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.
The SPE Library is just one of the great benefits of being an SPE member! Are you taking advantage of all of your SPE Benefits?
Conference Proceedings
MECHANICAL TESTING OF POLYPROPYLENE MATERIALS IN SHEAR ANALYSED BY DIGITAL IMAGE CORRELATION
H. Daiyan | F. Grytten | E. Andreassen | R. H. Gaarder | H. Osnes, November 2011
Three polypropylene-based materials (two talc-filled compounds and one unfilled homopolymer) were tested with two in-plane shear test methods (Iosipescu and V-notched rail). The three materials behaved differently in the shear tests. Most notably, cracks developed in tension near the notches for the particle-filled materials, while the unfilled homopolymer did not fracture. There were also differences between the materials regarding strain localisation between the notches, and thickness change in the sheared section. The stress-strain curves obtained with the two shear tests were quite similar.
MATERIAL MODELLING FOR SIMULATING IMPACT LOADING OF INJECTION-MOULDED POLYPROPYLENE PARTS
E. Andreassen | H. Daiyan | F. Grytten | O. V. Lyngstad | H. Osnes, November 2011
This paper describes the calibration and verification of a material model used in the numerical simulation of mechanical loading of plastic parts. The material model features strain rate dependent yield stress, pressure dependent yield stress, plastic dilatation and damage. The model was calibrated with data from tests in uniaxial tension, shear and uniaxial compression, utilising 3D digital image correlation for full-field displacement measurements. Two load cases were simulated; centrally loaded clamped plates and three-point bending of bars. The predictions of force vs. deflection were good to fair. The results are discussed in terms of deficiencies of the calibration data, heterogeneity and anisotropy of the injection-moulded components, and shortcomings of the model.
EVALUATING THE REACTIVE BLENDING OF PET/PEN IN A TWIN-SCREW EXTRUDER: AXIAL DISPERSION MODEL
Khonakdar HA | Golriz M. | Abedini H. | Wagenknecht U. | Heinrich G., November 2011
The transesterification of PET and PEN in a twin-screw extruder (TSE) was investigated. A theoretical model, able to predict the extent of transesterification reaction (X) and degree of randomness (RD) against processing parameters along the screw axis is presented. PET/PEN blends were prepared via the melt mixing process. The axial dispersion model (ADM) was developed for modeling the twin screw extruder. Extent of transesterification reaction and degree of randomness was examined via Nuclear Magnetic Resonance Spectroscopy (H-NMR). Theoretical and experimental results were in good agreement, allows the prediction of the X and RD as a function of processing parameters such as time, temperature and composition.
LIFETIME PREDICTION IN ENGINEERING PLASTICS - LIMITATIONS OF SHORT-TERM TEST EXTRAPOLATIONS
Kalyan Sehanobish | Alexander Chudnovsky | Wen Zhou | Haiying Zhang, November 2011
Using short term tests to predict future outcomes of any long term process is common in extrapolation techniques in Science, Social science and Engineering. However, in every process it is important to ascertain some sort of criterion before extrapolation techniques are employed. The criteria for predicting lifetime of an engineering plastics for the specific application must include the requirements of the test to (a) reproduce the mechanisms of field failures and (b) have a technically sound procedure for extrapolation of a the relatively short test data. We will finally propose a quantitative modeling approach as an alternative to “empirical” extrapolation.
POLY(LACTIC ACID) – INVESTIGATION AND MODIFICATION OF MECHANICAL BEHAVIOR
Balázs Imre | János Móczó | Károly Renner | Béla Pukánszky, November 2011
Both industrial and scientific interest in poly(lactic acid) (PLA) increased in recent years for various reasons; hopes are rising that this material may represent an alternative to commodity polymers. In order to answer these expectations, thorough characterization and modification of poly(lactic acid) is necessary. The actual presentation focuses on the mechanical properties, especially the impact resistance of PLA. Attempts were made to improve this characteristic by blending with both rigid and elastomeric polymer grades. The blends were characterized with various techniques in order to compare toughening methods in these systems, and enlighten the relationship between interactions, structure and macroscopic properties.
