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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An Advanced High Modulus (HMG) Short Glass-Fiber Reinforced Nylon 6: Part II - Mechanical Performance
Resent developments were oriented on two high-flow, high-modulus grades fiber-glass reinforced nylon 6 (HMG series) grades for automotive and other industrial applications requiring high stiffness and high strength. These materials combined the following improved technological (injection molding, vibration welding, etc.) and mechanical performance properties such as greater dimensional stability, higher short-term (strength and stiffness) and long-term (fatigue and creep). The current and possible applications of these plastics includes auto mirror housing brackets, clutch pedals, clutch master cylinders, ski bindings, steering wheels, levers, auto seat frames, door handles and door lock mechanisms. In Part I of this paper, we presented results on the role and kinetic of reinforcement with the influence of level of loading and geometrical parameters of used fiber-glass. In Part II of this paper, we are presenting results on short-term and long-term mechanical performance of developed high modulus reinforced plastics.
Improving Cycle Time in Polypropylene Molds
An attempt to reduce the injection molding cycle time of ethylene-propylene copolymer (EPP) molded pieces was performed by means of a change in the crystallization behavior of this material. A sorbitol-based third generation nucleating agent was employed to increase the nucleation sites for crystallization. The thermal and mechanical properties of the blends EPP/sorbitol were evaluated. Cooling time of injection molding was reduced and the appearance of the molded articles checked. It was found that when sorbitol is added to EPP, the crystallization temperature increases in about 6 C for a sorbitol concentration of 600 ppm. The tensile properties of the blends do not showed remarkable differences when compared to the pure EPP. A reduction in the warpage was obtained when the EPP/sorbitol blend was employed; the cooling time could be reduced and the quality of the molded articles does not decrease significantly.
Nanocomposite Polymer Film Technology
Polymer-silicate layered nanocomposites (PSLNs), which exhibit enhanced barrier properties such as increased oxygen permeability, are being explored for use in food packaging applications. End-users want to determine if clay additives would be an inexpensive way to enhance the barrier properties of their products. Experiments were conducted on Nylon-6/montmorillonite clay nanocomposite films to characterize structure and determine properties. Permeability tests were conducted to measure the effect of clay loading on permeability. Electron microscopy was used to view images of dispersion and orientation at and below the nanometer scale. Mathematical models were applied to describe the minimum flow line of oxygen through the film and predict the average diffusivity coefficient. A Java-language computer program was developed to visually analyze particle stacking and diffusion paths by creating 3D images from particle size and spacing specifications.
Nano-Effect in In-Situ Nylon-6 Nanocomposites
12-Aminododecanoic acid modified montmorillonite (ADA-MONT) has been incorporated in nylon 6 nanocomposites by in situ polymerization. Mechanical and barrier performance properties were evaluated for nanocomposites containing up to 8 wt.% ADA-MONT. The high aspect ratio of montmorillonite and the interaction between polymer chains and dispersed silicate nanolayers creates a 110% increase in flexural and tensile moduli, and a 175% increase in heat distortion temperature under load. In addition, smooth, transparent films were successfully cast using standard techniques and equipment. These films were tested for gas permeation at 65% relative humidity. Oxygen transmission rates (OTR) improve as ADA-MONT addition levels increase. At the 8 wt.% addition level, OTR reduction is ~ 80%.
Forward to Better Understanding of Optical Characterization and Development of Colored Polyamides for the Infra-Red/Laser Welding: Part II - Family of Colored Polyamides
Recent developments were oriented towards optical characterization (laser transmission, absorption, etc.) at a wide range of the infrared wavelengths and optimized mechanical performance of polyamides (PA) for the infrared/laser through-transmission welding technology (TTLW). The influence of coloring technology and type of pigments being used was also analyzed. During this study recommendations were developed for optimizing the non carbon black pigment loading in various non-reinforced and fiberglass reinforced PA 6 grades. Additionally we will discuss the efficiency of an advanced method of J-color technology (structural methods of coloring effects) for TTLW of the colored PA based plastic.
