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Wang G.,Tsinghua University | Guo B.,Tsinghua University | Li R.,China Textile Industrial Engineering Institute
Journal of Applied Polymer Science | Year: 2012

Long-chain branched poly(butylene succinate) were synthesized through a two-step process of esterification and polycondensation, using 1,2,4-butanetriol (1,2,4-BT) as a long-chain branching agent. The effect of long-chain branches on the crystallization behaviors, rheological properties, and tensile properties was investigated systematically. The results of differential scanning calorimetry and polarized optical microscopy showed that with the increasing of 1,2,4-BT segments, the crystallization temperatures and glass transition temperatures increase slightly, while the relative crystallinity degree decreases gradually. Also, the double-banded extinction patterns with periodic distance along the radial direction were observed in the spherulites of long-chain branched poly(butylene succinate), similar to that of linear poly(butylene succinate) (PBS). The result of wide-angle X-ray diffraction indicated that the incorporation of 1,2,4-BT segments had little effect on the crystal structure of PBS. However, based on data from rheology and tensile testing, the viscoelastic properties of long-chain branched PBS under shear flow were different from the linear PBS. For example, the complex viscosities, storage modulus, and loss modulus of long-chain branched PBS at low frequency were significantly enhanced in comparison with those of linear PBS. In addition, long-chain branched PBS showed higher tensile strength than that of linear PBS without notable decrease in the elongation at break when compared with linear PBS. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012.

Wang G.,Tsinghua University | Guo B.,Tsinghua University | Xu J.,Tsinghua University | Li R.,China Textile Industrial Engineering Institute
Journal of Applied Polymer Science | Year: 2011

Poly(butylene succinate) (PBS)/pristine raw multiwalled carbon nanotube (MWCNT) composites were prepared in this work via simple melt compounding. Morphological observations indicated that the MWCNTs were well dispersed in the PBS matrix. Moreover, the incorporation of MWCNTs did not affect the crystal form of PBS as measured by wide-angle X-ray diffraction. The rheology, crystallization behaviors, and thermal stabilities of PBS/MWCNT composites were studied in detail. Compared with neat PBS, the incorporation of MWCNTs into the matrix led to higher complex viscosities (|η*|), storage modulus (G′), loss modulus (G″), shear thinning behaviors, and lower damping factor (tan δ) at low frequency range, and shifted the PBS/MWCNT composites from liquid-like to solid-like, which affected the crystallization behaviors and thermal stabilities of PBS. The presence of a very small quantity of MWCNTs had a significant heterogeneous-nucleation effect on the crystallization of PBS, resulting in the enhancement of crystallization temperature, i.e., with the addition of 0.5 wt % MWCNTs, the values of T c of PBS/MWCNT composites could attain to 90°C, about 6°C higher than that of neat PBS, whereas the values of Tc increased slightly with further increasing the MWCNTs content. The thermogravimetric analysis illustrated that the thermal stability of PBS was improved with the addition of MWCNTs compared with that of neat PBS. © 2011 Wiley Periodicals, Inc.

Yu J.-L.,Dalian University of Technology | Dong S.,Dalian University of Technology | Dong S.,China Textile Industrial Engineering Institute | Yan X.-Q.,Dalian University of Technology | Liu M.,Dalian University of Technology
Dalian Ligong Daxue Xuebao/Journal of Dalian University of Technology | Year: 2012

There are still no reliable approaches to safety assessment on pressure vessels containing defects under multiple loads now. The 3D finite element method was adopted to calculate fracture ratio and load ratio used in safety assessment for nozzle containing through-wall crack at the shoulder under the combination of internal pressure and moment. Research results indicate that fracture ratio can be obtained by the stress intensity factor K Is of crack under internal pressure and moment, which is the summation of stress intensity factor of crack under internal pressure and that under moment. Load ratio can be obtained by actual external loads, limit internal pressure p and limit moment m, and the relation between p and m fits the linearity equation. Therefore, safety assessment of nozzle containing through-wall crack at the shoulder under internal pressure and moment can be accomplished.

