Published by De Gruyter

Volume 27 Issue 4

Issue of International Polymer Processing

Contents
Journal Overview

April 6, 2013

Page range: 405-405

Regular Contributed Articles

April 6, 2013

LLDPE/Proton Exchanged Layered Niobate K₄Nb₆O₁₇ Nanocomposites

H. Otaguro, A. Ruvolo-Filho

Page range: 406-413

Abstract

The potassium hexaniobate was synthesized by reacting, in stoichiometric proportions, Nb 2 O 5 and K 2 CO 3 at 1100°C and modified with octadecylamine from an acid-base reaction. Through X-ray diffraction, an interlayer space of 4.27 nm was observed in comparison with 0.79 nm of unmodified oxide; this was also shown by SEM microscopy. The hybrid nanofiller previously obtained was incorporated into LLDPE by melt intercalation (0 up to 10 wt.%) using a twin screw extruder and LLDPE-g-MAH as compatibilizer. From TGA results, all nanocomposites (LLDPE/LLDPE-g-MAH/lamellar oxide) have increased the onset degradation temperature, while the oxide lost during processing for LLDPE/LLDPE-g-MAH/lamellar oxide nanocomposites was higher for the highest content in comparison with LLDPE matrix. According to the Eyring equation, the activation volume of the samples could be calculated using the relationship between the yield strength and strain rate from tensile stress-strain curves. The activation volume decreased with increase of nanofiller concentration, suggesting a good adhesion between the layered oxide and the polymeric matrix for high concentration. This can be attributed to the restricted segmental motion near the nanofiller/polymeric interface, while a poor interaction between them was observed for low concentration. However, the Young's modulus showed a 50% improvement for low nanofiller concentration, especially in the case of 1 wt.% of nanofiller, which was also confirmed by modulus and toughness balance. Considering all the results, it has been revealed that the proton exchanged layered niobate can improve the thermal and mechanical properties of LLDPE/LLDPE-g-MAH/lamellar oxide nanocomposites.

April 6, 2013

Experimental Flow Visualization and Residence Time Distributions in a Co-Kneader

M. Brito-Bazan, L. Fradette, P. A. Tanguy

Page range: 414-426

Abstract

Flow patterns and residence time distributions have been investigated in a transparent laboratory-scale Co-Kneader with a viscous fluid and different combinations of operating conditions. An image analysis technique, already successfully applied in stirred tanks, has been applied here for the first time in a continuous system. The flow visualization results are presented as mixing curves, which show quantitatively the evolution of the macromixing along the Co-Kneader. It has been found that the image analysis technique gives new insight into the mixing mechanism of the Co-Kneader and may be used as a simple experimental method to quantify the degree of backmixing. Residence time distributions have been used to obtain axial dispersion coefficients. A comparison of the cumulative distribution functions between different systems is also presented.

April 6, 2013

Mechanochemical Milling of PP/Ground Tire Rubber Blends in Solid-State

A Cost-Effective Strategy for the Recycling of Tires

X. Zhang, Z. Zhou, X. He, J. Li, C. Lu

Page range: 427-433

Abstract

In this study, solid-state mechanochemical milling was investigated as a viable strategy to produce high performance blends composed of polypropylene (PP) and ground tire rubber (GTR), thereby providing a potentially new route to recycle discarded tires. The improved dispersion of the blends after mechanochemical milling was confirmed by fluorescence microscopy and polarized optical microscopy (POM) observation. After 20 cycles of milling, the tensile strength of PP/GTR (100/40) blends was enhanced by 13.8%, and the elongation at break was over 12 times than that of the unpretreated blend. The formation of smaller and less ordered spherulites of PP after mechanochemical milling as confirmed by POM observation and wide-angle X-ray diffraction analysis might be the reason for the significant enhancement of the elongation at break.

