Eni Sugiarti

Preparation of nano-sized particles from bacterial cellulose using ultrasonication and their characterization

As more applications for nano-sized natural particles are discovered, simple, environmentally friendly ways to produce these particles become more important. This work prepares and characterizes nano-size bacterial cellulose particles using ultrasonication. Pellicle from nata de coco containing nanofibers was broken up in an electrical blender, then sonicated using an ultrasonic probe at 20 kHz and 3 W/mL for 30, 60 and 90 min. Transmission electron microscope observations indicate the particles become nano-sized after 60 min ultrasound. The maximum decomposition temperature before sonication was 373 °C, decreased to 357 °C after 60 min ultrasonication. Moisture absorption of the 90 min sonicated particles film is 60% slower compared to non-sonicated particles. After ultrasonication, the crystallinity index of the cellulose decreases. The functional groups of non-sonicated and sonicated cellulose remain the same. This study promotes a potential method of fabrication of nano-sized particles from pure bacterial cellulose.

The Influence of Carboxy Methyl Cellulose (CMC) and Solution pH on Carbon Fiber Dispersion in White Cement Matrix

Dispersion of carbon fiber in cement matrix is one of main challenges for fabricating carbon fiber reinforced cement based materials. In this study, the dispersion of carbon fiber was improved by pre-dispersion of carbon fiber in basic aqueous solution using different concentrations of CMC. The relationships of CMC concentration and pH solution toward carbon fiber dispersion in aqueous solution was evaluated by UVvis spectroscopy. In order to understand how carbon fiber is dispersed in cement matrix, morphology fiber carbon reinforced composite was examined. Experimental results show that aqueous solution of CMC is effective to disperse carbon fiber. In addition, dispersion of carbon fiber increases with increasing of pH of CMC solution.

Effect of nanofibers fraction on properties of the starch based biocomposite prepared in various ultrasonic powers

This paper reported the results of the characterization of jicama (Pachyrhizus erosus) starch based biocomposite reinforced with varied nanofiber fractions, i.e. 35.4, 70.8 and 106.2 μg per 10 g of starch. The nanofiber was isolated from oil palm empty fruit bunches. During preparation, the biocomposite in form of gel was sonicated using an ultrasonic probe at various powers, i.e. 0, 480, 600, 720 watt at 20 kHz for 5 min. The results show that ultrasonication results in a significant improvement in biocomposite properties for each of the nanofiber fractions. The tensile strength, moisture resistance of the 35.4 μg nanofibers biocomposite increase significantly 278, 11% respectively after 600 watt ultrasonication. Field emission scanning electron microscopy of the fracture surface of the film showed ultrasonication resulted in it becoming smoother and more compact. These results indicate that ultrasonication improves the performance of the film.

Effect of different dispersants in compressive strength of carbon fiber cementitious composites

Carbon Fiber Cementitious Composites (CFCC) is one of the most important materials in smart concrete applications. CFCC should be able to have the piezoresistivity properties where its resistivity changes when there is applied a stress/strain. It must also have the compressive strength qualification. One of the important additives in carbon fiber cementitious composites is dispersant. Dispersion of carbon fiber is one of the key problems in fabricating piezoresistive carbon fiber cementitious composites. In this research, the uses of dispersants are methylcellulose, mixture of defoamer and methylcellulose and superplasticizer based polycarboxylate. The preparation of composite samples is similar as in the mortar technique according to the ASTM C 109/109M standard. The additives material are PAN type carbon fibers, methylcellulose, defoamer and superplasticizer (as water reducer and dispersant). The experimental testing conducts the compressive strength and resistivity at various curing time, i.e. 3, 7 and...

The influence of Cr and Al pack cementation on low carbon steel to improve oxidation resistance

Pack chromizing and aluminizing has been widely used for many years to improve hot temperature oxidation and corrosion resistance of metals. The coating process involves packing the steel in a powder mixture which contain aluminum and chromium source, and inert filler (usually alumina), and halide activator NH4Cl. Al and Cr were deposited onto carbon steel by pack cementation process using elemental Al and Cr powder as Al and Cr source, whereas NiCo alloys codeposited by electrodeposition. The position of Al and Cr could be under or over Ni-Co alloys deposited. Pack cementation was heated on dry inert gas at temperature 800 °C about 5 hours and 20 minute for Cr and Al respectively. Al and Cr was successfully deposited. Laying down effect of Al and Cr onto carbon steel whether up and down toward NiCo alloys coating have affected to oxidation resistance. The pack aluminizing as top layer given best resitance to restrain excessive oxide scale, in contrast pack chromizing reveal bad oxidation resistance, more...

Effect of cloric acid concentration on corrosion behavior of Ni/Cr coated on carbon steel

Corrosion is one of the causes of metal degradation. Carbon steel (Fe) is easy to corrode in the extreme environment. Coating on carbon steel is required to improve corrosion resistance owing to protection or hindrance to extreme environmental conditions. In this present work, carbon steel was coated by electroplating techniques for nickel and pack cementation for chrome. The corrosion rate test was performed by Weight Loss method on FeNiCr, FeNi, FeCr and uncoated Fe as comparator which was dyed in 37% HCl and 25% HCl which had previously been measured dimension and mass. The immersion test result of FeNiCr and FeNi specimen were better than FeCr and uncoated Fe in terms of increasing corrosion resistance. The corrosion rate for 56 hours in 37% HCl for FeNiCr was 1.592 mm/y and FeNi was 3.208 mm/y, FeCr only lasted within 32 hours with corrosion rate was 6.494 mm/y. Surface of the sample after the corrosion test there was pitting, crevice corrosion and alloy cracking caused by chloride. The higher the co...

The powerful combination of ion-milling method for XTEM preparation: Application to a diffusion barrier coating on Nb substrate

The sample preparation of coating system for use in a transmission electron microscope (TEM) is a thoroughly challenging process of viewing samples at the nano-level scale. Two different ion milling methods have be taken, argon ion slicer (AIS) and focused ion beam (FIB) which have the ability to reveal many of the characteristics of how thin films form. This Method has been applied to investigate cross-sectional structure of Re-based diffusion barrier coating on Nb substrate. The detailed micro-nano structure of coating specimen presented several crystal defects such as dislocations, stacking faults, voids and cracks.