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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Thermal Conductivity Improvements for Plastics Through the Use of Engineered Boron Nitride
Most plastic materials are insulators having very low thermal and electrical conductivity. Many different types of fillers are added to provide increased thermal conductivity but they can have deleterious effects on physical properties or cause increased electrical conductivity which may not be desired. New grades of hexagonal boron nitride are introduced that can provide increased thermal conductivity with improved physical properties. Thermal conductivity is improved without significantly changing the electrical conductivity.
Novel Approach in Fabrication of Printed Metal Tooling
A novel additive manufacturing approach was investigated for fabrication of steel tooling with microstructured surfaces. Varying processing parameters (printing pressure and speed) as well as material viscosity provided better control of microfeature height and width. Viscosity significantly affected feature uniformity, with higher viscosity materials producing narrow lines and more uniform feature heights. This tooling was unchanged after 5000 injection molding cycles, and so, has great potential as microstructured tooling for microfluidic devices.
Cemented Tungsten Carbide: An Innovative Material for Custom Core Pins in the Plastic Injection Molding Industry
Cemented tungsten carbide has revolutionized productivity in many applications throughout many industries and when used as a material for core pins has proven to reduce cycle time, increase core pin rigidity and extend core pin life in the plastic injection molding industry resulting in significant cost savings. To achieve profitability in the increasingly competitive global marketplace plastic injection molding companies must operate with maximum efficiencies and minimal unplanned downtime.
From Single Batch Process Control to Multiple Batch Processes Control: A Review and a Perspective for Injection Molding
This paper discusses control problem on batch processes, especially takes injection molding as an example. In the first part of the paper, the achievements about controlling single injection molding are reviewed. Motivations, advantages and challenges on controlling multiple batch processes together are addressed in the second part. Some detailed discussions from different perspectives of multiple batch processes control are illustrated as well to shed some light on future research.
Using Rheology to Understand Silcone Elastomers
Silicone thermoset elastomers are increasingly being used in over-molding or co-molding applications with thermoplastic polymers. Understanding the fundamental properties of silicone formulation components and the material property changes that occur during crosslinking is essential to successful molding and use. Rheological and dynamic mechanical characterization are outstanding tools for building an understanding of silicone thermal and elastic properties, as well as the cure reaction chemistry that takes place during silicone molding processes.
Enabling Durable Polymer Sheet and Films for Building and Construction Applications
This paper will review the development and attributes of next generation UV-light blocker technologies for engineering plastic glazing, sheet, and film used in the building & construction industry. Performance data in various polymer families will be reviewed to demonstrate the value of these products in enabling polymer materials to achieve the longevity required for durable weatherable applications.
Recycled Polymers in Injection Molded PP Ridge Vents
Injection molded accessory products are widely used in residential and commercial roofing systems. These products generally require complex polymeric formulations to meet roofing functionality. With the growth of polymeric accessory products, significant post-consumer recycled streams are available. The goal of this paper is to discuss performance of several post-consumer recycled PP streams in injection molded PP formulations while maintaining performance attributes.
Modified PEBA for Direct Adhesion to EFEP
New modified (Polyether Block Amides) offer tubing manufacturers a means of producing multi-layer fluoropolymer catheters via a co-extrusion method instead of the traditional manner of hand building a catheter. The ability to manufacture catheters without the need of etching or an adhesive layer provides for ease in manufacturing, reduction in costs, and improved adhesion between the different layers. In providing a modified PEBA which adheres directly to EFEP increases the catheter manufacturers the opportunity to produce safe, durable products.
Resin Selection for the FRP Products
For scrubbers, ducts, pipes and other FRP (Fiberglas Reinforced Plastics) products the cost of resin accounts for over half of the manufacturing expense. The selection process of searching for the best available resin for FRP product is made more reliable and easier with the diagram: the optical density coefficient (the Hammett acidity function) in the acidity environments - the top allowable temperature of the resin.
Engineering Modeling of Laboratory Internal Mixer
An engineering model for processing of stable molten resins in a laboratory internal mixer (torque rheometer) was developed. The model allows the prediction and correlation of torque and temperature in the steady-state processing stage, based on mixing chamber geometry, material properties, and operating conditions. Transient behavior was also analyzed, in order to predict the time to reach the steady-state. Experimental data to validate the model and to estimate the polymer-side heat transfer coefficient are presented.
Manufacturing Tougher PLA by the Liquid Feeding of Cellulose Nanofibers and Plasticizer
A polylactic acid (PLA) nanocomposite with 9 times higher toughness than neat PLA was prepared by compounding extrusion using cellulose nanofibers (CNFs) as an additive and glycerol triacetate (GTA) as a plasticizer. Liquid feeding was used to incorporate the CNFs and the liquid plasticizer into the extruder. Both additive and plasticizer were used to improve the PLA toughness and the plasticizer was also used to facilitate the dispersion and distribution of CNFs in the PLA matrix.
Hybrid Composite Materials Made of Polypropylene with Wood and Polyethylene Terephthalate Fibers
We aim to manufacture injection molded components which consist of thermoplastics reinforced with fibers and which have improved properties (high strength and high notched impact strength). Thus, we intend to access new application fields for the not readily visible area of the automobile interior.
The Role of Rheology in Non-Pressurized Polymer Foaming Systems
This work explores the influence of rheological properties on polymer foam development in non-pressurized systems. To understand the complex contributions of rheology on different stages of the foam processing in such systems, visualization studies were conducted using a polymer-foaming microscopy setup. Morphological analysis was used to determine the rheological processing window in terms of shear viscosity, elastic modulus, melt strength and strain-hardening, intended for the production of foams with greater foam expansion and more uniform bubble size distribution.
