Time filter

Source Type

Weinan, China

Li Y.,Weinan Normal University
International Journal of Adhesion and Adhesives | Year: 2014

The acetylation of eucalyptus wood fibers (WFs) was conducted in 50%/50% (v/v) of acetic acid and acetic anhydride catalyzed by sulfuric acid at 60 C for 2 h. Twenty one percent weight percent gain (WPG) level was achieved. Then the contact angles of three probe liquids on the surface of unacetylated and acetylated eucalyptus WFs were tested by the capillary rise method, and the surface free energies of unacetylated and acetylated eucalyptus WFs and their dispersion and polar components were calculated according to the method suggested by Owens-Wendt-Kaelble. The results show that the surface free energy of unacetylated eucalyptus WFs is 24.7 mJ/m2, and its corresponding dispersion and polar components are 14.8 mJ/m2 and 9.9 mJ/m 2, respectively. However, the surface free energy of acetylated eucalyptus WFs is 38.3 mJ/m2 which is higher than the surface free energy of PP (29.4 mJ/m2), and its corresponding dispersion and polar components are 35.6 mJ/m2 and 2.7 mJ/m2, respectively. So it is possible for the spreading of PP on the surface of acetylated eucalyptus WFs and forming a good interfacial adhesion between acetylated eucalyptus WFs and PP. The better interfacial compatibility between acetylated eucalyptus WFs and PP was corroborated by the scanning electron microscopy (SEM) micrographs. © 2014 Elsevier Ltd.

Xi C.,Weinan Normal University
Physica B: Condensed Matter | Year: 2013

We design and study a kind of gammadion-like chiral metamaterial (CMM), which uniaxially exhibits exceedingly strong optical activity and circular dichroism. The optical activity obtained by the proposed CMM rises to about 2280 /λ, which is much larger than that of the previously reported planar designs. Due to the giant chirality, the present CMM can realize negative refractive index easily at the resonant frequencies. The most fascinating property of the present CMM is that it can function as a 90 polarization rotator for wide incident angles, thereby holding great promise for future devices. © 2013 Elsevier B.V.

Li Y.,Weinan Normal University
International Journal of Polymeric Materials and Polymeric Biomaterials | Year: 2012

In this study, the influence of coupling agent concentration (0 and 3wt%), wood fiber content (50, 60, 70, and 80wt%), and size (40-60, 80-100, and 160-180 mesh) on the mechanical properties of wood/high-density-polyethylene (HDPE) composites (WPCs) was investigated. WPC samples were prepared with poplar wood-flour, HDPE, and polyethylene maleic anhydride copolymer (MAPE) as coupling agent. It was found that the tensile properties and the flexural properties of the composites were improved by the addition of 3wt% MAPE, and the improved interfacial adhesion was well confirmed by SEM micrographs. It was also observed that the best mechanical properties of wood/HDPE composites can be reached with larger particle size in the range studied, while too-small particle size was adverse for the mechanical properties of wood/HDPE composites. Moreover, the tensile modulus, tensile strength, and flexural strength of WPCs decreased with the increase in fiber content from 50 to 80wt%; the flexural modulus of WPCs increased with the increase in fiber content from 50 to 70wt% and then decreased as the fiber content reached 80wt%. The variances in property performance are helpful for the end-user to choose an appropriate coupling agent (MAPE) concentration, wood fiber content, and particle size based on performance needs and cost considerations. © 2012 Taylor and Francis Group, LLC.

Wang J.-X.,Weinan Normal University
Guangzi Xuebao/Acta Photonica Sinica | Year: 2014

The atom fidelity and degree of entanglement were calculated in the system consisting of M two-level atoms and M multi-mode fields by use of complete quantum theory and number computing method. Through number computing and analyzing, it was found that the atom fidelity and the atom entangled degree present always oscillatory with opposite in phase if initial atoms are in separate state, and both of their frequency gradually increase with the intensity of light field increasing. The atom fidelity tends to 0 and degree of entanglement tends to 1 under strongly coupling between atoms and light fields. The small fidelity is disadvantage of information transfer but high-fidelity atom information transfer can still obtained by controlling appropriately interaction time.

The objective of this study was to investigate the incorporation of poplar wood fibers both with and without a novel coupling agent, alkyl ketene dimer (AKD), on the mechanical properties of wood fiber/polypropylene (PP) composites. The resulting properties were compared to those obtained with the most commonly used coupling agent, maleic anhydride grafted PP (MAPP). Tensile and impact strengths of the composites decreased with increasing poplar wood fibers content. Tensile modulus of the composites increased by the incorporation of the wood fibers content up to 70. wt% but further increment in the wood fibers decreased the tensile modulus. At the constant content of poplar wood fibers (70. wt%), the tensile strength determined for the coupled composites with 5% AKD increased by 41% in comparison with the non-coupled composites while the tensile modulus increased by 45%, the impact strength of the coupled composites increased by 38%. The performance of 5% AKD on the mechanical properties of the composites is a little better than 3% MAPP. The good performance of 5% AKD is attributed to the enhanced compatibility between the poplar wood fibers and the polymer matrix. The increase in mechanical properties of the composites demonstrated that AKD is an effective coupling agent for wood fiber/PP composites. © 2014 Elsevier Ltd.

Discover hidden collaborations