SPE Library
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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Conference Proceedings
CAVITY PRESSURE CONTROL DURING INJECTION IN AN INJECTION MOLDING MACHINE
Many investigations have emphasized the importance of cavity pressure in determining final part quality in an injection molding machine. During the injection cycle the main factor affecting cavity pressure is the screw hydraulic pressure valve Y3. Cavity pressure has some nonlinear characteristics thus an advanced control strategy is developed. Experiments quantified the relationship between the nozzle pressure and the Y3 valve in order to design a predictive controller. The controller was implemented with good closed loop results.
SIMULATION OF THE FOUNTAIN FLOW EFFECT BY MEANS OF THE RADIAL FUNCTIONS METHOD (RFM)
The fountain flow effect affects the orientation of the macromolecules and the mechanical and optical properties of injection molded parts. The fountain flow effect is modeled using the Radial Functions Method (RFM). In this paper, the flow in a planar slit and a steady state is considered. Good agreement between the obtained results (velocity field, pressure field and front shape) and the existing data in the literature was attained.
INVESTIGATING THE EFFECT OF INJECTION PRESSURE SCREW POSITION BARREL TEMPERATURE AND OTHER VARIABLES ON CAVITY PRESSURE
An investigation into the effect of injection pressure screw position barrel temperatures and other variables on cavity pressure data is presented. This approach consists of monitoring key process data features and using a Projections to Latent Structures (PLS) multivariate modeling technique to correlate injection molding process variables to cavity pressure data.
INFLUENCE OF CROSSLINKING ON RHEOLOGICAL PROPERTIES OF ELASTOMER AND ITS FOAM EXTRUSION
In this paper, the effect of crosslinking on the flow properties in foam extrusion and injection molding was studied using. The change in flow resistance of Ethylene-Vinyl Acetate (EVA) from partial crosslinking of the resin was characterized, with and without the influence of the dissolved blowing agent. The shear and extensional viscosities of the resin were approximated through the analysis of the pressure drop across a Hele-Shaw die channel. The influence of blowing agent on the viscosity of the EVA resin was also investigated.
DEVELOPMENT OF CROSSLINKED WOOD FIBER/ELASTOMER FOAMS
In this paper, the development of crosslinked wood fiber/Elastomer foams was investigated using a batch foaming system. Potential cost reduction and improvement of certain mechanical performance are the motivations of this study. The cell morphology of the foamed products was optimized by varying processing. The influence of different parameters on the cell structure was analyzed. The mechanical properties (tensile modulus and durometer hardness) were also measured to pursue the effect of wood fiber.
INCORPORATION OF SILICONES INTIO WOOD USING SUPERCRITICAL CO2
Wood samples have been impregnated with silicones and subsequently crosslinked in-situ by utilizing supercritical CO2 as a solvent and transport medium.These wood-silicone composites have been exposed to controlled thermo-oxidative conditions under load to determine their time to failure. The time to failure of wood samples has been found to be related to temperature through an Arrhenius type relationship. The addition of silicone to wood significantly increases time to failure suggesting that the silicone is acting as a reinforcing scaffold during the thermal degradation of wood.
NEW ENVIRONMENTALLY PROGRESSIVE POLYESTER FR RESINS
New family of ENH flame retardant PBT (polybutylene terephthalate) thermoplastic polyester resins developed is aimed at helping electrical/electronics (E/E) manufacturers and suppliers comply with regulations restricting use and disposal of hazardous substances. The non-chlorinated non-brominated resin based on PBT delivers good ductility and strength than other nonhalogen flame-retardant PBT materials as well as electrical properties of standard flame-retardant PBT materials. Some of the resin properties will be discussed in this publication.
THE EFFECT OF EXTENSIONAL STRESS ON FOAMING BEHAVIORS OF POLYSYTRENE BLOWN WITH CARBON DIOXIDE
Stresses can induce cell nucleation and affect the final
cell morphology in plastic foaming processes. In our
previous work, a novel batch foaming visualization system
was developed in order to capture the in situ foaming
process of a plastic specimen under extensional stress.
Using the visualization system, this paper elucidates the
effects of extensional stress on the foaming behaviors of
polystyrene blown by carbon dioxide as processing
conditions are varied.
FATIGUE TO CREEP PREDICTION IN BIMODAL POLYETHYLENE
This paper describes the numerical analysis of cell growth during the filling and post-filling stages in injection foam molding. The pressure change with regard to a Lagrangian framework, as well as temperature distribution, was calculated using the Finite Element Method. The foaming initiation line was predicted by utilizing the solubility of the blowing agent in polymer. Individual bubble growth during the filling and post-filling stages was simulated using the Cell Model. Furthermore, cell trajectory during the filling stage was tracked.
NUMERICAL ANALYSIS OF CELL GROWTH DURING FILLING AND POST-FILLING STAGES IN INJECTION FOAM MOLDING
This paper describes the numerical analysis of cell growth during the filling and post-filling stages in injection foam molding. The pressure change with regard to a Lagrangian framework as well as temperature distribution was calculated using the Finite Element Method. The foaming initiation line was predicted by utilizing the solubility of the blowing agent in polymer. Individual bubble growth during the filling and post-filling stages was simulated using the Cell Model. Furthermore cell trajectory during the filling stage was tracked.