Rheology and Slot Die Coating Technology
Slot die coating technology is a function of the coating process, auxiliary system and fundamental technique. The decision to utilize a coating technology needs to be analyzed against these functions to determine best fit. In the era of clean, thin and precise converting operations, a customized coating system is necessary to have a technical edge. Building the system from the material up to the process sets the stage for a high precision tool designed around the process needs. This material up building process begins with the rheology of the fluid. Rheology is the study of flow. When you talk about squeezing, spreading, or lubricating a fluid, you are talking rheology. When you apply a force that causes a fluid to move, rupture, or flow you are describing a rheological force. Understanding rheology is fundamental to building fluid coating processes and inparticular a slot die coating head. The dramatic increase in the expectations of coated products, in areas as diverse as optical films to battery technology, has put substantial pressure on the systems used to produce the next generation of coated products. With increased speeds, thinner coatings and increased functional performance, awareness of coating techniques and technologies is required. The world is changing and new tools are needed to compete in the changing world markets. An awareness of coating techniques, technologies and systems allow for novel adaptations and application to new market opportunities. Rheological understanding and an application to slot die technology provides innovative tools that will help coating companies improve precision, tackle new markets, and develop new processes.
Oxygen Scavenging Films of PE and Maleic Anhydride-PE with a Commercial Iron-Based Oxygen Scavenger
The use of active packaging is one of the most successful techniques to extend the shelf life of food products, particularly those which high quality and consumer's safety can be deteriorated due to the presence of oxygen in the headspace. Hence, the incorporation of oxygen scavengers within the package has become more popular over the last decade. Since polyolefines are widely used in multilayer food packaging, we have studied the effect of adding a commercial oxygen scavenger to both, an LLDPE grade and a tie layer polyethylene. Such knowledge would be useful for the design of multilayer structures. Therefore, monolayer films were obtained by mixing a commercial masterbatch (OSM) at loadings of 10%, 35% and 50% in weight with an LLDPE film grade and a maleic anhydride-grafted PE (MAH-PE). At OSM concentrations of 35 wt% and 50 wt%, the active films based on LLDPE/OSM showed higher oxygen scavenging capacity with respect to the MAH-PE/OSM films. Thermal, mechanical and mechanical properties were measured for all blends and pure components. There was observed, in general, a decrease in crystallinity with increase of OSM concentration. In addition, the mechanical properties were not substantially affected for both systems with the presence of the OSM.
Preventing Squeeze-Out of Sealant during Hot Bar Sealing: Modeling and Experimental Insights
Excessive pressure and temperature during hot bar sealing can result in poor seals due to squeezing out of the sealant. A model is developed that shows the amount of squeeze-out increases with increasing seal bar pressure, seal temperature (by lowering the viscosity of the sealant), sealing dwell time, film thickness and decreasing seal bar width. Photomicrographs of the seal area reveal the change in sealant thickness near the edge of the seal area which correlates with the model predictions. The study shows that differences in rheological behavior of sealants, such as that between linear and branched polyolefins, can impact squeeze-out. Practical guidelines are proposed from the work to prevent problems associated with excessive squeeze flow.
Effect of Seal Process Parameters on Final Seal Strength Behavior for LLDPE
Heat sealing is joining two polymer surfaces while they are at least partially molten, by applying heat and pressure. The evolution of seal strength with seal process conditions was investigated in order to achieve high quality seals and high packaging production rates. This optimization of heat sealing process parameters (Time, Temperature and dwell time) in terms of seal strength was performed on a monolayer linear low-density polyethylene (LLDPE) film. Increasing dwell time enhanced seal strength, as expected, because of the more time available for diffusion. By increasing pressure, an increase in seal strength was observed; however, the effect of pressure was not as significant as the effect of dwell time. At very high pressure range, seal curves showed a narrower temperature window. Comparing dwell time and pressure effects, variation in dwell time had a larger effect than pressure on seal initiation temperature and plateau temperature broadness. The level of plateau seal strength changes slightly with process conditions. A 3D graph of process safety zones was introduced for seal strength in the range of heat seal process variables for the very first time.
Equipment and Material Considerations for Microcellular Foaming
Microcellular foaming processes are now proven technologies and integral part of the “mainstream” in polymer conversion operations. The present paper is a joint effort between two companies (Dow and Mucell) to address key aspects necessary to achieve a more efficient use of materials and resources via physical foaming. The paper reviews in detail all aspects that influence performance, paying special attention to the synergies that arise between hardware and material selection. A comparison of performance between chemical and physical blowing is analyzed, highlighting the advantages of microcellular foaming.
Predictive Analysis of Flexible Pouch Performance
The importance of flexible packaging is growing in the consumer products industry. This evolution in packaging is readily observable when walking down the food or cleaning products isle of the grocery store. As a packaging structure, however, flexibles pose a new and unique challenge to designers. Predictive computational methods, such as finite element analysis, can be broadly applied to the development of these packages, minimizing or eliminating the need to conduct trial and error development or testing. A total of six (6) case studies concerning flexible pouch simulation are presented in this paper, ranging from pouch formation, filling, heat seal strength and drop impact and tear-opening.
Machine Direction Orientation and its Effects on Multilayer Sealant Film
This study investigates the effects of machine direction orientation (MDO) on the performance of multilayer polyethylene sealant films. The study was designed to focus on how physical, sealant, and barrier properties of films, with varying core densities, would be modified after being MD stretched over a full range of possible draw ratios. Three layer linear low density polyethylene films were fabricated on a commercial-scale blown film line and were subsequently stretched on a machine direction orientation unit. Significant effects were seen in the areas of modulus, dart impact, haze, tear, heat seal, and barrier properties.
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