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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Agility™ Performance LDPE as a Blend Component in High Throughput and High Bubble Stability Blown Film Applications
Blends of LLDPE (linear low density polyethylene) and LDPE (low density polyethylene) are used in many film applications. This paper shows how several high performance LDPE resins can be used as a blending component to increase output or throughput on blown film lines. In addition, some of these LDPE resins are utilized in shrink films, providing a good combination of shrink and optics, and are also used in foams and extrusion coating among other applications.
Highly Resilient Non-Soften Thermoplastic Polyurethanes
Thermoplastic polyurethanes (TPUs) are a class of thermoplastic elastomers (TPEs) that are used in a variety of applications (1). TPUs exhibit low temperature flexibility, excellent abrasion resistance, high tensile strength and good processing characteristics. The current medical grade TPU’s have unique property that the flex modulus decreases (softens) when placed in the body. A new resilient non-soften (RNS) thermoplastic polyurethane has been developed that does not soften like the current grades.
Effects of Viscoelasticity on Film Die Flow Uniformity
This study shows the effect of viscoelasticity on the flow uniformity in a film die. Flow simulations were conducted on flat die geometries based on the rheology of different resins with different viscoelasticity characteristics. The results have shown that viscoelasticity can have a significant influence on flow uniformity and flow distribution becomes less uniform as the elasticity of the resins increases.
Phase Morphology Assembling in PP:PS Blends by Addition of MWCNT
Morphology evolution of polypropylene (PP):polystyrene (PS)/multiwall carbon nanotubes (MWCNT) composites were investigated. Selective localization of MWCNT in PS phase was investigated by means of electron microscopy observations. Morphology during melt mixing was characterized at different mixing times and morphology changes were analyzed. Addition of MWCNT led to an increase in coalescence and phase deformation with increasing mixing time. After compression molding, a transition from sea-island to more co-continuous morphology was observed upon increasing MWCNT concentration.
Automatic Optimization of Extrusion Dies
A newly developed extrusion die optimization software is used to optimize a sheet die and a square profile die with non-uniform wall thickness. The optimization software successfully optimized the two die geometries such that a uniform velocity distribution is obtained at the die exit without exceeding a pre-specified pressure drop across the die.
Holding Force Study of Polyolefin Resins for Stretch Hood Film Application
This paper investigated how polyolefin resin properties affect holding force performance for stretch hood film application. In this study, the effect of density/crystallinity and composition distribution on the holding force and elastic recovery of ethylene copolymers was examined. A large number of resins from different families were investigated in this study.
Effects of Annealing on the Bonding Properties of Polymer-Metal Hybrids
Polymer adhesion to a metal plate using an intermediate polymeric reactive layer was evaluated. A novel in-house adhesive powder coating was applied and compared with commercial ones, the influence of metal surface and a subsequent annealing process of the samples on the adhesive strength was also assessed through atomic force microscopy (AFM), mechanical test and differential calorimetry (DSC). Interesting results were obtained in terms of successful adhesion between the polymer and the metal, especially in samples that were annealed with the in-house coating.
Optimization of Maddock-Style Mixers for Single-Screw Extrusion
Maddock-style mixers are used extensively on singlescrew extruder screws to disperse materials into the molten resin matrix. Since the time LeRoy invented the device and Maddock perfected and commercialized it, the device has undergone several innovations. Two of these innovations have created processing issues. The goal of this paper is to describe the optimal flute geometry and mixing undercut dimension for a Maddock mixer with the goal of mitigating degradation gels and maximizing dispersive mixing stresses.
Short Pulsed Lasers in Marking
The world of laser technology continues to develop and grow. In the past 10 years lasers have evolved from CO2 and Nd:YAG systems to diode pumped and fiber lasers. The latest expansion is taking place in lasers that produce super short pulses. Some of these pulses are measured in the Pico and Femto second range.
This paper will look at what are the characteristics of a short pulsed laser, how the pulse width effects applications, and the applications that are using these lasers.
