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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The density of a rotomolded part can be directly related to several physical properties such as impact, flexural modulus and tensile strength. Depending on the rotomolding conditions, the part will have a range of these physical properties. Part or as is" density can help predict the performance of the final product. This paper will provide the link between the aforementioned physical properties and the rotomolded part density."
Polyethyleneterephthalate (PET) is widely used as a molding material, but increase in its uses has been limited by a tendency of the parts to distort in shape over long periods of time. These changes appear to be due to slow crystallization rate. In order to improve dimensional stability, experiments on the optimum drying condition on the rate of crystallization by adding polypropylene (PP) and TiO2 as nucleating agents and on the melt processing conditions were performed. DSC, WAXD and the Cone and Plate Rheometer were used.
Jim Fogarty, Dave Fogarty, Chris Rauwendaal, Antoine Rios, May 2001
This paper introduces a new screw design concept for foam extrusion developed recently (1, 2). This patented screw design achieves more efficient mixing and heat transfer allowing significant improvements in output rate and product end quality. First the Turbo-Screw geometry will be explained. Second, results from actual foam production operations will be discussed. Third, a 3D numerical analysis of flow in the Turbo-Screw will be described.
A flexible foam material having a high service temperature has been extruded from a blend of a low-density polyethylene resin and a syndiotactic polypropylene resin. Owing to its slow rate of crystallization, a syndiotactic polypropylene resin does not interfere with foam expansion of the polyethylene resin but provides the foam the desired temperature resistance by in-situ crystallization.
The dynamic torque for a 63.5-mm extruder was measured with a Wheatstone strain-gage bridge attached to its single-stage screw between the drive and flow channel. Measurements were made of torque for three resins: (1) LDPE pellets, (2) PET pellets, and (3) PET powder. The results show that the dynamic torque of each resin is unique, and that it depends upon screw speed and on solids' conveying barrel-metal temperature.
The focus of this paper is how creativity and innovation spurred new growth as management learned to fit the organization to the task, mission and culture of the company. Exploring ways leading industry companies are forging into the future with amazing results. This paper will address first, the environment needed to build and sustain creativity and innovation. Second, the methods companies are utilizing to stimulate that creativity and innovation.
John R. Collier, Simioan Petrovan, Bijan Seyfzadeh, Parag Patil, May 2001
Processing of polymer melts and solutions is strongly influenced by both shear and elongational rheology. Molecular weight, molecular weight distribution, degree of branching, branch length and their distribution on the host chain are influential on both. In this work the elongational viscosity and first normal stress coefficient are related to molecular parameters of some polyolefins.
Nylon-6 pellets were compounded with glass fibers in a twin-screw extruder and the resulting pellets were reprocessed for four times through twin-screw extrusion. Collected samples were injection molded and izod impact and tensile tests were performed. Also, fiber length distribution curves were obtained. Results showed that beyond a certain length, fiber attrition is almost stopped and the mechanical properties reach asymptotically low values.
Polybutylene terephthalate was reinforced by 10-40% of short (0.5 mm) and long (10 mm) glass fibers, using a range of process conditions to prepare test samples. Harsher process conditions gave shorter final fiber lengths. Tensile modulus and notched Izod impact strength correlated with glass fiber length and concentration.
Stress-relaxation behavior of various polyolefin films has been studied. It has been proved that the stress-relaxation technique is a more sensitive tool than usual tensile tests when discussing anisotropy in machine and transverse directions. An influence of irradiation dose on the relaxation time spectrum has been demonstrated. The relaxation behavior of three layer composite film has been studied. It was shown that the relaxation behavior of composite film can be predicted if one knows the relaxation time spectrum of each layer.
The world markets for the polyolefins, polyethylene and polypropylene are reviewed. The relative economics of these polymers in the US market are then reviewed to provide a background to assist the reader in forecasting possible future economic trends.
