Effects of heat treatment on the dielectric properties of aerosol-deposited Al2O3-polyimide composite thick films for room-temperature fabrication

Hyung-Jun KIM,Song-Min NAM 한양대학교 세라믹연구소 2009 Journal of Ceramic Processing Research Vol.10 No.6

Al2O3-polyimide composite thick films for integrated substrates were successfully fabricated at room temperature by an aerosol deposition method (ADM). When using as-received a-Al2O3 as a starting powder, the Al2O3-polyimide composite thick films exhibited a high dielectric loss and high frequency dependence. The relative permittivity and tan δ of the Al2O3-polyimide composite thick films using as-received Al2O3 powder were 6.7 and 0.026 at 1MHz, respectively. However, their dielectric loss was remarkably decreased from 0.026 to 0.007 at 1MHz after post-annealing at 100℃ although their relative permittivity did not change. It was determined that the decreases of dielectric loss mainly depended on the state of the Al2O3. Based on these results, the heat treatment of the Al2O3 starting powder was carried out in order to fabricate Al2O3-polyimide composite films with a low dielectric loss at room temperature. As a result, their tan δ was also decreased from 0.026 to 0.007 without a long post-annealing. It was confirmed that the preparation of the ceramic Al2O3 starting powder was important for the roomtemperature fabrication of the aerosol deposited Al2O3-polyimide composite thick films with a low dielectric loss. Al2O3-polyimide composite thick films for integrated substrates were successfully fabricated at room temperature by an aerosol deposition method (ADM). When using as-received a-Al2O3 as a starting powder, the Al2O3-polyimide composite thick films exhibited a high dielectric loss and high frequency dependence. The relative permittivity and tan δ of the Al2O3-polyimide composite thick films using as-received Al2O3 powder were 6.7 and 0.026 at 1MHz, respectively. However, their dielectric loss was remarkably decreased from 0.026 to 0.007 at 1MHz after post-annealing at 100℃ although their relative permittivity did not change. It was determined that the decreases of dielectric loss mainly depended on the state of the Al2O3. Based on these results, the heat treatment of the Al2O3 starting powder was carried out in order to fabricate Al2O3-polyimide composite films with a low dielectric loss at room temperature. As a result, their tan δ was also decreased from 0.026 to 0.007 without a long post-annealing. It was confirmed that the preparation of the ceramic Al2O3 starting powder was important for the roomtemperature fabrication of the aerosol deposited Al2O3-polyimide composite thick films with a low dielectric loss.

Surface modification of polymeric substrates to enhance the barrier properties of an Al₂O₃ layer formed by PEALD process

Kim, Hyun Gi,Lee, Jong Geol,Kim, Sung Soo ELSEVIER 2017 Organic Electronics Vol. No.

<P><B>Abstract</B></P> <P>Aluminum oxide (Al<SUB>2</SUB>O<SUB>3</SUB>) layers were deposited on various polymeric substrates by a low frequency plasma-enhanced atomic layer deposition (PEALD) process. Polyethylene naphthalate (PEN), polyethylene terephthalate (PET), and polyethersulfone (PES) were tested as substrates for barrier films. Each substrate has its own characteristics to have influences on the Al<SUB>2</SUB>O<SUB>3</SUB> layer formation and penetration into the substrate, which greatly affected the barrier properties. Prior to the deposition process, polymeric substrates were pretreated in argon and oxygen plasmas, and surface energy was leveled up due to the formation of polar group. Characterizations of the Al<SUB>2</SUB>O<SUB>3</SUB> layer by Time of Flight - Secondary Ion Mass Spectrometry (ToF-SIMS) revealed that plasma treatment lowered the level of OH<SUP>−</SUP> in Al<SUB>2</SUB>O<SUB>3</SUB> layer. X-ray photoelectron microscopy (XPS) confirmed that A12p peak of Al<SUB>2</SUB>O<SUB>3</SUB> layer was shifted to a higher core level by plasma treatment. Density of the layer on the plasma treated surface was greater than that of untreated surface. It was found that plasma treatment of the surface had significant effects on the formation of the Al<SUB>2</SUB>O<SUB>3</SUB> layer, which much improved the barrier performance. Optical transmittance was little affected by plasma treatment and PEALD process. After oxygen plasma pretreatment, the WVTR of the Al<SUB>2</SUB>O<SUB>3</SUB> layer deposited on the plasma-treated PEN substrate was around 7.2 × 10<SUP>−4</SUP> g/m<SUP>2</SUP>day, which is significantly lower than that of the untreated substrate.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Al<SUB>2</SUB>O<SUB>3</SUB> layers were formed on several polymer substrates by PEALD process, and characterizations of substrate properties were correlated with their barrier properties. </LI> <LI> The plasma pretreatment of polymer substrates with argon and oxygen prior to PEALD process much enhanced the barrier properties. </LI> <LI> The Al<SUB>2</SUB>O<SUB>3</SUB> layer formed on plasma-treated polymer substrates have a low level of OH<SUP>−</SUP> impurities and a higher refractive index compared to untreated samples. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Enhancement of the barrier property was attributed to the formation of a dense and conformal Al<SUB>2</SUB>O<SUB>3</SUB> layer by surface modification of the various polymer substrates.</P> <P>[DISPLAY OMISSION]</P>