A Novel Synergist for Flame Retardant Glass-fiber Reinforced Polyamide 66
A novel silicon based synergist, DynaSil™, was used in glass-fiber reinforced polyamide 66 which is flame-retarded with organic phosphinate and traditional synergists. Mechanical, physical and thermal properties, as well as fire testing results, are reported. DynaSil™ helps to lower the using amount of organic phosphinate and traditional synergists in flame retardant glass-fiber reinforced polyamide 66 composites, meanwhile improving properties and fire performance and lowering the cost of the composites.
Education for the 21st Century
Since the downturn of 2009, there have been a number of developments that have caused us to question the value of a Liberal Arts education in our country. The events of the last year including free speech on college campuses and the high level of debt of college graduates plus the personal experience of seeing college again through the eyes of our children has inspired this paper.
Manufacturing has an opportunity to grow again in this country but the level of skilled personnel is diminishing. This gap in talent threatens the revival of manufacturing in the USA. What can be done in our education system to meet this gap or need?
Novel Thermoplastic Polymer for Soft Touch Applications
Polymer Dynamix has developed a novel thermoplastic compound which combines an appealing soft, silky feel combined with flexibility. The results demonstrate that reactive modification decreases the Shore Hardness and increases the flexibility and soft, silky feel of a thermoplastic elastomer.
3D Printing Offers a Giant Step for Short Run Injection Molds
Learn how 3D printed tools for injection molding can be used to save you time and money when creating short run prototypes from production grade plastics. This paper, will discuss the business rational behind this solution, show how some of our customers are using it and provide technical tips and tricks for success. We will also touch on a few of the future developments we see for this solution.
Long Chain Branched / High Melt Strength Linear Low Density Polyethylene for Blown and Cast Film Applications
While the physical properties of LLDPE are highly desired for many blown and cast film applications, it lacks the melt strength compared with LDPE. While LDPE can be blended with LLDPE to improve melt processability, key properties are sacrificed. This paper describes a proven technique for obtaining LCB or HMS LLDPE by means of high energy electron beam modification that increases the melt strength of reactor grade LLDPE by 5-7 times without secondary compounding and without creating gels. These materials can be used as stand alone film grades or as melt strength modifiers for conventional LLDPE and other polyolefins.
When Standards Get In the Way of Innovation
Standardization is a cornerstone of modern civilization. The weathering testing industry of today exists because of the work of standards writers around the world. However, there can be too much of a good thing. Test standards in weathering sometimes get in the way of innovation. For example, the most common cycle for testing polymeric materials in xenon arc test chambers is the 102/18 cycle. That is, the test is run for 102 minutes with light only, followed by 18 minutes of light plus water spray. Users of weathering standards assume the prevalence of this test cycle must mean that it has been carefully validated for a wide variety of materials over the decades. They may also assume that this cycle was developed to provide good correlation to natural outdoor weathering, with extensive scientific research and statistical analysis to support its broad application. They assume incorrectly. The origin of this cycle dates back to the Victorian era when the first carbon arc weathering test chambers were developed. Rotating racks completed one revolution in two hours, and specimens were sprayed with water for 18 minutes as they moved past the fixed spray nozzles in the chamber. In other words, the 102/18 cycle was set in stone a century ago and has rarely been questioned since then.
Standards have also hindered innovation by overstepping their boundaries. For decades automotive OEMs bemoaned the lack of correlation between their laboratory tests and real outdoor test results. Through the development of SAE J1960 and similar standards, OEMs wrote their testing requirements around specific pieces of hardware rather than test conditions designed to simulate and accelerate natural weathering conditions. Flaws and limitations in the old technology thus became standardized, precluding any improvements to the test methods. A few of the OEMs decided to do something about it, and this was the origin of ASTM D7869, which is a true state of the art weathering test standard fo
Selecting the Best Remediation Option for Failing CPVC Piping Systems
Chlorinated polyvinylchloride (CPVC) is widely used for many piping systems including potable water, hydronic heating/cooling, corrosive liquid drains, and fire suppression systems. CPVC is popular because of its ease of installation and corrosion resistance. However, as with all plumbing products, occasionally pipes or fittings may fail. Our goal as forensic scientists is to determine the root cause of failure of the CPVC piping and to provide the client with data that will help them select the most appropriate remediation option for their building. This paper presents four unique case studies, the forensic tools we used to evaluate the CPVC piping systems, and the logic behind the remediation option selected by the client.