In this study we examine the use of a combination of CO2 and 2-propanol (PrOH), as blowing agents for PMMA foam. Gaseous CO2 was dissolved in liquid PrOH, allowing for injection of a homogenous liquid mixture into the extruder. The advantage of such a system is that the CO2/PrOH ratio remains constant, and the mixture can easily be metered with a suitable pump. The PMMA foamed with this equilibrium mixture was similar to foams prepared with separately injected CO2 and PrOH.
Besides improvements in the optical and mechanical properties as well as carrier-functions for conductive metal layers, the functionality of polymers in electronic applications can be extended through addition of specific fillers. Thereby, the properties of the filled polymer can approach those of the filler, Table 1. Compounding magnetizable fillers into a polymer matrix allows for the rational manufacture of more complex permanent magnets with improved material characteristics by the injection molding process.
Present-day blending technology was developed primarily to forcibly melt and mix polymers and additives. Desired morphologies are often pursued by time consuming iteration. In this study, a new continuous flow blending process is described where morphology develops progressively and more controllably by chaotic mixing. A variety of commercially important blend morphologies, including very highly multilayered blends, are described that have been extruded. The process may serve as a basis for new blending and multilayer film technologies.
B. Seyfzadeh, D.A. Zumbrunnen, R.A. Ross, May 2001
An engineering model was developed to predict the debris particle deposition of a non-Newtonian melt in an extrusion filter medium. The model is based on mass conservation in a three-dimensional finite volume space in conjunction with a power law modified Darcy's equation for porous media flows. Validation was performed by comparison to start-up pressure drops across filter media employed in fiber spinning. Parametric studies revealed the influence on debris deposition of various filter housing contours and power law indices.
A technique is described that enhances the ASTM D5397 Constant Tensile Load (CTL) test by replacing the standard type L" dogbone specimen with a Compact-Tension (CT) specimen. By measuring the center-line crack opening displacement (COD) of the CT specimen while stressed under a test solution one can describe crack growth properties in terms of a stress intensity factor (K) and estimate a corresponding crack growth rate."
For the task of designing cooling parts of a cable coating line, it is very helpful to use modeling of the temperature behavior of the product in cooling line. This presentation shows two models, which can be used for numerical simulations. Authors also deal with the question, if the heat flux in direction of the movement is negligible. The comparison of results of simulated cases and measurement on real coated cables is shown.
Paul Elkouss, Rajath Mudalamane, Yue Huang, Keita Broadwater, David Bigio, May 2001
The effect of operating and feeding conditions on the impact modification of Nylon 6,6 with Poly-Olefin Rubber Impact Modifier (POIM) were studied. The results indicated that the notched izod values are uniformly higher for the samples with POIM fed separately downstream than those of the preblended samples. The notched izod values also show a slight correlation to the throughput, Q. The existence of a critical interparticle distance was verified by image analysis.
As melt flows from the barrel of a capillary rheometer into a die the streamlines converge, producing a strong extensional flow. The entrance pressure loss is determined with orifice die and Bagley correction. The failure of the measurement with orifice die like outlet angle and length of the die is evaluated and extensional viscosity is calculated using the theory of Cogswell. The results of extensional viscosity will be compared with Rheotens elongation data.
The current system of injecting hot polymer into a comparatively cold mold results in the development of a solidified layer and reduction in part quality. As a consequence of this process limitation, molding systems continue to produce inferior components during production. This paper develops an innovative mold design and preheating process to dynamically control the temperature at the mold-polymer interface during the molding cycle. Simulation indicates that a preheat system can significantly reduce residual stress compared to conventional molding given equivalent cycle times.
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Any article that is cited in another manuscript or other work is required to use the correct reference style. Below is an example of the reference style for SPE articles:
Brown, H. L. and Jones, D. H. 2016, May.
"Insert title of paper here in quotes,"
ANTEC 2016 - Indianapolis, Indiana, USA May 23-25, 2016. [On-line].
Society of Plastics Engineers
Available: www.4spe.org.
Note: if there are more than three authors you may use the first author's name and et al. EG Brown, H. L. et al.
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