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Polymers and Polymer Composites

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Title: Experimental and theoretical study on the seismic performance of corroded RC circular columns strengthened with hybrid fiber reinforced polymers
Page Range: p.653-660
Author(s): Jianhui Li; Ying Li
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 22
Issue No: No.8

Abstract
Corroded RC columns do not possess necessary ductility to dissipate seismic energy during a major earthquake, the study investigates the use of hybrid fibre reinforced polymer (HFRP) wrapping as a method of retrofitting non-ductile corroded RC columns, the seismic performance of corroded RC circular columns strengthened with HFRP are tested under cyclic load and constant axial, and a model to determine the envelope response of RC corroded columns strengthened with HFRP are presented based on cross-section analysis for undamaged RC element. Results show that the rebar corrosion may introduce the reduction of seismic performance for RC columns in some extent, and the technique of strengthening corroded RC column with HFRP is quite effective, ductility and energy dissipation are improved significantly, but the bearing capacity can be only increased within limits. The envelope curve estimated using the linear plane assumption with modification by rebar slip model, may still be used as the envelope curve of RC corroded columns strengthened with HFRP, a good agreement between analytical and experimental results is observed. 10 Refs.

Title: Energy release rate of interface crack in RC beams strengthened with fiber reinforced polymer under four point bending
Page Range: p.661-668
Author(s): Xie Jian-he; Huang Kun-hong; Guo Yong-chang; Li Zi-jian; Cui Ming-yu
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 22
Issue No: No.8

Abstract
A popular method for strengthening reinforced concrete (RC) beams is to bond fibre reinforced polymer (FRP) plates to the soffit. An important failure mode for such retrofitted members is debonding of the FRP plates from the member due to high interfacial stresses near the intermediate crack. Accurate prediction of the energy release rate of interface crack between FRP and concrete is a prerequisite for designing against debonding failure. In this paper, a theoretical analysis was conducted to investigate the energy release rate of interface crack embedded in the FRP-plated RC beam subjected to four point bending. A mechanical analysis model including the consideration of the major flexural crack and tension steel reinforcement was established for the interface crack tip of plated RC beam. The deflection of the FRP-plated RC beam and the axial force in the plates were analyzed on the basis of the classical beam theory. The compliance of plated RC beam was derived before the tension steel yielding, and a theoretical solution of the energy release rate was then proposed. Moreover, numerical results based on the proposed theoretical model were presented to illustrate the effects of various parameters on the energy release rate of interface crack in the plated RC beam. 15 Refs.

Title: Impact of DMDHEU resin treatment on the mechanical properties of poplar
Page Range: p.669-674
Author(s): Tao Jiang; Hua Gao; Jianping Sun; Yanjun Xie; Xiurong Li
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 22
Issue No: No.8

Abstract
To increase the utilisation and the value of poplar, various concentrations of dimethylol dihydroxy ethylene urea (DMDHEU) were used to impregnate poplar, an important tree species from the north of China. The resin was fixed on the timber under certain conditions, after which the weight percent gain (WPG), flexural modulus (MOR), modulus of elasticity (MOE), impact strength, hardness and compressive strength of the poplar impregnated were tested and evaluated. The results showed that WPG of poplar is positively associated with the concentrations of DMDHEU after the resin treatment; when the WPG of poplar was 62.1% and the concentration of resin was 30%, the concentration of resin shows positive correlation with MOE, the hardness of each section, the compression strength perpendicular to grain, and the compressive strength parallel to the grain, but demonstrates negative correlation with MOR and impact strength. 12 Refs.