Impact Modeling of Single-Ply TPO Roofing Systems
A finite element model was developed to simulate dynamic stress distributions in thermoplastic polyolefin (TPO) roofing systems subjected to severe impact events, e.g., hail and hard object strikes. In order to build an integrated TPO layered composite roofing system model, separate sub-models are developed that include: the TPO membrane, polyester reinforcement scrim, low modulus closed-cell foam and fiber-glass stiffened facer sheets. A hyperelastic Mooney-Rivlin model of the TPO membrane is utilized to simulate the membrane’s large-deformation mechanical response during simple impact tests. Straightforward force-contact measurements on the TPO membrane material and low modulus foam backing, using spherical indenters, are shown to provide sufficient material properties for the impact model of interest. It is demonstrated that the local failure modes for the layered composite roofing system can be adequately characterized by using relatively simple failure criterion for each of the individual component layers in this type of roofing system. Both high-speed indentation and ice ball impact experimental tests have been performed to evaluate and verify the predicted performance of a single ply TPO roofing system. Excellent correlation is obtained between model predictions and experimental dynamic indentation tests.
Troubleshooting Extrusion Using chillWARE Computer Simulation for Sagging and Collapsing of Pipe Ends
The Extrusion process is a complex process in which a good product quality can only be achieved when all the parameters of influence (e.g. design of machinery, throughput, temperature set up, cooling situation, vacuum level, etc.) are set correctly. In everyday production on only one extrusion lines several products have to be produced (often more than 100 different products on 1 line). Following, process parameters have to be changed quite often to adjust the machine for the demands of the new product. During such a product change procedure, very often product quality problems occur.
Frequent problems like sagging, roughness on surfaces, geometric problems, deformations or a bad mechanical strengths are caused very often by the cooling situation and can often easily be reduced, if correct process parameters would be used. In this paper the use of a computational system is presented to analyze the reasons and possible solutions for such problems during extrusion. The computational system is based on finite difference method and finite element method and shows the capability to calculate the cooling process, the crystallization time and the residual stress distribution in the product.
Improved Troubleshooting and Appropriate Maintenance in Injection Molding Using Adequate Measuring Technique
Injection molding is a sensitive process. After implementing a stable process to achieve the required product quality, there are many potential external disturbances that might lead to downtimes or off-quality production. Machine manufacturers do a lot of research to adjust the process and react on external disturbances, e.g. varying residual moisture of the resin . Disturbances coming from the central cooling unit, air compressors or the nitrogen generator can also lead to low product quality or high production costs, but have not been studied sufficiently as of today.
Simulation Based Determination of the Crystallinity Distribution in Polymer Pipes
The crystallinity and density of extruded semi crystalline polymer products has an intensive influence on the mechanical, geometrical and optical properties. Basically, the final polymer morphology depends on the overall production process. For semi crystalline polymers, the crystallization process can be separated into three sequential stochastic processes: 1. Nucleation: Arising of spherulite origins 2. Growth: filling the space, starting from the origins 3. Secondary Crystallization: compilation of the final crystalline structures Thus, the overall production process has an impact on the degree and type of crystallinity. The crystallization process is very complex and is influenced by the thermal and structure-mechanical history during the production process. A unified modeling of the different phenomena is hard to realize.
The simulation system chillWARE® is utilized to calculate the degree of crystallinity in dependency of the cooling process (thermal history) for polymer pipes. It is shown, how the distribution of the degree of crystallinity and density can be influenced by using alternative cooling technologies like internal pipe air cooling.
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