Polystyrene-Al ₂ O ₃ composite solid polymer electrolyte for lithium secondary battery

Lim, Yu-Jeong,An, Yu-Ha,Jo, Nam-Ju Springer 2012 Nanoscale research letters Vol.7 No.1

<P>In a common salt-in-polymer electrolyte, a polymer which has polar groups in the molecular chain is necessary because the polar groups dissolve lithium salt and coordinate cations. Based on the above point of view, polystyrene [PS] that has nonpolar groups is not suitable for the polymer matrix. However, in this PS-based composite polymer-in-salt system, the transport of cations is not by segmental motion but by ion-hopping through a lithium percolation path made of high content lithium salt. Moreover, Al<SUB>2</SUB>O<SUB>3 </SUB>can dissolve salt, instead of polar groups of polymer matrix, by the Lewis acid-base interactions between the surface group of Al<SUB>2</SUB>O<SUB>3 </SUB>and salt. Notably, the maximum enhancement of ionic conductivity is found in acidic Al<SUB>2</SUB>O<SUB>3 </SUB>compared with neutral and basic Al<SUB>2</SUB>O<SUB>3 </SUB>arising from the increase of free ion fraction by dissociation of salt. It was revealed that PS-Al<SUB>2</SUB>O<SUB>3 </SUB>composite solid polymer electrolyte containing 70 wt.% salt and 10 wt.% acidic Al<SUB>2</SUB>O<SUB>3 </SUB>showed the highest ionic conductivity of 9.78 × 10<SUP>-5 </SUP>Scm<SUP>-1 </SUP>at room temperature.</P>

Effect of nano -Al2O3 addition on ion dynamics in polymer electrolytes

Shahzada Ahmad,S.A. Agnihotry 한국물리학회 2009 Current Applied Physics Vol.9 No.1

Polymer electrolytes, which hold the key of successful operation of all solid state ionic devices, have been investigated. An amorphous polymer was used to facsimile fast ion transport in the gel polymer electrolytes (GPE) and room temperature conductivity >10-3 S/cm can be attained. Further, these electrolytes were transformed into composites by dispersing inorganic particles of -Al2O3 (11 nm in size) in varying wt.%. An enhancement in the conductivity for an optimum concentration using LiClO4 as a salt can be obtained and is described in terms of free charge carrier concentration, while the other family of Lithium salts viz. LiTf, LiIm, LiBETI decreases the conductivity marginally. FTIR spectroscopy supports the observed decrease in terms of more association between fillers and salts. It has been realized that the mechanical integrity of these composites increases manifold, without affecting the conductivity, significantly. Polymer electrolytes, which hold the key of successful operation of all solid state ionic devices, have been investigated. An amorphous polymer was used to facsimile fast ion transport in the gel polymer electrolytes (GPE) and room temperature conductivity >10-3 S/cm can be attained. Further, these electrolytes were transformed into composites by dispersing inorganic particles of -Al2O3 (11 nm in size) in varying wt.%. An enhancement in the conductivity for an optimum concentration using LiClO4 as a salt can be obtained and is described in terms of free charge carrier concentration, while the other family of Lithium salts viz. LiTf, LiIm, LiBETI decreases the conductivity marginally. FTIR spectroscopy supports the observed decrease in terms of more association between fillers and salts. It has been realized that the mechanical integrity of these composites increases manifold, without affecting the conductivity, significantly.