CHEMICAL DEGRADATION DRIVEN CRACKING IN PE PIPES
Byoung-Ho Choi | Alexander Chudnovsky | Zhenwen Zhou | Kalyan Sehanobish, November 2011
Stress corrosion cracking (SCC) in polyolefin pipes usually starts as a microcrack colony within a degraded layer adjacent to the pipe surface exposed to combine action of mechanical stress and chemically aggressive environment. One can distinguish four stages of SCC: 1) microcracks initiate within the degraded polymer; 2) slow growth of individual cracks; 3) strong interaction of cracks and formation of clusters; and 4) clusters growth and crack/or cluster instability leading to the ultimate failure. The stage of crack initiation is primarily controlled by chemical degradation, and the second stage is strongly related with the effect of mechano-chemical degradation at process zone. The interaction of multiple cracks and clusters are typically observed after the many cracks grow individually. In this paper, the mechanism of crack initiation and growth due to mechano-chemical degradation is addressed and modeled.
AUTOMOTIVE SUNROOF SYSTEMS AND FRAMES IN XIRAN® SMA/ABS
Henri-Paul Benichou, November 2011
Automotive Sunroof Systems, which have become a must have for the added comfort and styling to today s cars, increasingly rely on engineering plastics functionalities to replace metals. Structural and semi-structural Sunroof module components, Sunroof frames in particular, typically need to meet a wide range of technical requirements, with a clear focus on integration of functions, safety, cost and weight reduction. The glass-reinforced materials, thermoplastics and thermosets, currently used for Sunroof frames are mostly based on PBT/ASA, PBT, PA, PP and unsaturated polyester SMC. These products are not a perfect match for the application needs of today and the future. Glass-reinforced SMA/ABS on the other hand offers an ideal, unique combination of properties required in Sunroof frames and systems. SMA/ABS-GF compounds such as Polyscope s Xiran® SG grades have clear technical and commercial benefits: • high dimensional stability and precision • very low warpage, compliance to mold cavity shape • good performance at low wall thicknesses • high creep resistance • excellent adhesion without surface treatment • low density, high economic value • good chemical resistance • easy recyclablility with efficient waste streams.
CARBON FIBRE REINFORCED LLDPE DEVELOPED FOR LIGHTWEIGHT APPLICATIONS BY TREATING THE FIBRES WITH A NEW TYPE OF COUPLING AGENT
Cs. Varga | L. Bartha | H. Szakács, November 2011
Scope of our work has been development of a new type of coupling agent by which processing of long carbon fibre reinforced composites by injection moulding will be possible since hindering the fibres from breakage and simultaneously improving the mechanical properties. Resistance of LLDPE of 1-10% carbon fibres against tensile and flexure stresses has been investigated. Tensile strength has increased by 30% and flexure strength has gained 90% related to the neat polymer. Fibre/matrix interaction has been studied on SEM graphs and a polymer layer has been observed to be connected to the fibre in additive treated fibre containing composites.
Ultraprecision Grinding of Aspheric Cemented Carbide Lens Mold for Plastic Injection Molding
Akihiko Nemoto | Hiroshi Ito | Yasuhiko Murata | Nobuhide Ito | Hitoshi Ohomori, November 2011
To cope with increasing demands on ultraprecision profiling and finishing of aspheric lens molds, we have implemented an ultra nanoprecision aspheric grinding system to be mounted with an ELID(ELectrolytic Inprocess Dressing)-capability and on-line feedback capability of profile accuracy. A cemented carbide mold has successfully ground and finished to be with several nanometric surface smoothness and with ultraprecise profile accuracy by just grinding process with ELID mechanism. Some specific conditions have been investigated to achieve better accuracy and quality on molds. This paper presentation introduce those R&D activities and also discuss on the latest achievements on this topics, with showing injected aspheric lenses by the molds.
ACOUSTIC TRANSMISSION PROPERTIES OF PLASTICS COMPOUNDS
Peter Allan | Ali Ahmadnia | Rob Withnall | Jack Silver, November 2011
Acoustic properties of polymer compounds are an important consideration for many applications. Currently there is a standard test method for the determination of the sound impedance and absorption properties of materials but there is no such test for the property of sound transmission loss (STL). The equipment used for the impedance and absorption standard test can, however, be adapted to measure the sound transmission property. The objective of this project was, therefore, to assess this testing method for STL and to carry out an initial investigation on the relationship between the structure of plastic compounds and their acoustic transmission property.
PHYSICAL FOAMING OF POLY(LACTIC ACID) – PROCESSING AND PROPERTIES
Age Larsen | Christoffer Neldin, November 2011
We describe the steps necessary to establish a stable extrusion process of physical foaming of poly(lactic acid) (PLA) with carbon dioxide. The low melt strength and poor thermal stability of PLA plays a role in optimizing processing conditions. Up to 10 wt% supercritical CO2 was added. The effect of a chain extender was also tested. Low density, microcellular foams with density down to 20-30 kg/m3 were obtained for three different PLA grades. Foams were characterized by density, cell structure, crystallinity and mechanical compression properties.
