Advanced Materials Research Vols. 239-242

Abstract: As the phase change material, paraffin microcapsule thermal performance of infrared camouflage coatings were studied, With blank contrastive experiments and changing the content of paraffin microcapsule, it is studied the thermal performance of infrared camouflage coatings. This study has shown that there has a high performance of storing and retaining the caloric of the infrared camouflage coatings, with the temperature 7°C. The content of paraffin microcapsule has a great effect on the infrared thermal performance in coating, the higher content of paraffin microcapsule, the better thermal performance of storing and retaining the caloric. The difference of the temperature can reach the highest value at 7°C between 35% or 40% and 25% paraffin microcapsule in the coatings.

Abstract: Iron ore reduction and carbon deposition under H₂-CO mixtures were investigated by using the non-isothermal method. Iron ore in three different configurations were used in this work: pellet, coarse granularity particles and fine granularity particles. The reduced samples were characterized by using X-ray diffraction (XRD), scanning electron microscopy (SEM) and accelerated surface area and porosimetry System(ASAP 2020M+C). In pure CO, the carbon deposition increases with decreasing of the sample size. In H₂-CO mixtures, the rate of carbon deposition is accelerated dramatically. Morphologies of samples treated in different reducing ambinent were investigated. Specific surface area of the treated sample increases with higher level of carbon deposition.

Abstract: The corrosion related electro-magnetic signature is easily detected by modern sensor deployed in mine and other signal measurement system, so the importance of reducing is rapidly growing today. The eliminating effect of shaft frequency signature by shaft insulating technique, passive grounding technique and active grounding technique was comparatively studied by physical scale model (PSM), and their influence on static electromagnetic signature was also studied by boundary element method (BEM). Simulation results suggested that active shaft grounding technique was the best way for eliminating shaft frequency signature, but static electromagnetic signature was stronger than that when the shaft was insulated from hull.

Abstract: A series of novel liquid crystal were synthesized with alkyloxyben- zimidoylbenzoic acid (CnABOH) and poly(4-binylpridind) (PVP) through hydrogen bond self-assemble between carboxyl groups of alkyloxybenzimidoylbenzoic and nitrogen of PVP. PVP was used as a hydrogen bond acceptor polymer. The CnABOH (n is the number of carbon atom) had been used as H-bond donor. The existence of H-bond was confirmed used FTIR spectroscopy. Optical microscopy was used to investigate liquid crystalline behaviors. The mesophases of the complexes (PVP-CnABOH) were obviously different from LC behaviors of the CnABOH. With increasing length of terminal group, the melting temperature reduced and the temperature range of the LC mesophase increased. For instance, while the number of carbon atom increased from 3 to 8, the melting temperature reduced from 180°C to 156°C and the range of LC mesophase increased from 36°C to 84°C.

Abstract: The thermal decomposition of wood treated with a series of silicates was characterized by thermogravimetric (TG) analysis, differential thermogravimetry (DTG), and thermogravimetry–mass spectrometry (TG–MS) analysis. The addition of these chemicals caused a decrease in the decomposition temperature, a reduction in weight loss, and an increase in the amount of char produced. The results showed that ion current intensity and ion peak area of the typical representatives of incombustible ion such as m/z = 18 and 44 MS signals were increased by the flame retardants but the inflammable ion such as m/z =12 and 28 MS signals were decreased at the meantime, which indicate that the flame retardants can significantly enhances the dehydration and inhibits the deploymerisation reaction of wood.

Abstract: During the last few years increasing attention has been paid to the exploitation of hemicelluloses as biopolymer resources because they are available in very large amounts in organic wasters from renewable forest and agricultural biomass. The efficient method to prepare the cationic biopolymers based on xylan-rich hemicelluloses from agricultural biomass has been developed in this paper. These biopolymers with cationic functional groups, having many good properties such as solubility, bio-degradation, cationic or ampholytic polymers, were synthesized by the chemical modification of sugarcane bagasse xylan-rich hemicelluloses with CHMAC and preferably with ETA in different media. These biopolymers based on xylan-rich hemicelluloses with the degree of substitution (DS) up to 0.55 could be obtained by varying the molar ratio of ETA or CHMAC to anhydroxylose units in hemicelluloses from 0.5 to 3.0. ¹³C NMR confirmed that cationic groups were grafted onto the backbone of hemicelluloses. In addition, their applications in papermaking as dry strengthen agent were investigated. It was found that these biopolymers could obviously improve the physical properties of hand sheets formed from old corrugated container pulp fibres. These results mentioned above highlight the remarkable potential for using the hemicelluloses-based biopolymers as wet end additives in papermaking.

Abstract: Ce³⁺ or Tb³⁺ ions activated lithium-barium-gadolinium-aluminosilicate oxyfluoride glasses have been prepared. The transmission, emission and excitation spectra were measured. It has been found that those Ce³⁺ or Tb³⁺-doped lithium-barium-gadolinium-aluminosilicate oxyfluoride glasses exhibit good UV-excited luminescence. Energy transfer process from Gd³⁺ ion to Ce³⁺ or Tb³⁺ ion is indicated.

Abstract: Effect of strain velocity on the refinement of severe plastic deformation structure of ECA pressed pure copper was studied using transmission electron microscope(TEM) and electron back-scattered diffraction (EBSD) analysis. Formation mechanism of unltra-fine grain with high angle boundary was discussed. It was found that exceedingly fast stain rate can significantly increase the fraction of high angle boundary, up to 76%, and make grain refine further, up to 0.23μm.

Abstract: Tamarind gum was obtained from the seeds of Tamarindus indica. It was rich in polysaccharide (79.96%) and protein (13.46%) contents. In this work, the dynamic viscoelastic properties of tamarind gum aqueous solutions were investigated with a Haake Rheometer RS75 as a function of gum concentration and temperature. Four types of sample solution systems: a dilute solution, a concentrated solution, a weak gelled system, and a gelled like system were observed. The effect of concentration showed that the typical shape of the mechanical spectra for the dilute solution occurred for 2.30 wt% and the gelled like behaviour arose for the higher concentration (≥7.05 wt%) as measured at 25°C. While the effect of temperature on the dynamic viscoelastic properties of tamarind gum solution (6.91wt%) showed that the gum solution behaved the weak gelled system (25°C) and subsequently gelled like system (≥30°C).

Abstract: We have found that La substitutions can improve the magnetic properties of the strontium ferrite films without reducing the saturation magnetization. In this work, SrCe_xFe_12-xO₁₉ nanocrystalline films (x=0, 0.2…0.8) with high coercivity were synthesized and deposited on SiO₂ substrate by sol-gel method and sintering at 900 OC for 2h. The films were characterized by various experimental techniques including X-ray diffraction analysis (XRD), Field Emission Scanning Electron Microscope (FESEM), Vibrating Sample Magnetometry (VSM) and vector network analyzer. The results show that with the increasing content of cerium the coercivity of the films improves greatly and reach the maximum 6678.78 Oe at x=0.2, which is larger than La-doped strontium ferrite films, however the saturation magnetization decreases a lot. In the frequency range of 11.5-12 GHz the electromagnetic properties of the Ce-doped strontium ferrite films are better than La-doped at x=0.2.