INFRARED THERMOGRAPHY APPLIED TO THE TENSILE TESTING OF PLASTICS
In this study, polypropylene tensile bars were tested at rates of 50, 100, 200, and 400 mm/min while monitoring their heat output using an infrared video camera. Stress-strain-temperature curves and plots correlating mechanical work with heat output were then generated. The results demonstrate that changes in deformation behavior may be quantified via this approach, providing a new means of relating loading conditions, microstructure and ultimate properties.
THE MICROSTRUCTURE AND QUALITY OF LASER-WELDED JOINTS
The microstructural characteristics of laser-welded joints of PC PA-6 and PA-6 reinforced with 30% glass fibers were examined using optical and polarized light microscopy and scanning electron microscopy. The influence of laser power on the tensile strength of the laser-welded joints was examined and discussed in terms of various microstructural aspects. The melt fronts at the contact interface of PA-6 joints were monitored as a function of laser power. Glass fiber re-orientation in the reinforced PA-6 was also examined.
POLYETHYLENE – LAYER DOUBLE HYDROXIDE NANOCOMPOSITES: FLAMMABILITY AND THERMO PHYSICAL PROPERTIES
Layer Double Hydroxides (LDH) as flame retardants
are a growing interest. The quest for non-halogen flame
retardants has led to the need to find non-toxic flame
retardants for commercial use in polymers. This article
reports the thermal and flammability properties of linear
low density polyethylene (LLDPE) incorporated with
LDH. The objective of this project is to evaluate the flame
retardance of polyethylene. Thermophysical measurements
and tensile results are also conducted.
NANOSCALE IR SPECTROSCOPY OF POLYMER SYSTEMS USING AN ATOMIC FORCE MICROSCOPE
We describe a lab based AFM based IR measurement
capability that can obtain local spectra and IR maps over
the spectral range of 1000-4000cm-1 with spatial
resolution as high as 100nm. We demonstrate this new
capability on a polymer multilayer.
A STUDY OF FOAMING MECHANISMS IN ROTATIONAL MOLDING
The presented research focuses on the fundamentals of the foaming process in rotational molding and control of final cellular structure. The experimental results of foaming experiments, performed under isothermal and non-isothermal conditions, indicate that the foaming process could be divided into three distinct phases: bubble nucleation, bubble growth and bubble coalescence. It was found that bubble growth and coalescence mechanisms are dynamically competing during the entire foaming process and the degree of uniformity and structure of the final foam are primarily determined by the nucleation stage.
MICRO INJECTION MOLDING OF LCP-MODIFIED PA66
Injection molded micro parts require accurate replication of micro-scale features. This replication is governed by complex mechanisms and its quality depend on the plastic material properties, the geometry of the features and the process conditions The objective of this paper is to improve the replication of the micro-scale features by decreasing the polymer viscosity. The effects of melt viscosity and molding conditions on replication of microscopic features in injection molded parts were examined for a PA66 blended with a LCP additive. The replication was measured at different contents of LCP and at different process conditions.
FACTORS CONSIDERED IN DARK COLORED WINDOWS AND SIDING Part I - THE COMPLEX COMBINATION OF REQUIRED VINYL PROPERTIES
Successful dark colored windows and siding require pigmentation for long-term durability and for solar reflection to avoid excessive temperatures, a durable polymer, limits on coefficient of linear thermal expansion to minimize buckling stresses, formulations with excellent initial and retained impact resistance, and a polymer base with sufficient glass transition temperature and buckling resistance to maintain shape at maximum solar heating for several decades of time.
INSERT FILM INJECTION MOLDING TECHNOLOGY FOR AUTOMOTIVE PLASTIC PARTS WITH THE MULTI-CAVITY MOLD SYSTEM
As modern users of automotive interior plastic parts demand to enhance higher surface quality and lower manufacturing cost, film insert molding method has been widely applied lately to these injection molded products. In this paper, the integration technique of vacuum thermal forming, insert film injection molding and cavity monitoring processes, which is performed on multi-cavity mold system, is proposed and performed both experimentally and numerically for an automotive plastic part model.
DEVELOPMENT AND TESTING OF NOVEL ORIFICE DIE DESIGN FOR
EXTENSIONAL VISCOSITY MEASUREMENTS
In this work novel patent pending orifice die design
for precise extensional viscosity data determination from
entrance pressure drop measurements has been developed
and tested both theoretically (through Finite Element
Analysis) and experimentally. It has been demonstrated
that the proposed novel orifice die allows much more
precise extensional viscosity measurements for polymer
melts in comparison with conventionally used orifice dies.
DEVELOPMENT AND TESTING OF NOVEL ORIFICE DIE DESIGN FOR EXTENSIONAL VISCOSITY MEASUREMENTS
In this work, novel patent pending orifice die design for precise extensional viscosity data determination from entrance pressure drop measurements has been developed and tested both, theoretically (through Finite Element Analysis) and experimentally. It has been demonstrated that the proposed novel orifice die allows much more precise extensional viscosity measurements for polymer melts in comparison with conventionally used orifice dies.
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