Duangdao Aht-Ong

Characteristic of fly ash derived-zeolite and its catalytic performance for fast pyrolysis of Jatropha waste

Fly ash from pulp and paper industries was used as a raw material for synthesizing zeolite catalyst. Main compositions of fly ash consisted of 41 wt%SiO2, 20 wt%Al2O3, 14 wt%CaO, and 8 wt% Fe2O3. High content of silica and alumina indicated that this fly ash has potential uses for zeolite synthesis. Fly ash was mixed with 1–3 M NaOH solution. Sodium silicate acting as silica source was added into the solution to obtain the initial SiO2/Al2O3 molar ratio of 23.9. The mixtures were then crystallized at 160°C for 24 and 72 h. Zeolites synthesized after a long synthesis time of 72 h showed superior properties in terms of high crystallinity, less impurity, and small particle size. The catalytic activities of fly ash-derived zeolites were investigated via fast pyrolysis of Jatropha wastes using analytical pyrolysis-gas chromatograph/mass spectrometer (GC/MS). Pyrolysis temperature was set at 500°C with Jatropha wastes to catalyst ratio of 1:1, 1:5, and 1:10. Results showed that higher amounts of catalyst have a positive effect on enhancing aromatic hydrocarbons as well as decreasing in the oxygenated and N-containing compounds. Zeolite Socony Mobil-5 (ZSM-5) treated with 3 M NaOH at 72 h showed the highest hydrocarbon yield of 97.4%. The formation of hydrocarbon led to the high heating value of bio-oils. In addition, the presence of ZSM-5 derived from fly ash contributed to reduce the undesirable oxygenated compounds such as aldehydes, acids, and ketones which cause poor quality of bio-oil to only 0.8% while suppressed N-compounds to 1.7%. Overall, the ZSM-5 synthesized from fly ash proved to be an effective catalyst for catalytic fast pyrolysis application.

In-Situ Electrochemical Synthesis of Novel Sensitive Layer of Polyaniline/Multiwall Carbon Nanotube/Tin Oxide Hybrid Materials for Ethylene Gas Detection

The development of a suitable sensing material for a high-sensitivity detection method for ethylene is needed to enhance the efficiency of estimating the life expectancy of agricultural products. A novel sensor for ethylene gas comprised of a polyaniline/multiwall carbon nanotube/tin oxide nanoparticle (PANi/MWCNT/SnO2NP) was successfully synthesized by electrophoretic deposition of SnO2NPs onto a gold interdigited substrate and then chronoamperometric deposition of the PANi/MWCNT film from an aniline/MWCNT solution. The sensitivity of the PANi/MWCNT/SnO2NP composite sensor was found to be almost linearly dependent on the concentration of ethylene gas in the parts per million range, with an ethylene-sensitivity of 10 ppm and a gas-sensitivity of 2.42%.

Natural Fiber/PLA Composites: Mechanical Properties and Biodegradability by Gravimetric Measurement Respirometric (GMR) System

Polylactic acid (PLA), one of the most promising bio-based materials currently available on the market, has gained much attention recently as an alternative to non-biodegradable synthetic polymers due to its comparable properties and biodegradability. The objectives of this work were to prepare a green composite between PLA and coconut fiber (CF) to investigate an aerobic biodegradation of the biocomposites under controlled composting condition according to the ISO 14855-2. The composites were prepared at various ratios by a twin screw extruder and compression molding, respectively. Based on this research, the maximum content of coconut fiber added was 4 wt%. The addition of coconut fiber can improve the impact strength of the PLA composites. The increasing amount of coconut fiber had no effect on the specific tensile properties. The prototype of biodegradation testing unit - Gravimetric measurement respirometric (GMR) system - was successfully set up according to the ISO 14855-2 standard. The coconut fiber/PLA composite can be degraded significantly, i.e., 60 wt% within only 26 days.

