SPE Library

The SPE Library contains thousands of papers, presentations, journal briefs and recorded webinars from the best minds in the Plastics Industry. Spanning almost two decades, this collection of published research and development work in polymer science and plastics technology is a wealth of knowledge and information for anyone involved in plastics.

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Conference Proceedings

Helibar® – a Powerful Single Screw Plasticizing System
Eberhard Gruenschloss, May 2007

A single-screw-extruder is presented, consisting of a barrel with grooved feed zone (helical grooves), a grooved melting zone (axial or helical grooves) and a barrier-screw with mixing and shearing elements. Compared with extruders with a smooth melting zone, significant process improvements are achieved regarding mass throughput, pressure build up, melt temperature, melt homogeneity, feed-zone cooling, processing wall-slipping polymers, abrasive wear, residence time, total degree of efficiency and economy. The processing principles of the new extruder are explained. Experimental results confirm the theoretical predictions. The system has proven to be very worth wile in more than 500 extrusion blow molding machines and other extrusion and injection molding applications since the year 1999.

Environmental Stress Crazing in Polystyrene: The Roles of Chain Length and Architecture in Craze Initiation
Davide S.A. De Focatiis, C. Paul Buckley, Lian R. Hutchings, May 2007

This work aims to assist in optimising the solid state performance of polymer products, by developing an understanding of the molecular factors involved in initiation of environmental stress crazing. Experiments measuring craze initiation stress in miniature rectangular beam samples saturated in diethylene glycol were performed on 26 isotropic atactic polystyrenes with molar mass from 66 kD to 1148 kD, including a wide range of monodisperse linear and branched materials. Results indicate that both solid-state molecular disentanglement and chain scission play roles, depending on the chain architecture and length of the polymer. A simple rule is suggested for predicting ESC raze initiation in polydisperse polymers.

The Influence of Fibre Length and Concentration on the Properties of Sisal Fibre Reinforced Polypropylene Composites
Christoph Burgstaller, Wolfgang Stadlbauer, May 2007

In this work we investigated the influence of length and concentration of sisal fibres in PP for injection moulded composites. The fibres were incorporated into the matrix with a co-rotating twin screw extruder, in order to get the different compounds, which were injection moulded subsequently. The actual fibre length was determined after an extraction with xylene. Tensile strength and modulus and Charpy impact properties were measured and the flow curves were recorded with a capillary rheometer. The results show good correlations with the fibre length of the composites, and the tensile strength as well as the notched Charpy impact strength can be evaluated using rule-of-mixture like models.

Sandwich Injection Molding of Polypropylene and Biodegrable Polymer
Yuji Fujita, Toshihiro Yoshida, Hironari Sano, Masaya Kotaki, Hiroyuki Hamada, May 2007

Polypropylene (PP)-based sandwich injection moldings with biodegradable polymers in the core were carried out. A compatibilizing agent and high flow PP were used as modifiers to improve interfacial adhesion between the skin and the core. In order to investigate the interfacial strength between the skin and the core, 180o peel test was conducted whereby the skin was peeled from the core. It was found that the interfacial strength between skin and core was improved by incorporation of modifiers, whose functions were understood by the morphological observation. From the combination of sandwich molding and polymer alloying technologies of this study, the possibility was derived to make products composed of PP and biodegradable polymer.

Generating Alternative Time and Energy Saving Processing Concepts for Rotational Foam Molding
Remon Pop-Iliev, May 2007

The nature of the rotational molding process is cyclic. It requires the temperature of the rotating mold and the plastic it is charged with to be elevated from room temperature to beyond its melting temperature and then cooled back to room temperature. Consequently, rotational molding cycle times are lengthy, which is often considered as the fundamental drawback of this plastic fabrication process. The motivation and objectives of this paper are twofold. First, the presently proposed research focuses on developing an innovative processing technology for the manufacture of integral-skin cellular composite moldings having adjacent, but clearly distinct, layers of non-cellular and cellular structures, consisting of identical or compatible polyolefin grades. Its primary goal is to significantly reduce the processing cycle time in comparison with respective currently implemented technologies.

