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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Foam Extrusion of Syndiotactic Polypropylene-Polyethylene Blends
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.
Dynamic Torque of a Single Screw Extruder
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.
New Growth Engines in Leading Industry Companies by Creating an Environment for Innovation
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.
Dispersion of Nanoparticles in High Performance Polymers Using Thermosetting Resins
A low molecular weight epoxy was used as dispersant of fumed silica in polyether sulphone (PES), a high performance polymer with typical processing temperatures of ~340-380°C. Small amounts of low molecular weight epoxy reduced the processing temperatures of PES by as much as 100°C and, due to polar nature, helped disperse fumed silica particles, which contained active silanol groups. Epoxy molecules were later crosslinked using suitable curing agents. An order of magnitude reduction in the size of dispersed fumed silica particles and significant improvement in HDT were observed.
Shear and Elongational Rheology of Some Polyolefins of Different Molecular Parameters
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.
Effects of Reprocessing on the Fiber Length and Mechanical Properties of Nylon-6/Glass Fiber Composites
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.
Glass Fiber Reinforcement of Polybutylene Terephthalate
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 of Oriented Polyolefin Films
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.
Review of World Polyolefin Markets
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.
Foaming PMMA with an Equilibrium Mixture of Carbon Dioxide and Isopropanol
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.
Rational Integration of Magnetizable Polymers for Sensor Applications
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.
On-Line Morphology Control and Novel Extruded Blends Produced by Continuous Flow Chaotic Mixing
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.
Non-Newtonian Flow and Debris Deposition in an Extrusion Filter Medium
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.
Use of the Compact Tension Specimen to Study ESCR in Polyethylene
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."
Cooling of Coated Cable
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.
Visualization of Polymer Blends Processing
The blending process of two blend systems, polystyrene/polypropylene (PS/PP) and poly(ether imide)/polycarbonate (PEI/PC), are studied by visualization of blending in an internal mixer. The study shows that higher RPM and higher barrel temperature accelerated the melting and blending process. For PEI/PC blends, the composition of PEI has no effect on the time for melting of PEI pellets. Times for softening PEI to a dough-like material at 340°C and 50rpm is 30s and to completely melt it is 40s. SEM photos and DSC data verify the visualization result that PEI/PC blends are partially miscible at higher PEI compositions.
Impact Modification of Nylon 6,6-An Experimental Study
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.
Extensional Flow Properties from Entrance Pressure Measurements Using Zero Length Die Versus Bagley Correction
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.
New Technique to Reduce Wall Thickness Tolerances in Pipes
Conventional pipe dies normally have no means to get rid of unsymmetrical differences of the local melt stream around the circumference of the die. Solutions to locally change the die temperature in order to influence the flow distribution are limited to dies with great diameters. But this creates undesirable differences in the temperature of the melt and causes trouble concerning straightness of the pipes. Integrating an elastic outer tubing into the die allows to locally alter the gap of the flow channel at the die exit. The theory of the technique and first practical results attained on a production line are described.
Dynamic Cooling Design for Injection Molding
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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