Electrochemical Synthesis of Polyaniline as Ethylene Gas Sensor

The aim of this work is to fabricate an ethylene gas sensor based on polyaniline (PANi). The conductive layer of emeraldine base PANi was prepared by electrochemical synthesis. The aqueous aniline solution in sulfuric acid was electrolyzed by repeating potential cycling between -0.4 and 1.0 V relative to the silver reference electrode and platinum counter electrode. The conductive layers of PANi were deposited on patterned interdigited gold substrate. The numbers of repeated potential cycles on the amount of deposited layers of PANi were investigated for ethylene gas detection. The morphology of PANi films was investigated by scanning electron microscope (SEM). The ethylene gas sensing of PANi-H2SO4 was evaluated based on the changes in conductivity of PANi-H2SO4. The results revealed that the magnitude sensing provided a good sensitivity against ethylene with concentration in the parts per million (ppm) ranges. The effect of amount of deposited layer of PANi on ethylene gas sensing will be presented.

Isothermal and non-isothermal crystallization kinetics of poly(butylene succinate) with nanoprecipitated calcium carbonate as nucleating agent

Poly(butylene succinate) (PBS) nanocomposites filled with nanoprecipitated calcium carbonate (NPCC) were prepared via melt blending. The hybrid materials were crystallized under isothermal and non-isothermal conditions in order to understand the influence of NPCC on the crystallization behavior of PBS matrix. For both of these conditions, the nucleating effect induced by the addition of NPCC was clearly shown by differential scanning calorimetry (DSC) additionally to an increase of crystallinity. The analysis of isothermal crystallization by Avrami theory allowed to notice a variation of the crystallization mechanism in the presence of the filler and the apparition of secondary stage crystallization. The nanocomposites exhibited higher nucleation activity than the neat PBS and a faster crystallization process as indicated by the values of the half-time of crystallization. Ozawa and Mo theory applied on DSC data highlighted the variations of PBS crystallization behavior in the presence of NPCC. Finally, the crystallization ability of each material was evaluated via the theories of Takhor and Augis–Bennett. The crystallization activation energy showed a promotion of polymer chain diffusion that was correlated with the simultaneous apparition of secondary crystallization stage.

Microwave-Assisted Modification of Cellulose as a Compatibilizer for Pla and Mcc Biocomposite Film: Effects of Side Chain Length and Content on Mechanical and Thermal Properties

This research focused on the utilization of modified banana leaf sheath (BS) to be used as the compatibilizer for biocomposite films based on poly(lactic acid) (PLA) and 40 wt.% banana leaf sheath microcrystalline cellulose (BS MCC). Two types of cellulose ester, i.e. cellulose butyrate and cellulose laurate were used as a compatibilizer. The cellulose esters were prepared via acylation process under microwave heating. The proper condition for preparing cellulose butyrate was 180 sec of reaction time and 80 watt of microwave power, while the suitable condition for preparing cellulose laurate was 150 sec of reaction time and 160 watt of power output, respectively. These optimum conditions led to the highest percentage of weight increase (%WI) and the absence of the degradation of cellulose. The butyrate and laurate were successfully grafted on the BS MCC which was confirmed by FT-IR and NMR spectroscopy techniques. For biocomposite films, although the increase of cellulose laurate or cellulose butyrate induced the decrease in Youngs modulus of 40 wt.% BS MCC/PLA composite, the elongation at break of 40 wt.% BS MCC/PLA composite was increased. Likewise, the presence of 5 wt.% cellulose butyrate or cellulose laurate contributed to the highest tensile properties, especially in elongation at break, when compared to other contents of cellulose ester. According to SEM micrographs, the presence of both cellulose esters can improve the compatibility between PLA and MCC as evidenced by the disappearance of many holes in 40 wt.% BS MCC/PLA composites. Comparatively, cellulose butyrate is an effective compatibilizer for improving the elongation at break of 40 wt.% BS MCC/PLA since it had better compatibility with BS MCC and PLA matrix than cellulose laurate. However, the addition of both cellulose esters, i.e. cellulose butyrate or cellulose laurate, led to the decrease in the degradation temperature (Td) of 40wt.% BS MCC/PLA, particularly when adding cellulose laurate.