Analysis and Validation of Mold Design Guidelines for Cooling Time and Runner Sizing
Nivant Zombade, Ryan Bean, Andrew Thompson, David Kazmer, May 2007

Injection molds have been designed over the years using rules of thumb" which have become almost standard guidelines in industry practice. This paper analyzes and validates two common guidelines for 1) estimation of cooling time and 2) determination of runner sizing. The common guideline for cooling time estimation is compared to the analytical solution of the heat equation and found to have a small average error but significance variance across material properties and processing conditions and validated against industry data. A common guideline for runner system design was found to provide very good results compared with optimal designs produced with the Hagen-Pouiselle flow equations."

Preparation and Melt Viscoelastic Properties Study of TPV Nanocomposite Using Peroxide Crosslinking System
A.Jalali, F.Goharpey, H.Nazockdast, A.A.Katbab, May 2007

Dynamically vulcanized thermoplastic elastomer (TPV)/organoclay nanocomposites based on EPDM/PP containing 2, 4, 6% of organically treated montmorillonite were prepared by using EPDM-g-MA and PP-g-MA as compatibilizer. Dicumylperoxide (DCP) and triallyl cyanurate (TAC) were employed as crosslinking system. X-ray diffraction (XRD) analysis has been performed to evaluate the extent of the intercalation.. In this study, attempts have been made to exclusively reinforce rubber dispersed phase. Rheological behavior and melt viscoelastic properties of the samples such as elastic modulus, and elastic response expressed in terms of relaxation time distribution, H (?) , were studied. The results were also supported by differential scanning calorimetry (DSC) and mechanical tests.

The Study of Particle Size and Surface Treatment of next Generation Radiopaque Fillers Used in Bio-Medical Device Applications
Charles J. O’Neil, Lawrence A. Acquarulo Jr., Sunil P. Mirji, Tony Listro, Stephen Burke Driscoll, May 2007

Medical tubing and catheters have revolutionized the medical industry by enabling minimal invasive surgery procedures. The trend in the medical-device industry is thinner walls, especially in critical applications. Extruding smooth surface using micron-sized radiopaque fillers forms a challenge since they can form rough surface due to non-uniform dispersion. An effort was made to study the effects of particle size and surface treatment of radiopaque fillers on the dispersion, rheological and mechanical properties of PEBA at three loading levels. New generation barium sulfate and bismuth trioxide radiopaque fillers were chosen for this study.

The Effect of Nucleation Specificity on Thermal Behaviour of Photodegraded Polypropylene
Jana Výchop?ová, Roman ?ermák, Martin Obadal, Vincent Verney, Sophie Commereuc, May 2007

This work focuses on thermal behaviour of UVirradiated polypropylenes (PP) containing ?- or ?- nucleating agents or their combination. After irradiation the samples were melted, then non-isothermally crystallized and subsequently melted again. It was found that ?-nucleated PP possessed the highest UV-stability. The photodegradation was also suppressed in materials containing ?-nucleating agent. The effect of UVirradiation led to a splitting of crystallization exotherms into two peaks. The strong efficiency of ?-nucleating agent used was reflected by predominant formation of ?- phase in non-irradiated material containing a combination of both ?- and ?-nucleating agents. However, after only 24 hrs of UV-irradiation this effect was reduced and a preferable formation into ?-phase in re-melted material was detected.

