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Polymers and Polymer Composites

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Title: COMPOSITE FROM WOOD FIBRES BONDED WITH RENEWABLE WOOD RESIN
Page Range: p.217-227
Author(s): Ghosh A; Sain M
File size: 209K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 14
Issue No: No. 3

Abstract
A renewable wood resin, used as a binder for wood fibres in the manufacture of environmentally friendly fibreboard composites is tested for its efficiency. It is used in combination with urea-formaldehyde resin to improve economy and performance, and to reduce the levels of formaldehyde emission in indoor applications. Fibreboard composites bonded with 5 wt% wood resin and 5 wt% urea-formaldehyde resin were considered as representative fibreboards for the purposes of investigating the effect of cure temperature and time in more detail. Results indicated that optimisation of the mechanical performance and dimensional stability of the fibreboard composites was achieved a the cure temperature of 200 degrees C, cure time of 10 mins and pressure of 7MPa. 26 refs.

Title: MEASUREMENT OF THE AVERAGE PERMEABILITY OF NATURAL FIBRE MATS IN RESIN TRANSFER MOULDING APPLICATION
Page Range: p.229-238
Author(s): Rouison D; Couturier M; Panthapulakkal S; Sain M
File size: 209K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 14
Issue No: No. 3

Abstract
The permeability of hemp fibre mats used in a resin transfer moulding process were computed from the measured mould filling time using a simplified mathematical approach. This approach could be applied because of the simple geometry of the mould and because a certain number of assumptions were made. The main assumption, which stated that the flow front of the resin was sharp and symmetric, was verified by observing some unfinished parts. Further simplification of the solution resulted in a non-dimensional number that was used for the computation of the permeabilities. In order to take into account the approximations made in the model, the solution was calibrated using data from the literature and experimental results for a 20% glass fibre preform. From this number, the permeability obtained from the experimental measurement of the injection time was found to decrease with increasing fibre content. The values obtained for hemp were lower than for glass fibres. This preliminary work is claimed to show the importance of studying the permeability of natural fibre systems in order to provide the data necessary for the proper design of industrial moulds. 18 refs.

Title: PREDICTING THE ELASTIC MODULUS OF HYBRID FIBRE REINFORCED THERMOPLASTICS
Page Range: p.239-249
Author(s): Facca A G; Kortschot M T; Yan N
File size: 177K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 14
Issue No: No. 3

Abstract
In this study, a modified hybrid rule of mixtures equation (HROM) was presented to predict the tensile moduli of hybrid composites. Experimental data from single fibre reinforced thermoplastics formed the basis of the modification. Combinations of E-glass, hemp and hardwood flour were blended into HDPE in total fibre loadings of 10 to 60 wt% to produce hybrid composites. The density and Young's modulus of the hybrid composites fell between the extreme values obtained for the single fibre composites. It was shown that by adding E-glass fibres or hemp fibres to hardwood flour, the tensile modulus of the single hardwood reinforced thermoplastics could be increased with a minimal increase in density. The modified rule of hybrid mixtures equation was found to adequately predict the tensile modulus of the hybrid composites. 9 refs.

Title: CONTACT ANGLE OF EPOXY RESIN MEASURED BY CAPILLARY IMPREGNATION AND THE WILHELMY TECHNIQUE
Page Range: p.251-259
Author(s): Min Li; Zuo Guang Zhang; Zhi Jie Sun
File size: 114K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 14
Issue No: No. 3

Abstract
The contact angle of an epoxy resin, as a widely used polymeric matrix, was studied by impregnation in single glass capillaries at the manufacturing temperature of the composites. In order to obtain the net wicking mass for capillary experiments, the meniscus force at the bottom of the glass tube was investigated using the Wilhelmy technique with glass sticks of various diameters. Results indicated that the contact angles resulting from equilibrium using both capillary impregnation and the Wilhelmy experiment are consistent, which proved the reliability of the practical evaluation of the effect of the meniscus on the penetration mass. The equilibrium contact angle of epoxy resin for the Wilhelmy method was 59 degrees and 61 degrees for the capillary impregnation of glass tubes. Therefore, the contact angle of epoxy resin is approximately 60 degrees a the test temperature of 80 degrees. 19 refs.

Title: SEMI-INTERPENETRATING CONDUCTING ELASTOMER COMPOSITE THIN FILMS FROM POLYANILINE
Page Range: p.261-269
Author(s): Sreeja R; Sharma P D; Najidha S; Jayan S R; Predeep P
File size: 124K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 14
Issue No: No. 3

Abstract
Conductive polyaniline (PANI) was blended with elastomers (NR and NBR) by a wet mixing process with the aim of producing flexible ultra thin conductive films. The rubbers used were raw, without any vulcanisation, and thus could be easily fabricated as thin films by solution casting. The compatibility of the polymer blends was estimated experimentally by spectroscopic and swelling studies. Good conductive properties were found for NR composite films with 30 wt% of HCl treated PANI and NBR composite films with 20 wt% of HCl treated PANI. Spectroscopic analysis and swelling measurements indicated that the composites were not just simple blends, but were rather complex macromolecular systems in which the electrical conductivity and mechanical properties of the composites depended on the nature and interaction between the rubber matrices. HCl treated PANI acted as both a reinforcement and a conductive filler in blends with NR. With nitrile rubber, HCl treated PANI improved the conductive behaviour and increased the rigidity of the films. The method is claimed to open up a new technique for the preparation of stable conductive thin films of PANI using dopants such as HCl. 24 refs.

