Sarunya Promkotra

Fabrication of Novel Polyhydroxybutyrate-co-Hydroxyvalerate (PHBV) Mixed with Natural Rubber Latex

Polyhydroxybutyrate-co-hydroxyvalerate (PHBV) is mixed with natural rubber latex to make better mechanical properties of PHBV. The various ratios between PHBV and natural rubber latex are examined to improve their mechanical properties. The PHBV are solid, easily broken, while natural rubber is excessive elastic materials. Concentrations of the employed PHBV solution are 1, 2, and 3 (%w/v). The mixtures of this solution to natural rubber latex are fabricated the biofilms in three different ratios, 4:6, 5:5, and 6:4, respectively. The films are characterized by electron microscope, universal testing machine, and differential scanning calorimetry (DSC). The electron micrographs of the mixed films and unmixed PHBV yield the lowest void distributions in 3%w/v PHBV. For mechanical properties, the averaged elastic moduli of 1, 2, and 3 (%w/v PHBV) mixed films are 773, 955 and 1,008 kPa, respectively. Their tensile strengths increase with increasing the PHBV concentrations. A similar trend is also found in elastic modulus. The crystallization and melting behavior of pure PHBV and the mixed films are examined by DSC. Melting transition temperatures of pure PHBV exhibit two melting peaks at 154°C and 173°C. In addition, the melting peaks of the mixed films remain in the range of 152-156°C and 168-171°C, respectively. According to their morphology, void distributions reduce twice, compared to the unmixed PHBV. Mechanical properties and thermal analysis indicate that the mixed PHBV can be improved their properties with more resilient and wide range temperature than usual.

Mechanical Behavior of Fired-Clay Bricks from Stream Sediments under Uniaxial Compressive Loading

In the northeast of Thailand, raw material for fired-clay brick is obtained from fine stream sediments in the lower Nam Phong and upper Chi River sub-watersheds. Hundreds of brickyards exist along the waterway producing rice husk ash (RHA) bricks for construction. Technical study on the production of these bricks is limited, therefore, detailed studies on mechanical and chemical properties will enhance the understanding of the production process in order for further improvement. In this study, a preliminary investigation of the brickyards and production process was conducted. Brick samples as well as raw sediment materials were collected from 6 randomly selected locations for laboratory testing on physical, chemical, and mechanical properties. A total of 300 brick specimens were collected being 50 specimens from each location. The brick dimensions are roughly 5×5×15 cm with an average weight of about 680 g. X-Ray Diffractometry show that the fired brick composition is approximately 90-98% quartz, 5-7% clay minerals, and less than 1% minor minerals. Mechanical behavior of the fired-clay bricks was evaluated by compressive loading of single brick units conducted under dry and submerged (with reverse osmosis water) conditions. The compressive strength of the brick unit is found to be proportional to its density with values in the range of about 0.4-1.2 MPa. Bricks with RHA to sediment ratio of 1:3 exhibit a higher average strength that that of other ratios.

Chemical Thermodynamics of Hydrocarbon Compositions in Natural Gas Field, Northeast of Thailand

The phase envelope of hydrocarbon species in natural gas can be predicted by using thermodynamic simulation. Conceptual thermodynamics depends on physical and chemical characteristics in equilibrium condition. The API gravity of condensate is expressed in a range of 55–63°. Its average density is similar to the specific gravity of 0.74. Pressures in each gas processing process are decreased from the gas well (74.754 bar g) to the condensate tank (0.02 bar g). Mostly methane is discovered approximately 96 mol%. Due to physical and chemical properties, this petroleum reservoir indicates the dry gas reservoir. Chemical reactions depending on hydrocarbon compositions can be valuable for evaluating phase equilibrium. These chemical reactions based on hydrocarbon species are fabricated by chemical species as reactants and products. For creating them, all compositions related to the genesis of petroleum in the same environment are combined as a reactant. They are possibly defined as phase related to Gibbs free energy. Carbon dioxide, hydrogen, and nitrogen gas in petroleum reservoir are 10, 8, and 2 mol%, respectively. The chemical thermodynamics is simulated by using Prode Properties, a computer software program, in which Peng–Robinson equation of state is used as the chemical thermodynamic model. Characteristics of phase envelope consist of the critical temperature and pressure at phase transformation between liquid and gas. Two types of conceptual schemes are varying the invariable and variable mole fraction to evaluate the phase envelope. For their invariable mole fraction, the carbon ratio is defined at 60:20 percentages. Temperatures of natural gas from the phase envelope are inversely proportional to equilibrium constant. High temperature at low equilibrium constant specifies the forward chemical reaction. For their variable mole fraction, the increased carbon atoms affect to gradually intensify the temperature and pressure. Hydrocarbon types and mole fraction of these components concern to the possibility of phase envelope at suitable phase.

