Advanced Materials Research Vols. 123-125

Abstract: Advanced oxidation processes (AOPs) are potential technologies for the treatment of wastewaters containing non-easily removable organic compounds. Isopropyl alcohol (IPA) is one of the groups with high toxicity and low biodegradability and is always interested by researchers. In this study, Chemical Vapor Deposition (CVD) was used to immobilize TiO2 photocatalyst on the titanium substrate plate and extra applied electric potential on the working electrode (anode) combined with a 365 nm UV lamp for irradiating the IPA wastewater to conduct a photoelectrocatalytic reaction. The experimental results showed, during the photoelectrocatalytic reaction, the extra applied electric potential could inhibit the recombination of the electron-hole pair and raise the overall removal efficiency. However, when the potential was more than 0.5 V, it would reduce the photoelectrocatalytic effect because of the recombination of electrons and holes. Moreover, adding different electrolyte solutions enhanced the different degree of effects of IPA removal. Among the electrolyte solutions added, sodium sulfate improved the photoelectrocatalytic effect most significantly.

Abstract: Dye-coupled polyhedral oligomeric silsesquioxane (POSS) were prepared and the coloured POSS particles were ultrasonically solution dispersed in poly(styrene-b-butadiene-b-styrene) (SBS). POSS molecules contained either isobutyl or phenyl groups to provide selective compatibility with either the soft (butadiene) or hard (styrene) phase within the block copolymer. The composition and thermal stability were characterised using thermogravimetry. Colour coordinates were measured. Tensile mechanical properties, creep and recovery were determined. Creep was modeled using the 4-element model of Maxwell and Kelvin-Voigt, while recovery correlated with the stretched-exponential function of Kohlrausch, Williams and Watts.

Abstract: The present work deals with the functionalization of graphene sheet and preparation of functionalized graphene/linier low density polyethylene (LLDPE) nanocomposites by solution-mix techniques. Dodecyl amine (DA) has been used for the surface modification of graphene oxide (GO) and hydrazine as reducing agent. Fourier transform infrared (FTIR) spectra exhibits the appearance of new peaks in the functionalized graphene (DA-G), which suggests the functionalization of graphene by DA. X-ray diffraction (XRD) analysis infers the formation of fully exfoliated DA-G/LLDPE nanocomposites. The tensile strength (TS) and elongation at break (EB) of the composites are higher in comparison to neat LLDPE. The nanocomposites with only 0.5 wt.% of DA-G content results in TS and EB to be 17% and 10% higher compared to neat LLDPE. TGA shows that the thermal stability of the DA-G/LLDPE nanocomposites is higher compared to pure matrix polymer.

Abstract: Chitosan and sodium alginate are two prominent biomaterials because they have some unique properties such as good biocompatible and biodegradable. In this study, sodium alginate was as swelling and moisture retention layer; Chitosan was antibacterial layer.Polylactic acid (PLA) blended in different weight ratios with low melting point polylactic acid (LMPLA) to fabricate nonwoven fabric which reinforced by needle punching and hot pressing. Afterward, chitosan/ sodium alginate compound solution were treated by UV light in order to form cross-linking. Then chitosan/ sodium alginate compound solution coated on the PLA nonwoven fabric to make PLA composite dressings. The mechanical properties of chitosan/ sodium alginate membrane and dressing were measured. The optimum parameters of chitosan/sodium alginate composite membrane was treated by UV light for five minutes and the volume ratio of chitosan (3 wt %) and sodium alginate (1 wt %) solution was 8:2. After we coated chitosan/sodium alginate solution on PLA nonwoven fabric, the Tensile strength, and tear strength were upgraded by 80 % and 98 %; its air permeability and flexibility length, however, dropped by 18 % and 60 %, respectively.

Abstract: The NiO-Cu composite films with various Cu contents of 0 – 18.17 at.% are deposited on glass substrate. An ultra high electrical resistivity (ρ) is obtained and cannot be detected by four point probe measurement when the Cu contents in the films are lower than 6.97 at.%. The ρ value is reduced significantly to 35.8 Ω-cm as Cu content is increased to 9.18 at.%, and it further decreases to 0.02 Ω-cm when the Cu content further increases to 18.17 at.%. The Hall measurement for all Cu-doped NiO films show p-type conduction. In addition, the transmittance of NiO films also decreases continuously from 96 % to 43 % as Cu content increases from 0 to 18.17 at.%. The XRD patterns of Cu-doped NiO films only appear NiO peaks and the crystallinity of NiO films becomes worse as Cu content is added to above 6.97 at.%. Large amount of lattice sites of Ni2+ ions in NiO crystalline are replaced by the Cu+ ions that leads to p-type conduction and result in the degradation of crystallinity for NiO-Cu composite films having higher Cu content.