Title: THE CHARACTERISTICS OF POLYPROPYLENE LAYERED-SILICATE NANOCOMPOSITES
Page Range: p.271-279
Author(s): Suzhu Yu; Songlin Liu; Jianhong Zhao; Hong Xie; Ming Shyan Yong
File size: 213K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 14
Issue No: No. 3

Abstract
Organoclay reinforced polypropylene nanocomposites were prepared by melt intercalation using extrusion, and their structural, rheological and mechanical properties were investigated. The morphologies of the composites were observed with TEM and the linear viscoelastic and flow properties were studied as a function of temperature and organoclay concentration. An increase in the organoclay concentration from 1 to 7.5 wt% resulted in an increase in the loss and storage moduli as well as in the steady shear viscosity of nanocomposites at different temperatures, particularly at low frequencies. The steady shear viscosity of both PP and its nanocomposites exhibited Newtonian behaviour at low shear rates followed by a shear thinning region. The onset of shear thinning occurred at significantly lower shear rates. The elastic modulus of the PP nanocomposite containing 10 wt% of organoclay was increased by around 25% compared to the neat PP. 20 refs.

Title: THERMAL AND DYNAMIC MECHANICAL PROPERTIES OF LOW DENSITY POLYETHYLENE-SILICA NANOCOMPOSITES: EFFECT OF ZINC-ION COATING ON NANOSILICA
Page Range: p.281-290
Author(s): Reddy C S; Das C K
File size: 255K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 14
Issue No: No. 3

Abstract
The effect of zinc coating nano-silica particles with zinc ions before incorporation into an LDPE polymer matrix is studied. It was found that the coating improved the reinforcing effect of the filler, and allowed for the use of much lower loading level. This is reported to be due to a decrease in the polarity of the nano-silica surface on zinc ion coating, which prevented agglomeration of the silica particles and thus promoted their effective dispersion in the polymer matrix. The zinc coated nano-silica filled LDPE was found to have 26% higher elastic modulus than the uncoated version and 58% higher elastic modulus. In addition, the coated nano-silica filled nanocomposite was found to be more thermally stable as indicated by TGA thermograms. AFM surface topography of the nanocomposite showed agglomerated particles which were not observed in the case of the coated silica nanocomposites, and more uniform surface and lower roughness was observed in the coated nano-silica composites. 21 refs.

Title: TOUGHENING OF POLYCARBONATE WITH ORGANIC-INORGANIC HYBRID MATERIALS
Page Range: p.291-300
Author(s): Zhiyi Zhang; Ning Zhao; Wei Wei; Dong Wu; Yuhan Sun
File size: 281K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 14
Issue No: No. 3

Abstract
Polycarbonate was modified with acrylic polymers to increase its impact strength. However, bending and tensile strength decrease as a result. In order to compensate for this, inorganic nanoparticles were added as modifiers. In addition to improving impact, bending and tensile strengths, the alloys exhibited lower melt viscosities and processing temperatures than polycarbonate. SEM results indicated that the inorganic particles (silicon dioxide, calcium carbonate, montmorillonite) and the acrylic ester polymer were all dispersed in the polycarbonate matrix, forming a co-continuous phase. 41 refs.

Title: PREPARATION AND CHARACTERIZATION OF EVA/MMT NANOCOMPOSITES
Page Range: p.301-306
Author(s): Qianping Ran; Hongyan Hua; Yan Tian; Shishan Wu; Jian Shen
File size: 94K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 14
Issue No: No. 3

Abstract
Polymer-layered silicate nanocomposites provide improved properties as compared to conventional filled microcomposites. In this paper, the montmorillonite was treated with hexadecyl trimethylammonium bromide (CTAB) swelling agent and then dispersed in EVA by melt intercalation to form EVA/MMT-CTAB nanocomposites. Their structures and properties were studied by FTIR, XRD, TGA, the Molau test, and tensile and tear strength measurements. The results showed that those silicate layers of MMT treated with the swelling agent were dispersed in the EVA matrix on a nanometer scale, and that intercalated EVA/MMT-CTAB nanocomposites had superior mechanical and thermal properties. 13 refs.

Title: FINITE ELEMENT SIMULATION ON THERMOFORMING ACRYLIC SHEETS USING DYNAMIC EXPLICIT METHOD
Page Range: p.307-328
Author(s): Dong Y; Lin R J T; Bhattacharyya D
File size: 1106K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 14
Issue No: No. 3

Abstract
Studies are carried out with the help of a dynamic explicit finite element software package, PAM-FORM, to understand the thermoforming mechanisms of a polymeric sheet and their effects on the final geometry. A hyperelastic constitutive law based on the Mooney-Rivlin model was successfully adopted to carry out the initial simulation on bubble inflation and to identify the material parameters. A good agreement of the deformation profile with the experimental results was found. Further investigations were concentrated on the thickness distribution analysis and the strain states of the bubble inflation along with a comparison with the results from kinematic Grid Strain Analysis. The numerical simulation of pressure forming of a cup, whose forming mechanisms were explained reasonably well with the available Williams' analytical solutions, is also presented. The adaptive mesh refinement scheme was used in the simulation of thermoforming a complex-shaped rectangular container to predict the wall thickness distribution. The final simulation results of the deformation at different stages of the forming process and the analyses of final part geometry are also included. 29 refs.

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