Optimized Mechanical Performance of Welded and Molded Butt Joints: Part II - Weld and Knit Lines Integrity
Recent developments were oriented on the analysis of the mechanical performance at local (knit lines and welds) and bulk (molded part) areas, with the influence of molding and welding conditions. It has been found that for non-reinforced and reinforced nylon, the mechanical performance in the knit planes and welded areas are approximately equal to the mechanical performance of a base resin (matrix). The observations on similarities and differences in the formation of knit and weld lines are presented in Part I of this paper. Analysis of mechanical performance at weld at knit lines of various nylons discussed in Part II.
Adhesion between PP-Based Elastomer and PVDF in Layered Structures by Interleafing a Grafted Copolymer
The build up of interfacial adhesion between incompatible polypropylene (PP) based thermoplastic elastomer and polyvinylidenefluoride (PVDF) in layered structures is investigated. To achieve this purpose, a compatibilizer containing PP and polmethylmethacrylate (PMMA) sequences is incorporated as a thin interleaf. The adhesive compatibilizer is obtained from two types of precursors, a poly(propylene-g-maleic anhydride) (PP-MAH) and a poly(methylmethacrylate-co- hydroxyethylmethacrylate) (MMA-HEMA), and results from the reaction between anhydride and alcohol mutually reactive functions. The conversion of this reaction was determined by a FT-IR spectroscopy method by measuring the amount of remaining alcohol functions. The efficiency of the compatibilizer is characterised by U-Peel tests. The fracture energy obtained, which is limited to 60 J/m2 without compatibilizer, varies approximately from 300 to 2000 J/m2, depending on the type of compatibilizer used. The tests have also showed that an increase of the (MMA-HEMA) precursor molecular weight improves the efficiency of the compatibilizer. Moreover, it seems that the crosslinking level in the compatibilizer influences its capacity to enhance the adhesion of PP with PVDF: the higher the crosslinking, the lower the compatibilizer efficiency.
Increased Vinyl Surface Energy through Plasticizer Choice
Printing on flexible PVC can be a problem due to the low surface energy of the vinyl compound. Many of the additives commonly used in vinyl will lower the relatively high surface energy of PVC. The increasing use of water based inks has increased the demand for higher surface energy flexible vinyl compounds. Velsicol Chemical has developed two new polymeric plasticizers that are capable of increasing the surface energy of flexible vinyl film and sheet by as much as 4 dynes/cm. The two plasticizers offer the same surface energy improvement in a high molecular weight-high permanence version and a lower viscosity easier handling version. The improvement offered by the new plasticizers can be reduced or eliminated by the improper choice of lubricant. This study shows that the choice of one compounding ingredient, the plasticizer, can increase the surface energy of a flexible PVC film by up to 4 dynes/cm. In addition it demonstrates the negative impact of a commonly used lubricant on printability. As a lubricant, stearic acid is a very common additive but studies have shown that it can also be generated in the vinyl product from some thermal stabilizers commonly used in vinyl (1).
Machine Innovation and Elementary Steps
The systematic scientific analysis of polymer processing machines leads to the definition of a small number of elementary steps, which in chemical engineering terminology are the 'unit operations' of these machines that transcend individual machine configuration and reflect the common experience of the processed material in any type of machine. The elementary steps reveal the detailed specific physical mechanisms that take place in these machines. These mechanisms, in turn, are powerful tools that when properly used can trigger machine innovation. Moreover, with proper abstraction they can also lead to a formal methodology for invention of new machine configurations. In this paper both processes of innovation and invention will be described through a few selected case studies.
