Biodegradable polymers have been more attractive for membrane materials, especially poly(lactic acid) (PLA) because they degrade in natural environment after use. In this study, the membranes were developed from a polymer blend of PLA and other biodegradable polymers, such as poly(butylene succinate) (PBS), poly(butylene adipate-co-terphthalate) (PBAT) and Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV). The membranes were formed via nonsolvent induced phase separation process using n-methyl-2-pyrrolidone (NMP) as a solvent and water as a nonsolvent. The pure water flux and BSA rejection were tested to determine the filtration performance of membranes. The microstructures and tensile strength of membranes were characterized by field emission scanning electron microscope (FE-SEM) and universal testing machine (UTM), respectively. All of membranes appeared finger-like and sponge-like structures in cross-section, and porous structure on surface. PLA/PHBV blend membranes had pure water flux and BSA rejection as high as PLA/PBS and PLA/PBAT blend membranes. The pure water flux and BSA rejection of the blend ratio (PLA/PHBV/NMP) of 15:1:84 were 65 l/m2•h and 79%, respectively.
Bangkok clay is a well-known soft clay among engineers around the world who work with soil-related fields. Many government institutions have to deal with many pipeline construction problems and open-cut trench technique due to many of its responsible regions containing Bangkok soft clay. The aim of this paper is to review the soil improvement techniques used in the construction of water supply pipelines and open-cut trench technique for solving pipeline construction & maintenance problems in responsible areas. Based on the related data, pipeline construction standards, backfill materials and zoning of construction, techniques have to be considered for improvement, and the effect of Bangkok clays must be considered in proposing suitable soil improvement techniques. In order to solve the problem, factors such as the ability for working on site with simplified components and techniques, efficient quality control, local and low cost material must be considered for the application of soil improvement. Due to the fact that the technique must be applicable to solve the problems, three soil improvement techniques were presented including: 1) Liquefied Stabilized Soil (LSS) technique 2) Controlled Low Strength Material (CLSM) technique and 3) Soil improvement with liquefied rubber technique. These techniques are appropriate for various conditions of the regions such as area constraint, constructions time, and material availability. Several materials can be applied for the two prominent techniques (LSS and CLSM). Those materials are excavated soil, reused or by-product materials, etc. On the other hand, using liquefied rubber for soil improvement requires short duration for hardening and construction. The essential composition of "Liquefied Rubber" is a natural product, which can be found locally. These are the dominant factors of this technique. Hence, the natural rubber value is added to rubber products industry in South East Asia region. This technique enhances the sustainable development of a Green Material in the future.
Class V flextensional actuator named "cymbal" is composed of a ceramic disk that is sandwiched between two truncated conical metal endcaps. It has received considerable attention for sensor and actuator applications due to their high displacement and moderate generative force. It is well known that the strain/displacement of the piezoelectric ceramic correlated to the piezoelectric coefficient and external electric field applied (S = dE). According to the piezoelectric coefficient (d 33 ) of KNN-LT-LS lead-free piezoelectric ceramic was comparable to PZT-8. Therefore, the purpose of this study was to investigate the effect of different ceramic driving elements (hard PZT and KNN-LT-LS ceramics) in the flextensional cymbal actuator on the strain amplification as well as the characteristic in strain-electric field loop response. The results showed that displacement of KNN-LT-LS cymbal (11.9±0.28 μm) were two times higher than that of PZT-8 cymbal (5.65±0.07 μm) at 10 kV/cm. Moreover, bi-polar S-E loop characteristic was larger in KNN-LT-LS cymbal compared to PZT-8 cymbal. This was due to easily domain reorientation in KNN-LT-LS ceramic observed by P-E loop. Under 10 kV/cm, P r and E c of KNN-LT-LS ceramic were 4.9 μC/cm 2 and 3.9 kV/cm whereas P r and E c of PZT-8 ceramic were 0.22 μC/cm 2 and 1.5 kV/cm, respectively.
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