Advanced Materials Research Vol. 486

Abstract: Oven ageing is a set of procedure to simulate the accelerated effects of ageing on pavements structures. In this study, the effect of long-term oven ageing on porous asphalt mixture made with SBS modified binder was investigated. The resilient modulus, water permeability and air voids test results were the performance indicators used to evaluate the effects of ageing. The test results showed that, the resilient modulus of long term aged specimens was higher than those of unaged specimens. From the permeability test results, unaged SBS mixes exhibit lower coefficient permeability compared to the corresponding long-term oven age specimens. Most likely, ageing caused binder hardening, making the mix more difficult to compact and hence exhibited more continuous voids which in turn lead to higher permeability. In addition, the coefficient of permeability decreases as the binder content increased.

Abstract: This research aimed to study the dyeing properties on the PLA and silk yarns of the natural dyes obtained from various materials, viz. marigold petals (Tagetes erecta L.), rhubarb rhizomes (Radix et Rhizoma Rhei), garcinia barks (Garcinia Dulcis Kurz), turmeric rhizomes (Curcuma Longa Linn.), sappan barks (Caesalpinia sappan Linn.) and catechu barks (Acacia catechu Willd.). The color properties of the dyed yarns was determined and compared. The results observed the different color properties (L*, a* and b* values) and a shift of λ_max of the dyes on the PLA and silk yarns. This change in color properties of each natural dye was expected to be affected by the types of substrate (textile fiber) and also the chemical nature of the natural dyes. The study of the build-up properties indicated that the turmeric dye is the only natural dye which showed an outstanding performance on PLA and silk. A high degree of color yield of turmeric dye was obtained on both yarns, whereas a poor build-up was observed for the rest of the dyes.

Abstract: Using the urea intercalated montmorillonite (Urea/MMT) as the precursor, a novel nanocomposite biurea intercalated montmorillonite (Biurea/MMT) was prepared via the in-situ synthesis process through the introduction of hydrazine hydrate (HY). The resulted nanocomposites were characterized by using techniques such as XRD, FTIR, solid state NMR as well as thermal analyses, etc. The influence of the concentration of the HY on the products was also investigated. The XRD results showed the variation of the interlayer spacing of MMT from 1.51 nm to 1.71 nm for Urea/MMT. When the concentration of HY was low, the substitution of urea by HY was taken place which resulted in the decrease of the interlayer distance to 1.27nm. When the concentration increased to greater than 40%, the new phase with basal spacing of 1.75 nm was dominated. It indicated that a novel nanocomposite was synthesized in-situ. The solid state NMR results confirmed the in-situ formation of Biurea/MMT in which the chemical shifts of ¹³C and ¹⁵N of the intercalated biurea were slightly different from the bulk biurea. The intercalated biurea decomposed easily than those bulk powders due to the highly dispersion in the interlayer space of MMT.

Abstract: To evaluate the combined cytotoxicity effects between functionalized multi-walled carbon nanotubes (MWCNTs-PC) and cigarette smoke solution (CSS), 16-HBE cells was used as the target cells and exposed to various concentrations of MWCNTs-PC and CSS combined together. Cell proliferation, cell apoptosis, DNA damage were detected by Methyl thiazolyl tetrazolium (MTT) assay, flow cytometry, single cell gel electrophoresis assay (SCGE) and micronuclear assay, respectively. The dose-dependent cytotoxic and genetic effects of CSS were found in our study. However, compared to the control group, the MWCNTs-PC exposed groups showed no significant difference in all concentration, with or without CSS exposure. It suggests that the MWCNTs-PC did not influence cellular toxicity or DNA damage of CSS on 16-HBE cells. No combined cytotoxic effects between NWCNTs-PC and CSS were found in this study.

Abstract: In this paper, the thermal oxidation behavior of TiAlCrSiN and AlCrTiN films coated on hastelloyX substrate, typically used for fuel nozzle in gas turbine engine application, have been studied. The thermal oxidation behavior at 950, 1050 and 1150 °C in controlled atmosphere were investigated. The surface appearance, microstructure, chemical composition and adhesion of films were investigated. The thermal oxidations were observed in all testing conditions showing oxide films at the surface with thicker oxide film at higher temperature. However, spalling of oxide scales was found in both coated and uncoated specimens at 1150°C suggesting the maximum working temperature of < 1150 °C for turbine engine applications. The critical loads corresponding to the full delamination of the thermal oxidation coated specimens were found to be higher than the non-thermal oxidation specimens. The effect of thermal oxidation on damage patterns during scratch tests, i.e. less chipping and cracking for thermal oxidation specimen, were also observed.