The Carbon Dioxide Technology Platform
What if the electronics industry used specially designed photoresists that could be deposited using a spin coating process based upon liquid CO2 instead of organic solvents? Also what if this industry didn’t have to use hundreds of millions of gallons of water per day to remove sub-micron particles during the manufacture of integrated circuits and flat panel displays? Imagine polymerizing monomers in a continuous stirred tank reactor with the resulting polymers instantly dry, avoiding the trillions of BTUs needed every year to dry commercial polymers made in aqueous reaction media. Imagine an automotive industry that doesn’t expose its employees to toxic chlorinated solvents during metal degreasing processes. Imagine a textile industry that doesn’t need to use 100 lbs of water for every 1 lb of yarn that was dyed. Imagine local dry cleaners that don’t need to clean garments in perchloroethylene and local businesses that don’t need to pay exorbitant, newly enacted taxes on solvent use or carry newly mandated liability insurance policies. What if the demands on municipal water systems and municipal waste water systems could be dramatically reduced by changes in manufacturing technology? Imagine an educational environment where students become grounded in the fundamentals of their core disciplines, are exposed to cutting-edge, multidisciplinary science, and can experience the satisfaction and excitement that comes from doing research that makes a difference to society. The discussion will focus on the latest developments from the NSF Science & Technology Center for Environmentally Responsible Solvents and Processes. In particular, the detailed synthesis and CO2 solution properties of fluorinated and siloxanebased homopolymers and block copolymers will be discussed. The utility of such macromolecules will also be demonstrated for use in coatings (photoresists and textiles), separations, stabilizers for polymerizations, and scaffolds for catalysis. Particular attention w
Analysis of the Failure of a Polyethylene Natural Gas Service Line
Leaking natural gas from a 23 year old polyethylene pipe service line migrated into the basement of a public building. The explosion which occurred upon ignition of the gas destroyed the building and killed six of the seven occupants. Fracture of the line was found to have occurred at the connection of the polyethylene pipe to a service tap on a steel gas main. The critical issue of this investigation was understanding whether the pipe resin had acceptable creep rupture strength for the application and was over stressed or had inadequate long term strength to resist typical stresses to which buried polyethylene gas lines are exposed. This presentation will examine some of the considerations involved in arriving at a conclusion as to which condition existed in this incident.
Polyurethane and Silicone as Non-Allergenic Alternatives to Latex for Medical Balloons
Recent developments in the formulation and processing of polyurethane and silicone have resulted in making these polymers viable non-allergenic alternatives to natural latex in the medical products field. Advancements in the dip molding of polyurethane and silicone enable a variety of products to be produced in volume, including low-pressure balloons for cardiovascular, oncology, and urology products, as well as gloves, condoms, stent coatings, scope tubing, and multifunctional sleeves. These polymers can provide the same advantages offered by latex, without the negatives, and are especially well-suited for medical balloons.
Design of Stiffening Features in Rotationally Moulded Plastic Parts
Polyethylene is a very convenient and popular material for rotational moulding because it is readily available in powder form and it has good thermal stability. Unfortunately polyethylene is one of the least strong plastics and it has a low modulus. It is a feature of rotationally moulded parts that designers have to use shape very effectively in order to impart stiffness to the end product. This is not a straightforward matter because rotational moulding does not easily create features such as ribs. Increasing the wall thickness of the part is often the simple solution but more cost-effective designs involve the use of corrugations or unique configurations such as kiss-off" points. This paper describes the results of experimental and analytical studies to optimise the design of corrugated sections for rotationally moulded parts. Factors such as corrugation shape width depth spacing etc are considered and designs are optimised to give maximum axial and transverse stiffness for minimum weight. The use of a solid skin with a foamed core is also considered particularly in regard to the best ratios of skin to core thickness. Charts are provided to assist designers in deciding the best shapes for rotationally moulded parts."
Are You Ready to Sell in the Next Millennium? Identifying the 12 Key Functions of Selling, Rating Them and Improving Them
Successful managers and their companies continually (and holistically) assess the effectiveness of their organizations. This paper addresses the 12 separate functions within a firm’s sales and marketing structures and explains how other companies rate whether any or all of these areas: 1) fall below acceptable standards; 2) can be enhanced with small improvements; or 3) are in excellent shape. From this information and insight, readers will be able to go back to their companies armed with new and better techniques to spot sales shortfalls and their causes.