April 6, 2013

Development of Polymer Extrusion Extruder for Evaluating with a Small Amount of Polymeric Material

Evaluation of Shear Viscosity and Processability of Film

H. Uematsu, S. Tanoue, Y. Iemoto, M. Sugimoto, T. Taniguchi, K. Koyama

Page range: 434-441

Abstract

We developed the extrusion system to evaluate the extrusion behavior such as the shear viscosity, which is one of basic properties, and the processability of mono/multilayer film with a small amount of polymeric material. In order to measure the shear viscosity, the gear pump, the return path and the pressure sensors were introduced into the extruder with intermeshing co-rotating twin screws. The viscosity could be evaluated on-line from the volumetric flow rate of molten polymer and the pressure drop in the return path before film processing. The capacity of gear pump, the shape and size of return path were optimized to evaluate the viscosity of polymeric material, which generally undergoes shear rate of 10 ∼ 1000 s −1 in the film processing. The apparatus for mono and multilayer film processing consisted of two extruders including the multichannel feedblock and T-die with the manifold and land section. The compact feedblock was designed to receive two feedstreams, so that the product can have two layers. We investigated the on-line viscosity measurement methodology and the processability, which is the neck-in phenomenon for monolayer film and the interface stability for multilayer film, using typical polymer material of 30 grams at once. The viscosity evaluated with our system corresponded with the result of commercial rheometer. It was also confirmed that the processability of mono and multilayer film could be evaluated quantitatively with our system.

April 6, 2013

A 3D Simulation Analysis of Reactive Flow in Screw Elements of Closely Intermeshing Twin Screw Extruders

Scale-up Calculations

E. Ortiz-Rodriguez, C. Tzoganakis

Page range: 442-451

Abstract

The peroxide-initiated degradation of polypropylene in conventional screw elements of closely intermeshing twin-screw extruders is analyzed by means of a three-dimensional (3D) simulation approach. The 3D simulations of the reacting flow are implemented under the assumption of steady-state flow conditions, and scale-up considerations are addressed by simulating screw elements of two different size extruders. The effects of the initial peroxide concentration and reference mass throughputs on processing parameters are analyzed in terms of the specified extruder size. In this study, the scaled-up mass throughput is determined under the assumption of constant residence time. For the implemented processing conditions, the final values of the weigh-average molecular weight (Mw) and polidispersity index (PDI) for both the reference and scaled-up screw elements are similar when the flow rate is close to that corresponding to the maximum conveying capacity of the screw elements. For more restricted flow conditions, however, lower values of both the Mw and PDI are obtained for the larger screw element. Additionally, a previously proposed scale-up procedure from one-dimensional (1D) simulations is evaluated by means of a 3D simulation analysis. The results of this evaluation show a good agreement between the trend of the 3D and 1D simulation results.

April 6, 2013

Morphology and Mechanical Properties of Compatibilized Bio-sourced PA/Plasticized Starch Grafted PP Ternary Polymer Blends

F. Teyssandier, P. Cassagnau, J. F. Gérard, N. Mignard

Page range: 452-460

Abstract

Polymer blends of biosourced polyamide (Rilsan XD) and thermoplastic starch grafted polypropylene (LAB4270) were processed by means of a co-rotating twin-screw extruder, using a solid epoxy resin (D.E.R. 664UE) as a compatibilizer. Morphologies as well as rheological, thermal and mechanical properties of the blends were characterized. The morphology of the reference blend was characterized by nodules of the micron order of magnitude of the dispersed phase (LAB4270) embedded in the polyamide matrix. Even though the morphologies of the blends were not impacted by the addition of the epoxy resin, the mechanical properties as well as the impact resilience were proved to be enhanced. The thermal properties of the blends were as well influenced. A shift of the crystallization temperatures and a decrease of the crystallization enthalpies of both the polypropylene and the PA XD were observed. Thus the addition of the epoxy resin as compatibilizer had proved to be truly effective to obtain a material mostly biosourced with mechanical properties that tend towards combined optimal properties of the different components of the blend.

