Papers by Keyword: Chemical Structure

Abstract: In this study, the water hyacinth was used as a reinforcement of green composites. The chemicals for treatment of water hyacinth were solutions of alkaline, soap and water to determine water absorption. The chemical treated process of the water hyacinth fibers had important influences to the chemical structures and mechanical properties of the green composites. Micrographs analyses of scanning electron microscope (SEM) showed obviously roughness of fiber surface after the chemical treatment as well as arrangement of structures among the water hyacinth fibers. Similarly, the results of analysis by Fourier transform infrared spectroscopy (FT-IR) showed that most of the intensity of the absorbed peaks was decreased markedly at the wavenumbers of 1375 cm^-1 and 1542 cm^-1. These are related to lignin extraction with alkaline solution, effectively. In particular, the compressive strength of the water hyacinth/roving composite has high value approximately to that of fiberglass composites (unfriendly composites). The water hyacinth/roving composites have significantly improvements in flexural and compressive strengths and this proves that the environmentally friendly composite responded to high requirements for various applications.

Abstract: SBS modified bitumen membrane used in underground engineering and coastal buildings would be corroded by chemical media, which greatly influenced the service life of waterproofing membranes. In this paper, SBS modified bitumen (MB), SBS modified bitumen with stone powder (MBS) and SBS modified bitumen with talc powder (MBT) were corroded by acidic, alkaline, and saline solutions for different time to evaluated the effect of chemical corrosion on the properties of SBS modified bitumen waterproofing membrane. The mass change ratio, low temperature flexibility, softening point and viscosity of SBS modified bitumen were investigated, and Fourier infrared spectroscopy (FTIR) was used to analyze the chemical structural changes of SBS modified bitumen after corrosion. The results showed that the mass of SBS modified bitumen decreased, the low temperature performance decreased, and the softening point increased after corrosion by chemical solutions. The influence of acidic and saline solution was more serious on SBS modified bitumen with fillers, and the properties of MBS has greatest degradation in acidic solution compared with MB and MBT. In alkaline solution, the properties degradation of MBT and MBS was less than that of MB, which indicated that filler could inhibit the alkaline corrosion of SBS modified bitumen. FTIR showed that C=C decreased more in acidic solution, while C=O and S=O of SBS modified bitumen increased significantly after alkaline solution corrosion, which indicated that acidic solution corrosion easily caused SBS degradation, while alkaline solution corrosion was easy to oxidize SBS and bitumen.

Abstract: Polymer electrolyte membranes (PEM) with good properties are essential for the improvement of electrochemical operations. The increase in properties of polymer electrolyte membranes will develop the performance of polymer electrolyte membranes in the fuel cells. The importance of polymer electrolyte membranes is increasing recently due to its activity and simplicity in energy associated applications like automobiles and various portable applications. PEM has various properties like proton conductivity, chemical stability, mechanical properties, thermal stability and so on. These properties are enhanced and influenced by various factors like morphology, the molecular weight of the membranes, chemical structures, cross linkages etc. The present chapter attempts to summarize about the properties of polymer electrolyte membrane involved in the different types of electrochemical utilizations. Keywords: Polymer electrolyte membrane, fuel cells, morphology, proton conductivity, chemical structure.

Abstract: Elucidation of the chemical structure changes that take place of high density polyethylene (HDPE) used as rotational packaging case by attenuated total reflection infrared spectroscopy (ATR-FTIR), when natural aging of Lasa Tibet and xenon aging. The variations of carbonyl index (CI), hydroxyl index (HI), branching degree (N) and crystallinity (Xc) have been studied from qualitative and quantitative. Finally, the correlations between natural and xenon aging have been closely followed. It found that the oxidation and growth of unsaturated compounds play a leading role in the natural aging progress, but the polymeric chain scission is weak effect. However, the samples show a slower growth of unsaturated compounds and a sharp increase in polymeric chain scission after xenon aging. The CI, HI and N increased generally in a line fashion after natural and xenon aging while the Xc changes little.

Abstract: Fourier transform infrared spectroscopy was used to investigate the chemical structure of down fibers in this paper. Contact angle was calculated to determine the wetting property of down. Experiments demonstrated that the surface chemical structure affected the fiber wetting property strongly. The surface substance by FTIR was forecast to be the mixture of sterol and triphosphate ester. After Soxhlet-extracted the fibers contact angle increased greatly.

Abstract: The paper presents the observation of the influences on the features of selected chrome creep-resisting steel concrete parts from material chemical structure, through the influence of heat treatment and by this also the influence of microstructure on the resulting operational features of selected steels. This article has shown results of project VEGA No 1/3173.

Abstract: Food coloring pollution is most widely occurred in food safety affairs in our country. The abused food additives and illegal ingredients belong to industrial dyes or chemical bleaching agents, which have chemical pollutions to the food and affect health. This paper introduces the compositions, structures, and industrial use of these illegal ingredients and the possibly illegal ingredient-added kinds of food as well as the harms done to body health.

Abstract: Chemical structure and liquid crystal behavior of mesogenic monomer(Trans, trans)-4-propyl-4’-vinyl- bicyclohexane(3HHV) with platelet texture of a blue phase and mesogenic monomer(Trans, trans)-4-propyl-4’-propenyl –bicyclohexane(4HHV) with cholesteric phase were studied. The chemical structure of mesogenic monomers were determined by Fourier transform infrared spectroscopy, and Hydrogen-nuclear magnetic resonance spectra. Liquid crystal behavior of mesogenic monomers were analyzed by polarizing optical microscopy and X-ray diffraction. Thermal properties of mesogenic monomers were researched by differential scanning calorimetry. The results were that: 3HHV showed the platelet texture of a blue phase was considerably different from single color texture of blue phase we always refer to, and assuredly belong to a new kind of blue phase liquid crystal. These two kinds of cyclohexane liquid crystal monomer also showed good thermal stability.

Abstract: Reactive interface combination agent (RIC) was synthesized by using reaction mixture technique starting from polypropylene（PP）, ethylene-propylene or butadiene-styrene elastomer, epoxy compound and monomer-assisted in the presence of a free radical initiator. The chemical structure of the RICs and the effects of change in the ratio of raw material during its preparation on constitute and structure was investigated using fractional extraction and infrared spectroscopy. The prepared RICs consisted of unreacted PP and/or elastomers, homo-and/or copolymerization of monomer, and graft copolymer of PP and elastomers, and crosslinked copolymer of PP and/or elastomers in conjunction with polymer bridge chains derived from monomer.

Abstract: In order to reduce CO₂ emissions, the cement industry has developed a new class cements. The Calcium-Silicate-Hydrates (CSH) that form are generally characterized by a low stoichiometric ratio for CaO and SiO₂. This low C/S ratio affects the C-S-H layer structure and has a significant effect on the mechanical properties. This work exploits a novel statistical nanoindentation technique (SNT) to study the effect of the C/S ratio on the mechanical properties of synthetic CSH. Different CSH types were prepared by varying the C/S ratio of the starting materials. After undertaking a grid nanoindentation approach for each sample, the statistical analysis allowed extracting the mechanical properties, such as elastic modulus, hardness and creep. The results of this preliminary work shed new light on the implications of C-S-H stoichiometry on mechanical properties.