Title: Preparation of nanocrystalline cellulose from corncob acid-hydrolysis residue and its reinforcement capabilities on polyvinyl alcohol membranes
Page Range: p.675-682
Author(s): Meiling Yan; Shujun Li; Feng Dong; Shiyan Han; Jian Li; Lei Xing
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 22
Issue No: No.8

Abstract
The sodium chlorite process was utilized successfully to remove the lignin from corncob acid-hydrolysis residue (CAHR), and the intermediate was used to prepare nanocrystalline cellulose (NCC) with a very mild ultrasonic treatment (600W). When the duration of the ultrasonic treatment increased, the absolute value of the zeta potential became stronger and the particle size smaller. When the duration reached 30 minutes, the zeta potential of the NCC reached -23mV, and the particle size was 28.7 nm. The FTIR, XRD, and TEM analysis results proved that the cellulose product was nanocrystalline in Type I structure with a high crystallinity index (79.74%), with a diameter less than 10 nm. The reinforcement of polyvinyl alcohol (PVA) membranes using NCC was also investigated. When the dosage of the NCC was 1.0 wt.%, the tensile strength increased from 34 MPa to 37 MPa. This work provides a novel and cost-effective way to utilize corncob acid-hydrolysis residue. 25 Refs.

Title: Molecular characteristics analysis of wood extractives from pinus massoniana trees
Page Range: p.683-686
Author(s): Zhong-feng Zhang; Kai Huang; Yong-jun Ye; Jun-you Shi; Xu Zhang
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 22
Issue No: No.8

Abstract
Pinus massoniana is a fast growing tree widely grown in China that is, unfortunately, difficult to process and develop due to the extractive substances. The molecular characteristics of the wood extractives from Pinus massoniana were removed by a method of petroleum ether/Benzene extraction and analyzed by gas chromatography-mass spectrometry (GC-MS) in order to provide scientific guidance for improving the processing and utilisation of this plant. Twenty-eight chemical components were discovered, including: 1,2-Benzenedicarboxylic acid, butyl octyl ester (62.69%), 1,5-Hexadien-3-yne (6.00%), Squalene (3.31%), 9,12-Octadecadienoic acid (Z,Z)- (1.29%), Heptadecane (1.14%) and Eicosane (1.01%). The analysis of the GC-MS results show that the main retention time of the wood extractives is 20-30 minutes with a total content percentage of 80.18%, and the richest components are esters, which compose 80.01%. 13 Refs.

Title: Research on pretreatment technology for corn husk degumming
Page Range: p.687-692
Author(s): Rong Zhou; Mingxia Yang; Haixia Zhang
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 22
Issue No: No.8

Abstract
In this study, chemical degumming was applied to corn husks, and the optimal degumming procedure and pretreatment method were determined. Through orthogonal experiments, it was determined the optimal pretreatment parameters are: H2O2 concentration of 8 g/L, urea concentration of 8 g/L, pretreatment temperature of 20 deg C and pretreatment time of 30 min. The effectiveness of this combination of parameters was validated by its resultant glial removal rate of 85.32%. 17 Refs.

Title: Mechanical properties of polymer rubber materials based on a new constitutive model
Page Range: p.693-698
Author(s): Sang J B; Sun L F; Xing S F; Liu B H; Sun Y L
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 22
Issue No: No.8

Abstract
A new constitutive model, which is a modification from Gao's second constitutive model, has been introduced by using the finite deformation theory. The new model fulfils the condition that strain energy becomes zero under no deformation. For incompressible polymer rubber materials, when n=1 and ==0, the new constitutive relation may be simplified to the Mooney-Rivlin model; when n=1 and ==1, the new constitutive relation may be simplified to the Neo-Hookean model. The discussions of basic finite deformation examples illustrate how the new constitutive model reasonably describes the deformation properties of polymer rubber materials, and how the applied range of polymer rubber materials have been broadened by using the new constitutive model. 15 Refs.

Title: Fabrication and characterization of TiO2-organic thin film from an aqueous solution
Page Range: p.699-704
Author(s): Mu W N; Shi S Z
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 22
Issue No: No.8

Abstract
TiO2-organic thin films were fabricated on SAMs-coated silicon substrate based on layer-by-layer self-assembly process and chemical bath deposition method by a hydrolysis of TiCl4 in acid aqueous solution. The influences of deposition time and solution pH value on structural properties and the thickness of TiO2 films were investigated. The results of UV-vis spectrum show the absorbance of aqueous solutions at 410 nm decreases gradually with increasing deposition time and solution pH value. The thickness of TiO2-organic thin film elevates as increasing deposition time and pH value. The deposition time has significant influence on the surface morphology of films, and when the time is 2 h, a continuous, density and homogeneous film is gained from SEM micrographs. The deposited films consisting of TiO2 nanoparticles are believed to be fully amorphous layers from the results of XRD. The major chemical compositions of thin films are titanium and oxygen as presented in EDS results, and O/Ti atomic ratio is close to the corresponding ratio of 2:1 for stoichiometric TiO2. The transmission infrared spectrum and UV/Vis spectrum of TiO2 film indicate excellent structure and optical properties of films. 28 Refs.

