Technology Development Center for Polymer Processing Engineering of Guangdong Colleges and Universities

Guangzhou, China

Technology Development Center for Polymer Processing Engineering of Guangdong Colleges and Universities

Guangzhou, China
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Geng L.-H.,South China University of Technology | Peng X.-F.,South China University of Technology | Jing X.,South China University of Technology | Li L.-W.,Technology Development Center for Polymer Processing Engineering of Guangdong Colleges and Universities | And 4 more authors.
Journal of Materials Research | Year: 2016

Poly(lactic acid) (PLA)/graphene oxide (GO) nanocomposites were prepared by solution mixing. Differential scanning calorimetry results indicated that GO was an effective nucleating agent. The size of spherulites decreased, the density of spherulites increased with increasing GO and the crystallinity of PLA increased from 4.34 to 49.01%. For isothermal crystallization, the crystallization rates of PLA/GO nanocomposites were significantly higher than that of neat PLA, in which t0.5 reduced from 9.0 to 2.8. Spindle-like nanopores (about 100-200 nm) that arranged like spherulites were prepared by low temperature foaming. It was found that the crystallization rate increase and spherulite morphology change were insignificant when the content of GO exceeded 0.5 wt%, because the excessive GO increased the number of nucleation sites while restricting the PLA crystal growth. Thus, the arrangement of nanopores did not mimick the spherulites because of imperfect crystal morphology. Copyright © Materials Research Society 2016.


Xu B.-P.,Technology Development Center for Polymer Processing Engineering of Guangdong Colleges and Universities | Turng L.-S.,Polymer Engineering Center and Wisconsin Institute for DiscoveryUniversity of Wisconsin MadisonMadison53706 Wisconsin
Journal of Applied Polymer Science | Year: 2015

The residual thicknesses of the skin and the inner layers are important quality indicators of water-assisted co-injection molding (WACIM) process or overflow WACIM (O-WACIM) parts. At the curved section, the residual thicknesses change significantly. A numerical simulation program based on the computational fluid dynamics method was developed to simulate the O-WACIM process. After the numerical simulation program was validated with the experimental results, it was used to study the effects of the bending radii and bending angles on the residual thicknesses of the skin and inner layers of O-WACIM parts. The results showed that the penetration of the inner melt and water was always close to the inner concave side due to the higher local pressure gradient and temperature. The effects of processing parameters on the residual thicknesses of the skin and inner layers were investigated using the orthogonal simulation method. It was found that the residual thicknesses of the skin/inner layer at the inner concave/outer convex side are mainly influenced by different parameters. © 2015 Wiley Periodicals, Inc.


Xu B.,Technology Development Center for Polymer Processing Engineering of Guangdong Colleges and Universities | Xu B.,Hunan University of Technology | Yu H.,Technology Development Center for Polymer Processing Engineering of Guangdong Colleges and Universities | Yu H.,Hunan University of Technology | And 4 more authors.
Jixie Gongcheng Xuebao/Journal of Mechanical Engineering | Year: 2012

A geometry in which the mixing of single screw extruder is enhanced by a reciprocating baffle is proposed and the effect of baffle amplitude on mixing in the screw channel is investigated. The corresponding physical and mathematical models are developed. The periodic flow and mixing of Newtonian fluid in such an extruder are investigated. Finite volume method is used and flow domain is meshed by staggered grids with the periodic boundary conditions of the baffle motion being imposed by the mesh supposition technique. Fluid particles tracking is carried out by fourth order Runge-Kutta scheme and the Poincaré section mappings are used in order to show the scale of chaotic mixing. The evolution of mixing patterns of the tracers and their growth of interface stretch with time are obtained which are released from different initial positions. The results reveal that the reciprocating motion of the baffle can lead to chaotic mixing region surrounded by the pseudo-periodic regions with two KAM tubes inside. The tracers will experience the exponent growth with time when captured by the chaotic mixing zones with the linear growth when trapped in the pseudo-periodic zones. The larger the baffle amplitude is, the smaller the inner pseudo-periodic region is, the larger the chaotic mixing region is. © 2012 Journal of Mechanical Engineering.


