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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NUMERICAL SIMULATION OF ENHANCED MELT MODULATION APPLIED TO INJECTION MOLDING
A new approach to the control of melt modulation during injection molding processes has been investigated using numerical simulation. Based on a new development in melt flow control for cold runner base injection molding, numerical simulations were used to replicate the behavior of a melt flow with multiple control valves incorporated into a single runner system. It is demonstrated that a new control technique in which all valves can be controlled as a function of ram position allows the user to locally determine the amount of flow in each runner section more precisely.
A NEW NON-CONVENTIONAL CONCEPT FOR DESIGN OF SHEET EXTRUSION DIES
A new non-conventional die design for extrusion of plastic sheet is introduced. Instead of using a conventional sheet die design, such as the coat-hanger, or fishtail design, a completely non-conventional innovative die geometry was developed to achieve a highly uniform velocity distribution at the die exit (die balancing). While balancing the flow at the die exit, with the new die concept, the pressure drop in the die was reduced to about 29% of the original value, and the sharkskin instability was also eliminated from the extrusion process.
PROFILE EXTRUSION COOLING PROCESS OPTIMIZATION VIA SIMULATION
This paper deals with the optimization of the cooling process in profile extrusion through the use of simulation and its application on a real process. Firstly, it will be shown how the simulation is calibrated" with respect to the heat transfer conditions in the different parts of the cooling process to get realistic results. This leads to the development of a novel simulation approach for hollow profiles. It will also be shown how the improved understanding of the cooling was applied towards improving the process productivity."
POSS DISPERSANTS AND FLOW AIDS FOR HIGH TEMPERATURE THERMOPLASTICS
Polyhedral Oligomeric Silsesquioxanes (POSS) were tested as processing aids and dispersants in polyetheretherketone (PEEK). Up to a 500% increase in melt flow index was observed in neat PEEK with no noticeable change in mechanical properties. POSS silanols were used as filler dispersants and showed effects similar to stearic acid but with much greater thermal stability. Thermal analysis showed that POSS is stable up to 400 ?øC. These attributes compare favorably to commercial surfactants, which cannot survive similar processing temperatures.
MODELING THE FUTURE: MANAGING THE TOOLS THAT ENABLE INNOVATION
As the global economy evolves toward an increasingly complex future, businesses are searching for a strategy toensure long-term stability. The best strategy, in many cases, may simply be to learn how to change faster than the world changes around you ' to innovate faster than your competitors. To succeed at this, companies need to make effective choices on where to invest scarce resources. Good tools lead to good results, good decisions, and compelling products. So what defines a good tool?
THE DEVELOPMENT OF INTERNAL WATER COOLING TECHNIQUES FOR THE ROTATIONAL MOULDING PROCESS
This paper reports the findings from internal mould cooling trials using a water spray configuration applied at various internal mould air temperatures from 120?§C to 180?§C for an aluminium mould. To achieve maximum benefit in terms of cycle time reduction, internal mould water cooling was used in conjunction with a combination of external forced air and water cooling. Savings in cooling times of up to 30% were achieved compared to conventional external only forced air cooling.
NOVEL DESIGN METHODOLOGY FOR PLASTIC GEARS
This paper presents a unique methodology for designing plastic gears to enhance strength and life while allowing size and wear reduction. This new approach, trade named Direct Gear Design (DGD), optimizes the gear geometry to impart superior drive performance versus traditional gear design methods. This paper explains this alternative approach and demonstrates its effectiveness for plastic gear applications.
MICROSTRUCTURAL STUDY OF GRAPHITE FILLED POLYETHYLENE TEREPHTHALATE NANOCOMPOSITES
Nanographite (NG) produced from milling by high pressure homogenisation was compounded in a Twin Screw Extruder with Polyethylene Terephthalate (PET). The resultant PET-NG pellets, produced in a variety of compositions (0-2% w/w) were subjected to Rheology, DSC, Electrical Resistivity and Tensile Analysis. No nucleation of the PET was noted even at low concentrations - 0.1%w/w NG. Viscosity of the blends was increased with addition of NG thus allowing for greater continuity of the fibres spun at the faster haul off rate.
