Z-6040 was used to stabilize the Zr–QR. The acceleration of the curing reaction between silicone-modified cycloaliphatic epoxy (SEP) and methylhexahydrophthalic anhydride (MHHPA) caused by the Zr–QR was investigated. Differential scanning calorimetry and FT-IR spectroscopy investigations showed that the Zr–QR first reacted with MHHPA, producing chelating ligands and carboxylic acid. Unlike in the conventional method (adding acetic acid to cause non-reactive chelating ligands to form the carboxylic acid), the carboxylic acid can accelerate the curing reaction between the SEP and MHHPA effectively. The chelating ligand generated from the Zr–QR and MHHPA suppressed the gelation of the Zr–QR itself during the nanocomposite (SEP–Zr–QR) curing process. The cured SEP–Zr–QR nanocomposite exhibited excellent optical transmittance which was above 88% at visible wavelengths.