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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Warpage is one of the most crucial problems in
injection molding quality control. Since many factors will
cause shrinkage and warpage it is very difficult to
distinguish which factor always dominates warpage. In
this study we have developed Three Dimensional
Thickness Control Method (3DTCM) to manage the
warpage of the injected parts. Using this method we will
specify the geometry of parts with non-uniform three
dimensional structures. After integrated with special gate
design material selection various operation conditions
warpage of injected parts can be managed significantly.
Also to verify our results both numerical and
experimental investigation will be performed in this study.
Warpage is one of the most crucial problems in injection molding quality control. Since many factors will cause shrinkage and warpage, it is very difficult to distinguish which factor always dominates warpage. In this study, we have developed Three Dimensional Thickness Control Method (3DTCM) to manage the warpage of the injected parts. Using this method, we will specify the geometry of parts with non-uniform three dimensional structures. After integrated with special gate design, material selection, various operation conditions, warpage of injected parts can be managed significantly. Also, to verify our results, both numerical and experimental investigation will be performed in this study.
Abul B.M. Saifullah , S. H. Masood , Igor Sbarski, May 2010
Cooling channel design in injection moulding is very important as it greatly affects the cycle time as well as the shrinkage and warpage of the plastic part. Traditionally, cooling channels have been machined into mould components with gun-barrel drilling, with that only straight channels were possible to manufacture. An advanced method of cooling system that 'conforms' to the shape of the part in the mould can be made possible with free form fabrication technique such as DMD (direct metal deposition). This paper presents an investigation on the optimization of mould design of conformal cooling channels of different cross sections for plastic injection moulding. Comparative study has been done with the conventional straight cooling channels. ANSYS thermal simulation software has been used to get comparative temperature profile on the mould and Moldflow simulation software has been used to compare shrinkage, warpage and temperature profile of the part itself during moulding process . Comparative results are presented based on temperature distribution and cooling time for the mould and warpage deflection, volumetric shrinkage and temperature profile of the part. The results provide a uniform temperature distribution with reduced shrinkage and warpage and reduction in cycle time for the plastic part.
The overall objective of this research was to prepare paclitaxel-delivering poly(L-lactic acid) (PLA) - poly(hydroxyalkanoate) (PHA) blend films focusing on drug attachment to the films. Blend films (10 wt% PHA) were melt extruded using a single screw extruder. A sequential two step photografting approach was used to photograft poly(acrylic acid) (PAA) to the film surface.Acid groups from PAA were then reacted with a specific ƒ?? OH group on paclitaxel using water soluble carbodiimide chemistry. To assess the extent of drug attachment the resultant films were characterized using ATR-FTIR spectroscopy.
The overall objective of this research was to prepare
paclitaxel-delivering poly(L-lactic acid) (PLA) -
poly(hydroxyalkanoate) (PHA) blend films, focusing on
drug attachment to the films. Blend films (10 wt% PHA)
were melt extruded using a single screw extruder. A
sequential two step photografting approach was used to
photograft poly(acrylic acid) (PAA) to the film surface.
Acid groups from PAA were then reacted with a specific –
OH group on paclitaxel using water soluble carbodiimide
chemistry. To assess the extent of drug attachment, the
resultant films were characterized using ATR-FTIR
spectroscopy.
Shia-Chung Chen , Jen-An Chang , Jin-Chuan Cin, May 2010
The study shows the molding of a high gloss surface notebook computer (NB) display support without painting using dynamic mold temperature control. The required mass production rate is 300,000 pieces per month. Both water heating/cooling and induction heating/water cooling were employed to investigate the cycle time, mold and machine requirements. The former requires 60s cycle time whereas the later needs only 36s to achieve a weld line free surface. The associated cost reduction in energy consumption is US $23,700 per month, injection machine operation is US $52,800 per month, mold making cost is US $75,000 and painting cost saving is US $190,500. Annual savings could reach US $3,237,900.
William M. Aquite, Iván D. López, Tim A. Osswald, May 2010
Polymer flow through circular tubes is a common occurrence in injection molding runner systems. Viscous dissipation affects the temperature distribution of the melt as it enters the cavity. The Radial Functions Method was used to model the flow and heat transfer inside runner systems in dimensionless form. Temperature increases are obtained from simple expressions as a function of the dimensionless Brinkman and Graetz numbers. This eliminates the necessity of simulation or experimental test of such flows when predicting temperature increments as a function of processing conditions.
