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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Polypropylene Produced by Binary Supported Catalyst Based on Metallocene
The binary silica supported catalyst system comprising the Cp2ZrCl2 and SiMe2(Ind)2ZrCl2 metallocene compounds was prepared with different immobilization methods and evaluated at different propylene polymerization conditions. The homogeneous isolated catalysts and also the homogeneous catalyst mixture were also employed for comparison. High activities were obtained with the supported systems and the molecular weight of the produced polypropylene was invariably higher than the homogeneous precursor.
Predicting the Heat Seal Performance of Ionomer Films
The heat seal strength of a flexible plastic package depends on the extent of molecular penetration at the seal interface, which in turn is a function of sealing jaw temperature, line speed and film thickness. Thinner films reach the maximum seal strength at lower jaw temperature or faster line speed than thicker films. A model is developed that combines heat transfer with molecular diffusion at the interface. The model points to how laboratory data may be used to predict the sealing performance of ionomers in high-speed packaging lines.
Prediction of Failure and Fracture Mechanisms of Fiber Reinforced Composites Using Finite Element Analysis
A finite element (FE) model is developed to study the stress transfer from matrix to fiber in a short fiber reinforced composite. The critical length of fibers to insure the ultimate stress transfer, is predicted by the model. The interfacial stresses evaluated by FE model are compared with the well known shear lag (SL) and modified shear lag (MSL) models. The competing failure mechanism in short fiber reinforced composites and the triggering stresses for that are recognized.
Prediction of Parison Swell in Extrusion Blow Molding Using Neural Network Method
A neural-network-based model approach is present where the effect of the die temperature and flow rate on the diameter and thickness swells of parison in the continuous extrusion blow molding of HDPE was incorporated. Comparison of the neural network model predictions with experimental data yields very agreement and demonstrates that the network model can predict the parison swells at different processing parameters at a high degree of precision (within 0.001).
The Prep Virtual Factory: A Suite of Processing Simulators
The Plastics Resources for Educators Program (PREP) has produced a vast array of multimedia training materials for plastics educators and the plastics industry. Products completed so far include graphics, animations, and teaching modules. The latest product is a suite of plastics processing simulators called the PREP Virtual Factory." This fully interactive teaching facility includes "machines" for extrusion injection molding and blow molding. Using these tools learners can discover proper operating procedures and investigate the influence of various process parameters on product properties."
Pressure Distribution in Screw Extruders
Pressure in extruders is usually measured only at the end of the extruder barrel (P-barrel) and at the die inlet (P-die). In some extruders multiple pressure transducers are placed along the length of the extruder barrel so that the axial pressure profile can be measured. Such information provides invaluable information about the behavior of the extruder and is extremely useful in troubleshooting extrusion problems. This paper discusses various pressure profiles and explains what they tell us about the processes occurring within the extruder.
Product Designer Wish List Can Be Done Now!
This paper will cover the use of Patent Number: 5,932,164 and its effect in product design. It will briefly review the economic and physical barriers put on the product designer by the injection molding process. These include, draft angle, surface finish, and physical ejector placement. It will show how a designer can design a product with minimal draft angle, and/or no mechanical ejector system, and/or less expensive mold, and/or less cost to produce.The above will include very deep texture with little or no draft angle, and no stripper ring (to flash) on round parts.
Properties of High Density Polyethylene and Poly(Ethylene-CO-octene) Blends
In this work the mechanical properties of high density polyethylene toughened with two grades of metallocene elastomers based on ethylene/1-octene (EOC) were studied . It was observed a synergistic effect on the tensile properties and a supertough behavior for blends with elastomer concentrations higher than 5 wt%. Cavitation, plastic deformation and fibrillized cavitation were the operating mechanisms in the deformation processes.
PVC/Wood Flour Composites Compatibilized with Chlorinated Polyethylene
Chlorinated polyethylene (CPE) has been demonstrated to be an effective compatibilizer for dissimilar materials in various mixed-polymer or recycled-polymer systems. In this paper the use of chlorinated polyethylene to compatibilize polymer/natural fiber composites is discussed. Examples of applications in PVC/wood flour composites are given.
Raman Spectroscopy: A Useful Tool for Characterizing the Polymerization Kinetics of Polyurethanes
In this study, the polymerization kinetics of an uncatalyzed polyester based thermoplastic polyurethane formulation was investigated with Raman spectroscopy. The normalized scattering intensity of the 1530 cm-1 diisocyanate band was used to calculate conversion as a function of time. Kinetic parameters obtained from these experiments correlated well with those obtained from analogous calorimetric experiments.