알루미나가 포함된 복합산화물의 제조와 열물성 특성평가

임샛별,유희정,홍태환,정미원,Lim, Saet-Byeol,You, Hee-Jung,Hong, Tae-Whan,Jung, Mie-Won 한국재료학회 2010 한국재료학회지 Vol.20 No.9

$Al_2O_3$ has received wide attention with established use as a catalyst and growing application in structural or functional ceramic materials. On the other hand, the boehmite (AlO(OH)) obtained by sol-gel process has exhibited a decrease in surface area during phase transformation due to a decline in surface active site at high temperature. In this work, $Al_2O_3$-CuO/ZnO (ACZ) and $Al_2O_3$-CuO/CeO (ACC) composite materials were synthesized with aluminum isopropoxide, copper (II) nitrate hemi (pentahydrate), and cerium (III) nitrate hexahydrate or zinc (II) nitrate hexahydrate. Moreover, the Span 80 as the template block copolymer was added to the ACZ/ACC composition to make nano size particles and to keep increasing the surface area. The ACZ/ACC synthesized powders were characterized by Thermogravimetry-Differential Thermal analysis (TG/DTA), X-ray Diffractometer (XRD), Field-Emmision Scanning Electron Microscope (FE-SEM), Bruner-Emmett-Teller (BET) surface analysis and thermal electrical conductivity (ZEM-2:M8/L). An enhancement of surface area with the addition to Span 80 surfactant was observed in the ACZ powders from 105 $m^2$/g to 142 $m^2$/g, and the ACC powders from 103 $m^2$/g to 140 $m^2$/g, respectively.

Preparation of Al@Fe2O3 Core-Shell Composites Using Amphiphilic Graft Copolymer Template

김종학 ( Jong Hak Kim ),라즈쿠마파텔 ( Rajkumar Patel ),김상진 ( Sang Jin Kim ),김진규 ( Jin Kyu Kim ),박정수 ( Jung Su Park ) 한국화학공학회 2014 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.52 No.2

A graft copolymer of poly(vinyl chloride)-g-poly(oxy ethylene methacrylate) (PVC-g-POEM) was synthesized via atom transfer radical polymerization (ATRP) and used as a structure-directing agent to prepare Al@Fe2O3 core-shell nanocomposites through a sol-gel process. The amphiphilic property of PVC-g-POEM allows for good dispersion of Al particles and leads to specific interaction with iron ethoxide, a precursor of Fe2O3. Secondary bonding interaction in the sol-gel composites was characterized by Fourier transform-infrared (FT-IR) spectroscopy. The wellorganized morphology of Al@Fe2O3 core-shell nanocomposites was observed using scanning electron microscopy(SEM) and transmission electron microscopy (TEM). Energy dispersive X-ray (EDX) and X-ray diffraction (XRD) were used to analyze the elemental composition and crystallization structure of the composites.

30 wt% β-Tricalcium Phosphate/Al₂O₃ 복합재료의 제조 및 특성

정희철,하정수,Jeong, Heecheol,Ha, Jung-Soo 한국재료학회 2018 한국재료학회지 Vol.28 No.3

${\beta}-Tricalcium$ phosphate (TCP) was added to $Al_2O_3$ to make a biomaterial with good mechanical properties. Using a TCP powder synthesized by a polymer complexation method, $Al_2O_3$ composites containing 30 wt% TCP were fabricated and characterized for densification, phase, microstructure, strength, and fracture toughness. With optimizing the powder preparation conditions, a high densification of 97 % was obtained by sintering at $1350^{\circ}C$ for 2 h. No reaction between the two components occurred and there was no transition to ${\alpha}-TCP$. TCP grains with a size of $2-4{\mu}m$ were well surrounded by $Al_2O_3$ grains with a size of $1{\mu}m$ or less. Strength 61(Brazilian) or 187(3-p MOR) MPa, and fracture toughness 1.7 (notched beam) or 2.5 (indentation) $MPa{\cdot}m^{1/2}$ were obtained, which are large improvements over the strength of $TCP/Al_2O_3$ composites and toughness of TCP and hydroxyapatite in previous studies.

