摘要: In order to improve the value-added applications of low-quality wood, a novel Wood-Polymer Composite was fabricated by in-situ synthesis of copolymer from monomers within wood porous structure. The structure was characterized with SEM and FTIR, and its dimensional stability was also tested. The SEM observations showed that copolymer filled up wood pores and contact tightly with wood matrix, indicating strong interactions between them. FTIR analysis indicated that when the monomers copolymerized in situ wood porous structure, they also reacted with wood matrix by reaction of hydroxyl groups and ester groups, indicating chemical bond between the two phases, which is agreement with SEM observations. The volume swelling efficiency and contact angle of such composite were higher than those of wood, respectively, indicating good dimensional stability involving volume swelling efficiency and contact angle. Such composite could be potentially applied in fields of construction, traffic and indoor decoration.
摘要: For studying the effectiveness of externally pouring Ultra High Toughness Cementitious Composites (UHTCC) in improving the flexural behaviors of existing reinforced concrete beams, four-point bending tests were conducted up to failure on seven RC beams and strengthening beams. The flexural strength, failure mode and crack propagation of composite beams were investigated. The results showed that pouring UHTCC on the bending surface of reinforced concrete beams properly to improve the ductility and load capacity of composite beams. It was also found that UHTCC layer restricted the development of cracks in upper concrete and dispersed them into multiple fine cracks effectively. Compared with post-poured concrete, UHTCC was more suitable for working together with reinforcement. The load-deflection plots obtained from three-dimensional finite-element models (FEMs) analyses were compared with those obtained from the experimental results, which showed close correlation.
摘要: In this paper, several UV curable polyurethane acrylates were synthesized by using isophorone diisocyanate(IPDI), polyethylene glycol(PEG) , Dipropylene Glycol Diacrylate (DPGDA), trimethylolpropane triacrylate (TMPTA), and hydroxyethyl acrylate(HEA) as the raw materials and dibutyltin dilaurate(DBTDL) as the catalyst. The structure was confirmed by the Fourier transform infrared spectroscopy (FTIR). The characterization showed the coatings have a good property.
摘要: Au/NiCr/Ta multi-layered metallic films were deposited on Al2O3 substrate by magnetron sputtering at different substrate temperature. The effect of substrate temperature on magnetron sputtering Au/NiCr/Ta films in crystal orientation, residual stress and resistivity was investigated. The all magnetron sputtering films were highly textured with dominant Au-(111) orientation or a mixture of Au-(111) and Au-(200) orientation. The residual stress in magnetron sputtering films at different substrate temperature was tensile stress with 155MPa-400MPa. A smallest resistivity of 3.6µΩ.cm was obtained for Au/NiCr/Ta multi-layered metallic films at substrate temperature 180°C. The experiment results reveal that the resistivity increased with the increase of the residual stress of metallic films.
摘要: Key workability characteristics of SCC can be described in terms of filling ability, passing ability, and resistance to segregation. These properties are typically characterized by data that relate to specific testing methods. In general, these methods include the components required for evaluating simultaneously filling ability, passing ability, and resistance to segregation, since these properties are rather interrelated. In this investigation, 33 SCC mixtures made with various mixture proportioning parameters, including maximum size and type of aggregate, type and content of binder, and w/cm were evaluated. Comparisons and correlations among various test results used in evaluating the workability responses obtained for these mixtures are established. This is done to highlight advantages and limitations of the various test methods that can be used to assess workability of SCC designated for precast, prestressed applications. Ranges of acceptance of the various test methods are also established.
摘要: In this study, the urethane reaction of several phenols with isocyanate was monitored with in-situ FT-IR. Reaction rate constants were calculated out to investigate the effect of substituents in phenols, as well as the polarity of different solvents. It showed that the polarity of solvents largely affected the reaction rate even without catalyst. The reactivity increased in the following order: Xylene < 1,4-Dioxane < Cyclohexanone. Furthermore, an electron-withdrawing substituent in phenols increased the reactivity of hydroxyl with isocyanate. The reason may be that the H-O bond in phenols could be easily polarized under the influence of electron-withdrawing substituent, where the hydrogen atom was more likely to attack the nitrogen atom of -NCO, thus the nucleophilic addition happened easier.
摘要: The inversion method combining the genetic neural network and the discrete element simulation of triaxial tests is firstly described for determining the discrete element model parameters of the conditioned soil. The purpose is to make the error of the simulation curves and the laboratory curves of the triaxial test minimum. The solve approach is the parameters identification based on the genetic neural network. The network training sample is provided by the discrete element simulation. The input sample is the simulation curves of triaxial test, and the output sample is the model parameters. The laboratory triaxial test curves of the conditioned soil are used to determine its model parameters. The simulation curves calculated with the inversed parameters match the laboratory curves well, which illustrate that the discrete element model can accurately predict the deformation characteristics and flow patterns of conditioned soils.
摘要: Melamine polyphosphate (MPP) and pentaerythritol(PTL) were used as intumescent flame retardants to improve the flame retardance of polypropylene(PP). As a synergistic agent, nano-ZrO2 was incorporated into the composites at different proportions. The synergistic effects of nano-ZrO2 were studied by cone calorimeter tests and thermal gravimetric analysis (TGA). Based on scanning electron microscopy (SEM) and Fourier transform infrared spectra (FTIR), it was evident that nano-ZrO2 efficiently promoted the formation of charred layers with phosphocarbonaceous structures and enhanced the flame retardance of the composites.
摘要: Two types of low-emissive coatings were deposited onto glass substrates by magnetron sputting method, which were designed as Ag and TiO2/Ni-Cr/Ag/Ni-Cr/TiO2. The transmittance and thickness of the samples were measured by TH1901 spectrophotometer and NKD-8000V ellipsometer. Fourier transform infrared spectrometer (FTIR) was employed to detect the low emissivity properties, it demonstrated that the silver-based multilayer coatings showed an efficient heat isolation due to their low emissivity properties. And they had a good performance in the visible range compared to the single Ag layer according to the transmittance spectra as well. The surface morphology of the samples was investigated by scanning probe microscope (SPM), it was determined that the Ag layer formed a homogeneous grain size when deposited onto the Ni-Cr layers.