Hybrid Tooling Technologies and Standardization for the Manufacturing of Inserts for Micro Injection Molding
G. Tosello, B. Fillon, S. Azcarate, A. Schoth, L. Mattsson, C. Griffiths, L. Staemmler, P.J. Bolt, May 2007

This paper is based on the European Platform’s activities within the 4M Network of Excellence “Multi- Material Micro Manufacturing”. To overpass limitations of the current existing micro tooling capabilities, a new generation of micro hybrid tooling technologies for micro replication was developed. A metrological approach was applied to standardize the employed tooling processes (micro milling, ?EDM, laser micromachining, electrochemical ?-milling). The micro tools were then tested with different polymers (PP, PP + nano fillers, PC, COC). The paper provides a comparison of these technologies concerning obtainable feature sizes, surface finish, and aspect ratios of both micro tools and micro molded parts.

Evaluation of Oriented Polypropylene/Cast Polypropylene Film at the Heat-Sealing Part and the Edge
Yumi HASHIMOTO, Yasuo HASHIMOTO, Yew Wei LEONG, Kazushi YAMADA, Hiroyuki HAMADA, May 2007

Heat-sealing process is often employed in packaging applications of polymeric films, especially for plastic bags. Often, the failure of plastic bags would initiate from a pinhole, crack, and/or the edge near the heat-sealed part. In this study, effects of heat-sealing temperature on mechanical properties of heat-sealing part and the edge of Oriented Polypropylene/Cast Polypropylene films were investigated. Fracture toughness and tear tests were conducted with the heat-sealed Oriented Polypropylene/Cast Polypropylene films. The thermal properties of the heat-sealed parts obtained by differential scanning calorimetry (DSC) were also investigated.

Long-Term Thermal Insulation Performance of Polystyrene Foam Boards with Decay of Blowing Agents
Zhenjin Zhu, Jinho Zong, Chul B. Park, May 2007

This paper studied the long-term thermal insulation performance of polystyrene foam boards with the decay of blowing agents. A transient cell-to-cell diffusion model was developed to predict the decay of blowing agents. The Mie Theory was used to quantify the radiative conductivity. A cubic-parallel-series analogy of electric circuit was employed to acquire the thermal conductivity of gaseous phase and polymer matrix. Thus, the thermal insulation performance was estimated as the blowing agents decayed. The effects of foam morphology and blowing agent type on thermal insulation capacity were examined.

Understanding Melt Rheology & Foamability of PP-Based TPO Blends
F. Gunkel, A.N.J. Spörrer, G.T. Lim, D.S.B. Sampath, V. Altstädt, May 2007

Rubber-toughened PP is an important resin for many engineering applications. By structural foaming, material cost-saving and lightweight structures can be achieved. In this study, physical blends of PP and poly(ethylene/octene) with various compositions were characterized regarding their melt strength and shear viscosity. The high pressure MuCell® foaming process was used to obtain structural foams with average cell diameters of < 50 ?m and cell densities of ~ 8 × 106 cells/cm3. This study presents key correlations between material rheology and its suitability for structural foaming and elucidates how the foaming behavior is linked to blend composition and melt temperature for an optimum system.

A Shrinkage Prediction in Rubber Compression Moulding
Supasit Rodkwan, Watcharapong Chookaew, Nuchanat Na Ranong, Chana Raksiri, Kunnayut Eiamsa-ard, May 2007

One of the common problems found in rubber compression moulding is the shrinkage of rubber products leading to the loss of shape. In this research, an application of artificial neural network in prediction of the rubber product shrinkage in compression moulding is presented. A back propagation neural network was developed to determine the shrinkage based on the variables of the rubber compound, processing variables such as mould temperature and mould sizing. The neural network prediction for an inside diameter shrinkage and a cross section diameter shrinkage indicate that the architectures 5-11-21-1 and 5-11-16-1 provide a good prediction within 95.9% and 96.1% accuracy, respectively.