An Experimental Investigation on the Influence of Barrel Temperatures on the Output of a Constant Depth Screw with Grooved Barrel Feeding
Output for a grooved feed extruder with constant channel depth of 0.210 [5.33mm] was measured for the extrusion of a LDPE and found to be influenced by grooved feed bushing temperatures below 100°F [38°C]. Comparison to an earlier work shows reasonable agreement between experimental and calculated outputs. Further work needs to be done at deeper screw channel depths."
Dispersion in High Viscosity Ratio Polyolefin Blends
This study will focus on dispersion in high viscosity, low interfacial tension PE/PP and PP/PP blends. Typically, in high viscosity ratio blends, the particle size distribution can be wide ranging, with particles as large as a hundred microns and finer dispersed ones in the sub-micron range. In this study, the dispersion state will be examined by several techniques to measure particle size from the sub-micron to the 500 mm range. The effect of material and processing parameters will be investigated.
Bank Measurement Leads to Improved Quality of Extruded Sheets or Films
High quality thermoplastic films and sheets are run through a nip of a polishing roll stack while being produced. During the extruding procedure the quality is decisively affected by the size and distribution of the bank of melt which builds up in front of the nip of the polishing rolls. Thus it is extremely important to measure the bank and optimize it. With the help of the new developed measuring system WUMSY the size and the exact location of the bank can be measured for the first time. Based on the exact knowledge of the bank size and the bank distribution over the width of the roll stack the operating people can further optimize the production line. As a result of this optimization differences for instance in the thermoforming behavior over the width of the product, as often occur with conventional extrusion techniques, can be reduced by eliminating bank differences in the nip. Thus films or sheets with a more isotropic behavior will be achieved.
Latest Developments Concerning Slit Dies with Integrated Flexible Adjusting Membranes
The successful development of the Membrane Technology which more and more replaces conventional restrictor bar dies started in the beginning of the nineties. The first membrane die was presented to the public on a running pilot line during the 18th Kolloquium of the Institut für Kunststoffverarbeitung (IKV) in Aachen (Germany) 1994. The technique is now protected by various patents being granted in most of the important industrial countries and it is distributed all over the world by eight licensees. The basic construction ideas are explained by describing some important practical industrial applications. Finally the actual situation of the development of the third generation of the Membrane Technology is explained.
Anticipated Electrical Guidelines for the Upcoming Mold Safety Standard
The Society of Plastics Industry (SPI) has a working committee to address safety issues with injection molds. Part of this committee's work is to address electrical aspects of safety. To do this, a Mold Electrical Safety Sub Committee has been created under the Committee on Mold Safety specifically to review electrical standards for injection molds. Proper design of hot runner system wiring is one of the key areas of focus because of the adverse environment these systems operate in. This paper will seek to give a heads-up" in what to expect in one part of the electrical safety standard that is to be released in the next couple of years. A proposed method for proper selection of heater conductors (wires) will be reviewed as there are no existing guidelines for applications that expose wire to this high a temperature and conductor bundle size (number of conductors)."
The Effect of Feeding Mode on Dispersive Mixing Efficiency in Single-Screw Extrusion
In the case of dry colour compounds, where polymer granules are coated with a pigment powder, the latter tends to form agglomerates during extrusion, due to the hydrostatic pressure that prevails in the screw channels. In single-screw extruders, this pressure is due to the Coulombic frictional transport in the solids conveying zone. The formation of agglomerates can be prevented to a considerable extent by operating the extruder in an underfed mode. This result has emerged from a study of the problems encountered when dispersing pigments in poly(butylene terephthalate) (PBT), but can also be applied in the case of numerous compounds where a fine dispersion of solids in polymers is required.
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