April 6, 2013

Preparation and Characterization of Polyurethane/Polysulfide Miscible Blend Nanocomposites

Effect of Nanoclay Reinforcement on Morphology, Mechanical and Thermal Properties

P. K. Guchhait, M. Rahaman, L. Nayak, T. K. Chaki

Page range: 461-468

Abstract

Novel elastomeric miscible blend nanocomposites have been prepared by co-reacting isocyanate terminated liquid polyurethane pre-polymer with thiol terminated polysulfide together with chain extender, modified organic nanoclay, and curator. The studies report the influence of nanoclay loading on the morphology, mechanical and thermal properties of the nanocomposites. The morphology and state of dispersion of nanoclays in the nanocomposites were studied by high resolution transmission electron microscopy (HRTEM). It was seen that nanoclay particles were well dispersed in the blend at 1, 3, and 5 wt.% nanoclay loadings. The reactive miscibility of blend was confirmed by differential scanning calorimetry (DSC) and fourier transform infrared spectroscopy (FTIR). The effect of clay loading on thermal stability of polysulfide PS/IPU blend and their nanocomposites was studied by thermogravimetric analysis (TGA). It was observed that thermal stability of nanocomposite progressively increased with increase in nanoclay loading. However, about 123% increment in adhesive strength, 78% increment in tensile strength were observed at 3 wt.% clay loaded nanocomposite when compared to control blend. This enhancement in thermal, adhesion and mechanical properties demonstrate that the resulting nanocomposites can be tailored as novel adhesive and coating materials for aerospace application.

April 6, 2013

Modelling the Solids Throughput of Single Screw Smooth Barrel Extruders as a Function of the Feed Section Parameters

J.-S. Leßmann, R. Weddige, V. Schöppner, A. Porsch

Page range: 469-477

Abstract

In a smooth barrel extruder, the throughput is generally dominated by the metering sections pumping ability. Within the feed zone, more granules can always be conveyed than can melt in the compression zone and be discharged in the metering zone. At high screw speeds, this effect will only occur if the granules flow quickly enough out of the hopper into the screw channel and this is fully filled. In this case, the solids throughput up to maximum screw speed shows an approximately linear relationship to the speed. These linear solids conveying characteristics necessitate constructional changes to the hopper opening. In this article, solids conveying processes with approximately linear conveying characteristics up to speeds of 2,000 min −1 (peripheral velocities up to 3 m/s) are simulated with various feed hopper geometries. The simulations are carried out by means of DEM (Discrete Element Method) in which the granules are approximated by single spherical particles. From the simulation results, via dimensional analysis a model is derived for describing the throughput as a function of the geometry and process parameters of the solids feed zone.

April 6, 2013

Experimental Investigation and Theoretical Prediction of Extrudate Swell Using Conformational Rheological Models

M. K. Yazdi, A. Ramazani S. A., H. H. Amoli, A. Kamyabi

Page range: 478-485

Abstract

In this study the extrudate swell of polymer solutions is estimated using the microstructure of polymer molecules. When a flexible polymer chain goes through a narrow die shear stress exerting on the chain will cause the polymer chain to be stretched along the flow direction. After emerging from die all external stresses vanish immediately and the chains tend to recover their previous state due to elastic recovery. This phenomenon will results in a gradual increase in extrudate diameter and this is used as the key idea for estimating swell ratio. A Giesekus based conformational model was used in order to predict polymer chains microstructure everywhere in the domain. The resulting PDE set including, continuity, momentum, and conformational rheological model were solved using a finite volume method with the OpenFOAM software. Numerical results were compared with experimental data which were obtained for aqueous solutions of Carboxymethylcellulose. It was found that model predictions are in good agreement with experimental data. The results were also compared to results which were obtained by the Tanner relation which underestimates experimental data.