Title: Miscibility and isothermal crystallization behavior of poly-(l-lactideco-glycolide)/ poly(rho-dioxanone) blends
Page Range: p.705-712
Author(s): Xiaojin Zhang; Chi Ma; Wei Bai; Chengdong Xiong; Dongliang Chen
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 22
Issue No: No.8

Abstract
We prepared a series of blends from solution co-precipitation of poly-(L-lactide-co-glycolide) (PLGA) and poly (p-dioxanone) (PPDO) at various mass ratios. Using a scanning electron microscopy (SEM), PLGA and PPDO were revealed to be immiscible. The crystallisation behaviour of PLGA/PPDO blends was investigated by differential scanning calorimetry (DSC) under isothermal conditions. Through comparing the crystallisation exothermic peak location and the PLGA/PPDO blends' shape, the crystallisation rate was determined to slow as the temperature increased. We applied the Avrami equation to analyze the primary stage of the isothermal crystallisation and obtained relevant crystallisation kinetic parameters. The data revealed that the PPDO component acted as nucleation sites in blends and accelerated the PLGA crystallisation rate by increasing the crystallisation rate constant k and decreasing the half-crystallization time (t1/2). The Arrhenius equation was used to analyze the crystallization's activation energy. Our analysis confirmed that blending with PPDO accelerates PLGA crystallisation. Our micrograph imaging of the spherulites via a polarizing optical microscopy (POM) revealed that the PLGA/PPDO blends' crystals were smaller in size but greater in number than that of pure PLGA. This finding indicated that PPDO is a good nucleation agent for PLGA. All these results suggest that it is possible to control the PLGA crystallisation rate by adding a PPDO component. 36 Refs.

Title: Parametric study on heat transfer for tow placement process of thermoplastic composite
Page Range: p.713-722
Author(s): Zhenyu Han; Zhongliang Cao; Zhongxi Shao; Hongya Fu
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 22
Issue No: No.8

Abstract
Fibre placement process of thermoplastic material is an in situ consolidation process which can significantly reduce consolidation process time and save costs compared with autoclave consolidation. The heat and crystallisation behaviours play very critical role in the quality control during the process. In this work, two dimensional model of finite element is presented to perform heat transfer analysis of fibre placement process. The relationship between heat distribution of lamination and process parameters, including roller velocity, main heating temperature, preheating temperature, preheating length and preheating location, is deeply investigated. The numerical results show that for certain heating temperature there is a safe roller velocity which should not be exceeded, and such parameters as main heating length, preheating length and preheating location could be optimized to obtain better quality of product. 11 Refs.

Title: Characterization of PEO-X ionic conductive polymer for anodic bonding
Page Range: p.723-728
Author(s): Xu Yin; Cuirong Liu; Yue Nan; Qingsen Meng
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 22
Issue No: No.8

Abstract
Anodic bonding is a common technology in MEMS packaging. However, only the bonding between glass and metal or semiconductor can be implemented at present. In this work, a new type of composite, solid polymer electrolyte (taking PEO as the matrix with a small amount of nano-sized inorganic filler), was prepared as a new anodic bonding material. We studied the interaction and conduction mechanism between PEO and the inorganic filler through DSC and XRD analyses, and also discussed the application feasibility of the solid polymer electrolyte being packaging material in anodic bonding. The results showed that adding inorganic filler can reduce the interface resistance of the macromolecule solid electrolyte, and control the diffusion of alkali metal ions in the solid lithium molecule electrolyte when under a strong electric field. The anodic bonding technique may promote the application of this new macromolecule material in MEMS. 13 Refs.

