Dody Ariawan

Elastic anisotropy of kenaf fibre and micromechanical modeling of nonwoven kenaf fibre/epoxy composites:

In this work, nonwoven kenaf fibre/epoxy composites were produced by using resin transfer moulding. The effect of kenaf fibre volume fraction on the composites’ tensile properties and Poisson’s ratio was investigated. Experimental results show that highest tensile properties and Poisson’s ratio were attained at volume fraction = 0.42. A simple method has been developed to predict the fibre transverse modulus and has allowed the characterisation of kenaf fibre’s elastic anisotropy. The performance of the Tsai–Pagano model in predicting the composites’ tensile modulus and Poisson’s ratio was compared with the Manera and Cox-Krenchel model. Results showed that the consideration of fibre’s elastic anisotropy in the Tsai–Pagano model yielded a good prediction of both composites’ modulus and Poisson’s ratio. Meanwhile, the Bowyer–Bader model produced a better tensile strength prediction owing to the inclusion of fibre length and orientation factors in the model.

Effect of Heat Treatment on Properties of Kenaf Fiber Mat/Unsaturated Polyester Composite Produced by Resin Transfer Molding

This study investigated the effect of heatingtime during heat treatment on mechanical and physical properties of the kenaf fiber and its composites. Kenafbast fibers were modified by heat treatmentat 140°C for2.5, 5, 7.5, 10 and 12.5 hours. Composites were fabricated by resin transfer molding process with unsaturated polyester as matrices and needle-punched kenaf fiber mat as reinforces. The fiberswerecharacterized by Fourier Transform-Infra Red (FT-IR) and X-Ray Diffraction (XRD). FT-IR resultsshowedthe changesin intensity ofhemicelluloce wavelength (1736 cm-1). Besides XRD observation also confirmed the increase of cellulose content in kenafthat described to the increase of crystallinity index ofkenaf fiber with heat treatment. The single fiber strength investigation stated that the highest strength and modulus was obtained bykenaf fiber heated for10hours indrying oven. SEM observation showed the decreasing numbers of impuritieson thefibers surface with fiber treatment compared to untreated kenaf fibers. The flexural properties of composites showed a similar trend to fiber strength, but the fracture toughnesshas showedcontrary results.

Mechanical properties and micromechanical analysis of nonwoven kenaf fibre/epoxy composites produced by resin transfer moulding

In this paper, the mechanical performance of resin transfer moulded nonwoven kenaf fibre/epoxy composites in the fibre volume fraction (V f ) range of 0–0.42 was investigated. The effect of the needle-punching direction on the tensile properties of the composites was also investigated. The highest tensile, flexural and fracture properties were attained at a V f of 0.42. The nonwoven kenaf fibre/epoxy composites were proven to exhibit tensile isotropy. The typical load versus displacement graph and scanning electron microscopy micrographs of the epoxy and nonwoven kenaf fibre/epoxy composites revealed that the energy absorbing events caused by the fibres led to improvements in the fracture toughness. Meanwhile, the micromechanical parameters of the composites were determined by a micromechanics analysis using the Cox–Krenchel model. The analysis proved the applicability of the model for nonwoven kenaf fibre/epoxy composites as the calculated efficiency factors were comparable to the values from previous literatures.

Effects of Alkali Treatment on the Properties of Kenaf Fiber-Unsaturated Polyester Composites Prepared by Resin Transfer Molding

Composites of untreated and 6% sodium hydroxide (NaOH) treated kenaf fiber mat and unsaturated polyester resin matrix were manufactured via a resin transfer molding (RTM) technique. The treated fibers were characterized with SEM and XRD. Contact angle measurements of the fibers were performed using a tensiometer. Alkali treated fiber-unsaturated polyester composites showed superior flexural properties than the composites with untreated fibers. The water absorption pattern of these composites was found to follow Fickian behavior. The tendency of the composites to absorb water decreased when alkali treated fiber mats were used.

Interfacial characterisation and mechanical properties of heat treated non-woven kenaf fibre and its reinforced composites

Abstract This paper reports on the comprehensive characterisation of heat treated kenaf fibre (KF) and its composites. The kenaf fibres were modified by heating for 2.5–12.5 h inside a drying oven. Heat treatment produces an increase in the crystallinity index and fibre strength of KF. The highest value of KF strength was recorded by applying heat treatment of 10 h on KF. The heat treatment results in the partial removal of impurities/extractives on the KF surface which is detected by scanning electron microscopy and X-ray photoelectron spectroscopy. Atomic force microscopy results signify the decrease of roughness, the increase in peak area density and the increase of the adhesion force on the surface area of heat treated KF. The effect of the heat treatment in enhancing the interface bonding characteristics between the KF and unsaturated polyester matrix can be reflected by the interlaminar shear strength (ILSS) and dynamic mechanical analysis value of the composites. The flexural properties of the composites showed a similar trend to ILSS. However, the fracture toughness revealed contrasting results. Water absorption induced a drastic loss of the mechanical properties of the composites albeit better retention of properties was observed in the case of heat-treated KF composites.

Simulation and Validation of an Anisotropic Magnetorheological Elastomers Mold with Various Alignment Angles

In this study, anisotropic magnetorheological elastomers (MREs) mold design with capability of aligning the filler in several angles (0 ̊, 45 ̊, and 90 ̊) were developed. The mold was equipped with electromagnet coil to generate the magnetic flux. The distribution of magnetic flux density in the mold and inside the chamber was investigated by using finite element magnetic analysis. Magnetic flux density of 0.3 T was considered best value to form good particle alignment in the matrix. Moreover, the mold design was fabricated using same material as in the simulation. The magnetic flux density was taken at casing wall and measured by gauss-meter. The data was compared with simulation results. The differences between experimental and simulation is in the range of 6-40 mT. Since the difference is insignificant, it can be said that the data is valid. Finally, the model can be used for further magnetic flux density prediction inside the chamber. In the simulation, it was found that the current needed to generate at least 0.3 T inside the chamber for 0 ̊, 45 ̊, and 90 ̊ are 0.2A, 0.1A, and 3A, respectively.

Surface Characterization of Alkali Treated Kenaf Fibers by XPS and AFM

Kenaf fibers were immersed in 6% solution of sodium hydroxide (NaOH) for 1, 2, 3, 4 and 5 hours. The treated fibers were characterized with X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The XPS results showed that the alkali treatment increased the proportion of oxygen atoms on the fiber surface as indicated by the increase in oxygen-carbon ratio. An increase in C2 peak (C-OH bonds) was also observed suggesting the present of cellulose on the fiber surface. The decrease in C1 peak (C-C bonds) suggested that lignin was removed from the fiber surface following the alkali treatment. Scale-like structures were observed from the AFM topographic images to indicate the presence of cellulose microfibrils in the primary cell wall of the treated fiber. Alkali treated fiber surface showed lower mean surface roughness than the untreated fiber indicating smoother fiber surface. The fiber surface became relatively smooth after the alkali treatment due to the removal of non-cellulosic layer.