Hexadecyltrimethylammonium Bromide-Modified Sericite Mica-Based Polyimide Composites: A Comparison Between In situ Polymerization and Solution Intercalation Processes

Qi Zhang,Duxin Li,Dengwang Lai,Baoli Ou 한국고분자학회 2015 Macromolecular Research Vol.23 No.9

In order to increase the spacing between clay layers and study the effects of processing on the morphology and properties of PI/organoclay composites, polyimide (PI) composites containing multi-step procedure-modified sericite mica were prepared via in situ polymerization and solution intercalation. The structure-property relationships of the composites were studied by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), dynamic mechanical analysis (DMA), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS). The results of XRD patterns revealed d002-spacing of clay was expanded from 0.99 to 2.77 nm. TEM photographs indicated majority of the organoclay exhibited an exfoliated morphology in composites prepared by in situ polymerization. TGA summarized the composites prepared by solution intercalation and in situ polymerization had a 9 and 29 oC increment in T5 compared with pristine PI respectively. XPS indicated the interaction of organoclay and polymer matrix in composites prepared by in situ polymerization was stronger than other types of composites. The glass transition temperature (Tg) and storage modulus of the composites prepared via in situ polymerization was much higher. Especially the Tg of this composites revealed a 33 oC increase compared with pure PI.

Influence of stereoisomerism of epoxy hardeners on fracture toughness of carbon fiber/epoxy composites

Dongjun Kwon,Minkyu Lee,Woong Kwon,Eunsoo Lee,Euigyung Jeong 한국탄소학회 2019 Carbon Letters Vol.29 No.5

Interfacial adhesion between carbon fiber and epoxy resin mostly determine the mechanical properties of the carbon fiber/ epoxy composites and the chemical structures of epoxy resin and hardener plays an important role. In this regard, stereoisomerism of epoxy hardeners, such as 3,3′ and 4,4′-DDS (diaminodiphenylsulfone), can have significant influence on the fracture toughness of the cured epoxy and related carbon fiber composites. Therefore, this study aims to investigate the influence of stereoisomerism of epoxy hardeners on fracture toughness of the carbon fiber/epoxy composites. Triglycidyl aminophenol (TGAP) are selected as epoxy resin and 3,3′- and 4,4′-DDS are selected as epoxy hardener. Wetting behaviors and fiber matrix adhesion of TGAP/DDS mixtures onto carbon fiber are investigated and fracture toughness (KIC) of TGAP/ DDS mixtures are also investigated. Then, the mode II fracture toughness test of the carbon fiber/TGAP/DDS composites are carried out to investigate the influence of hardener stereoisomerism on fracture toughness of the resulting composites. Wetting and fiber matrix adhesion to carbon fiber of TGAP/3,3′-DDS was better than those of TGAP/4,4’-DDS and KIC of TGAP/3,3′-DDS was also better than that of TGAP/4,4′-DDS. As a result of the synergistic effect of better wetting, fiber matrix adhesion, and fracture toughness of TGAP/3,3′-DDS, the mode II fracture toughness of the carbon fiber/ TGAP/3,3’- DDS composites was almost twice of that of the carbon fiber/ TGAP/4,4′-DDS composites. Based on the results reported in this study, stereoisomerism of the epoxy hardeners can influence the fracture toughness of the resulting composites as well as that of the resin itself. In other words, only small difference, such as the spatial arrangement of the molecular structure of epoxy hardeners can cause huge difference in the mechanical properties of the resulting composites.

Roles of silica-coated layer on graphite for thermal conductivity, heat dissipation, thermal stability, and electrical resistivity of polymer composites

Kim, Yeongseon,Kim, Minjae,Seong, Hong-Gyu,Jung, Ji Young,Baeck, Sung-Hyeon,Shim, Sang Eun Elsevier 2018 Polymer Vol.148 No.-

<P><B>Abstract</B></P> <P>Amphiphile-assisted silica@graphite with a surface resistivity of 10<SUP>12</SUP> Ω·sq<SUP>−1</SUP> was prepared via a one-step process using either an Ostwald ripening agent (Triton-X) or a bridgemer (PEG) under mild conditions. The composites containing coated fillers showed advantages in terms of their thermal and electrical properties over those using mixture of fillers. The filler possessing optimal size of graphite was incorporated with various polymer matrices such as TPEE, PDMS, epoxy, or HDPE, all of which have different processing characteristics due to their inherent viscosities. Consequently, the silica@graphite incorporated composites were found to have a superior effect on thermal and electrical properties including conductivity, dissipation, stability, and resistivity than boron nitride or alumina filled composites with the conservation of the electrical insulating property above 10<SUP>10</SUP> Ω·sq<SUP>−1</SUP> for a filler loading of 0–30 vol%.</P> <P><B>Highlights</B></P> <P> <UL> <LI> There is an optimal graphite size, which is not too small and not too big, for ensuring the high thermal conductivity of the composite. </LI> <LI> The coated silica layer acts as an efficient barrier which insulates against the electrical flow and induces less phonon scattering than when hybrid fillers are used. </LI> <LI> Silica@graphite incorporated composites were found to have a superior effect on thermal and electrical properties including conductivity, dissipation, stability, and resistivity. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