He L.,Technology Development Center for polymer Processing Engineering of Guangdong Colleges and Universities | Xu B.P.,Technology Development Center for polymer Processing Engineering of Guangdong Colleges and Universities | Xu B.P.,Hunan University of Technology | Yu H.W.,Technology Development Center for polymer Processing Engineering of Guangdong Colleges and Universities | And 2 more authors.
Advanced Materials Research | Year: 2013

The novel geometrical configuration of embedded planetary-screws is proposed in the paper. The corresponding numerical simulation and the experimental investigation are carried out to characterize the mixing performance. Adopting commercial software FLUENT, the simplified physical model is presented with the boundary conditions imposed by UDF codes which are developed by us. Compared with the traditional single screw extruder, the flow and mixing are primarily investigated by using particle tracking technology. The sensitivity to initial positions is found in the novel screw configuration, which is caused by the periodic perturbation of planetary-screws. In contrast, the traditional laminar mixing occurs in single screw extruders. Compared with the traditional twin screw extruder, the experimental characterization of filled system of adding active nanometer CaCO3 into LLDPE matrix is conducted. No obvious difference in dispersion of CaCO3 is found when the extrusion samples are observed through scanning electron microscopy (SEM), on the condition that the both extrusion outputs are equal. The shear rate in the novel screw configuration is relatively smaller, and the extrusion characteristic is more excellent. © (2013) Trans Tech Publications, Switzerland.


Du Y.,Wuyi University | Shi S.,Wuyi University | Yin X.,South China University of Technology | Xu B.,Technology Development Center for Polymer Processing Engineering of Guangdong Colleges and Universities
Gaofenzi Cailiao Kexue Yu Gongcheng/Polymeric Materials Science and Engineering | Year: 2016

Polymer mixing properties processed by three kinds of novel blending unit, namely barrier unit, chaos unit and vane unit, were simulated and compared through using Polyflow as polymer fluid dynamic software. The results show that mixing index of vane unit is larger than that of barrier unit and chaos unit, material in the runner of three kinds of novel blending unit suffers stretching action mainly, and vane unit is of the largest stretching action strength in the runner. Residence time expectations of chaos unit, barrier unit and vane unit are about 4 s, 5 s and 6 s respectively, and distribution mixing effect of vane unit is better. Stretching action in vane unit is obviously higher than in barrier unit and chaos unit. The transient mixing efficiency order of three kinds of novel blending unit is vane unit, barrier unit and chaos unit. Time averaged mixing efficiency of barrier unit is higher than that of chaos unit. With the increasing of axial distance, the influence of vane unit on mixing properties is more obvious. © 2016, Chengdu University of Science and Technology. All right reserved.


Luo J.-S.,Technology Development Center for Polymer Processing Engineering of Guangdong Colleges and Universities | Luo J.-S.,Wuyi University | Xu B.-P.,Technology Development Center for Polymer Processing Engineering of Guangdong Colleges and Universities | Xu B.-P.,Wuyi University | And 3 more authors.
Fibers and Polymers | Year: 2015

Thermoplastic polyurethane (TPU)/polypropylene (PP) blends of different weight ratios were prepared with a self-made co-rotating non-twin screws extruder (NTSE), which rotates at a speed ratio of 2.0, and a traditional twin-screw extruder (TSE), which rotates at a speed ratio of 1.0. The mechanical properties, phase morphology and thermal stabilities were investigated to characterize the effect of different processing methods. The experimental results revealed that the samples prepared with a NTSE had superior mechanical properties compared to those of the samples prepared with a TSE. High-resolution scanning electron microscopy showed a structure feature of fiber morphology of TPU/PP blends prepared with a NTSE and the particle size of dispersed phase of blends prepared with NTSE is smaller than that prepared with TSE, indicating that the NTSE is more efficient in mixing for immiscible polymer blends. Furthermore, thermogravimetric analysis curves indicated the strong interaction of the TPU/PP blends influenced by the flow field in NTSE, compared to that of TSE-extruded. © 2015, The Korean Fiber Society and Springer Science+Business Media Dordrecht.


PubMed | Technology Development Center for Polymer Processing Engineering of Guangdong Colleges and Universities and South China Normal University
Type: | Journal: Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy | Year: 2015

Fluorescent and colorimetric pH probe possess many advantages including rapid response time, nondestructive testing, and excellent pH sensitivity. However, they usually cannot be utilized simultaneously in both acidic and basic pH ranges. In this study, a new selective and sensitive fluorescent and colorimetric pH probe, 4-(8-quinolyl)amino-7-nitro-2,1,3-benzoxadiazole (1), was designated and synthesized. The optical probe exhibited dual-responsive pH ranges to both acidic and basic aqueous solutions. When the solution pH was gradually increased from 8.5 to 13.3, the absorption spectra of 1 showed an obvious hyperchromicity, accompanied with a red shift of the absorption band at 340 nm, a blue shift of the absorption band at 482 nm, and a distinct color change from orange to violet pink to yellow. Within the pH range from 2.2 to 0.2, the fluorescent spectra of 1 showed a turn-on response signal to solution pH. In order to understand the response mechanism of the probe to solution pH, the probe molecule was split into two parts, 8-aminoquinoline (2) and 4-amino-7- nitro-benzofurazan (3). UV-vis absorption and fluorescent experiments of 2 and 3 indicated that both are sensitive optical pH probes. Furthermore, the NMR experiment of 1 was explored in basic and acidic conditions. The results indicated that the colorimetric responses of 1 to pH under basic condition should be attributed to the deprotonation of the imino group on the quinolyl ring, and the fluorescent recognition of 1 to pH under acidic condition was probably due to the protonation of the nitrogen atoms from the benzofurazan and quinolyl rings.


