Hendra Suherman

Effect of Acid- and Ultraviolet/Ozonolysis-Treated MWCNTs on the Electrical and Mechanical Properties of Epoxy Nanocomposites as Bipolar Plate Applications

Carbon nanotubes (CNTs) have a huge potential as conductive fillers in conductive polymer composites (CPCs), particularly for bipolar plate applications. These composites are prepared using singlefiller and multifiller reinforced multiwalled carbon nanotubes (MWCNTs) that have undergone a chemical functionalization process. The electrical conductivity and mechanical properties of these composites are determined and compared between the different functionalization processes. The results show that UV/O3-treated functionalization is capable of introducing carboxylic functional groups on CNTs. Acid-treated CNT composites give low electrical conductivity, compared with UV/O3-treated and As-produced CNTs. The in- and through-plane electrical conductivities and flexural strength of multifiller EP/G/MWCNTs (As-produced and UV/O3-treated) achieved the US Department of Energy targets. Acid-treated CNT composites affect the electrical conductivity and mechanical properties of the nanocomposites. These data indicate that the nanocomposites developed in this work may be alternative attributers of bipolar plate requirements.

Electrical Properties of Carbon Nanotubes-Based Epoxy Nanocomposites for High Electrical Conductive Plate

Electrical properties of carbon nanotubes-based epoxy nanocomposites for high electrical conductive plate were investigated. Dispersion and incorporation mechanism between two conductive fillers with different sizes (CNTs and Graphite) in the polymer matrix are the key factors in the fabrication of high electrical conductivity plate. Different variation of carbon nanotubes (CNTs) (1~10 wt %) and Graphite (G) (60 ~ 69 wt %) loading concentration were added into the epoxy resin. Dispersion of CNTs and G in epoxy resin were conducted by the internal mixer with a Haake torque rheometer. The mixture of G/CNTs/EP was poured into the steel mold, and G/CNTs/EP nanocomposites had been fabricated through compression molding. The electrical conductivity of nanocomposites in terms of variation of G and CNTs concentration were measured by the four point probe for in a plane electrical conductivity. The results revealed that addition of G/CNTs and increasing curing temperature are effective ways to produce high electrical conductive nanocomposites. The highest electrical conductivity was reached on 104.7 S/cm by addition 7.5 wt% of CNTs. Dispersion quality of G and CNTs in the epoxy matrix was observed on the fractured surface by scanning electron microscopic.

Optimization Mixing Parameters on the Electrical Conductivity of Polymer Nanocomposites Based on the Taguchi Method

The objective of this paper is optimization mixing parameters in terms of mixing process of polymer nanocomposites using Taguchi method. Considering the mixing parameters such as rotational speed, mixing temperature and mixing time were performed to reveal the electrical conductivity data. Taguchi method was used by electrical conductivity analyses based on three level factorial designs. Orthogonal arrays of Taguchi, the signal-to-noise (S/N) ratio, and the analysis of variance (ANOVA) were utilized to find the optimal levels and the effect of mixing parameters on electrical conductivity. Confirmation analysis measurements with the optimal levels of mixing parameters were carried out in order to show the optimum electrical conductivity of Taguchi method. The result shows that Taguchi method is effective in solving the quality problem occurred on the mixing parameters of the polymer nanocomposites.

Analysis of Energy Absorption on Pultruded Composite Tube under Oblique Loading

The capability of structures to absorb as much amount energy, particularly in automotive structures to reduce the damages due to impact energy during collision attract attention of many reserachers. During the actual collision, the crash box is not only experienced axially crash, but also in oblique crash. In this study, an experiment was carried out to study the crashworthiness parameters and behaviour of pultruded fibre E-glass/polyester pultruded composite tubes under oblique loading. Quasi-static loadings were applied axially and oblique on the pultruded composite to investigate the response of force-displacement during progressive collapses. The pultruded wall thickness of 6 mm tubes were used and four oblique angles of 0˚, 5˚, 10˚ and 15˚ were selected to study their effect on crushing behaviours and collapse modes using compression moulding. All specimens were chamfer 45˚ on top end for purpose to work as a collapse trigger mechanism. The results showed that the energy absorption of the structures increasing with decrease of the loading angle.

Effect of Wet Oxidation on the Dispersion and Electrical Properties of Multi-Walled Carbon Nanotubes/Epoxy Nanocomposites

Carbon nanotubes (CNTs) have excellent mechanical and electrical properties than conventional materials (carbon black and glass fibers), and are promising candidates as reinforcement material for composites. Formation of electrical conductive with effective dispersion of filler remains a main challenge in the polymer matrix and fillers in order to achieve a good electrical conductivity. Therefore, one of the solutions is to functionalize through wet oxidation of the CNTs besides adding surfactants or assisted liquids. Functionalization of CNTs involves the generation of chemical moieties on their surface that can improve the solubility and processibility. Any functionalization that is undertaken must preferably not influence other key properties such as strength and electrical conductivity of the nano-composite. The matrix used in this study was epoxy and reinforcement filler was multi-walled carbon nanotubes (MWCNTs). MWCNTs were treated with sulfuric acid and nitric acid at 3:1 (v/v) ratio. The present of functional groups on CNTS were investigated using Fourier Transform Infrared (FT-IR). Different weight percentages of MWCNTs (functionalized and as produced) / epoxy composite were prepared. The electrical conductivity of functionalized MWCNTs nanocomposites and as produced MWCNTs nanocomposites were measured by the four point probe. Dispersion state of CNTs in epoxy matrix was observed on fractured surface by scanning electron microscopic. Functionalized CNTs gave better dispersion stability in solvents than non-functionalized CNTs. As expected, non- functionalized CNTs (as produced MWCNTs) are not dispersed at all in all the solvents. However, functionalized CNTs composites give low electrical conductivity. Defects from acid treatment are assumed will damage the original chirality of as produced CNTs and give unbalance polarization on the CNTs, which are the reasons for no formation of conductive pathway networks of acid treated CNTs under electric field.