April 6, 2013

Controllable Self-organization of Polyphenylene Oxide Honeycomb Microstructure

H. Chen, X. Shang, D. Zhang, I. Hagiwara

Page range: 486-492

Abstract

Polymer films with patterned microstructure have been widely applied in various industrial areas such as micro reactors, chemical sensors and micro-molded template etc. In this paper, a self-supporting polymer film with regular honeycomb microstructure is fabricated by self-organization via evaporation of polyphenylene oxide (PPO) solution in which carbon disulfide is used as solvent under humid ambience. Apart from investigation of self-organization mechanism of PPO honeycomb including nucleation, growth of water droplets condensed upon liquid supporting substrate, the quantitative relationship between honeycomb microstructure and ambient conditions is built through tremendous self-organization experiments. The controllable formation of honeycomb microstructure with desirable hydrophobicity was achieved by use of built quantitative relationship. Moreover, hydrophobicity mathematical model of self-organized honeycomb thin film was proposed, and its validation was experimentally verified.

April 6, 2013

An Investigation on Usage of Sodium Borohydride and Zinc Oxide as Oxygen Scavengers in Polyethylene Terephthalate Films

İ. Özen

Page range: 493-497

Abstract

The aim of this work is the production and characterisation of a plastic film having active oxygen barrier properties. The films have been obtained by adding an oxygen scavenger (either sodium borohydride (NaBH 4 ) or zinc oxide (ZnO)) into a polyethylene terephthalate (PET) matrix during the extrusion process. In order to investigate the activity of the scavengers used, the produced films have been subjected to permeability measurements. It was revealed that NaBH 4 – though a strong reductive agent – didn't cause any degradation in matrix polymer but served as an ineffective oxygen scavenger as in the case of ZnO.

PPS-News

April 6, 2013

PPS News

Page range: 498-498

Seikei Kakou Abstracts

April 6, 2013

Seikei-Kakou Abstracts

Page range: 499-499

About this journal

International Polymer Processing offers original research contributions, invited review papers and recent technological developments in processing thermoplastics, thermosets, elastomers and fibers as well as polymer reaction engineering. For more than 25 years International Polymer Processing, the journal of the Polymer Processing Society, provides strictly peer-reviewed, high-quality articles and rapid communications from the leading experts around the world.
All articles are subject to thorough, independent peer review.
Editor: Polymer Processing Society

Volume 27 Issue 4

Issue of International Polymer Processing

Contents

LLDPE/Proton Exchanged Layered Niobate K4Nb6O17 Nanocomposites

Abstract

Experimental Flow Visualization and Residence Time Distributions in a Co-Kneader

Abstract

Mechanochemical Milling of PP/Ground Tire Rubber Blends in Solid-State

A Cost-Effective Strategy for the Recycling of Tires

Abstract

Development of Polymer Extrusion Extruder for Evaluating with a Small Amount of Polymeric Material

Evaluation of Shear Viscosity and Processability of Film

Abstract

A 3D Simulation Analysis of Reactive Flow in Screw Elements of Closely Intermeshing Twin Screw Extruders

Scale-up Calculations

Abstract

Morphology and Mechanical Properties of Compatibilized Bio-sourced PA/Plasticized Starch Grafted PP Ternary Polymer Blends

Abstract

Preparation and Characterization of Polyurethane/Polysulfide Miscible Blend Nanocomposites

Effect of Nanoclay Reinforcement on Morphology, Mechanical and Thermal Properties

Abstract

Modelling the Solids Throughput of Single Screw Smooth Barrel Extruders as a Function of the Feed Section Parameters

Abstract

Experimental Investigation and Theoretical Prediction of Extrudate Swell Using Conformational Rheological Models

Abstract

Controllable Self-organization of Polyphenylene Oxide Honeycomb Microstructure

Abstract

An Investigation on Usage of Sodium Borohydride and Zinc Oxide as Oxygen Scavengers in Polyethylene Terephthalate Films

Abstract

PPS News

Seikei-Kakou Abstracts

LLDPE/Proton Exchanged Layered Niobate K₄Nb₆O₁₇ Nanocomposites