Mathematical Model of Petroleum Dynamics in Closed Conduit

Petroleum transport from a gas well to the gas production plant is relevant to the petroleum production of the natural gas field. This migration affects movement direction on distance and chemical components under the emphasis upon the relationship between condensate and other fluid hydrocarbons. The physical properties of condensate are analyzed on the basis of API gravity (55.52–62.84°), density (0.73–0.76 g/cm3), specific gravity (0.7362–0.7566), Reid vapor pressure, and true vapor pressure. The highest hydrocarbon composition is methane, 96.70 %. Hydrocarbon concentrations from the gas processing plant are found overall C7+ (heptane, C7H16) to C16 (hexadecane, C16H34), and found most octane (C8H18). Petroleum dynamics is evaluated in the criteria of petroleum transport in closed conduit. Mathematical model of petroleum dynamics is defined by the diffusion coefficient of the specific chemical reactions depending on methane–ethane and methane–propane which are 15.71 and 9.20 cm2/s, respectively. The quantities of molar fluxes gradually increase from one location to another location when phases change from gas to liquid, and decrease to the condensate storage tank due to the completion of liquid. The liquid phase preferably occurs because propane is slightly heavier than ethane. Their physical properties have been less affected to molar flux in the chemical reaction of propane. According to methane–ethane combination, molar fluxes as a function of sampling distances of methane in reactants are higher than methane in products. Besides, the molar fluxes of other components are expressed in the systematic trend.

Compressive Aggregates of Two-Dimensional Mono-Disperse to Assess Flaw Dissemination

Polystyrene particles of 4 μm in diameter are aggregated as the monolayer clusters rearranged themselves when the compressive forces are applied to the clusters. Oriented structures of the clusters are then examined and characterized the failure mechanisms of two-dimensional (2D) aggregation. Failure mechanisms cause rearrangement of particles within the aggregates. Their flaw locations of each applying force change due to the particle bonding-rebonding themselves. Particles can move either relatively to each other or the small aggregates. Even though, these orientations occur in the small scale and barely significant, disturbed particles gradually accumulate stress. Small aggregates or particles inside the bulk perhaps cannot immediately change the cluster shape, but regularly oriented until reaching to yield. Compression to 2D aggregates can make an existing dislocation and fractures of this aggregated structure. Crack propagation of the dense is possible to proceed dynamically. The clusters collapse until reaching to yield. Two-dimensional structures of compressive aggregated polystyrene are always mechanical instable that increases in propagating rupture. Therefore, the quake will reasonably occur.

Interactive Force of Two-Dimensional Compressive Deformation by Discrete Element Method (DEM)

Discrete Element Method (DEM) computer simulation is used to examine the influence of contact force between two-dimensional aggregates of polystyrene microsphere formed on the air-liquid interface. Colloidal aggregates have been treated as the granular material or discontinuum materials. The interaction force models are related to experiment which had done by digital video microscopy. The interaction mechanisms of the contact forces between particles in the colloidal system can be considered as a combination of spring and dashpot force and van der Waals force. According to the DEM, the interaction forces are evaluated to introduce relations between particles and the result comparison between the computer simulation and the experimental work. This study indicates that the behavior of the colloidal aggregates depends on the long-ranged (spring and dashpot) and the short-ranged interaction force (van der Waals). Besides, the behaviors shown in both computer simulation and the experiment are in good agreement. Thus, this computer simulation method can mimic the behavior of colloidal aggregates forming as a monolayer at the air-liquid interface.

Quality Improvement and Characteristics of Polyhydroxyalkanoates (PHAs) and Natural Latex Rubber Blends

