Effect of Nano-ZnO on Decay Resistance and Artificial Weathering of Wood Polymer Composite
Wood polymer nanocomposite (WPNC) was prepared by impregnation of styrene and Nano zinc oxide into poplar wood (Populus deltoids Marsh.). WPNCs containing different loading of nano zinc oxide, namely 0, 0.5, 1 and 1.5 percent (by weight of monomer), were made. Then the effect of addition of nanoparticles on the decay resistance and artificial weathering were studied. The WPNCs were subsequently exposed to the artificial weathering test with duration of 200, 400 and 800 hours and decay test according to a modified ASTM D1413 standard. The results showed that the amount of color change of samples treated with nano zinc oxide was less than untreated one, also the decay resistance of the composite against the fungi with increasing of concentration was improved.
Fabrication of Cu Hollow Microspheres by Liquid Reduction Method
Cu hollow microspheres have been successfully synthesized through a two-step liquid reaction method. Firstly, Cu(OH)2 precipitates were formed by adding CuSO4•5H2O into NaOH and they were reduced to Cu2O solid microspheres by glucose. Then, PVP and allylthiourea were added to the Cu2O suspension and they were further reduced to Cu hollow microspheres by hydrazine hydrate. The sample was characterized by X-ray diffraction, Field-emission scanning electron microscopy, and transmission electron microscopy. The results showed the Cu hollow microspheres with average diameter about 800nm. The growth process of Cu hollow microspheres was proposed and the photocatalytic property in degradation reaction of methylene blue (MB) was also explored. It was found that the morphology and hollow structure of the Cu microspheres are highly dependent on the amount of allylthiourea added. Compared to the Cu microparticles with irregular morphology, Cu hollow microshperes show much higher photocatalytic activity in the degradation reaction of MB.
Some Mechanical Properties of Carbon Nanotubes Heterojunctions
In the present research work, the structure of linear heterojunctions between two CNTs of different chirality’s, but similar radii, joined together through an interface that require more than one pentagon-heptagon defects have been studied. The elastic properties of carbon nanotube heterojunctions are investigated using secondgeneration improved reactive empirical bond order potential by Brenner and co-workers. In this study, the coordinates of carbon nanotube heterojunctions are generated. Each and every structure thus generated is allowed to relax till a minimum of energy is obtained. The requisite compressions, elongations and twists to the structures are applied and thus computed elastic moduli. Young’s Modulus increases with radius for small radii and attains a constant value of the order 1TPa. Poisson’s ratio and shear modulus have also been computed.
Copper selenide (CuxSe) particles were prepared by heating copper carbonate and selenous acid in diethylene glycol in the presence of various dispersing agents. The impact of reaction conditions on the structural and morphological properties of the precipitated particles were assessed by X-ray diffraction (XRD) and electron microscopy. Although all additives promoted anisotropic growth, it was found that polyvinyl alcohol (PVA) was particularly effective in generating dispersed high aspect ratio CuxSe platelets. The optimum reaction conditions for the formation of hexagonal copper selenide were 190°C and a Cu: Se molar ratio of 1 to 1.2.