LEAN SIX SIGMA AND INNOVATION CAN SYNERGISTICALLY FIT WITHIN PRODUCT DEVELOPMENT
In a June, 2007 Business Week article the author outlined the issues 3M faced when integrating the disciplined Six Sigma methods and tools into their innovation-oriented culture. This paper suggests the Lean Six Sigma and innovation are linked as part of an evolutionary journey and that DMAIC and Design for Lean Six Sigma are key first steps for enabling effective, efficient and predictable delivery of innovative products first to the marketplace.
CFRP LINER QUALITY CONTROL FOR REPAIR OF PRESTRESSED CONCRETE CYLINDER PIPE (PCCP)
Presented in the paper are the most recent methods developed for the safe and reliable installation of carbon fiber liners. Discussion of mobilization concerns, material requirements and related verification testing, critical paths for installation, and inspection methods for both during and post installation are provided. The installation of carbon fiber liners has many critical steps. Development of a usable quality control standard for material selection, design, installation, and inspection is critical for a successful installation.
MELT PROCESSABLE, FIBERGLASS REINFORCED, HIGH HEAT THERMOPLASTIC POLYIMIDES
The addition of fiberglass to a new high temperature (Tg 267?øC), thermoplastic polyimide yields blends with enhanced performance (these blends fall under US export control restrictions). High stiffness and low CTE make these good candidates for metal replacement. Their facile melt processability on standard injection molding machines makes them suitable for electrical connector applications. The resins are also inherently flame retardant. Physical properties, as well as processing conditions for injection molding, are discussed and compared to unfilled materials.
A NOVEL MINIATURE MIXING DEVICE FOR POLYMERIC BLENDS AND COMPOUNDS
Polymeric compounds and blends are typically developed via a mechanical mixing process during which time the ingredients are subjected to both shear and extensional deformations. The overall integrity of said compounds strongly depends upon the shear and extensional rheological properties of the polymeric matrix. In addition, the rheological properties also control the final quality and commercial attractiveness of the final products. Often times when working with new experimental fillers and polymers, material quantities may be available in extremely limited amounts thereby constraining material compounding protocols and the physical property characterizations associated therewith. A new miniature mixer has been developed to monitor and optimize the preparation protocol of various polymeric compounds and blend systems. The effect of mixing time and other basic processing parameters on the shear and extensional rheological properties of said compounds is examined in order to understand the effect of undermixed and/or overmixed conditions on the rheological properties and thus the quality of the final products. Results from said new miniature mixer are compared with the results from other conventional mixing techniques in order to assess the scalability of the new mixing protocol.
THERMAL AND RHEOLOGICAL STABILITIES OF PE AND PP DUE TO REPEATED PELLETIZNG
It is known that polymers properties could change due to repeated exposure to high temperatures and shear during processing and recycling. In this research the rheological and thermal properties of polyethylene (PE) and polypropylene (PP) were investigated. A twin screw extruder (Farrel FTX20) was used to expose PE and PP to repeated thermal history during pelletization. PE and PP were exposed to thermal histories up to 12 times during pelletization and re-pelletization processes. The rheological and thermal properties of the virgin polymer were compared to the re-pelletized ones. It was noticed that the melt viscosity of PE increased and that of PP decreased as the polymer was exposed to repeated pelletization. Additionally, the evaluated thermal properties of those of PE were not significantly changed, whereas, those of PP were affected.
USING MELT FLOW INDEX TO CHARACTERIZE SOME RHEOLOGICAL USING MELT FLOW INDEX TO CHARACTERIZE SOME RHEOLOGICAL
This paper is a sequel to a previous publication that was presented at ANTEC '08. That paper addressed a variety of uses of the Melt Flow Index (MFI) equipment, which were achieved by changing the heating temperature, the dwell time, and load. Some of these conditions were used to judge the temperature and / or load sensitivity of polyethylene (PE) and polypropylene (PP).In the current paper we will show a new set of applications for the MFI equipment. Some of polyolefin's properties that are presented here and could be characterized by MFI equipment are; melt density, extrudate swell, and viscosity. These properties were measured and compared for high density PE (HDPE), linear low density PE (LLDPE), low density PE (LDPE), and PP.
