Wirunya Keawwattana

Study the Effect of HAp Content in PLA/HAp Microsphere on the Efficiency of Drug (Clindamycin) Loading Process

An ultrasound field was applied to obtain Polylactic acid (PLA)/Hydroxyapatite (HAp) biocomposite microspheres with the specific core-shell structure to be applied as a carrier of a drug. The hydroxyapatite was obtained from crocodile bone by thermal process. Sample characterization was achieved by powder X-ray diffraction (XRD), Energy-dispersive X-ray spectroscopy (EDX) Scanning electron microscopy (SEM) and High Performance Liquid Chromatography (HPLC). As the result, the PLA/HAp loading clindamycin with different polymer-to-ceramic part wt.% ratio (100:0, 90:10, 80:20, and 70:30) showed the agglomeration of sphere-like particles. In addition, the loading efficiency of clindamycin increased with increasing HAp content up to 20%.

Filled-NR Conductive Thin Film: A Simple Route of Graphene Dispersion in Natural Rubber Latex

Reliable quantification techniques for graphene oxide (GO) and graphene nanosheets (GNs) in ESD rubber product are limited. We demonstrated an effective ultrasonically−assisted latex mixing (ULM) technique for dispersion of GO and GNs at low concentration (0.5, 1.0 and 1.5 part per hundred of rubber; phr) in natural rubber latex (NRL) to produce NR/GO and NR/GNs conductive thin film. The filled−NR composites were prepared by ULM, followed by latex dipping coagulation. The morphologies from transmittance electron microscopy (TEM) of stabilized GO and GNs dispersion showed successfully dispersion and exfoliation in NR matrix. Compared to pure NR, the tensile strengths of NR/GO and NR/GNs (1.5 phr) increased by ~58% and ~32%, respectively, while there were decreased in the %elongation at break and were no significant change in the force at break. In case of studying the electrical properties, sheet resistances of filled−NR composites declined with the incorporation of GO and GNs. However, the NR composite with 1.5 phr of GNs showed the best conductivity.

The Effect of Kaolin Clay on Fire Retardancy and Thermal Degradation of Intumescent Flame Retardant (IFR)/Natural Rubber Composite

Study the effect of kaolin clay as a synergistic agent on flame retardancy and thermal degradation in natural rubber based on intumescent flame retardant (IFR); consisting of ammonium polyphosphate (APP) as acid source, pentaerythritol (PER) as a carbonization agent and melamine (ME) as a blowing agent was undertaken. The intumescent was examined at different loading (60, 80 and 100 phr). Kaolin clay was incorporated into flame retardant at four different concentrations (0.5, 1.0, 1.5 and 2.0 wt% of flame retardant) to investigate the synergism between the flame retardant materials. The flammability and thermal degradation of composites were characterized by UL-94 rating (vertical burning) test, cone calorimeter (CONE) and thermogravimetric analysis (TGA). All composites could meet the UL94V-0 standard. A synergist effect was observed when kaolin clay is used in combination with the intumescent flame-retardant through the TGA and CONE results. Moreover Scanning Electron Microscope (SEM) was done for the char morphology.

Preparation and Magnetic Properties of La Substituted Barium Ferrites Synthesized by the Oxide one Pot Synthesis (OOPS) Process

Lanthanum (La) substituted barium ferrite, Ba1-xLaxFe12O19 (x=0.00-0.40) has been synthesized by the oxide one pot synthesis (OOPS) process. The crystalline structure and magnetic properties have been investigated by means of XRD, SEM and VSM. The XRD pattern matched with the barium ferrite structure. The saturation magnetization (Ms) and coercive field (Hc) of ferrites increased by substitution of La ions on Ba sites at the content up to x=0.15 and then decrease.

Study the Effect of the Addition of HAp from Crocodile Bones on the Mechanical Properties of PLA/HAp Composites

In this work, hydroxyapatite (HAp) was produced from crocodile bones by thermal process at 900°C. X-ray diffractometer (XRD), Fourier transform infrared spectrometer (FTIR) and Scanning electron microscope (SEM) were used to characterize the obtained HAp. Polylactic acid (PLA)/HAp composites were prepared by melt blending as follows: 95/5, 90/10 and 85/15 (weight ratio). The effect of the amount of HAp on the mechanical properties including tensile strength, modulus, elongation at break and impact strength of PLA/HAp composites was undertaken. It was found that tensile strength and elongation at break of the composites decreased with an increase of HAp content, while modulus and impact strength showed no significant effect.

Improvement Filler-Rubber Interaction and Mechanical Properties of Silica/NR Vulcanizates by Using Masterbatch Processing

Due to the dispersion of silica and reducing filler-filler interaction, the improvement of filler-rubber interaction was enhanced the physical properties of silica/NR compounds. This research was then focused on the production of silica masterbatches with surface treatment by surfactant to enhance the silica dispersion. The silica dispersion examined by scanning electron microscopy (SEM)c and the mechanical properties of vulcanizates prepared from the masterbatches were compared with those prepared by a conventional direct mixing method. The mechanical properties of silica/NR masterbatches exhibited greater modulus, tensile strength and hardness compared to the corresponding conventional mixes. A better silica/NR interaction of silica/NR masterbatch was achieved confirming by higher the bound rubber content and lower Payne effect, leading to the greater mechanical properties.

In Situ Synthesis and Mechanical Properties of Polylactic Acid/Hydroxyapatite Functionalized Graphene Nanocomposite

The hydroxyapatite functionalized graphene (HAp-GnP) was prepared by precipitation method. It was characterized by Fourier Transform Infrared Spectroscopy (FTIR), X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM). Polylactic acid (PLA)/HAp-GnP and PLA/HAp-GnP composites were prepared in film by solution casting. The amount of HAp-GnP and HAp/GnP filled in PLA was fixed at 5% (by weight). The influence of HAp-GnP in the mechanical properties including tensile strength (TS), tensile modulus (E) and elongation at break (EB) of composites was investigated. It was found that tensile strength (TS) and tensile modulus (E) of the PLA/HAp-GnP composite were higher than those of PLA/HAp/GnP composite as a result of HAp making the interfacing with graphene leading to the greater distribution of HAp-GnP in PLA matrix. The PLA/HAp-GnP composite is applicable to be applied as bone substitute in the future.

Effect of Ashes as Biomass in Silica Filled Natural Rubber

Silica has been used as reinforcing filler in natural rubber for a period of time as it results in excellent properties for NR vulcanizes. Rice husk ash (RHA), bagasse ash (BA), and oil palm ash (OPA) obtained from agricultural wastes are mainly composed of silica in the percentage of 80.00%, 57.33%, and 40.20% by weight, respectively. The effect of these fillers on cure characteristics and mechanical properties of natural rubber materials at fixed silica content at 35 parts per hundred of rubber (phr) were investigated. The results indicated that ashes showed greater cure time compared to that of the silica. The incorporation of ashes into natural rubber gradually improved compression set but significantly decreased tensile strength, elongation at break, and resilience. Moreover, youngs modulus increased, while hardness showed no significant change with the addition of ashes. Overall results indicated that ashes could be used as cheaper fillers for natural rubber materials where improved mechanical properties were not critical.