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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Computer Simulation of Plastics Compounding Operations in Twin-Screw Extruders
This presentation is concerned with the development of process simulators for the analysis of compounding operations in modular corotating intermeshing twin-screw extruders. Approximate flow and heat transfer models are presented and implemented in a personal computer based software package for the fast simulation of the processing behavior in realistic settings.
Microlayer Coextrusion Technology
Coextrusion with three or more layers is commonly used to produce end products that have properties with a good mix of the individual components. Layer multiplying technology allows for coextruded samples to be multiplied into tens or even thousands of layers, producing microlayers. In this manner, a wide variety of polymers can be combined intimately with minimal mixing. Microlayers have several distinct advantages as both a research tool and as a method of producing end products with enhanced properties. The effect of large interfacial area and of scaling is discussed with several example systems.
Rapid Adhesives Bonding: Kinetic or Process Control?
Adhesive bonding typically produces slow strength build. Accelerating processes are used to heat the adhesive rapidly. Two approaches are used: heat the adherends, which transfers heat to the adhesive, or heat the adhesive directly using added susceptor material. In this paper, the relative merits of both approaches are examined using induction and microwave heating as examples. Each approach is discussed along with the importance of curing kinetics at temperature.
A Melting Rate Model Based on Extrusion Data
To design an extruder screw for a given polymer, the barrel length for melting is needed for a given flow rate and speed. The melting rate needed for calculating the length is given through the conservation laws in cylindrical coordinates based on defined fundamental average parameters. Extrusion machine data are used to calculate the functions of the parameters. Results based on polyethylene data are given.
Study of the CaCO3 Filled PP/HDPE Composites Using Different Surface Modifiers
This article describes the surface modification of CaCO3 filler with three titanate and one zirconate coupling agents and its effects on the properties of the PP/HDPE blends. CaCO3 was coated with these coupling agents of varying concentration (0.3-1 wt. %). The best performance in terms of tensile modulus was observed in blends having 0.7% titanate coupling agent (LICA 12). SEM microgrhaps indicated better dispersion and decreased agglomeration of the smaller CaCO3 particles.
Effect of the Filler Size and Composition on the Properties of Injection Molded PP and PP/HDPE-Wood Flour Composites
The effect of the filler size and composition on the mechanical properties of wood flour-PP composites was studied. The blends were prepared in an intermeshing co-rotating twin screw extruder and injection molded. The best properties (elastic modulus and tensile strength) were obtained for the 40 wt. % wood flour composites for all filler sizes employed. PP/HDPE blends (80/20 wt. %) were prepared based on the higher wood flour content of the composites tested previously.
Measuring Depolymerization Kinetics of a Methacrylate Using a Novel Optical Technique
A new and inexpensive analytical tool, thermovolumetric analysis (TVA) is similar to thermogravimeti-ic analysis (TGA) except that it is volume rather than mass which is being monitored. This is a new application of laser interferometry which is especially applicable to thin films of polymers which depolymerize at elevated temperatures. Coatings 300 to 1500 nm thick of poly(n-butyl methacrylate) on silicon are removed in an orderly manner when heated at temperatures up to 300°C. The technique can also be employed with the temperature increasing at a constant rate.
Future Overlays for Composite Bridges
The smooth surface of a composite bridge deck pose a significant problem for bonding of an overlay surface. Previous research conducted using cementitious overlays have shown significant delaminations of the overlay when subjected to flexural loading. Epoxy overlays possess superior bonding and other mechanical characteristics, and have been successfully used on concrete-filled steel grid and steel orthotropic decks. Besides, they reduce the overall dead load on the structure due to its thin application. This work presents a brief overview of the properties and future potential of epoxy overlays for composite bridge decks.
Mixing Performance of Twin Screw Extruders during Melt-Melt Blending
The mixing performance of a co-rotating twin screw extruder during melt-melt blending of polypropylene was experimentally investigated using an interfacial reaction between reactive polymer tracers. The conversion was dependent on the formation of interfacial area between the two melt streams, and therefore, the distributive mixing performance was directly measured using this technique. The focus of the experiments was to determine the effects of machine parameters (screw design and operating conditions) on the mixing performance.
Extrusion of LLDPE through Polypropylene Coated Dies
Polypropylene (PP) coated dies were used in an attempt to decrease the die pressure and eliminate surface melt fracture during the extrusion of linear low density polyethylene (LLDPE). The investigated coatings were: controlled-rheology PP, hydrosilylated PP, amorphous PP wax, and maleic anhydride grafted PP. Extrusion stability, die pressure, and extrudate appearance were used to compare the effectiveness of the different coatings.
