Liren Xiao

Electrospun nitrogen and carbon co-doped porous TiO2 nanofibers with high visible light photocatalytic activity

Nitrogen and carbon co-doped porous TiO2 nanofibers (NCPTNs) were exploited by a combination of electrospinning and controlled calcination technologies. Polyvinyl pyrrolidone (PVP) was employed both as a template and as a nitrogen and carbon source. It is clear that the prepared NCPTNs exhibit high absorption in the visible light region, suggesting that the co-doping of nitrogen and carbon onto TiO2 not only leads to a shift of the absorption edge to lower energy by inducing new band levels, but also creates large amounts of single-electron-trapped oxygen vacancy. Besides, the porous structure and high surface area provide large active points for the photodecomposition reaction of methylene blue. Moreover, the NCPTN obtained in 5 wt% urea shows the highest photocatalytic activity for methylene blue decomposition under the visible light irradiation.

Non-isothermal crystallization kinetics of poly(ethylene terephthalate)/mica composites

The non-isothermal crystallization kinetics of pure poly(ethylene terephthalate) (PET), PET/mica and PET/TiO2-coated mica composites were investigated by differential scanning calorimetry with different theoretical models, including the modified Avrami method, Ozawa method and Mo method. The activation energies of non-isothermal crystallization were calculated by Kissinger method and Flynn–Wall–Ozawa method. The results show that the modified Avrami equation and Ozawa theory fail to describe the non-isothermal crystallization behavior of all composites, while the Mo model fits the experiment data fair well. It is also found that the mica and TiO2-coated mica could act as heterogeneous nucleating agent and accelerate the crystallization rates of PET, and the effect of TiO2-coated mica is stronger than that of mica. The result is further reinforced by calculating the effective activation energy of the non-isothermal crystallization process for all composites using the Kissinger method and the Flynn–Wall–Ozawa method.

Influence of Reactive Compatibilizer on the Morphology, Rheological, and Mechanical Properties of Recycled Poly(Ethylene Terephthalate)/Polyamide 6 Blends

Recycled poly(ethylene terephthalate) (R-PET) and virgin polyamide 6 (PA6) blends compatibilized with glycidyl methacrylate grafted poly(ethylene-octene) (POE-g-GMA) were melt blended. The morphological, rheological and mechanical properties of the prepared blends were investigated by scanning electron microscopy, rheology, and an electromechanical testing instrument, respectively. All of the blends showed a droplet dispersion type morphology, and the PA6 particle size decreased with increase in the POE-g-GMA concentration. The storage modulus (G′), loss modulus (G′′), and complex viscosity (η*) of the blends significantly increased at low frequency with the addition of POE-g-GMA. In addition, ‘‘Cole-Cole’’ plots showed that the elasticity of the blends was also increased by raising the compatibilizer dosage. It was also found that 10 wt% of POE-g-GMA caused 88.46 and 171.05% increments in Charpy impact strength and elongation at break with only a 21.66% decrement in tensile strength.

The structure and properties of long-chain branching poly(trimethylene terephthalate)

A multifunctional epoxide chain extender (ADR4370S) was used to increase the molecular weight of poly(trimethylene terephthalate) (PTT). And the effects of ADR4370S content on the molecular structure, melt viscosity, and rheological properties of PTT were studied. It is found that a star-type topological structure is formed in PTT by introduction of ADR4370S, and the balance torque, intrinsic viscosity, and molecular weight are increased by increasing ADR4370S dosage. The rheological measurement results show that the elastic modulus, complex viscosity, and shear thinning behavior of long-chain branching PTT are increased with the concentration of ADR4370S. The presence of broadened relaxation time spectrum and a long relaxation time mode for the PTT with 1.50 wt% ADR4370S demonstrate that the cross-linking reaction occurs, and the gel forms in the PTT system.

Y 2 O 3 :Eu 3+ luminescent nanofibers from electrospun PVA/Y(NO 3 ) 3 /Eu(NO 3 ) 3 composite fibers

poly (vinyl alcohol) (PVA)/Yttrium (III) nitrate /Europium (III) nitrate composite nanofibers were prepared using electrospinning technique. The electrospun nanofibers were used as precursors to fabricate Y 2 O 3 :Eu3+ luminescent nanofibers by calcination at 800 °C. The calcinated fibers exhibited gear-like morphology with a diameter range of 54–96 nm. FTIR spectra and XRD pattern indicated that the organic component of the composite materials was completely burned out and the single-phase Y 2 O 3 was synthesized at 800 °C. Photoluminescence spectra showed that the prepared Y 2 O 3 :Eu3+ luminescent nanofibers possessed excellent luminescence characteristics and could be applied as an appreciable luminescent material.

S-Doped Sb 2 O 3 Nanocrystal: an Efficient Visible-Light Catalyst for Organic Degradation

The S-doped Sb2O3 nanocrystals were successfully synthesized using SbCl3 and thioacetamide (TAA) as precursors via a facile one-step hydrothermal method. The effects of pH of the precursor reaction solution on the product composition and property were determined. The results indicated that the doping amount of S could be tuned by adjusting the pH of the precursor solution. Furthermore, the S entered into the interstitial site of Sb2O3 crystals as S2−, which broadened the absorption wavelength range of the Sb2O3 nanocrystal. The S-doped Sb2O3 exhibited an excellent visible-light-driven photocatalytic activity in the decomposition of methyl orange and 4-phenylazophenol. Last, a possible photocatalytic mechanism of the S-doped Sb2O3 under visible light irradiation was proposed.

Effect of OMMT on Morphology and Property of PTT/ASA Blends

Nanocomposites of poly(trimethylene-terephthalate)/poly(acrylonitrile-styrene-acrylate)/organic montmorillonite(PTT/ASA/OMMT) were prepared by means of melt-blending intercalation. The effect of OMMT contents on the phase morphology, crystallization behavior, rheological- and mechanicalproperties were investigated. The results show that the size of dispersed phases decreases with increasing OMMT content. The crystallization peak shifts to high temperature and melting peak moves to low temperature owing to the heterogeneous nucleation of OMMT. The exfoliated OMMT is located in the PTT matrix and at interface of PTT/ASA phases The rheological measurements show that the elastic modulus and complex viscosity increase with increasing OMMT content. The interfacial modulus and interfacial layer thickness predicted by Palierne and Gramspacher-Meissner models are enhanced by introduction of OMMT. The tensile strength and notched impact strength of blends increase with increasing OMMT content.