Papers by Keyword: Modified

Abstract: Forecasting the per capita GDP of minority area is very important for the economic development for a society. This paper is to establish a model for prediction, and this model is based on the exponential smoothing (ES). First of all, the result of exponential smoothing model (ESM) is analyzed, and the accuracy of it is rather low. Then, we modified the exponential smoothing model and use the new model to predict again, with the average error being only 2.88%. The results show that the modified exponential smoothing model (MESM) is effective. The innovation of this paper is that the model is built based on a series of data collected from eight places, while normally a model is built based on data from one place.

Abstract: Graphene oxide was modified with phenyl isocyanate first, and then reduced by a two step method-reduction with hydrazine hydrate first and an additional reduction in H₂/Ar. The reduction with hydrazine hydrate in the first step can effectively remove the epoxy groups on the graphene, and the disposure of reduced graphene oxide (RGO) with H₂ will change the residual amides and carbamate esters into conjugated C=N-ph structure. The introduced phenyl isocyanate not only acts as a functionalized group to prevent the aggregation of graphene but also will increase the electron concentration because of additional benzene. The resulted functionalized graphene can well dispersed in DMF, and the electrical conductivity of the functionalized graphene can reach 3.42×10⁴S/m,which is far high than the method only reduce with the chemical reductant or H₂/Ar. The prepared functionalized graphene is beneficial for the fabrication of graphene-based polymer nanocomposites. The conductivity of resulted modified graphene/PMMA composite with 5wt% filler content is 3.2S/m.

Abstract: On the basis of orthogonal experiment, the effect of heat treatment on structure and mechanical properties of Al-30 wt.% Si alloys refined and modified with Sr+B+RE has been investigated. The results show that the solution temperature and holding time on the alloy microstructure and hardness are affected. When the holding time is constant, as the solution temperature increased, primary silicon more fully integrated into the matrix, the matrix divided by the effect of more and more obvious, eutectic structure becomes coarse, roundness becomes high, the alloy hardness to improve. When the solution temperature is constant, with the holding time increased, primary silicon more fully integrated into the matrix, the matrix divided by the effect of more and more obvious, eutectic structure becomes coarse, roundness becomes high, the alloy hardness increase. When the temperature reaches 540°C, the holding time makes eutectic roundness variation, the hardness declines, the alloy hardness is hardest when solution temperature is 540°C and the holding time is 7h. Optimum heat treatment parameters: 540°C×7h.

Abstract: Polyether imidazole ionic liquid (PIIL) was blended with general-purpose epoxy resin (EP). PIIL/EP was cured by ethylenediamine curing agent. The structure of PIIL/EP was determined by FTIR. The effect of the content of PIIL on the impact strength of EP was studied. The toughness of epoxy resin could be significantly improved by PIIL. The impact strength of the modified EP was improved with the increase of PIIL and leveled off when the content of PIIL was more than 45%, and the modified EP showed rubber elasticity obviously.

Abstract: In this paper, the unitary structure characteristics and the super-hydrophobic properties of the lower surface of the lotus leaf and artificial biomimetic surfaces were investigated through scanning electron microscopy, field emission scanning electron microscopy, x-ray photoelectron spectroscopy and contact angle measurement. The measurement of wettability showed that artificial unitary structure surfaces modified with the lower surface energy material exhibit a super-hydrophobic property with a water contact angle of about 150°. The artificial structure characteristics and the super-hydrophobic properties are similar to those on the lower surface of the lotus leaf. The contribution mechanism of the unitary structure on the hydrophobic property was discussed for the surfaces of the lotus leaf and artificial biomimetic surfaces based on the Cassis-Baxter model.

Abstract: In this paper nanoSiO₂ particles were prepared with the surface grafted fluorine coupling agents and double bond by using surface modification technology. Dispersion effect of nanoSiO₂ particles were studied in different solvents ultrasound cavitation. Test results showed in infrared spectroscopy, TEM and laser particle size distribution analyzer that both F8261 and KH-570 have been grafted onto the surface of nanoSiO₂ , particle size and distribution of nanoSiO₂ after modified by the two coupling agent became smaller and more narrow; Tg-DSC analysis showed that when the amount of of the coupling agent is up to 10%, fluorine coupling agent and double bond grafted onto surface of nanoSiO₂ particles reach the saturation.

Abstract: P(BA-St), a good modifier for epoxy resin, was prepared by BA and St in situ polymerization. The modified resin system was based on diglycidyl ether of bisphenol and methyl tetrahydrophthalic anhydride, tris (dimethylaminomethyl) phenol. The influence of the copolymer on mechanical properties and thermal performance of the systems was studied. When 15 wt% of the BA/St with a weight ratio composition of 7.5/7.5 was added to epoxy, high performance modified epoxy resin was obtained.

Abstract: A new polymer amine modified phenyl phenol cresol resin preparing reports, physico-chemical constants and the ability to dissolve resin was determined, on the basis ofthe resin and the ring emulsion resin curing were studied.

Abstract: 50% solid content of nano-SiO₂/silicon modified polyacrylate composite emulsion was synthesized by emulsion polymerization and sol-gel technique with MMA, BA, silane coupling agent (KH-570) and tetraethoxysilane (TEOS) as the main raw material. The influence of some parameters on the properties of emulsion and film were studied, such as initiator, emulsifier, 3-methacryloxypropyltrimethoxysilane(KH-570), tetraethoxysilane(TEOS). The results showed that as the dosage of tetraethoxysilane (TEOS) and organic silicon(KH-570) increased, the stability of emulsion polymerization decreased; The emulsion with good polymerization stability and film with good water resistance were obtained when the mass of initiator is 0.5%, the mass of compound emulsifier is 4%, of which the ratio of OP-10/SDBS/DNS-86=5:3:2, the mass of KH-570 is 2% and the mass of TEOS is 1%.

Abstract: The use of melamine / urea modified phenol formaldehyde resin binder in the glass-fiber felt has led to products with lower free formaldehyde, higher water repellency and flexibility. This study gives a detailed description of the influence on the mechanical properties of the glass-fiber using the phenol formaldehyde resin with different levels of melamine and urea. Results show that, the free formaldehyde content reduced with the increase of the amount of urea and melamine, a small molecule of melamine and urea destroy the macromolecular chain of phenol formaldehyde resin leading to the decrease of breaking strength. At the same time, the decrease of the molecular chain is accompanied by the increase of flexibility.