MEASUREMENT OF THE ABRASION CAPACITY OF FLEXIBLE FOAMS FOR FINISHING CRUDE POTTERY
Ceramics processing industry employs foam materials in order to finish crude pottery because of its softness, elastic recovery, abrasion capacity, among others. At the moment, the ceramists in Colombia use marine sponge despite the increasing economic and environmental costs of this practice. This work explores the methods to produce a synthetic and feasible alternative for Colombian ceramic materials manufacturers based on morphologystructure- properties of the marine sponge and a comparison with thermoset and thermoplastic flexible foams. In addition, the abrasion capacity is calculated based on superficial quality in crude pottery by means of contact methods
WELDABILITY OF POLYLACTIC ACID SHEETS AND FILMS
In this work the weldability of PLA (Polylactic acid), a biodegradable polymer derived from corn starch was examined. Samples of biaxial oriented PLA films of various thicknesses were impulse and ultrasonic welded at various processing parameters. The results showed that relatively high weld strengths could be achieved with impulse welding over a relatively wide range of parameters. In addition, ultrasonic welding produced samples of relatively high strength too. However, while this process can be used with faster cycle times, it was less robust. In detail, ultrasonic welded samples of a thickness of 254 'm that were welded with a cycle time of 0.25 s had a average strength of approximately 160 N, while the results showed a standard deviation up to 50 N. In impulse welding samples of 100 'm thickness welded at 2 and 3 s had a strength of approximately 75 N, while the deviation was approximately 3 or 4 N. It was also seen that sample thickness affected the optimized welding parameters as well as ultimate strength. Having a thickness of 305 'm the weld of the samples had a strength of 80 N while the strength was 25-30 N at a thickness of 200 and 254 'm and a weld time of 0.15 s.
A STUDY ON LIGA NANOFABRICATION FOR SUB-WAVELENGTH OPTICS
This research focuses on the research and development to fabricate anti-reflection films within sub-micro features. The LIGA process was used to fabricate such structures in sub-micrometer scale. The e-beam writer defines the pattern of the X-ray mask. The golden absorber on the X-ray mask was fabricated by electroforming. After lithography and development, PMMA photoresistant with micro features was achieved.The micro master mold was then made by nickel electroforming. Finally, the anti-reflection films were formed by hot embossing. The micro-structures on thePMMA film were about 0.8 ?¬m wide and 5.1 ?¬m high.This film exhibited a better light anti-reflection effect.
POLYPROPYLENE - CUP CONVERSION FROM INJECTION MOLDING TO THERMOFORMING
Food containers such as cups can be made by injection molding (IM) or thermoforming (TF). Typical materials are high density polyethylene (HDPE), polypropylene (PP) and high impact polystyrene (HIPS). For many years the preferred choice for polypropylene cups was IM because it produces a high quality part with excellent part-to-part consistency. Conventional TF to make similar containers in PP results in wider dimensional tolerances. On the other hand, in-line, trimin- place thermoforming overcomes many of the limitations of conventional TF and allows for the production of high quality containers. This paper outlines the conversion from IM to trim-in-place for a 235-ml cup and compares the physical properties of cups from each process.
EXPERIMENTAL STUDY OF HOT PLATE WELDING OF POLYCARBONATE USING DISPLACEMENT VERSUS PRESSURE CONTROL
During hot plate welding the final forging phase can be controlled by either pressure or displacement. When using pressure control, the parts are placed under constant pressure thereby simultaneously squeezing and cooling the melt until the interface solidifies. In displacement control, the parts are pressed together until mechanical stops are reached and the weld cools further under no pressure. In this work, we studied contact hot plate welding of polycarbonate using low and high temperature hot plate with both pressure and displacement control. It was found that high temperature hot plate welding produced stronger joints than low temperature hot plate for both control methods.
INTEGRATION IN DESIGN AND MANUFACTURING OF POLYMER SMART DEVICES
Integration of functions in single components is pursued in order to manufacture smaller and smarter polymer micro devices at less cost, through e.g. less assembly steps. It requires integration on both product and production side. This paper addresses the use of molded interconnect device (MID) technology for the integration of electronic circuitry into polymer products. Shown will be new approaches of selective metallization for creating conductive tracks. The supply chain of MID parts is still seen as vulnerable, resulting in concerns on reliability of production and product. A solution is integration of processes in one production cell. Shown is the feasibility of integrating a surface patterning process into an injection molding tool.
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