Papers by Author: M. Phiriyawirut

Abstract: Aloe vera extracts, consisting of active compounds that decrease pain and inflammation and stimulate skin growth and repair, are selected as a drug model in this work. Polyvinyl alcohol (PVA) was used as base material. Release profiles of Aloe vera extracts from PVA electrospun fibers were compared to those from PVA hydrogel films prepared by freezing/thawing method. This method provided a physical crosslinked polymer. The concentration of PVA solution used for electrospinning and hydrogel preparation was 10% wt with different contents of Aloe vera extracts (0, 30, 50, 70 and 90% w/w). The properties of electrospun fibers and hydrogel films were evaluated in terms of morphology, chemical structure, swelling behavior and release profiles. The morphological properties of electrospun fibers and hydrogel film were observed by SEM. Electrospun fibers were smoothly round, high surface area, and non-woven, while hydrogel film possessed rough surface and was covered with porous. Fourier transform infrared spectroscopic measurement exhibited the existence of relevant functional groups of both PVA and Aloe vera extracts. The results showed relevant functional groups of Aloe vera extracts in both electrospun fibers and hydrogel film. The release of Aloe vera extracts from both electrospun fibers and hydrogel film was evaluated in phosphate buffer of pH 5.5 at 25 °C and was monitored by UV–vis spectroscopy. It was revealed that as the content of Aloe vera increased, the amount of Aloe vera extracts released from electrospun fibers decreased. This result contrasts with the release of aloe vera from hydrogel film which increased when the content of aloe vera increased. It was also noticed that the amount of Aloe vera extracts released from electrospun fibers was more than that from hydrogel films at 600 minutes. The results also showed that the releasing rate of Aloe vera from electrospun fibers was faster than that from hydrogel films. This is probably because electrospun fibers had much higher surface area than that of hydrogel film thus, the release was faster.

Abstract: Preparation of cellulose acetate (CA)/TiO₂/WO₃ composite nanofibers via sol-gel with electrospinning process for improving the photocatalytic efficiency was conducted. CA was removed from fibers by a heat treatment. Microstructure and elemental composition of TiO₂/WO₃ nanofibers were evaluated by scanning electron microscope (SEM) and energy dispersive microscopy (EDX), respectively. The results showed that the nanofibers of TiO₂ and WO₃ were achieved with the average diameter range of ca. 310-701 nm and both TiO₂ and WO₃ are well dispersed along fiber length, confirmed by an EDX analysis. The results also showed that the smoothness of fiber surface decreased with decreasing WO₃ contents. The photocatalytic activity of the materials were also tested for methylene blue degradation. TiO₂/WO₃ exhibited the highest activity comparing to pure TiO₂ and WO₃. Moreover, it was found that a TiO₂/WO₃ specimen possessed the energy storage ability as a result, it showed the photocatalytic activity in the absence of light.

Abstract: Water resistant is drawback property of thermoplastic starch. Blending of hydrophobic starch to natural one is another solution. Different blending ratio of tapioca/octenyl succinate starch (OSA) at 0/100, 25/75, 50/50, 75/25, 100/0 were prepared using internal mixer, and molded by compression molding at 135-140°C, 1000-1500 MPa for 9 minutes. Density of the blend was decreased, due to lower density of OSA starch. There was mechanical properties improvement in 25% OSA blended tapioca starch i.e. tensile strength, Young’s modulus & elongation at break, due to synergy effect of OSA & tapioca starch. There was improvement in degradation temperature of the blend studying by TGA technique. Water resistance of the blend is improved related to the content of OSA starch in the blend on short time contact (10 min), but no impact at longer time exposure (1hr). The blend had a better resistant to degradation with a-amylase, which OSA starch could retard the degradation.

Abstract: The property of cellulose microfibril reinforced natural rubber film was studied. Cellulose microfibril was prepared from banana powder (300 µm). The interconnected structure of cellulose microfibril having a diameter of 27 nm was observed by TEM. The effect of cellulose microfibril content (0.8-3.2 % wt) in the property of NR nanocomposite film was studied. Tear strength and thermal properties of the NR nanocomposite film is improved by increasing the cellulose microfibril content. Moreover, water absorption of the nanocomposite film is increased by increasing cellulose microfibril content. Increasing of cellulose microfibril content also enhances water permeation of nanocomposite films.

Abstract: Electrospinning has been recognized as an efficient technique for the forming of polymer nanofibers. In this project interest fabricated Soy Protein Isolate (SPI) nanofibers by electrospinning with different supply voltages, positive and negative charge. SPI was dissolved in 80%-95% w/w acetic acid solution and 80%-90% w/w formic acid solution. Only droplet formation of SPI were found instead of fibril formation, and the droplet morphology of SPI is depended on supply voltage, and type of solvent. SPI droplets from the negative supply voltage have smaller and more nodular than droplets from positive supply voltage. Formic acid SPI solution gives smaller size of droplet and more nodular than acetic acid SPI solution. In order to forming SPI nanofibers, zein/SPI blend were performed. The zein/SPI blend was studied at difference blending ratio. The 95/5 Zein/SPI was found to be the best blend composition for electrospun fiber. In addition, the effects of electrostatic distance and electrostatic voltage on electrospun fiber were also investigated. Increasing electrostatic distance or increasing voltage, smaller size of fiber was obtained.