MICROWAVE ENHANCED FOAMING OF SELECTED POLYMERIC MATERIALS
Aleksander Prociak | Slawomir Michalowski | Tomasz Sterzyński | Dariusz Bogdal, November 2011
Microwave heating has a number of advantages in comparison to the conventional method due to the ability to heat a part of polymeric material directly through specific interaction of electromagnetic radiation with selected types of materials. Most thermoplastics are relatively transparent for microwave irradiation and they do not absorb microwaves to a sufficient extent to be heated. In such case, enhanced microwave heating can result from the use of fillers such as carbon black. In this paper, the ability of different thermoplastic polymers as polyurethane, poly(vinyl chloride) and carbon black filled polypropylene to absorb microwave irradiation and to be foamed using chemical blowing agents is discussed. The temperature changes of such materials as the heating effect under microwave irradiation with various power were investigated. Selected polymeric materials with additive of chemical blowing agents were foamed under microwave irradiation and the influence of foaming conditions on cell structure and apparent density of porous products was analyzed.
UPGRADING PERFORMANCE OF RECYCLED POLYAMIDE WITH ZEMAC®
Ashok M. Adur, November 2011
Polyamides are widely used in many applications. There is a vast amount of recycled polyamide coming from the carpet and textile and other industries. Due to degradation and loss of viscosity, this recycled polyamide has reduced performance and limited its use. The unique chemistry of alternating copolymers of ethylene and maleic anhydride provide several advantages for upgrading recycled polyamide. This paper discusses the results obtained with compounding prime grade polyamide as well as recycled polyamide with the addition of small quantities of this copolymer and specific property improvements for applications in injection molded compounds.
GRAPHICS ON PLASTICS - A REFERENCE GUIDE
Jodie Laughlin, November 2011
Processes to print, stamp, mark, label or otherwise deposit graphics onto molded plastic products are collectively known as plastics decorating. Given decorating processes, graphic types and production requirements, no single decorating method fits all projects and, conversely, most projects have more than one viable decorating method. For your latest new product design or redesign, one challenge is determining which decorating processes are options. This challenge is an equation of sorts with several factors to consider including: 1. graphics details required; 2. molded plastic part characteristics; and 3. production demands. The following pages guide a discussion of these factors.
MATERIAL TESTING AND QUALIFICATION FOR TODAY’S ADVANCED MEDICAL DEVICES
Len Czuba, November 2011
Although the process of selecting the right polymer for new medical devices has not changed very much in the last 10 to 15 years, the degree of complication seems to have grown exponentially. The variety of specially designed materials, the number of suppliers, some under the same name or others with a new corporate moniker, and the availability of reference databases puts a glut of information into the hands of the design engineers. But how does one successfully navigate through this information and decide on the one material that is best for their particular application. It is much more difficult to find live technical support from either suppliers or from database providers. With staff reductions and department consolidations, many companies have also lost experts from their library of specialists that in the past have led the selection of the optimum polymer for new applications. No longer do companies have the historical databank of material expertise or on-staff resources for guiding new project efforts. The level of experience in many companies is down while the breadth of knowledge is much more focused. This coupled with the evolution of far more complicated devices that often combine advances in multiple new technologies such as conductive polymers, shape memory materials, drug eluting devices and polymers that dissolve in the body all complicate the process of selecting the right polymer for the application. Medical devices designers and engineers are tasked with selecting just the right polymer for their devices; and this requires keeping in mind all the various requirements that must be satisfied including functional requirements, chemical and biological requirements and manufacturing, assembly and sterilization. Collectively, results of the evaluation of the materials used in the construction of medical device and the function of the devices together contribute to what many refer to as the biocompatibility of the device.