Abstract: Porous materials were prepared by sintering using C as place holder and SiO2 as based, mixed with paraffin. Then Organic-inorganic Core-shell Particles were made by crushed. With the help of XRD and SEM, on the 60°C Study on Sulfate-Corrosion Resistance of cement Mixed with Organic-inorganic Core-shell of Preparation. The Organic-inorganic Core-shell Particles made by accounted of C 15% and heat preservation 4h in 920°C were the best. The results showed that when the content of Organic-inorganic Core-shell Particles was 15%, the Sulfate-Corrosion Resistance reached the climax.

Abstract: Nanocomposite films containing Au nanoparticles were fabricated by alternating adsorption of poly(diallydimethyl ammonium chloride) (PDDA) and HAuCl4 using layer-by-layer self-assembly technique and subsequent in situ electrochemical reduction of the AuCl4- ions. The composition and properties of the composite films were characterized by ultraviolet-visible spectroscopy (UV-vis), X-ray photoelectron spectroscopy (XPS), and cyclic voltammetry (CV).The UV-vis characteristic absorbances of PDDA and Au increase almost linearly with the number of bilayers, which suggests a progressive deposition with almost an equal amount of the PDDA and Au in each cycle. X-ray photoelectron spectroscopy further confirms the presence of the main components (such as PDDA and Au) of the nanocomposite films. Furthermore, the nanocomposite films also exhibit good electrocatalytic activity for the oxidation of ascorbic acid (AA), which may be used in electrochemical biosensors.

Abstract: Poly (lactic acid) (PLA), a biodegradable polyester, derived from renewable resources has been widely used in biomedical and packaging applications. However, the shortcomings for using PLA including its processing instability, low melt viscosity and low flexibility limited its applications. To overcome these shortcomings, poly (butylene adipate-co-terephthalate) (PBAT) was blended with PLA to improve ductility of PLA. However, PLA and PBAT are incompatible. Maleic anhydride grafted PLA (PLA-g-MA) was used to enhance the compatibility of the blends. Moreover, the blend of PLA and PBAT exhibited higher elongation at break but lower tensile strength and Young’s modulus than the pure PLA due to the addition of a ductile phase. Therefore, the addition of calcium carbonate (CaCO3) to PLA/PBAT blends led to achieve balanced properties of the blends. In this study, PLA/PBAT blends and PLA/PBAT/CaCO3 composites were prepared by an internal mixer. PLA-g-MA was as a compatibilizer. Mechanical properties and rheological properties of the blend and composites were investigated. In addition, morphologies of PLA/PBAT blend and their composites were observed by a scanning electron microscope (SEM). The incorporation of PBAT gave rise to remarkable improvement in elongation at break and impact strength of PLA. Tensile strength of PLA/PBAT blend was enhanced by adding PLA-g-MA. With increasing CaCO3 content, Young’s modulus of the composites increased while tensile strength and elongation at break decreased.

Abstract: Nanopowders of Cr and Al2O3 was fabricated from CrO3 and 2Al by high energy ball milling. Dense nanocrystalline Cr-Al2O3 composite was consolidated by pulsed current activated sintering (PCAS) method within 1 min from mechanically alloyed powders. Highly dense Cr-Al2O3 with relative density of up to 99% was produced under simultaneous application of a 80 MPa pressure and the pulsed current. The average grain size and mechanical properties of the composite were investigated.

Abstract: This paper presents the theoretical developments of an exact finite strip for the buckling and initial post-buckling analyses of symmetrically laminated composite plates. The so-called exact finite strip is developed based on the concept that it is effectively a plate. The present method, which is designated by the name Full-analytical Finite Strip Method in this paper, provides an efficient and extremely accurate buckling solution. In the development process, the Von-Karman’s equilibrium equation is solved exactly to obtain the buckling loads and the corresponding form of out-of-plane buckling deflection modes. The investigation of thin flat plate buckling behavior is then extended to an initial post-buckling study with the assumption that the deflected form immediately after the buckling is the same as that obtained for the buckling. The post-buckling study is effectively a single-term analysis, which is attempted by utilizing the so-called semi-energy method. In this method, the Von-Karman’s compatibility equation governing the behavior of symmetrically laminated composite plates is used together with a consideration of the total strain energy of the plate. Through the solution of the compatibility equation, the in-plane displacement functions are developed in terms of the unknown coefficient in the assumed out-of-plane deflection function. These in-plane and out-of-plane deflected functions are then substituted in the total strain energy expressions and the theorem of minimum total potential energy is applied to solve for the unknown coefficient. The developed method is subsequently applied to analyze the initial post-buckling behavior of some representative thin flat plates for which the results are also obtained through the application of a semi-analytical finite strip method. Through the comparison of the results and the appropriate discussion, the knowledge of the level of capability of the developed method is significantly promoted.