Dong Wha Park

A Review on Thermal Conductivity of Polymer Composites Using Carbon-Based Fillers : Carbon Nanotubes and Carbon Fibers

Recently, the use of thermal conductive polymeric composites is growing up, where the polymers filled with the thermally conductive fillers effectively dissipate heat generated from electronic components. Therefore, the management of heat is directly related to the lifetime of electronic devices. For the purpose of the improvement of thermal conductivity of composites, fillers with excellent thermally conductive behavior are commonly used. Thermally conductive particles filled polymer composites have advantages due to their easy processibility, low cost, and durability to the corrosion. Especially, carbon-based 1-dimensional nanomaterials such as carbon nanotube (CNT) and carbon nanofiber (CNF) have gained much attention for their excellent thermal conductivity, corrosion resistance and low thermal expansion coefficient than the metals. This paper aims to review the research trends in the improvement of thermal conductivity of the carbon-based materials filled polymer composites.

Electrical, thermal, and rheological properties of carbon black and carbon nanotube dual filler-incorporated poly(dimethylsiloxane) nanocomposites

AbstractConductive nano-sized carbon black (CB) and carbon nanotube (CNT) are widely used in the polymer industry due to their excellent electrical and thermal conduction behavior and reinforcing ability. Herein, poly(dimethylsiloxane) (PDMS) nanocomposites filled with both conductive CB and CNT were fabricated using a planetary mixer and two-roll mill. Due to excellent thermal, electrical, and physical properties of CB and CNT, both the thermal and electrical properties of the composites and the dynamic mechanical properties were improved by the incorporation of CB and CNT into PDMS. The thermal conductivities of the composites linearly increased with filler concentration, and the electrical threshold was determined to be low. The rheological properties of the PDMS/CB and PDMS/CB/CNT nanocomposites were significantly influenced by filler incorporation.

Electrospun BMIMPF6/nylon 6,6 nanofiber chemiresistors as organic vapour sensors

AbstractNylon 6,6 nanofiber containing an ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate (BMIMPF6), was prepared via electrospinning and used as a chemiresistor for detecting organic vapors, such as methanol, ethanol, tetrahydrofuran (THF), and acetone. The diameter of the nanofibers was varied by changing the concentration of BMIMPF6 by changing the solution viscosity and surface tension. The surface resistivity of the nanofibers decreased with increasing amounts of BMIMPF6. When the hybrid nanofibers were collected on an interdigitated electrode and exposed to solvent vapors, the resistance suddenly decreased upon exposure to all of the solvent vapors at room temperature. In contrast, the resistance dramatically increased when the organic vapors were removed. The stable cyclic test reveals that the ionic liquid containing nylon nanofiber can be used as a useful sensing material for organic vapors.

Production of Carbon Black/Silica Composite Particles by Adsorption of Poly(vinyl pyrrolidone)

ConclusionsTo reinforce the mechanical and electrical properties of materials, carbon black has been widely used as a filler in polymer industry because of its excellent properties such as heat, chemical, and weathering resistance, lightweight, electroconductivity, and low thermal expansion.1,2 The dispersibility of carbon black is important to show such abilities in organic solvents and polymer matrices. Therefore, many researches have been reported that the dispersibility of carbon black in solvents and polymer matrices is remarkably improved by grafting of polymers on the surface of carbon black.3,4 Silica offers a unique combination of tear strength, abrasion resistance, and aging resistance compared to carbon black.5 In tire treads, silica yields a lower rolling resistance at an equal wear resistance and wet grip than carbon black.6 Therefore, the use of a dual filler system separately composed of carbon black and silica in polymer matrices can give the benefits from each component.7 To the best of our knowledge, carbon black/silica hybrid composite particles have not prepared to date.

Colloidal Heterocoagulation for Preparation of Multi-Walled Carbon Nanotube/PMMA Nanocomposite Started with Bulk Resin

Recently, a heterocoagulation process has been emerged as a new technique to prepare polymer/nano-filler composites in water. Conventionally, heterocoagulation has been utilized only for as-prepared emulsion latex. However, we aimed to extend heterocoagulation process in order to use commercial polymer resin. Bulk PMMA resin was dissolved in a solvent and precipitated in SDS aqueous solution to make a stable colloid system. After removing the solvent, the PMMA dispersion was mixed with CTAB-stabilized MWCNT dispersion. A heterocoagulation process was conducted at room temperature. Upon the completion of the heterocoagulation, all MWCNTs were embedded into PMMA matrix. Experimental results show that MWCNTs were uniformly distributed in PMMA and their thermal stability was significantly improved. More importantly, the percolation threshold for the electrical conductivity was achieved at a low concentration (1 wt%) of MWCNT using this heterocoagulation process.