Jing Wang, John W. S. Lee, Jae D. Yoon, Chul B. Park, May 2010
Recently, a circular notched specimen (CNS) is
selected for studying the crack initiation characteristics of
pipe grade polyethylene as a part of understanding quasibrittle
failure. In this study, four types of pipe grade
polyethylene were chosen and tested under variable
fatigue loading conditions using CNS with various notch
depths. The fatigue characteristics of four polyethylenes
were evaluated, and the fracture surface of CNS after
failure is analyzed by optical microscope and scanning
electron microscope (SEM) to evaluate the fracture
mechanism of pipe grade polyethylenes. In addition, the
technical issues with CNS during tests were also
investigated by finite element analysis.
Jing Wang , John W. S. Lee , Jae D. Yoon , Chul B. Park, May 2010
Foaming of a thin-wall part during injection molding is challenging. Cell nucleation and growth are significantly constrained by rapid cooling from the mold by limited cavity space and by high mold cavity pressure generated by the viscous polymer melt. In this paper we study the influence of injection speed and gate geometry on the cell size uniformity and void fraction control of a foamed thinwall part. Real-time mold cavity pressures were recorded using pressure transducers and a computer system. It was found that high injection speed and proper gate design can minimize cooling from the mold maximize shear thinning at the gate and thus making possible uniform foaming throughout the part volume.
Jun’ichi Mausda , Katsuyuki Wakabayashi , Philip J. Brunner , John M. Torkelson, May 2010
A continuous, industrially scalable process method called solid-state shear pulverization is shown to be effective in producing well-dispersed polypropylene/ carbon nanotube and polypropylene/ as-received graphite nanocomposites that cannot be obtained by conventional melt processing alone. Major improvements in Young's modulus (> 100% increase) and yield strength (65% increase) are obtained in the nanocomposites made by SSSP, with the maximum increases being observed in samples containing the highest concentrations of nanofiller that are well-dispersed. In contrast, electrical conductivity is correlated to dispersion of carbon-based nanofiller in a different manner, with conductivity increasing with increasing nanofiller content even when an increase in nanofiller content results in less effective dispersion or exfoliation.
Karen Stoeffler , Minh-Tan Ton-That , Johanne Denault , John Luong , Crystal Wu , Mohini Sain, May 2010
Polylactide (PLA) nanocomposites based on microcrystalline cellulose (MCC), nanocrystalline cellulose (NCC) and cellulose nanofibers (CNF) were prepared in the molten state by microextrusion. The dispersion was investigated by optical and electron microscopy. The mechanical properties of the nanocomposites were analyzed by dynamic mechanical analysis (DMA). The thermal properties were analyzed by differential scanning calorimetry (DSC). The effect of the addition of a proper coupling agent on dispersion and mechanical properties was analyzed.
H. Inoya , Y. W. Leong , S. Thumsorn , S. Thitithanasarn , H. Hamada, May 2010
The morphology of RPET and PP pellets has been shown to have a profound effect on the properties of injection moldings. The size of PP dispersed phase is critical as it dictates the ductility of the blend. It has been shown that the size of a dispersed phase could grow by either coalescence or relaxation during and immediately after extrusion where temperatures are high. This study focuses on the chronological development of PP dispersed phase throughout the extrusion line during RPET/PP blending prior to pelletizing. The effect of compatibilizer content will be correlated to the growth rate of PP phase and also on the mechanical properties of subsequent injection moldings.
Michael J. Molitor, Mark Weinberg, Mark D. Wetzel, May 2010
The compounding of polymer nanocomposites involves
the handling, feeding and cleaning of high volumes
of potentially low bulk density powders. The
Nanorisk Framework document [1] guides practitioners
in how to assess the effectiveness of operations and engineering
controls designed to contain nanomaterials and
minimize the risk of exposure or environmental release.
This paper reviews a new approach for measuring and
evaluating the effectiveness of engineering controls and
operating procedures when feeding nanofiller powders
into a compounding extruder. A method will be described
that uses the extruder itself as an effective means
to reduce dust generation from the feed system.
In this study we investigate and compare the deformation behavior of SEBS triblock copolymers with lamellar and cylindrical morphology. Structural changes that occur at various length scales have been studied using a simultaneous small- and wide-angle X-ray diffraction (SAXD/WAXD) technique during uni-axial tensile deformation. Further deformation calorimetry is used to investigate the energetics involved during the deformation of these materials. Series of results from these various techniques indicate that the deformation takes place in three stages.
