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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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.
A Study of Cooling for Steady-State Injection Molding
Since many current CAE softwares assume the initial temperature condition of the mold to be constant, this research investigates how the initial temperature distribution condition of the mold affects the accuracy of the estimation of the cooling time. Two cases, a mold with uniform temperature and a mold with steady-state temperature distribution due to continuous molding, are analyzed, and indicate a 30% error in cycle time prediction. Finally, the effects of different insert materials on cooling time and the production cycle are discussed.
Polymer Alloys of Polyvinyl Butyral: A Viable Means of Recycling Windshield Interlayer
Polyvinyl butyral (PVB) sheet is used as the energy absorbing interlayer in most safety glass applications including automobile windshields. A large supply of industrial and post-consumer PVB scrap is currently being disposed of by burning and landfilling. Polymeric modifiers can be used to compatibilize blends of PVB with PVC and polyolefins. These alloys can have a wide range of useful properties ranging from super-tough thermoplastics to thermoplastic elastomers.
Applications of Successive Self-Nucleation and Annealing (SSA) in Polyolefin Blends Characterization
The technique of Successive Self-Nucleation and Annealing (SSA) has been applied to thermally fractionate two types of ethylene/ -olefin copolymers and their blends. The results demonstrate the usefulness of SSA to determine the distribution of lamellar thickness and short chain branching (SCB) in the neat polymers and the miscibility of their blends.
Design of a Data Acquisition System for Predictive Control of Melt Temperature
This paper presents the design of a data acquisition system for model predictive control of the injection molding process in particular, five zones of melt temperature. Factors influencing the selection of sensors, sensor failure modes and intelligence, and the data acquisition requirements are presented. The predictive control strategy for controlling these interactive zone temperatures with the energy input disturbance caused by screw recovery is discussed.
Study of the Characteristics of Cellular PVC and a Suitable Processing Aid
The morphology of cellular PVC and the results of model experiments compared with Polystyrene suggested that cellular PVC products contain a high ratio of open-cells, but PVC can retain foam-ability even after the cells are partly broken. This characteristic is enhanced by its high melt elasticity, which is strongly related to the molecular chain entanglement between PVC and Processing Aid dispersion. From this aspect, a suitable processing aid was designed and its remarkable foam-ability was confirmed.
Effect of Iron Compounds (Oxide, Salt or Complexes) on Poly(Vinyl Chloride) Thermal and Photochemical Stability
Iron has always been known to have a detrimental effect on PVC aging but was never systematically studied when present as an impurity or as a component of the additives used in PVC formulations. A quick weathering test was designed to evaluate the effect of iron in PVC formulations and clearly demonstrated the correlation between iron content and PVC photo and thermodegradation. A threshold concentration of iron above which PVC degradation is catalyzed was determined and a specific look was given to color pigments containing iron.
Extrusion of Engineering Thermoplastic Polyurethanes
The results of extrusion trials on several single and barrier-flighted screws which highlight the importance of proper screw design for engineering thermoplastic polyurethanes are presented. Fundamental properties of the resins, including solid bulk density, coefficients of dynamic friction, melting rates and thermal properties are included to demonstrate their use in screw design.
Master Molding Technician Training Program at Lucent Technologies, Omaha, Nebraska
Growing" Production Technicians in an injection molding shop takes quite a bit of time. Even with a strong curriculum a company can be encumbered when after the training takes place employees are in a position to retire. In order to promote a continuous flow of talent a program was created jointly among management and union resulting in a "fast track" to higher paying jobs. Everyone benefits from the new Master Molding Technician Program- a 2 1/2 year curriculum based on the moldmaker apprenticeship idea."
Master Molding Technician Training Program at Lucent Technologies, Omaha, Nebraska
Growing" Production Technicians in an injection molding shop takes quite a bit of time. Even with a strong curriculum a company can be encumbered after the training takes place when employees are in a position to retire. In order to promote a continuous flow of talent a program was created jointly among management and unionresulting in a "fast track" to higher paying jobs. Everyone benefits from the new Master Molding Technician Program- a 2 1/2 year curriculum based on the moldmaker apprenticeship idea."
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