Abstract: The effects of four impact modifiers: natural rubber (NR), poly (cis-1,4-isoprene) (IR), poly (acrylonitrile-co-butadiene) (NBR) and poly (ethylene-co-vinyl acetate) (PEVA), on the morphology, thermal and tensile properties by solution blending of poly (lactic acid) and 5 and 10 wt% impact modifier were investigated. Results showed that Youngs modulus and T.S. at break decreased in all PLA/impact modifier blends. In addition, Youngs modulus in all blends and T.S. at break in PLA/NR, PLA/IR and PLA/NBR blends was not significantly affected by the type and content of impact modifiers in the blends, but T.S. at break in PLA/PEVA blends was decreased by increasing the PVEA content from 5 wt% to 10 wt%. By contrast, the elongation at break significantly increased in all PLA/impact modifier blends and only PLA/NBR blends was affected by the content of impact modifier. Finally, the increase in ductility of all PLA/impact modifier blends confirmed the toughening capability of all impact modifiers. Thus, it is evident from tensile properties obtained indicated that PLA/impact modifier blends exhibit greater flexibility with all impact modifiers. Phase separation morphology of dispersion of impact modifier in PLA matrix indicating poor interfacial adhesion was observed. T_g and T_m of PLA/impact modifier blends exhibited almost the same as pure PLA, this suggested that there was no molecular interaction between PLA and impact modifiers, therefore, the PLA/impact modifier blends were immiscible.

Abstract: FePt thin films with perpendicular c-axis orientation have potential for application as magnetic media for data storage, In order to be used as perpendicular magnetic storage media,The chemically synthesized cubic FePt nanoparticles is easier to assembed oriented nanoarray, especially the cubic FePt nanoparticles with shape anisotropy is expected to trigger magnetic anisotropy.In this study we provide a simple method to synthesize single crystalline FePt nanoparticles with cubic shapes.The key factor to formation of cubic morphology is using Mo (Co)₆ as a reducing agent. As-synthesized FePt nanocubes with size that are close to 7-10nm The self-assembly FePt nanocubes are chemically disordered with face centre cubic (fcc) structure where as after annealing these particles changed to face centre tetragonal (fct) ordered structure. The phase analysis, structure, and magnetic properties were determined by X-ray diffraction (XRD), High resolution transmission electron microscope (HRTEM), Scanning electron microscope (SEM) and vibrating sample magnetometer (VSM) techniques.

Abstract: Multiferroic La-doped Bi_1-xLa_xFeO₃ thin films were prepared on conductive indium tin oxide (ITO)/glass substrates through a simple sol-gel process. The crystal structure of La-doped Bi_1-xLa_xFeO₃ thin films annealed at different temperature was determined to be rhombohedral of R3m space and free of secondary phases. The grain size of La-doped BiFeO₃ thin films tends to become larger and the grain boundary is gradually ambiguous compared to pure BiFeO₃. The double remanent polarization 2Pr of Bi_0.9La_0.1FeO₃ thin film annealed at 500°C is 6.66 µC/cm², which is slightly improved than that of pure BiFeO₃ thin film. With the increase of La-doping levels, the dielectric constant is increased and the dielectric loss is obviously decreased.

Abstract: The aim of the present study is to investigate the efficacy of nanobiphasic calcium phosphate (nanoBCP) bioceramic in the treatment of periodontal osseous defects. Alveolar bone defects were surgically created bilaterally at the buccal aspects of four second premolars in two beagle dogs. After root leveling, nanoBCP was randomly filled in one defect and nothing was put into the contralateral defect as negative controls. Bioglass was randomly filled in one of left defect as positive controls and nothing was put into the contralateral defect as negative controls. Dogs were killed at the 12th week. Histological observations were processed through a light microscopy. The results reveal that a great amount of functional periodontal fissures formed in the defects in the nanoBCP groups and bioglass groups while no new bone formed in the control groups at all. In this study, nanoBCP has proven to work well as a biocompatible and bioactive material to promote periodontal regeneration effectively.

Abstract: Sulfonation of waste high impact polystyrene from commercial food packaging was studied in this work. The obtained sulfonated polystyrene was characterized by using Fourier Transformed Infrared spectroscopy. Effect of the reaction time and temperature on the degree of sulfonation was observed. Waste high impact polystyrene resin from food packaging showed degree of sulfonation at 72.2% level. This degree of sulfonation was lower than the same reaction on pure polystyrene and pure high impact polystyrene, which showed degree of sulfonation at 97.7% and 85.2% level, respectively. Simulation of flocculation test using kaolin suspension was conducted to evaluate the application of sulfonated polystyrene as a polymeric flocculant.