Surface and Mechanical Properties of Cellulose Micro-Fiber Reinforced Recycle Polyethylene Film

This work involved a study of polymer-fiber composites as biodegradable packaging made from recycled polyethylene (r-PE) and chemical-treated cotton fabric waste micro fibers. A compatibilizer, polyethylene-graft-maleic anhydride (PE-g-MA), was used to improve properties of the composites. Factors affecting composite properties were investigated including % PE-g-MA loading, and % fiber loading. The fiber composites were prepared by melt-blending technique. The materials were first mixed by a twin-screw extruder and shaped into samples by an extrusion blow molding machine. The samples were then characterized for mechanical, and morphological properties. It was found that properties of the composites were improved by adding the compatibilizer. Optimum properties of the composites were found at 10% (wt%) PE-g-MA loading. It was also revealed that tensile strength and modulus was found to increase as the % fiber loading was increased. SEM micrographs confirmed that interfacial bonding between the cellulose fibers and the r-PE matrix was enhanced as fewer voids at the interfaces were revealed by adding the PE-g-MA compatibilizer to the composites. Film formation occurred on all composites even if the polymer itself was inert biodegradation. The microbial colonization affected mainly of surface properties r-PE composites while changes were monitored also in the bulk properties of cellulose microfiber.

Effect of 3-Aminopropyltrimethoxysilane-g-Rice Husk Silica on Flame Retardant of ABS/Organomontmorillonite Nanocomposites

This work focused on an improvement of flame retardant properties of acrylonitrile-butadiene-styrene (ABS) by varying amount of silica and organomontmorillonite (OMT). The silica was extracted from agricultural waste such as rice husk by chemical treatment. The obtained silica was characterized by SEM-EDX, XRF, FTIR, laser particle size analysis, and surface area analysis. After that, the rice husk silica (RHS) was surface-modified with 3-aminopropyltrimethoxysilane (AMMO) before blending with ABS and OMT at various ratios by melt blending technique using twin-screw extruder. The effect of silane coupling agent on flammability properties of ABS nanocomposites was studied. The prepared nanocomposites were characterized by TEM to examine the dispersibility of OMT and AMMO-g-RHS in ABS matrix. The flammability properties were evaluated by measuring the limiting oxygen index (LOI) values and UL-94 classes. The TEM results revealed that the ABS/OMT/AMMO-g-RHS nanocomposites were a kind of exfoliated structure. The modified silica particles and OMT were found to disperse and reside in the SAN phase of the matrix. Furthermore, OMT and modified silica could enhance flame retardant properties of ABS polymer matrix because of a synergistic effect between OMT and modified silica during the combustion of ABS nanocomposites.

Physicochemical Properties of Carbons Prepared from Physic Nut Waste by Phosphoric Acid and Potassium Hydroxide Activations

Char derived from pyrolysis of physic nut waste at 400-800°C was used for the preparation of activated carbon by chemical impregnation of phosphoric acid and potassium hydroxide. The original char exhibited the BET surface area in the range of 120-250 m2·g-1. The surface area increased to 480 and 532 m2·g-1 when activated with H3PO4 and KOH, respectively. Equilibrium adsorption data was found to be best represented by the Langmuir isotherm with maximum monolayer adsorption capacity of 560.13 mg·g-1 at 30°C. The adsorption capacity of the physic nut residue activated carbon was comparable to commercial activated carbon.

Effect of Microcrystalline Cellulose from Banana Stem Fiber on Mechanical Properties and Crystallinity of PLA Composite Films

This work focused on the preparation of the biocomposite films of polylactic acid (PLA) reinforced with microcrystalline cellulose (MCC) prepared from agricultural waste, banana stem fiber, and commercial microcrystalline cellulose, Avicel PH 101. Banana stem microcrystalline cellulose (BS MCC) was prepared by three steps, delignification, bleaching, and acid hydrolysis. PLA and two types of MCC were processed using twin screw extruder and fabricated into film by a compression molding. The mechanical and crystalline behaviors of the biocomopsite films were investigated as a function of type and amount of MCC. The tensile strength and Young’s modulus of PLA composites were increased when concentration of MCC increased. Particularly, banana stem (BS MCC) can enhance tensile strength and Young’s modulus of PLA composites than the commercial MCC (Avicel PH 101) because BS MCC had better dispersion in PLA matrix than Avicel PH 101. This result was confirmed by SEM image of fractured surface of PLA composites. In addition, XRD patterns of BS MCC/PLA composites exhibited higher crystalline peak than that of Avicel PH 101/PLA composites