Title: Photo-anodic polymerization of pyrrole on nanoclustered TiO2 from hydrothermal one-step on pure Ti
Page Range: p.729-736
Author(s): Fu-fang Zhou; Delong Li; Weiping Li; Xilou Zhu; Ping Wang; Yuan Ming Huang; Chunxu Pan
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 22
Issue No: No.8

Abstract
Nanoclustered TiO2 networks were synthesised hydrothermally one-step in 0.45 M tetramethylammonium hydroxide (TMAOH) aqueous solution directly on pure polished Ti substrate for 12-hour growth. Polypyrrole (PPy) nanofilm was subsequently electropolymerised with galvanostatic photo-anodisation on the nanostructured TiO2 sheet as the working electrode. Tafel polarisation curve was employed to determine galvanostatic condition. Investigations of SEM, cyclic voltametry, potential-time growing curves, photo-response currents, UV-vis spectroscopy and Fourier Transform Infra-red (FTIR) spectroscopy revealed that photo-anodic polymerized pyrrole film could thoroughly change properties of nanoclustered TiO2 electrode. The networks of nanoclustered TiO2 was covered with homogeneous PPy nanofilm, the cyclic voltammetry revealed two reduction peaks, suggesting a compact and a porous layer of PPy. Moreover, PPy could enhance the photo-response by over 100 times compared with that of bare TiO2 nanonetworks. Optical absorbance visualized the full spectral absorptive feature of PPy, and FTIR further confirmed the vibrations of chemical bonds from PPy. This demonstrated that PPy infiltration in TiO2 nanonetworks could be successfully achieved via photo-anodic polymerisation, and TiO2 nanonetworks/ photo-anodic polymerized PPy are promising in applications of polymer-inorganic solar cell. 28 Refs.

Title: Strain-amplitude and strain-rate dependent craze damage of poly(methyl methacrylate)
Page Range: p.737-742
Author(s): Liu Xiu; Luo Wenbo; Yin Boyuan
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 22
Issue No: No.8

Abstract
Dynamic mechanical analysis tests and quasi-static tensile tests were conducted on polymethyl methacrylate (PMMA). Craze damage images on PMMA samples' surface were acquired by using an optical microscope. Evolution of the crazing damage was investigated. The results suggest that crazing is loading rate and strain-amplitude dependent. In dynamic mechanical tests, the craze damage becomes more and more serious with the increase in strain amplitude, resulting in the Payne effect. Under quasi-static loading, there is a critical strain over which the surface crazes become visible; the greater the loading rate, the greater the critical strain. Moreover, stretching at different rates leads to difference to the morphology of crazes. The surface crazes stressed at lower loading rate are longer and more fully developed than those at higher loading rates, which results in a faster decline in static elastic modulus. 15 Refs.

Title: Methodology to analyze the influence of microcellular injection molding on mechanical properties with samples obtained directly of an industrial component
Page Range: p.743-752
Author(s): Elduque D; Claveria I; Fernandez A; Javierre C; Pina C; Santolaria J
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 22
Issue No: No.8

Abstract
Microcellular injection moulding is a process that offers numerous benefits thanks to the internal structure generated, thus many applications are being arising in different fields, especially home appliance. In spite of it, when changing the manufacturing process of a component from conventional injection moulding to microcellular injection moulding, it is necessary to ensure the mechanical properties of the component. In this paper a study of the mechanical behaviour of samples obtained directly from a manufactured component both by conventional injection moulding and microcellular injection moulding is carried out. This kind of samples take into account the process conditions under the final component is processed and the influence of these conditions on the mechanical properties. For this purpose special devices have been developed taking into account the characteristics of the component and the samples obtained. An X-ray 3D computed tomography is also carried out to validate the internal structure of the microcellular injection moulded component. Tensile properties are reduced between 20-22% regarding flow direction when using microcellular injection moulding. Impact properties are reduced up to 27%. However, flexural properties reduction for samples processed by microcellular injection is only 6.8%, so microcellular injection moulding arises as a very suitable process for components working under this kind of load. Moulding and impact tests are carried out by using specially developed devices. 17 Refs.

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