Advanced Materials Research Vol. 1096

Abstract: Carboxylic multi-walled carbon nanotubes (MWCNTs-COOH) were modified by using ethylene diamine (EDA) to prepare amino-modified multi-walled carbon nanotubes (MWCNTs-NH₂). The chemical structure of MWCNTs-NH₂ was characterized by FT-IR, Raman spectroscopy, X-ray diffraction (XRD) test, TG analysis and elemental analysis. The results show that MWCNTs-COOH was effectively modified by EDA. Key words: MWCNTs-COOH; ethylene diamine; chemical modification; elemental analysis

Abstract: Polyvinylidene fluoride (PVDF)/PEG-POSS hybrid membrane was prepared by immersion phase separation process. The hybrid membranes were characterized by pure water flux, retention ratio to BSA, contact angle, shrinkage ratio and scanning electron microscopy (SEM). The hydrophilicity of the membrane was improved. The contact angles decreases from 82.2°to 76.3°. The shrinkage ratio decreases and the pure water flux increased when 1.0% POSS was used. Keywords: polyvinylidene fluoride (PVDF); PEG-POSS; hybrid membrane; hydrophilicity

Abstract: In this study, there were four content of jute fibers were added into cement-based mortar to improve their mechanical properties. Results obtained have shown that jute fibers can effectively improve the mechanical properties of cement-based composites. When the jute fiber of 10mm after alkali treatment, the compressive strength, flexural strength, impact strength of fiber-reinforced cement-based composite materials were better than the pure mortar. When the jute fiber of 19mm after alkali treatment, the results showed that the mechanical properties were best under 1.2 Kg/m³ fiber content.

Abstract: A series of castor oil-based polyurethane (PU)/poly (methyl methacrylate-butyl methacrylate-styrene) (PA) grafted interpenetrating polymer networks (IPNs) were prepared. The effect of composition of the IPNs on the damping, thermal and mechanical properties were studied systematically. PU/PA (60:40, weight ratio) IPNs with methyl methacrylate/butyl methacrylate/styrene (MMA/BMA/St = 80/10/10, weight ratio). In the paper castor oil (CO) was used as PU’s branch units, the damping properties affected by the branch units ratio (ρ) were studied. Mechanical tests showed the tensile strength of the IPNs was improved after increasing the ρ value and PA content. The thermal stability was improved by incorporating heterocyclic imide rings into the PU molecular chains using isocyanate reacting with pyromellitic dianhydride (PMDA). It was found that the IPN composition with ρ value = 0.2 and PU/PA = 60:40 would be useful as structural damping materials, having tanδ values higher than 0.3 for a temperature range of 102°C (5.0-106.9°C).

Abstract: The effect of Poly (ionic liquid) (PIL) on the crystallization of polylactide (PLA) has been investigated by means of differential scanning calorimetry. The nonisothermal crystallization result showed that PIL enhanced the crystallization of PLA. The Avrami method was used to describe the isothermal crystallization behavior of PLA/PIL composites. The Avrami exponent (n) revealed that the PIL accelerated PLA crystallization through heterogeneous nucleation.

Abstract: Polydimethylsiloxane (PDMS) pervaporation (PV) membranes are promising for the recovery of aromatic compounds in water. The novel oleyl alcohol-modified PDMS membranes were prepared using n-heptane as solvent, tetraethyl orthosilicate (TEOS) as crosslinker, di-n-butyltin dilaurate (DBTL) as catalyst and oleyl alcohol as organic modifier. The PV performances were investigated for separating phenol/water mixtures at different temperatures. The results showed that the oleyl alcohol-modified PDMS membranes had better selectivity than those without oleyl alcohol. For 0.50 wt% phenol in feed mixture at 80 °C, these membranes had a flux of 0.115 kg m^-2 h^-1 and separation factor of 8.77.

Abstract: Dye-sensitized solar cells are attracted much interest in the fields of clean energy. In this work, a novel ruthenium terpyridine dimeric complex (N749 dimer) was designed and synthesized through the coordination of 4,4',4"-tricarboxy-2,2':6',2"-terpyridine with ruthenium trichloride, bridging with 4,4'-bipyridine and basic hydrolysis. The calculated and experimental UV-vis absorption spectrums for N749 dimer were compared to those of the commercial black dye N749. The results showed that N749 dimer exhibits wider spectrum absorption range and higher molar extinction coefficient. Dye sensitized solar cells were fabricated based on the N749 dimer. The cell efficiency could reach 2.9% battery efficiency under simulated sunlight irradiation of 100 mW/cm² power AM1.5G ruthenium. The results provide a new direction for designing the ruthenium dyes.

Abstract: Surface enhanced Raman scattering (SERS) has been proved to be a highly sensitive method to detect organic molecules at very low concentrations. In recent years, many researchers have reported that 1-dimension semiconductor nanomaterials assembled noble metal nanoparticles can get a strong SERS effect. In this paper, we succeeded to synthesize TiO₂ nanorod thin films on fluorine-doped tin oxide (FTO) glass with hydrothermal synthesis which were able to be used as SERS substrates. Gold nanoparticles were assembled to TiO₂ nanorod thin films using the physical sputtering method and the citrate reduction method, respectively. The field emission scanning electron microscope (FESEM) images show that the later method could achieve the more desirable and uniform distribution of gold nanoparticles. Rhodamine 6G (R6G) was chosen as the probe molecule to study the SERS performance of our novel SERS substrates. Raman scattering measurement proved that the substrates were able to enhance Raman signals by several orders of magnitude and could be applied to biochemical detection. The whole fabrication process was facile and cost-effective, and the SERS activity and reproducibility of the substrates were pretty good.

Abstract: Sr₃Al₂O₆:Eu³⁺ red phosphor was synthesized by co-precipitation and investigated their crystal structures and luminescent properties in detail. EuCl₃ was used as rare earth sources to replace Eu₂O₃, which saving cost significantly. X-ray diffraction(XRD) and scanning electron microscopy (SEM) result indicated that the as-prepared phosphors was calcined at 1150 ^oC for 2h crystalized in cubic phase with space group of Pa-3 and uniform morphology. The average diameter of the phosphors were 1.8um. Excitation spectrum and emission spectrum results shows when Boric acid was added 3wt% and Eu³⁺ was added x=0.04((Sr_1-xEu_x)₃Al₂O₆), the red emission of Eu³⁺ centers was shown at peak of 611nm under near ultraviolet excitation with wavelength of 393nm. The emission spectrum was line spectrum. Luminous intensity achieved the optimum. The thermal quenching experiments indicated that it had thermal stability in the temperature of 20 ^oC -80 ^oC.

Abstract: The electrochromic properties of an electrochemical polymerized composite consisted of poly (3,4-ethylenedioxythiophene) doped with fluorescent yellow dye (PEDOT-FY) with different polymerization time are reported. The structures of PEDOT-FY were characterized via cycle voltammograms and spectroelectrochemistry. The PEDOT-FY films can appears orange-yellow and purple in the neutral state, and yellow-green and deep green in the oxidized state. Polymerizing for 6 min, the PEDOT-FY film comes out a new pair of oxidative and reductive peaks around 0.3V and-0.15V. In addition, the PEDOT-FY films also have short response times. It is shown that acid dye doping is an effective method to broaden the color change range of the electrochromic mateials.