Xu B.,Technology Development Center for Polymer Processing Engineering of Guangdong Colleges and Universities | Feng Y.,South China University of Technology | Cheng J.,Technology Development Center for Polymer Processing Engineering of Guangdong Colleges and Universities | Yu H.,Technology Development Center for Polymer Processing Engineering of Guangdong Colleges and Universities | He L.,Technology Development Center for Polymer Processing Engineering of Guangdong Colleges and Universities
Huagong Xuebao/CIESC Journal | Year: 2014

Numerical investigation was conducted to study the mixing behavior of Stokes flows in a rectangular cavity stirred by alternating motion of three square rods. The square loops of rod moved in two different ways that a Pseudo-Anosov map could be built in the flow domain in the augmented phase space. The finite volume method was used to solve the flow field with the periodic boundary conditions of the rod motion being imposed by the mesh supposition technique. The flow domain was meshed by staggered grids and the discretization schemes for control equations were accurate to the second-order resulting from the use of central differencing. Fluid particle tracking was conducted by a fourth-order Runge-Kutta scheme. The Poincaré section was obtained to reveal the size of the domain in which the Pseudo-Anosov map almost covered the whole cavity region except for four corner zones. The evolution patterns of tracers from different initial positions were computed to characterize the mixing process. Tracer interface stretches experienced exponential increases and had the larger power index than that predicted by the Pseudo-Anosov(pA) map matrix, which was due to the local secondary folding caused by the details of flow field, such as shapes of rods, rod trajectories and so on. ©All Rights Reserved


He G.-J.,South China University of Technology | Zheng T.-T.,South China University of Technology | Ke D.-M.,South China University of Technology | Cao X.-W.,South China University of Technology | And 2 more authors.
RSC Advances | Year: 2015

In this work, rapid ozone degradation of polypropylene (PP) was developed for the aim of rheology control using a reactive extrusion process. Experiments were carried out in a co-rotating intermeshed twin-screw extruder with varied polymer throughput and reaction temperature. Ozone was introduced into the extruder to rapidly oxidize molten PP in just several seconds period. The oxidized PP was characterized through melt flow index (MFI), rheological measurement, differential scanning calorimetry (DSC), and Fourier transform infrared (FTIR) spectroscopy tests. The influence of reactive temperature and polymer throughput on the degradation reaction was studied. It was noted that molten PP could be fast and successfully degraded during this reactive extrusion process. The oxidized PP had higher MFI than that of the origin PP resin, indicating the decrease of molecular weight of PP. Carbonyl groups were formed on the PP molecular chains. This rapid oxidization process has higher reaction efficiency than the ozone degradation of PP in solid state and no harmful byproduct would be generated from this ozonizing reaction. © The Royal Society of Chemistry 2015.


Xu B.-P.,Technology Development Center for Polymer Processing Engineering of Guangdong Colleges and Universities | He L.,Technology Development Center for Polymer Processing Engineering of Guangdong Colleges and Universities | Wang M.-G.,Technology Development Center for Polymer Processing Engineering of Guangdong Colleges and Universities | Tan S.-Z.,Technology Development Center for Polymer Processing Engineering of Guangdong Colleges and Universities | And 2 more authors.
International Polymer Processing | Year: 2016

A kind of discontinuous baffle, which had the same length as the non-baffle zone distance, was inserted in the unwound channel of a single screw extruder to enhance mixing in the screw channel. The periodic unit of the flow channel was modeled as a dynamic system of complex duct flow. The finite volume method was used to solve the three-dimensional flow of purely viscous non-Newtonian fluid. Fluid particle tracking was performed by a fourth-order Runge–Kutta scheme. The effect of the baffle height on the mixing kinematics was investigated numerically. Poincaré sections were applied to reveal the different patterns and sizes of the KAM tubes. Distributive mixing was then visualized by the evolution of passive tracers initially located at different positions. The variance index and residence time distribution (RTD) were used to evaluate the statistical results. Among the four test cases, the results showed that the case with the baffle height equal to the screw depth had the largest chaotic mixing region, but the shortest mean residence time and the narrowest broadening of RTD under the same pressure gradient. © Carl Hanser Verlag, GmbH & Co. KG.

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