RHEOLOGICAL CHARACTERIZATION OF MELT MIXED PCL - MWCNT NANOCOMPOSITES PREPARED AT DIFFERENT MIXING SPEEDS
Petra Potschke | Tobias Villmow, November 2011
Composites of poly(caprolactone) (PCL) and multiwalled carbon nanotubes (MWCNTs) were produced by melt-mixing in a small scale compounder by varying the screw speed between 25 and 400 rpm at a constant mixing time of two minutes. By that, different levels of dispersions, as assessed by quantitative analysis of area ratio of remaining primary agglomerates from light microscopy, were achieved. With increasing screw speed the state of dispersion increases and levels off starting at about 100 rpm. Melt rheological properties were measured in frequency sweeps. Interestingly, distinct differences in the complex viscosity * and the storage modulus G’ were found in dependence on the agglomerate area ratio, whereas the loss modulus G’’ was not much influenced. The storage modulus at 0.1 rad/s initially increased with decreasing area ratios, showing that especially the storage modulus is very sensitive to the nanotubes dispersion state. It increased up to a mixing speed of about 75 rpm illustrating improved dispersion followed by a decrease when further increasing the speed. As GPC investigation showed no significant differences in the degradation of the PCL matrix depending on the rotation speed, the effect of decreasing rheological parameter was assigned to nanotube shortening. Both effects improved dispersion and nanotube shortening are also reflected in the electrical resistivity values of compression molded samples. Here, up to 75 rpm a decrease in resistivity due to the better dispersion was observed, whereas above 75 rpm, where dispersion had leveled off, again an increase was found reflecting the reduction in nanotube aspect ratio. Thus, it could be shown that rheological measurements are suitable to detect differences in the dispersion state in composites with a fixed type of CNTs and concentration but also the effect of nanotube shortening reflected in lower aspect ratios.
Strippability in cable extrusion
E. Calvo González | Jean-Marc Gonnet, November 2011
In cable industry, the ease with which a piece of jacket can be removed (stripped) from insulated multiwires is called strippability. A low stripe force is not only requested by customers and installers but it also makes the cable more flexible. The purpose of this paper is to present a method based on numerical approach to reduce the stripe force for a cable during extrusion. A correlation between the numerical parameter (pressure applied around the wires) and the stripe force measured on samples has been demonstrated afterwards it is used to design future extrusion pressure tooling.
Low Smoke Polyphenylene Ether Blends for Building and Construction and Transportation Applications
K. Sharma, November 2011
Recent statistics on building fires show that smoke and toxic gases emitted due to burning of materials are much more harmful than the fire itself posing serious health hazard and sometimes fatal to the occupants1. It is for this reason, that many governing and regulatory bodies have laid Fire, Smoke and Toxicity (FST) standards for the use of plastics in public buildings and transportation in Europe, as well as the rest of the world. High-end engineering plastics like polysulphones are well known2 for their low smoke and flame retardance performance according to various standards, but their high cost could limit their use in certain areas of application. This work is an attempt to overcome these cost limitations by using an innovative technology and presents the development of a new poly(arylene ether) resin (PPE) based low smoke, flame retardant, halogen free, Noryl® NI-160 I OB resin (from here-on refe1Ted to as PPE+PS blend) that meets many of the FST requirements applicable to building codes and mass transit bodies in Europe and America. PPE resin is usually modified with polystyrene (PS) [ either crystal polystyrene (CCPS) and/or High Impact Polystyrene (HIPS)]. The PPE+PS blend utilizes a proprietary eco-friendly smoke suppressant technology that helps build robust char during its combustion. The robust char is believed to play a role in reducing smoke while maintaining outstanding flame retardancy and low toxicity. In addition, the PPE+PS blend offers advantages in terms of good proccessability, good mechanical and them1al properties, and low specific gravity.
DEFORMATION AND FAILURE MECHANISMS IN POLYOLEFINES AND THE ROLE OF THE ENTANGLEMENT NETWORK
Rudy A.C. Deblieck | D.J.M. van Beek (Linda Havermans) | Klaas Remerie, November 2011
The occurrence of two brittle ductile transitions is explained in terms of craze propagation and craze-crack transition models. The first and most familiar transition occurs at low temperatures and high strain rates and it is linked to chain scission. The other less well known transition occurs at elevated temperatures and low strain rates and is linked to molecular disentanglement. The importance of the entanglement network for these transitions is highlighted. The relation between these transitions and the molecular mobility transitions such as the glass transition and the -relaxation are discussed. Strategies for increasing the crack propagation resistance are reviewed. The present paper is taken from the authors’ feature article that appeared recently.
Noryl GTX for thermal breaks
Jan Matthijssen, November 2011
Aluminum has a high thermal conductivity which make them less suitable for window frames unless the inner and outer skin are separated by a thermal break. Currently glass reinforced Polyamide66 is used for this application. Noryl GTX* however has a thermal conductivity, measured on a extruded sample which is clearly below the thermal conductivity of Polyamide. Noryl GTX is also capable to withstand the high powder coating curing temperatures and meets the mechanical requirements for thermal breaks. By the upcoming, more stringent regulations on energy saving using Noryl GTX will help to meet these requirements.
.jpg)
.jpg)
.jpg)
.jpg)