Biopolymers of hard, brittle and low flexible polyhydroxyalkanoates (PHAs) and a soft and high elastic natural-latex rubber are blended at room temperature by using a combination technique. Concentrations of the PHAs solution are constituted at 1%, 2% and 3% w/v and mingled with fresh natural latex in different ratios (PHAs : Latex Rubber = 0:10, 1:9, 2:8, 3:7, 4:6, 5:5, 6:4, 7:3, 8:2, 9:1 and 10:0). After vigorous blending, forming polymeric sheets leave a dried-film pattern. Only the best 3 different ratios (4:6, 5:5 and 6:4) are selected by evaluating morphological-based information. These lead to actually define and characterize for their morphological and mechanical properties. The morphological attributes are exemplified by polarized optical microscopy and X-ray diffractometry (XRD) while the thermal characterization is determined by differential scanning calorimetry (DSC). Morphological analysis for the criterion of blending achievement indicated that there is a significant relationship among porosity, texture and shrinkage. The porosity shows obviously low to high for gradually increasing PHAs and decreasing the latex. Thus, dense texture and shrinkage relate to blending compositions between PHAs and latex. The XRD and DSC reveal certain aspects of decreasing crystallinity arising from enhancing of the latex content. A high degree of crystallinity and melting temperature relates to greater PHAs ratio. The mechanical investigations have revealed complex localization patterns of tensile strength and elastic modulus. The more PHAs concentration at 2% w/v indicates the greater elastic modulus than 3% and 1% w/v. Significant differences are found on polymeric composites of mechanical analyses between PHAs and natural latex. The constituted superiority in the ratio of 5:5 significantly differs in extension to break. Additionally, both tensile strength and elastic modulus of 2% w/v PHAs present the maximum value among them.

Applicable Fine Stream Sediments from Upper Chi River Produced Fired Clay Bricks

Stream sediments from the upper Chi River basin, including Chi and Nam Phong sub-watershed, are applicable to be a source of raw materials to produce fired clay bricks. The sampling locations of clay materials are generally found along the river terrace where are covering three different regions (upper-, mid-and lower sub-watershed) nearby brickyards. Quartz is the main mineral of all samples. Moreover, mainly clay mineral groups consist of mica, kaolinite, and chlorite group composing totally around 5%. Other mineral compositions, such as carbonate, evaporite, corundum, hematite and pyrolusite are normally found both in fine stream sediments and fired clay bricks. Additional minerals in fired bricks are forsterite, zircon and mullite group which are less than 0.2%. Their strength in submersion test expressed in the air-dried to pure water both 1 day and 5 days is revealed that their strength and strain intend to increase with the submersed brick. Besides, prism compressive strength decreases in half related to a fired brick unit. Their impact resistances are significantly distinctive by mineral composition of clay mineral group and silica. The compressive strength of air-dried fired brick at the ultimate stress and strain corresponding by time in water absorption test show that water filled in void or pore can enhance their strength and strain. Thus, fired clay bricks are capable to resist compressive force than the normal condition.

Dynamics of Suspended Sediments Related to Fine Particles in Lower Mekong River

Analytical results are considered the factors of suspended sediment concentration, fall velocity, dimensionless shear stress, transportation rate and stream discharge. As a result of suspended sediments of Loei, Huang and Mekong River, fine particles account for the applicability in sediment deposits. Floating suspended sediments explicit more clay minerals than suspended sediments. Suspended sediment concentration (SSC) in the estuarine of Loei River and Huang River are moderately less than Mekong River. Flow directions of the interconnected rivers to the mainstream-Mekong River lead to the quantity of SSC. Sediment concentrations attain to the dynamic response. Dimensionless shear stress relates to shear velocity, geometry and grain size of particles, and difference of flow velocity. This shear stress is directly comparative to flow velocity and clay mineral concentrations. The transport rate involves in the flow velocity, SSC and depth of the river. Moreover, stream discharge can be presumed by the geometry of the river and topography of sampling locations.

Phase Equilibria of Condensate and Natural Gas

Condensate and natural gas from a gas field in the northeast of Thailand are examined for their physical and chemical properties, and phase behaviors referring to phase equilibria. The physical properties of condensate are analyzed based on API gravity, density, Reid vapor pressure, true vapor pressure, pressure and temperature, viscosity and specific energy. Chemical components of natural gas are grouped depending on the amount of organic hydrocarbons which are methane, light hydrocarbons, heavy hydrocarbons, aromatic and cyclic compounds and non-hydrocarbon contents in the mole per cent of 97.15, 1.16, 0.22, 0.019 and 1.50, respectively. Pristane and phytane ratio is 1.73 which refers to an oxidizing environment during the deposition of the petroleum reservoir. Phase behavior of condensate is found only one phase, liquid phase at 15°C and 101.327 kPa, which indicates the critical temperature of 592.13 K and the critical pressure of 2,372.96 kPa. However, natural gas can be separated in two phases, vapor and liquid phases. The results show that the cricondentherm and cricondenbar of natural gas are 326.36 K and 1,295.28 kPa, respectively. These results can be useful for controlling and managing condensate and natural gas.