Using solid-state shear pulverization (SSSP) to process poly(ethylene terephthalate) (PET) without addition of chemical agents, we demonstrate that linear PET can be transformed into lightly branched PET, with resulting improvements in physical and mechanical properties. Rheological characterization demonstrates an increase in the melt viscosity of the pulverized PET while intrinsic viscosity characterization yields data consistent with no increase in linear chain length. These results indicate that branching occurs in situ during SSSP via mechanochemistry involving the production of polymeric radicals that result from low levels of chain scission accompanying SSSP. A hypothetical mechanism for this mechanochemical transformation is discussed. The lightly branched PET resulting from SSSP yields a dramatic increase in the crystallization rate of the PET, improving its processability. The ability to increase the melt viscosity of PET by SSSP may contribute to sustainable engineering of PET; a long-standing issue with recycling PET for high-value applications is the fact that melt processingof PET results in reduction of molecular weight and thereby melt viscosity, making the recycled material often unusable for the original application for which it was made.
Meaghan Charest, Jose Mauricio Hernandez, Rickey Dubay, May 2010
A new method of obtaining open loop responses of a three barrel injection moulding machine is investigated. The method involves limiting the amount of heat transfer between adjacent zones by using a controller to create an artificial adiabatic wall. Since most barrel zones are run at or near to the same temperature, the system identified by the adiabatic wall method better represents industrial operating conditions. A predictive controller was designed to handle the dynamics of the adiabatic system and compared to a conventionally-tuned controller
Dana Hnidáková, Roman Cermák, Jana Výchopnová, May 2010
The current study tests cavity pressure sensors and in-mold temperature sensors to determine their effectiveness for the process monitoring of microcellular foam injection molding. Piezoelectric pressure transducers were placed behind ejector pins. Exposed junction, microbead thermocouples were installed in the ends of ejector pins, with direct exposure to the melt. Sensors were located near the gate and near the end of fill in a two cavity production mold. Cavity pressure and melt temperature profiles, peak pressures and peak melt temperatures at each position were logged as well as the time to reach these peak values. These process data were then analyzed relative to part weights and part dimensions.
Staking is a common joining method to assemble similar and dissimilar materials. Ultrasonic staking, hot air cold staking, heat staking, and infrared staking are common techniques used in the industry. Recently, impulse staking and laser staking are also reported. Regardless of the different staking techniques, the concept of staking is to deform a stud or hollow boss to form a button (or mushroom) to mechanically hold two materials together. The varieties of staking design guidelines developed by equipment suppliers possess significant discrepancies. This work utilized finite element (FE) modeling to study the effect of stake geometry on pull strength on a TPO material. Both 2-D axial symmetric and 3-D solid models were constructed to simulate the stake under tensile load. Geometric parameters such as button radius and button height were studied. It was found that mushroom height is the most critical parameter in achieving high retention force. Tall and large button provides highest retention force. However, tall and standard radius button provides compatible retention force and manufacturing advantages.
Shia-Chung Chen , Pham Son Minh , I-Sheng Hsieh , Yan-Chen Chiou, May 2010
In recent years, the variotherm molding technologies is more and more popular; and the pulsed cooling approach is one of the variotherm processing. However, the complicated cooling control system and the transient behavior of the mold made it difficult to optimize the process. In this study, through applying the comprehensive consideration with various operation specifications in simulation method, including pulsed time, coolant temperature, mold open and mold close temperatures, the cycle time can be dramatically reduced comparing to that of conventional method. In addition, experimental study will also perform to verify and realize the core issues in the near future.
The Stratablend (trademark Newcastle), Energy Transfer, Variable Energy Transfer, and DM2 with Eagle mixer are well known single screw extruder (SSE) mixers. They have been diligently compared by mixing black ABS color concentrate pellets into a bright opaque ABS. This contrast reveals color striations and unmelts. The comparison is readily seen by eye.
This paper compares a Recirculator screw and an Elongator screw using the same technique. Since no striations could be seen by eye, the extrudate was sectioned and examined by microscope at 100 and 200 times magnification showing no striations with the Elongator screw.
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Any article that is cited in another manuscript or other work is required to use the correct reference style. Below is an example of the reference style for SPE articles:
Brown, H. L. and Jones, D. H. 2016, May.
"Insert title of paper here in quotes,"
ANTEC 2016 - Indianapolis, Indiana, USA May 23-25, 2016. [On-line].
Society of Plastics Engineers
Available: www.4spe.org.
Note: if there are more than three authors you may use the first author's name and et al. EG Brown, H. L. et al.