Real-Time Monitoring of Fluorescence Anisotropy and Temperature during Processing of Biaxially Stretched Polypropylene Film
Using an optical sensor, fluorescence anisotropy and fluorescence temperature measurements were carried out during the processing of biaxially stretched polypropylene films in a tenter. The fluorescence derived from a dye that was doped into the resin. Anisotropy measurements were made as a function of machine stretching ratios.
Residual Strength-Based Lifetime Prediction of Polymeric Composite Materials
In this work, we present the philosophy of a lifetime prediction scheme for polymeric composite materials based upon damage accumulation concepts that allow the calculation of the residual strength. Key features of the method are that it readily admits the effects of multiple damage mechanisms and can be used to develop design guidelines based upon reliability concepts.
Reverse Engineering of Polymeric Materials
Introduction The real value of polymer/additive analysis becomes apparent when it is put to solve relevant industrial problems, to study important materials or to control vital processes. At a par with Manufacturing or Operational Excellence programs industry also strives for Analytical Excellence. In this paper we present best industrial practices related to the analysis of additives in polymers.
A Review of Recent U.S. Utility Patents on Tamper-Evident Resealable Push-Pull Bottle Closures
A review of design options, disclosed in recent U.S. utility patents, for tamper evidence in resealable push-pull bottle closures is presented. Each of the selected patents is analyzed with regard to choice of location and nature of tamper evidence means.
Rheological and Tensile Strength Characteristics of Polymer Melts
Cogswell  and Wagner  methodology was employed to determine the rheological and tensile strength properties of two LDPEs and two metallocene LLDPEs resins through capillary and Haul-off (Rheotens-like) measurements. It has been shown that the tensile strength properties obtained by both methods yield almost the same values. Moreover, these values can be correlated to the drawability in tubular film blowing for corresponding materials.
Rheological and Thermoanalytical Investigations of a Class A" LP-SMC Paste"
Because of the good light-weight potential, the good resistance against corrosion and a good permeability for electro-magnetic waves more often SMC parts will be used in european automotive applications. As a result of varying qualities of the SMC prepreg or paste there exist still problems during the compression molding process.The paper discusses the used measuring methods for quality control and the influence of aging effect, which occurs during the storage of Sheet Molding Compound (SMC), on the viscosity and the curing behavior of a LP-SMC paste.
Rheological Behavior of Blends Based on Polypropylene and Commercial Ethylene-Octene Copolymers
Rheological studies were performed on polymer blends of different grades of commercial ethlene-octene copolymers (EOCs) and polypropylene (PP). The oscillatory flow properties of EOC, PP and EOCs/PP blends were analysed using a Rheometrics Dynamic Stress rheometer, SR 200. The results showed that the systems with different grades of elastomers presented different rheological behaviors. This fact probably is related to the differences in molecular weight and long chain branch present in the copolymers.
Rheological Properties of Phosphate Glass (Inorganic)-PS-LDPE (Organic) Ternary Hybrids
Binary and ternary hybrids of low-density polyethylene (LDPE), polystyrene (PS), and a low Tg tin- based phosphate glass (Pglass) were prepared at compositions ranging from 0 - 50 (vol)%. Phase behavior, rheology and morphology of the PS-LDPE blends and binary and ternary Pglass-polymer hybrids were investigated. Four-region" steady shear flow behavior and transient rheology was observed for the hybrids. Optical shearing and SEM micrographs were employed in order to confirm the evolution of this microstructure under particular shear conditions."
Rigid Toughening of Polyolefin with Calcium Carbonate Particles
Most engineering polymers are toughened by impact modifiers/rubbers and it is known that some inorganic fillers have to be used to enhance the toughness-stiffness balance. Recently, it is reported that toughness-stiffness balance of high-density polyethylene can be enhanced by blending with rigid particles such as calcium carbonate. The objective of this work is to examine the rigid toughening concept and its applications in polyolefins. The toughness stiffness balance of several HDPE/CaCO3 and PP/CaCO3 blends and the rigid toughening mechanisms in these systems are discussed.
Root Cause Analysis; Fundamentals and Applications
This paper discusses the fundamentals of root cause analysis in identifying a failure, investigating its causes, and suggesting the corrective actions. Examples of hinge failure analysis are discussed. A descriptive statement of each failure is formulated followed by the suggestion of its probable causes and their investigation. Finally, the most probable causes are identified and recommendations are made. The cases at hand discuss the importance of material choice and part design to hinges failure.
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