Ariadne L. Juwono

FATIGUE PERFORMANCE OF CLAY-EPOXY NANOCOMPOSITES

This paper presents an investigation of the possibility of improving the fatigue properties of an epoxy resin through dispersion of modified layered silicates within the polymer matrix. Montmorillonite-epoxy nancocomposites were successfully synthesized with a commercially available 1-Methylimidazole curing agent. The morphology of these materials was investigated by XRD and TEM. The findings demonstrated a pattern of clay morphology typically found in nanocomposite systems. Four point loading measurements showed an increase in modulus for 2.5 wt% and 10 wt% clay contents when compared to the unfilled epoxy, whereas the moduli showed a decrease for 5 wt% and 7.5 wt% clay contents. This behavior is typical for most particulate-filled systems. Fracture surfaces were examined using an E-SEM. The failure mechanism of the nanocomposites varied from that of the unfilled epoxy. Below a critical strain amplitude, the fatigue life of the filled epoxy improved significantly compared to that of the unfilled epoxy. In conclusions, the addition of silicates changes the fatigue failure mechanism and improves significantly the fatigue life.

The Treated Rice Straw as Potentially Feedstock of Wood and Rice Straw Fiber Blend for Pulp and Paper Making Industry

The study aimed to describe the alkaline treatment advantage to remove ash component from natural rice straws. Most of the ash component in the rice straw is silica. High ash content is particularly harmful to cutting tools and to chemical to recovery systems in the pulp paper industry. In this study, the silica content has been removed simply through by immersion process in the 5% sodium hydroxide solution to obtain de-silicated rice straw. The study revealed the effectiveness of this alkaline process and the compatibility in commercial practice. The rice straw pulping is considered competitively to complement the global demand of raw material in paper production. Therefore, the treated rice straw plays an important role in providing raw material in the form of wood and rice straw blend feedstock for pulp and paper industry.

Stabilizer Effect on Thermal Decomposition of Aged Solid Propellant

Composite solid propellants experience aging process during storage, and their properties will alter. The stabilizer added was used to reduce the effects of aging. This research studied the influence of the stabilizer on changes of the composite solid propellant thermal decomposition due to the onset of aging during the 40 days of storage at a temperature of 333 K. AO 2246 as a stabilizer added by as much as 0 to 1% by weight of propellant binders. The testing method used is heating the samples at various heating rate using DSC. And the Ozawa method was used to determine the values of the activation energy and frequency factor on the Arrhenius parameters. The optimal composition of stabilizer was 0.5 wt% for those on the value of activation energy and frequency factors for unaged and aged propellants were nearly the same i.e. 196 kJ/mol and 1.22 x1012 min-1.

Tensile Properties and Deflection Temperature of Polypropylene/Sumberejo Kenaf Fiber Composites with Fiber Content Variation

The use of synthetic fibers as reinforcement in composites has disadvantage which are unsustainable and an adverse impact on the environment. An alternative reinforcement for composites is natural fiber. Polypropylene and Sumberejo kenaf fibers were used respectively as the matrix and reinforcement. The aim of this research was to obtain the optimum tensile properties and deflection temperature with the variation of kenaf fiber fractions. Polypropylene/kenaf fiber composites were fabricated by hot press method. The kenaf fiber was soaked in NaOH solution before being used as the reinforcement and polypropylene was extruded before being used as the matrix. The weight fractions were varied to produce composites and pristine polypropylene samples were also prepared for comparison. The optimum tensile strength, modulus and deflection temperature were found in the composites with the 40 wt% kenaf fiber fraction with an increase up to 80% and 170% compared to the pristine polypropylene with the values of (60.3 ± 4,3) MPa and (159.1 ± 1,8) °C respectively. The Scanning Electron Microscope observation results in the fracture surface of the composites with the 40 wt% fiber fraction showed a relatively good bonding interface between fibers and the matrix and the failure modes were fiber breakage and matrix failures.

Synthesis and characterization of immobilized Ni-Co bimetallic using Tapanuli clay for catalyst application

Heterogeneous catalysts hold various advantages, namely, easy to separate from their products, reusable and regarded as environmental friendly materials. The synthesis of immobilized Ni monometallic, Co monometallic and Ni-Co bimetallic by Tapanuli clay were carried out using intercalation method. Firstly, the synthesis of Na-Bentonite was conducted to provide sufficient area to immobilize bimetal in the clay interlayer. Secondly, Ni, Co and Ni-Co were immobilized in the Tapanuli clay interlayer. Several techniques, such as X-Ray Diffraction, Fourier Transform Infra Red and Energy Dispersive X-Ray Analysis were applied to characterize and compare the properties of the synthesized materials. The results showed that the insertion of Ni, Co and Ni-Co in the clay interlayer occurred through a cation exchange reaction. The Energy Dispersive X-Ray analysis for Ni-Co bimetallic showed that the immobilized Ni and Co in the clay is in the ratio of 1:1. Catalytic test with Gas Chromatography showed that Ni-Co bimet...

Tapanuli Organoclay Addition Into Linear Low Density Polyethylene‐Pineapple Fiber Composites

Linear low density polyethylene‐Tapanuli organoclay‐pineapple fiber composites were succesfully synthesized by a melt intercalation method. The clay was modified as an organoclay by a cation exchange reaction using hexadecyl trimethyl ammonium bromide (HDTMABr) surfactant. The X‐ray diffraction results of the organoclay exhibited a higher basal spacing of 1.87 nm compared to the unmodified clay of 1.46 nm. The composite tensile strength was enhanced up to 46.4% with the 1 wt% organoclay addition. Both tensile and flexural moduli increased up to 150.6% and 43% with the 3 wt% organoclay addition to the composites. However, the flexural strength of the composites was not improved with the organoclay addition. The addition of organoclay has also decreased the heat deflection temperature of the composites.