Fabrication of Porous Al₂O₃-(m-ZrO₂) Composites and Al₂O₃-(m-ZrO₂)/PMMA Hybrid Composites by Infiltration Process

Lee, Byong-Taek,Quang, Do Van,Song, Ho-Yeon The Korean Ceramic Society 2007 한국세라믹학회지 Vol.44 No.6

Porous $Al_2O_3-(m-ZrO_2)$ composites were fabricated by pressureless sintering, using different volume percentages (40% - 60%) of poly methyl methacrylate (PMMA) powders as a pore-forming agent. The pore-forming agent was successfully removed, and the pore size and shape were well-controlled during the burn-out and sintering processes. The average pore size in the porous $Al_2O_3-(m-ZrO_2)$ bodies was about $200\;{\mu}m$ in diameter. The values of relative density, bending strength, hardness, and elastic modulus decreased as the PMMA content increased; i.e., in the porous body (sintered at $1500^{\circ}C$) using 55 vol % PMMA, their values were about 50.8%, 29.8 MPa, 266.4 Hv, and 6.4 GPa, respectively. To make the $Al_2O_3-(m-ZrO_2)$/polymer hybrid composites, a bioactive polymer, such as PMMA, was infiltrated into the porous $Al_2O_3-(m-ZrO_2)$ composites. After infiltration, most of the pores in the porous $Al_2O_3-(m-ZrO_2)$ composites, which were made using 60 vol % PMMA additions, were infiltrated with PMMA, and their values of relative density, bending strength, hardness, and elastic modulus remarkably increased.

Synthesis and Characterization of Al(OH)₃/Polystyrene Nanocomposite Latex Particles by Emulsion Polymerization

Park, Eun Ju,Heo, Hoon,Lim, Kwon Taek WILEY-VCH Verlag 2007 Macromolecular symposia Vol.249 No.1

<P>The inorganic/organic core-shell type nanocomposite particles of Al(OH)<SUB>3</SUB>/PSt were synthesized through the emulsion polymerization of styrene (St, shell monomer) with ammonium persulfate (APS, initiator), polyoxyethylene (50) nonyl phenyl ether (NP-1050, nonionic surfactant), and ammonium (POE) alkyl arylether sulfate (EU-S133D, anionic surfactant) in the presence of the modified Al(OH)<SUB>3</SUB> particles. The improved compatibility of Al(OH)<SUB>3</SUB> surface with St achieved by the modification with 3-(trimethoxysilyl) propyl methacrylate (γ-MPS) enabled to form a polymer shell around the mineral particles. The structure of nanocomposites prepared from different feed ratio of Al(OH)<SUB>3</SUB>/St was investigated by scanning (SEM) and transmission (TEM) electron microscopies.</P>

The effect of Al2O3 nano additions on failure of GFRP plate with two parallel pin loaded holes

Mohammadmahdi Attar,S. Mahdi Ahmadpour,S. Shahin Banisadr,Arash Mohammadi,S. Zahra Mirmoradi,Zohreh Shirazi 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.6

The aim of this study is to scrutinize the effect of nano-additions on failure modes and loads of glass-epoxy laminate subjected two parallel pin-loaded holes, experimentally and numerically. Furthermore, the effect of physical and geometrical parameters such as the ratio of free edge distance of laminated composite to holes diameter (e/d) and the ratio of centre to centre distances of holes to holes diameter (M/d) have been investigated. Afterwards, to exactly prognosticate failure modes and the ultimate load obtained from the experimental procedure, a numerical simulation in finite element software was implemented. There have found a close agreement between two methods. It should be acknowledged that after augmenting glass-epoxy laminate with nano-addition Al 2 O 3 , there was seen to be a clear difference between the two samples while the bearing strength of reinforced samples has been improved.