ISO/QS Process Certification: Measuring the Proper Variables
The trend in the injection molding industry today is to measure and record machine specific process variables. The goal of this paper is to explain the concept behind measuring and recording process conditions rather than equipment setpoints. The purpose of doing so, will be to convince molders everywhere that a non-machine specific process sheet will enable the processor to produce identical parts from machine to machine. The benefits are numerous, especially when one considers ISO and QS certification and the financial investment that they bring.
New Olefin Polymerization and Copolymerization Catalysts
Two transition metal-based catalytic systems for the homo and copolymerization of olefins will be discussed. The first encompasses palladium(II)-catalyzed alternating copolymerization of olefins with carbon monoxide. The polymers synthesized include chiral isotactic copolymers derived from both simple olefins, as well as those bearing a variety of functional groups. The second system involves palladium(II) catalyzed homopolymerization of norbornene derivatives and their copolymerization with acrylates.
Prediction of Viscoelastic Behaviour of Thermorheologically Complex Polymeric Materials
A simplified numerical computational technique based on a Gaussian spectral distribution model developed by Dutta and Edward  has been used to describe the stress relaxation behavior of polystyrene (PS) and isotactic polypropylene (iPP) over a wide range of, time and temperature. An excellent fit between experimental data and the mathematical model is observed. The method may be applied generally for any linear viscoelastic property and for any polymer.
Dynamic Mechanical Analyzer, DMA, as an Equipment to Determine Sonic Damping of Plastic Materials
A Dynamic Mechanical Thermal Analyzer, DMTA, instrument can be used to study noise reduction of thermoplastic composites. In this study, a polyamide 66 matrix modified with impact modifier, impact modifier plus foaming agent, and 30% glass fibers have been studied. In this study, the addition of impact modifier enhances the noise damping of the composite material by a factor of two.
Fracture Mechanics of a Shaft-Loaded Blister Delamination - Transition from a Bending Plate to a Stretching Membrane
Mechanical Properties and adhesion strength of a thin polymer coating on a rigid substrate can be measured directly by two tests: (i) a one-dimensional V-peel (pull-off experiment); (ii) a central point load (shaft-loaded blister). In either case, it is found that G = ? (Fw0 / A) with ? a numerical constant depending on the ratio of bending to stretching stresses on the film. It is shown that delamination behavior depends strongly on the film thickness and the extent of deformation.
Measuring Mechanical Properties of Thin Films by a Hemispherical Capped Shaft-Loaded Blister Test
A new shaft-loaded blister test is used to directly measure the mechanical properties of thin polymeric films. The shaft tip is rounded to a hemispherical cap to avoid film puncture. An elastic solution is suggested for the applied load as a function of shaft displacement, which depends on the ratio of shaft radius to blister dimension. To avoid concentrated load, an alternative way of loading the blister is by a horizontal cylinder of finite radius.
Studies of Plastic Boss Design and Methodology
Plastic bosses are fundamental components of many parts and assemblies. Due to the multiple functions and configurations, they can be difficult and time-consuming to properly design. Plastic type, size, and structural reinforcements are some of the design parameters that need to be determined. Current design methods follow set standards and produce inefficient designs for many applications. This paper explores the possibility of automating the boss design process given the needed clamping force, orientation, pullout force, torsion, and pressure configurations between the parts to be fastened.
Defect Cost Analysis
The defect cost analysis investigates the various contributions of conflicting quality objectives towards the total cost, using a probabilistic approach estimating the total effect of defects on product quality cost. Two cost drivers occur in every design, material cost and processing cost. The additional cost due to defect parts is usually seen only as one cost driver, however, it can be broken down towards the cost created by each defect type, based on the likelihood of the occurrence of those defects. By reducing those defect-related costs, a more robust design is achieved.
Transfer Function Development for the Injection Molding of Optical Media
The competitive nature of optical molding requires constant productivity improvements. In order to stay competitive, improvement in productivity through reduction in process cycle time and improved yield is required. Understanding how each input material and process parameter affects each quality output is the key to productivity and yield gains. This paper develops detailed and fundamental quantitative transfer functions that require only material and machine properties to provide specific processing conditions for optimal productivity and media quality.
Productivity Evaluation with a New Stiffness-Based Ejection Criterion of Injection Molding
In this paper a new stiffness-based ejection condition for injection molding is introduced and used for evaluation of different polymer materials. Comparison with industrial practice and other commonly used criteria, such as ejection temperature, indicates that this approach not only can be an alternative when the ejection temperature of the polymer part is unavailable, but also is more effective to help designer improve the design or reduce the cost by increasing the production rate while simultaneously ensuring injection molded part quality.
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