Engineering Thermodynamics, Heat Transfer and Fluid Flow in Natural and Industrial Processes
Computational Analysis of Heat Transfer in Fluids and Solids
Physics and Technology of Nanostructured Materials IV
Superplasticity in Advanced Materials - ICSAM 2018
Transfer Phenomena in Fluid and Heat Flows V
Diffusion in Materials DIMAT-2017
Engineering and Innovative Materials VI
Compound Materials and Nanotechnology
Recent Trends in Mass Transport in Solids and Liquids
Transport Problems with a Focus on Fluid and Heat Flow
Transfer Phenomena in Fluid and Heat Flows IV
New Development for Heat Transfer in Solids and Fluid Flow
Materials and Technologies in Dentistry: Defects, Processing and Characterization
Engineering and Innovative Materials VI
摘要: Chitosan membrane (Ch) has mechanical stability, physical, and chemical low thus limiting their application to a variety of purposes. Therefore in this study examined the effect of adding silica and polyethylene glycol (PEG) on the mechanical properties, physical, and chemical chitosan-based membranes. A source of silica used is tetraethyl orthosilicate (TEOS). Composite membrane Chitosan-silica-PEG (Ch/Si/P) was prepared using the sol-gel process and characterized morphology, crystallinity, and changes in functional groups. In general, the addition of silica in the preparation of composite membrane Ch/Si, increases tensile strength, Young's Modulus, pore size distribution, as well as lower percent Elongation but does not affect the crystallinity and the change of functional groups on the membrane. The addition of PEG on manufacture composite membrane Ch/Si/P, increases the percent Elongation, Young's Modulus decrease and decreased pore size distribution, but does not affect the crystallinity, as well as to changes in the functional groups on the membrane. The results showed that membrane with a mass ratio of chitosan/silica/PEG of 1:0.7:0.5 have a maximum percent Elongation and the minimum Young's Modulus.
摘要: This study investigated the synthesis and characterization of poly(lactic acid)-grafted natural rubber (PLA-g-NR) in molten state. The grafting was carried out in an internal mixer without and with the presence of tin octoate catalyst (TO). The grafting of lactide onto NR was carried out by using maleic anhydride (MA) as a linker. The FTIR and 1H-NMR spectra revealed new peaks for the MA-grafted NR (NR-g-MA) and PLA indicating that MA was grafted onto NR and that LA was successfully polymerized into PLA. It was also found that MA grafted onto NR could assist as a linker for connecting PLA with NR via esterification reaction between hydroxyl group (OH) at the end chain of PLA and carboxylic group (COOH) from ring opening reaction of MA. Moreover, the decrease of residual LA peak in FTIR spectra suggested that the presence of TO catalyst in the reactive blend promoted higher degree of polymerization of PLA from ring opening reaction of LA.
摘要: This paper provides information on the effects of organoclay (OC) impregnation in the thermal, physical and mechanical properties of recycled composite materials. The raw material was a flexible industry trimmings from a food packaging manufacturing plant. Various material testing standards were employed to determine the properties of the recycled materials. Results showed that the recycled material has significant effect in retarding the linear rate of burning due to the yielded ρ – value equal to zero (0). The resistance factors showed that the recycled material is potential as insulation, barrier, or roofing tile. These information is an indication that impregnation of OC enhanced the recycled material to be thermal resistant, gas and water vapor barrier and as potential barrier material.
摘要: Both synthetic and natural rubber latex can be used to form rubber latex glove films for medical and dental applications. The objective in this research is to study the natural and synthetic rubber latex glove films formation by dipping process with the bone china ceramic hand molds for 5, 10, and 15 min. From the experimental, the obtained natural rubber latex glove films are good appearance and good physical-mechanical properties i.e. smooth film surface, light pale yellow color, soft, translucent, high tensile strength, high elongation at break, and high flexibility better than those of synthetic rubber latex glove films. When the dipping time of bone china hand mold into natural rubber latex compound increases effect to tensile strength, thickness, and elongation at break increase. Tensile strength, elongation at break, and tensile stress of natural rubber latex films dipped for 15 min are equal to 12.82 ± 1.19 MPa, 1090.91 ± 4.92%, and 39.23 ± 3.63 N, respectively.
摘要: The mechanical stability time (MST) of latex is an important parameter indicating the colloidal stability of concentrated natural rubber latex (CNRL). This stability is crucial for the transport and storage of CNRL before the product forming processes. A popular method to increase the MST of CNRL in Thailand is by adding laureth soap or other surfactants. Nevertheless, the laureth soap provides a steady but slow increase in the MST without reaching a stable value after 30 days. At the same time, the phospholipids on the surfaces of natural rubber latex particles will naturally undergo hydrolysis reaction leading to even higher MST. For long storage, too high MST leads to coagulation problem in the product-forming step. Therefore, alternative methods were studied in this research to expedite phospholipid hydrolysis, which results in the increase in MST for CNRL without causing problems from excessive negative ions in the product-forming process. The alternative methods including heating in the presence of metal chips and the use of enzyme lipase were compared to the popular laurate soap addition method. It was found that lipase addition was the most effective method to expedite the hydrolysis of phospholipids to reach the standard MST value within 3 days, and reach a plateau within 10 days.