Structure-property-processing investigation of electrically conductive polypropylene nanocomposites

Abstract This paper investigates the structure-property-processing correlations of electrically conductive polypropylene (PP) nanocomposites. The process parameters and fabrication techniques of PP-based composite materials were studied. Various structures of carbon allotrope-based materials, including synthetic graphite (SG), exfoliated graphene nanoplatelets (xGnP), multi-walled carbon nanotubes (MWCNTs) and carbon black (CB), were used to fabricate the PP-based nanocomposites. The nanocomposites were prepared by either direct melt mixing using an internal mixer or by ball milling of components before the melt mixing process. The electrical and flexural properties were measured. In order to understand the conductivity behavior, both in-plane and through-plane electrical conductivities were measured. The results showed that the incorporation of the xGnP into PP/60 wt.% SG composites resulted in a slight increase of the in-plane conductivities and had a minimal effect on the through-plane conductivities. The addition of MWCNTs and CB to the PP/SG/xGnP composites had a significant effect on the electrical properties and was more pronounced in the case of MWCNTs. The flexural properties of all samples were much lower than those of pure PP. The interface between the filler and the PP matrix and the morphology of the composite materials were observed from the fracture surfaces of the composites using scanning electron microscopy (SEM). In addition, SEM was employed to observe adhesion, microstructural homogeneity, orientation of the xGnP platelets and agglomeration in the composites.

Effect of Molding Parameters on the Flexural Strength of Carbon Black/Graphite/Epoxy Nanocomposites Using Taguchi Method

Optimization of molding parameter on the flexural strength of carbon black/graphite/epoxy (CB/G/EP) nanocomposites using Taguchi method was studied. Three molding parameters was chosen in this study which are molding temperature, molding pressure and molding time. Experimental trials were carried out based orthogonal array design using those three parameters. The results were analyses using the signal to noise (S/N) and analysis ofvariance (ANOVA). Flexural strength of the CB/G/EP nanocomposites increases from 56.23 MPa to 65.11 MPa usingoptimize parameter obtained from the analysis method. These results shown that the Taguchi method is successfully to get optimum parameters of molding parameters to produce CB/G/EP nanocomposites.

Properties of Epoxy/Carbon Black/Graphite Composites for Bipolar Plate in Polymer Electrolyte Membrane Fuel Cell

Epoxy resin (EP) composites including carbon black (CB) and graphite (G) were produced and investigate. The in-plane electrical conductivity of EP/CB/G composites was measured. Various weight percentages (wt.%) of CB as a secondary filler and G as a primary filler were added into the EP as a matrix. Dispersion of CB and G within matrix were conducted by an internal mixer (Haake Reomix). Mixture of EP/CB/G was poured into the steel mold, and produced through hot press machine. In-plane electrical conductivity of EP/CB/G composites in terms of variation of CB and G concentration were measured by the Jandel multi high four point probe. The highest in-plane electrical conductivity of the EP/CB/G composites obtained was 120 S/cm. This value exceeds the requirement of U.S Department of Energy (DOE) target for bipolar plate application (> 100 S/cm).

Electrical Conductivity and Hardness Property of CNTs/Epoxy Nanocomposites

This study investigates the effect of carbon nanotubes (CNTs) as conductive fillers and epoxy resin as matrix on the electrical conductivity and hardness property. The different CNTs weight percentage (0 ~ 10 wt.%) were added into the epoxy resin. The dispersion of CNTs in epoxy resin was conducted by high speed mixer through mechanical shearing mechanism. The mixture of CNTs/epoxy was poured into the mold and compression molding was conducted for fabrication of CNTs/epoxy nanocomposites. The electrical conductivity and hardness of CNTs/epoxy nanocomposites by several of CNTs loading concentration were measured by the four point probe and dynamic ultra micro hardness tester. Agglomeration of CNTs in epoxy matrix was observed on fractured surface by scanning electron microscopic. Non conductive epoxy polymer becomes conductor as addition of CNTs. Electrical conductivity of CNTs/epoxy nanocomposites were increased with increasing of CNTs loading concentration. Hardness property of CNTs/epoxy nanocomposites ware reached the highest value at 5 wt.%, and then it was decreased.

Effect of Mixing Parameter on Electrical Conductivity of Carbon Black/Graphite/Epoxy Nanocomposite Using Taguchi Method

Polymer composite has attracted many researchers from various field of application due to its unique features and properties including light weight, low cost, ease to process and shaping and corrosion resistant [1-3]. Fillers is typically added to enhance the chemical and physical properties of polymers [4, 5]. One of the properties is the electrical conductivity. Carbon based filler such as graphite (G), carbon black (CB), carbon fibers (CF) and carbon nanotubes (CNT) has been extensively used to improve electrical properties of polymer composite [6-8]. Electrical properties of the composite can be explained from percolation theory which means electrical percolation in mixtures of electrically conducting and non-conducting materials [9]. The concentration of conducting phase must above the critical value called percolation threshold, in order for the material become electrically conductive [10].