Functionally Graded Polymer Nanocomposites (FGPNCs) Filled with Nano Sized Filler
Sandeep S. Ahankari, K.K. Kar, May 2007

A novel FGPNCs has been developed using polymer matrix (polyisoprene) and nanomaterials (amorphous carbon). Its performance is evaluated for structural application through storage modulus, loss tangent, tensile strength, modulus, hardness, hysteresis loss, tear strength, SEM, etc. The functionally graded nanocomposites show better properties i.e., modulus, tear strength, hysteresis loss and strain energy density compared to homogeneous composite at the same percentage of nano filler loading. As for examples, 20, 35 and 40% improvement in modulli at 50, 100 and 200% elongation with respect to homogeneous composites are observed where the average nanomaterial is 30% by weight.

Manufacture and Mechanical Characterization of a Composite Material Made of Wasted Tires and Recycled Polyethylenetherephtalate (PET)
R. Mis-Fernandez, J.A. Azamar-Barrios, J. Rodriguez-Laviada, C.R. Rios-oberanis, May 2007

Solid residue was obtained by two processes to reduce discarded tires: pyrolysis and thermal shock. Techniques such as X-ray, FTIR, TGA and SEM were used to characterize the samples. Two types of polyethylenetherephtalate, PET (virgin and recycled) were analysed physicochemical and mechanically to be used as matrix. A composite material was manufactured by employing a Brabender mixing chamber in order to use the granules as filler on PET at different concentrations. The mixed material was laminated and tension test were undertaken in samples to acquire the mechanical properties. Studies of fractography were performed to understand the failure mechanics.

An Optimization of Natural Rubber Injection Molding Process Using CAD/CAE: A Case Study on the Motorcycle Rubber Step
Supasit Rodkwan, Seksan Winyangkul, Kittinan Unnanon, Chana Raksiri, Kunnayut Eiamsa-ard, May 2007

This research aims to apply Computer Aided Design/Engineering (CAD/CAE) techniques for an optimized rubber injection molding condition using a case study of rubber steps used in motorcycles. The input parameters include both physical and mechanical material properties of natural rubber and operating conditions such as gating and runner positions. The simulated variables such as temperature, pressure and velocity profiles were founded and analyzed. The numerical results are correlated well with empirical data using the vertical injection molding machine. This research provides researchers the computational tool to obtain the optimized rubber injection molding.

Relationship between Surface Microstructure and Improved Scratch Whitening Resistance of Thermoplastic Polyolefins for Automotive Applications
Theresa Hermel-Davidock, James Seliskar, James Oelberg, May 2007

This paper will examine the scratch whitening resistance of PP rich, injection molded Thermoplastic Polyolefins (TPOs) for exterior automotive applications. Significant attention will be given to the influence of the molecular architecture of the polypropylene (PP) component on the surface morphology and resultant scratch whitening resistance of the injection molded part. Material parameters and surface crystallinity which contribute to enhanced scratch whitening resistance will be highlighted.

Shape Memory Polyurethane-Clay Nanocomposites
Feina Cao, Sadhan C. Jana, May 2007

In this paper, we present results on shape memory behavior of polyurethane (PU)/clay nanocomposites. These nanocomposites were prepared via bulk polymerization method and contained exfoliated clay particles as revealed by transmission electron microscopy and wide angle X-ray diffraction method. The PU matrix contained a crystalline soft segment, which was responsible for shape fixity. The presence of clay decreased the crystallinity of soft segments and consequently shape fixity, but the magnitude of shape recovery stress increased, e.g., by 20% with only 1 wt% clay. The mechanism of reinforcement was studied by monitoring stress relaxation and phase separation.

Injection Molding Process Optimization Using the Process Monitoring System
Joong-Keun Kang, Hyung Keun Chang, Young-Kee Cho, Byung-Ohk Rhee, May 2007

To make sure the stable state of resin in the process optimization test, the process monitoring system (PMS) was applied in a wide range in this study. For each critical step of the test, the way to utilize the PMS depended upon the phenomenon in the mold and the purpose of the test. The dependent variables such as switchover point and holding time were properly set with the aid of the PMS. Based on the relationship of the state of the resin with pressure and temperature, a new PMS index was proposed. The index showed the best correlation with the part weight among various indices through the correlation analysis.

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