PEEK/SiO2 Composites with High Thermal Stability for Electronic Applications

RK Goyal,K.A. Rokade,A.S. Kapadia,B. S. Selukar,B. Garnaik 대한금속·재료학회 2013 ELECTRONIC MATERIALS LETTERS Vol.9 No.1

Thermal and mechanical properties of new high performance polymer matrix composites based on poly(etheretherketone)(PEEK) as matrix and crystalline-silica (SiO2) as reinforcement were discussed for application in electronic packaging substrates or printed circuit boards. The content of SiO2 was varied between 0 and 50 wt. %. Scanning electron microscopy showed uniform dispersion of SiO2 particles in the matrix. Thermogravimetry analysis showed significant increase in thermal stability and char yield with increase in SiO2content in the matrix. Differential scanning calorimetry showed that SiO2 had a heterogeneous nucleating effect on PEEK, leading to an increase in peak temperature of crystallization and onset crystallization temperature of the composites compared to a pure matrix. The microhardness increased approximately 42%. A modified rule of mixtures with a strengthening efficiency factor equal to 0.06 fit the data nicely. The results show that the prepared PEEK/SiO2 composites may have potential applications in electronics.

Polymer matrices for carbon fiber-reinforced polymer composites

Fan-Long Jin,Seul-Yi Lee,Soo-Jin Park 한국탄소학회 2013 Carbon Letters Vol.14 No.2

Carbon fibers (CFs) have high service temperature, strength, and stiffness, and low weight. They are widely used as reinforcing materials in advanced polymer composites. The role of the polymer matrix in the composites is to provide bulk to the composite laminate and transfer load between the fibers. The interface between the CF and the resin matrix plays a critical role in controlling the overall properties of the composites. This paper aims to review the synthesis, properties, and applications of polymer matrices, such as thermosetting and thermoplastic resins.

A critical review of nanodiamond based nanocomposites: Synthesis, properties and applications

Zhang, Yinhang,Rhee, Kyong Yop,Hui, David,Park, Soo-Jin Elsevier 2018 Composites. Part B, Engineering Vol.143 No.-

<P><B>Abstract</B></P> <P>Diamond is a metastable allotrope of carbon. Monocrystalline diamond with particle size less than 100 nm (designated as nanodiamond) has been widely studied during the past decades. Nanodiamonds have recently attracted attention owing to their exceptional mechanical and optical properties, tunable surface structure, and high specific surface area. The specific core-shell structure and abundant functional groups on its surface endow it with a variety of functional applications. Their excellent physical properties enable their application as ideal fillers in reinforcing polymer composites, resulting in superior mechanical properties, thermal stability, thermal conductivity and tribological properties. In addition to polymer composites, nanodiamonds and its composites are also widely used in sensors, optical computing, and quantum computing. As nanoscale materials, nanodiamonds and its composites are also used in electrical energy storage, wastewater treatment and bioapplications. Due to its superior biocompatibility and low cytotoxicity, nanodiamonds and its composites are now becoming crucial in biological applications. In this study, the properties of nanodiamonds and their application in polymer composites, electronics, energy, environmental areas and biological areas were analyzed.</P>

Structural and dielectric properties of polyvinyl alcohol/barium zirconium titanate polymereceramic composite

T. Badapanda,V. Senthil,S. Anwar,L.S. Cavalcante,N.C. Batista,E. Longo 한국물리학회 2013 Current Applied Physics Vol.13 No.7

The polyvinyl alcohol (PVA)/barium zirconium titanate Ba[Zr0.1Ti0.9]O3 (BZT) polymereceramic composites with different volume percentage are obtained from solution mixing and hot-pressing method. Their structural and electrical properties are characterized by X-ray diffraction (XRD), Rietveld refinement,cluster modeling, scanning electron microscope and dielectric study. XRD patterns of PVA/BZT polymereceramics composite (with 50% volume fractions) indicate no obvious differences than the XRD patterns of pure BZT which shows that the crystal structure is still stable in the composite. The scanning electron micrograph indicates that the BZT ceramic is dispersed homogeneously in the polymer matrix without agglomeration. The dielectric permittivity (εr) and the dielectric loss (tan d) of the composites increase with the increase of the volume fraction of BZT ceramic. Theoretical models are employed to rationalize the dielectric behavior of the polymer composites. The dielectric properties of the composites display good stability within a wide range of temperature and frequency. The excellent dielectric properties of these polymereceramic composites indicate that the BZT/PVA composites can be a candidate for embedded capacitors.