摘要: Poly (ester urethane) s (PEUs) based on L-lactic acid (LA) and ricinoleic acid (RA), 1,6-hexamethylene diisocyanate (HMDI) were synthesized via polycondensation-chain extension reaction. Melt polycondensation reaction was carried out to produce the prepolymer poly (L-lactic acid-co-ricinoleic acid), with number average molecular weights (Mw) ranging from 3,000 to 10,000 g/mol. The weight ratio between LA with RA were 100:0, 95:5, 90:10, 80:20. The PEUs PEU100:0, PEU95:05, PEU 90:10 and PEU 80:20 were observed to be soft solids. Molecular weights increased after chain extension/coupling reaction with the diisocyanate, producing polymers with Mw ranging from 60,000 to 115,000 g/mol. The production of poly (L-lactic acid-co-ricinoleic acid urethane) was verified by infrared (FTIR) and proton-nuclear magnetic (H1-NMR) spectroscopy. The poly (L-lactic acid) and the urethane groups are believed to form hard segment while the poly (ricinoleic acid) segment is the soft segment group. Moreover, oxygen plasma surface modification was also employed to alter the surface properties of the PEU samples Based on scanning electron microscopy (SEM), the surface roughens and hydroxyapatite mineralization were improved after the plasma treatment. The PEU materials were also found to be biocompatible with L929 mouse normal fibroblast cells.
摘要: The food packaging material provides protection against moisture, heat, enzymes, oxygen penetration etc. The shelf life of food can be increased by coating barrier materials on plastic films. In this work the oxygen transfer rate (OTR) and water vapour permeability (WVP) of Polyethylene terephthalate (PET) films were adjusted via coating of Polyphenols and Gelatin mixture (PGM) with different concentrations while maintaining the other properties of modified PET films. This article deals with the changes in properties of PGM coated PET films with some innovative ideas of multilayer film formulation. Polyphenolics were extracted from Terminalia Catappa (Indian almond), Camellia sinensis (Green tea leaves) and Trachyspermumammi (Ajwain). The results showed that WVP was decreased from 1.0±0 to 0.12±0.03 g/in2/day (p < 0.01) in comparison with uncoated (1.3±0.07g/in2/day). Similarly, same trend was obtained for OTR (63.5±0.02 to 38.1±0.03g/in2/day) with respect to uncoated film (82 ± 3.5). This study provides important evidence that addition of PGM on PET films leads to improved films in terms of OTR and WVP with minor changes in optical properties.
摘要: For nanocomposite production, montmorillonite clays are often modified with organic surfactants to favor its intermixing with the polymer matrix. In the present study, Na+-montmorillonite (Na+-MMT) was subjected to organo-modification by cation exchange with protonated 12-aminolauric (ALA). The amount of the amino fatty acid surfactants loaded were 25, 50, 100 and 200% times the CEC of Na+-montmorillonite. X-ray diffraction (XRD) analysis revealed the interlayer spacing of the clay increased from 1.25 to 1.82 nm with increasing ALA content. The amino fatty acid chain were considered to be arranged into a flat monolayer structure at low surfactant loading, while they form a bilayered to a pseudotrilayered structure at high surfactant loading. Infrared spectroscopy (FTIR) revealed the alkylchains adopt a gauche conformation indicating their disordered state. Thermogravimetric analyses (TGA) revealed that the surfactant in the clay were thermally stable with Td ranging from 353 to 417°. The difference in the melting behavior of the pristine fatty amino fatty acids and confined fatty acids in the interlayer galleries of the clay were evaluated differential scanning calorimerty (DSC). The melting temperatures (Tm) of the amino fatty acid in the clay were intitially higher than the free amino fatty acid but decreased with increasing surfactant loading. The amino fatty acid may be tethered to the clay structure via ionic interaction or ion-dipole attraction. Scanning electron microscopy (SEM) revealed that the organo-clays have a disordered and flaky morphology. The present study suggests that 12ALA is a suitable intercalating agent for the production of organophilic clay materials.
摘要: An amoprphous and nanocrystalline ribbon is produced applying the technology of rapid molten metal quenching. The chemical composition of the alloy is required to contain elements ensuring the amorphous structure formation in the course of quenching. A great number of various chemical elements in amorphous and nanocrystalline alloys contribute to the complex process of the structure formation in the course of heat treatment of the amorphous precursor. After heat treatment, the structure of the soft magnetic material can remain amorphous or partially crystallized or nanocrystalline. The results of an investigation into the melts’ property of iron-based amorphous and nanocrystalline alloys are presented in the paper. The structure has been shown to influence mechanical properties of the material in preparing the melt before casting.