Che Y.,Beijing University of Chemical Technology | Qu Y.,Beijing University of Chemical Technology | Wang S.,Beijing University of Chemical Technology | Zhou X.,China Textile Industrial Engineering Institute | Zhang S.,China Textile Industrial Engineering Institute
Beijing Huagong Daxue Xuebao (Ziran Kexueban)/Journal of Beijing University of Chemical Technology (Natural Science Edition) | Year: 2010

The convective heat-transfer coefficient α is one of the important parameters in the design of an indirect rotary dryer. A model that correlates α with several process parameters for an indirect rotary dryer without flights has been developed through dimensional analysis. According to the model, α increases with the product of the drum diameter D and rotation speed n, the moisture content x1, the tap density of the mixture ρbt̄ and the virtual viscosity η; α decreases with the qualitative length of the dryer δ̄ and the specific heat of the mixture λ.

Wang D.,Beijing University of Chemical Technology | Li Z.-P.,Beijing University of Chemical Technology | Gao Z.-M.,Beijing University of Chemical Technology | Huang J.-Q.,China Textile Industrial Engineering Institute
Guocheng Gongcheng Xuebao/The Chinese Journal of Process Engineering | Year: 2010

The flow characteristics in an impinging jet mixer were experimentally investigated by using particle image velocimetry (PIV). The inner diameters of two inlet jets and the mixing chamber were 3 and 16 mm, respectively. The effects of flow ratio and distance between the axis of jets and the top wall of the mixing chamber on the distribution of velocity and turbulent kinetic energy were investigated. The results show that the impingement point locates in the middle of the chamber, and normalized velocity and turbulent kinetic energy distribution are almost consistent when the flow rates of two jets are equal. The region with high turbulent kinetic energy is in the vicinity of impingement point, and the maximum normalized turbulent kinetic energy is about 3 times of that near the impeller region of a standard Rushton turbine stirred tank. Flow ratio has significant effect on the location of impingement point. When the distance between the axis of jets and the top wall of mixing chamber decreases, the region with high turbulent kinetic energy is enlarged, which is beneficial for mixing in the chamber. The results are of importance to the design and optimization of industrial impinging jet mixer.

Hong G.T.,CAS Technical Institute of Physics and Chemistry | Luo B.J.,CAS Technical Institute of Physics and Chemistry | Luo B.J.,University of Chinese Academy of Sciences | Li J.G.,CAS Technical Institute of Physics and Chemistry | Hua G.,China Textile Industrial Engineering Institute
AIP Conference Proceedings | Year: 2010

This paper introduces a liquid helium (LHe) cryogenic target, developed at the Technical Institute of Physics and Chemistry, which has a separated vacuum interval and a gas cooled shield for heat insulation. The target can work in a poor vacuum (∼100 Pa) container with the target plate directly facing the room temperature surface of the shock system. By using continuous flow liquid helium and an exhausting pump to decrease the back pressure in the liquid helium reservoir, the temperature in the target sample cabin has reached 3.6 K and can be adjusted to any point between 3.6 K and 80 K with temperature stability better than ±0.2K. In the target, an adhesive was used for cryogenic seal between different materials and has been proven to be reliable with special seal structural design. This cryogenic target can be used for shock compression experiments of helium and other gas substances. After shock compression testing, all the cryogenic system parts except the main target body can be re-used. The test apparatus for the target tests and shock compression experiments is also introduced in the paper. © 2010 American Institute of Physics.

Wang L.-W.,China Textile Industrial Engineering Institute | Zheng S.-H.,Shanghai Harbour Soft Soil Design and Research Institute
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2010

The in-situ experiment of High Vacuum Densification Method (HVDM) is carried out before a large area soft soil foundation treatment. Construction settlement, underground water level and excess pore water pressure are measured in the experiment. The results show that construction settlement is 55~60 cm and the construction circle time limit is 30~35 days. The effect of foundation treatment is inspected after 14 days when the in-situ experiment is completed. The contents of inspection include static cone penetration test, vane shear test, plate loading test and indoor soil test, which indicate that water content and void ratio are reduced, and modulus of compressibility, P s, shear strength and bearing capacity are greatly improved. The influence depth of HVDM is about 8 m. A conclusion is drawn that if HVDM is adopted, the circle time limit is shorter and the treatment effect can meet design requestment. The results of the experiment can be used for reference to other similar projects.

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