Mechanical Analysis of Woven Composites at High Strain Rates and Its Application to Predicting Impact Behavior

류한수,임지호,정관수 대한금속·재료학회 2008 METALS AND MATERIALS International Vol.14 No.6

The deformation behavior of woven composites at high strain rates was analyzed using a constitutive equation developed to describe the nonlinear, anisotropic/asymmetric and rate-dependent mechanical behavior of woven composites. The rate-dependent nonlinear behavior of woven composites was characterized at high strain rates (1 s-¹ to 100 s-¹) using a tensile testing method first proposed in this research. The material properties for the developed constitutive equation were determined and subsequently used in a finite element analysis of the deformation behavior of woven composites at high strain rates. Finally, the impact behavior of woven composites was predicted using the constitutive equation and the results were compared with experiments, showing that the current constitutive equation including the characterization method is adequate to describe the deformation behavior of woven composites at high strain rates up to impact level. The deformation behavior of woven composites at high strain rates was analyzed using a constitutive equation developed to describe the nonlinear, anisotropic/asymmetric and rate-dependent mechanical behavior of woven composites. The rate-dependent nonlinear behavior of woven composites was characterized at high strain rates (1 s-¹ to 100 s-¹) using a tensile testing method first proposed in this research. The material properties for the developed constitutive equation were determined and subsequently used in a finite element analysis of the deformation behavior of woven composites at high strain rates. Finally, the impact behavior of woven composites was predicted using the constitutive equation and the results were compared with experiments, showing that the current constitutive equation including the characterization method is adequate to describe the deformation behavior of woven composites at high strain rates up to impact level.

Facile design of a domestic thermoelectric generator by tailoring the thermoelectric performance of volume-controlled expanded graphite/PVDF composites

Zhang, Yinhang,Rhee, Kyong Yop,Park, Soo-Jin Elsevier Science Ltd 2019 Composites Part B, Engineering Vol.176 No.-

<P><B>Abstract</B></P> <P>Polymer-based thermoelectric materials have attracted considerable interest for green energy conversion over the past decades. In this study, polymer/inorganic thermoelectric generators were prepared by integrating film-forming polyvinylidene fluoride (PVDF) and expanded graphites (EGs) to tailor the thermoelectric performance of the resulting PVDF/EG composites by adjusting the expansion volume of EGs with different thermal treatments. The charge carrier rate and phonon scattering are responsible for the divergent performance of the prepared polymer/EG composites. The prepared composites exhibited superior thermoelectric properties, where the PVDF/EG composite containing 20% EG expanded at 600 °C showed an electrical conductivity of 883 S/cm, a Seebeck coefficient of 8.77 μV/K, and a high power factor of 6.79 μW m<SUP>−1</SUP>K<SUP>−2</SUP>. This composite outperforms many other graphene- or graphite-based composites reported in the literature. This study provides a facile avenue to prepare an inexpensive, lightweight, nontoxic, and highly efficient thermoelectric generator for green energy conversion and energy harvesting.</P>

Effect of Mercapto-Terminated Silane Treatment on Rheological and Mechanical Properties of Rice Bran Carbon-Reinforced Nitrile Butadiene Rubber Composites

Yinhang Zhang,박수진 한국고분자학회 2018 Macromolecular Research Vol.26 No.5

This paper aims at correlating the silane treatment of rice bran carbon (RBC) in nitrile butadiene rubber (NBR) matrix with the rheological properties of RBC/NBR composites. The surface morphology and structure of RBC were characterized by X-ray diffraction, thermogravimetric analysis, high-resolution scanning electron microscopy (HR-SEM), Raman spectroscopy, and adsorption analysis. The RBC/NBR polymer-matrix composites were fabricated by using the latex compounding technique, based on the superior hydrophilic characteristics of RBC. The silane treatment process was conducted by in situ interfacial modification technique. The dispersion of RBC and the interfacial morphologies between the RBC and NBR matrix were confirmed by HR-SEM. The bonding mechanism was analyzed in detail by mechanical and dynamic rheological determinations. At the same filler concentration, the (3-mercaptopropyl) trimethoxysilane (MPTMS) treated composites exhibited stronger mechanical properties and higher storage modulus than original RBC/NBR composite, as the interfacial interaction via MPTMS connected RBC and NBR molecules was stronger than the interaction in RBC/NBR composites connected by hydrogen bonds and weaker π-π stacking.