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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Anthony Filip, Stephen Kapantais, William Landsman, May 2001
The affect of back pressure, screw speed, and injection rate on melt temperature of three materials was examined using full factorial designs of experiment. The most significant factor affecting melt temperature of polypropylene and impact modified polystyrene was the screw speed. With these materials, the injection rate also influenced melt temperature, but back pressure and interactions between the primary factors had only minor or insignificant effects. The melt temperature was raised by shear on the polymer and increased soak time. In contrast, the melt temperature of polycarbonate was not significantly affected by back pressure or screw speed; injection rate was not be examined.
James M. Caplan, Steven A. Claar, Andrew D. Schaaf, May 2001
An advantage of collecting process information, after qualifying parts from an injection molding process, is that trends and indicators can be identified that allow you to reject bad parts before they are ejected from the mold. In a similar fashion, it is believed that relationships between some of these indicators can be used to detect long-term deterioration of some elements of the molding process. This study developed a model using a regression analysis that can be used in the monitoring process to identify early indicators of check ring wear, which is a common maintenance item in injection molding.
Cloisite 30A and sodium montmorillonite clays have been added to poly (ethylene terephthalate) and 2, 6, and 10 mol% sulfonated poly (ethylene terephthalate) ionomers in 1,1,1,3,3,3-hexafluoro-2-propanol to form solvent cast nanocomposite materials. Differential scanning calorimetry (DSC) was used to compare and observe differences in crystallization temperatures as well as rates of crystallization for each polymer-clay system. Analysis shows that addition of the clays into poly (ethylene terephthatlate) and sulfonated poly (ethelyene terephthalate) 2 and 6 mol% ionomers increases the crystallization temperatures and decreases crystallization half-times.
Ryan M. Case, Andrew P. Korzen, Steven B. MacLean, May 2001
This study examined the effect regrind levels and heat history on the mechanical properties of polycarbonate. Increasing regrind content and heat history produced no significant change in the tensile and flexural moduli and yield strength of polycarbonate. The Izod impact properties were not greatly affected when the regrind levels were increased, but decreased severely after the fourth heat history. Comparable decreases in transfer (fill) pressure suggest that the molecular weight was reduced. While mixing the single-heat-history regrind with virgin resin produced cloudy samples, increasing the number of thermal cycles caused discoloration of the material.
This study examined the effects of packing and holding conditions on the cooling of an injection molded part. Increasing packing of molded parts initially resulted in lower surface temperatures of the ejected parts. However, the introduction of more melt into the part increased the overall part temperature, thereby reducing the cooling rate. Thus, highly packed parts exhibited higher surface temperatures at long cooling times. For amorphous materials, the part surface temperature was less dependent on packing pressure. Air gaps measured at part ejection suggested that the time of part surface to mold wall contact was less than five seconds.
The use of Polystyrene has been greatly increased since its introduction by the Koppers Chemical Company in the 1940's. Due to this rise in the use of Polystyrene many new and easier ways of production have been conjured. Some of these processes work better than others considering the exact heat that is needed to properly expand the beads to their full capacity. This paper will address issues on how molding conditions, mixture ratios, and mold quality will affect the molding characteristics and outcome of Polystyrene beads and Polyol Isocyanate products. The products in this paper will be duck decoys.
The notch radius affects the crack propagation rate through polycarbonate upon instantaneous impact loading. The relationship between notch radius and impact strength has been shown to be directly related. Depending on the notch radius, the failures will be either ductile or brittle. Notch sensitivity is a function of impact force divided by the area of the radius. Small radii have less area than a larger radii, thus, an equal force will affect the smaller radii to the greatest degree. Notch radii vary between 0.005 and 1.000 inches. Additionally, ABS, which is not notch sensitive, is added to determine its affect.
Polyethylene and Acrylate-Styrene-Acrylonitrile were mixed with carbon nanofibers and copper particles. The composites were mixed with high shear conditions to break-up nanofiber agglomerates and disperse copper. The thermo-physical, electrical and mechanical properties of the composites were analyzed. Electrical measurements showed a drop in resistivity as function of nanofiber concentration. Crystallization temperature of PE composites was not altered; glass transition temperature of ASA was altered. Dynamic mechanical studies showed increases in stiffness for both systems.
Greg A. Horsemanko, Jason Osborne, Antonio Geraci, May 2001
Through the use of a system that reads flow analysis results directly into the injection molding machine controller, it is believed that the process obtained will be better than one obtained using conventional process setup methods. Capability analyses of the automated setup parts and the conventional setup parts will be used to compare the processes. Estimates of the time required for each method will also be made. A part that would be inherently difficult to process was designed with the use of flow simulation software. The part included such processing difficulties as air traps, converging and diverging flow, and thin to thick regions (refer to Figure 2). After the design was complete the mold was designed and built along with a measuring fixture that would be used to evaluate part length and with dimensions (part weights were also measured). A general purpose Acrylonitrile-Butadiene-Styrene was the material of choice to process. The best process was determined by part weight, length, and weight capability studies.
Plasticizers are included in many (PVC) polyvinyl chloride formulations. Polyvinyl chloride's soft texture is accomplished using plasticizing chemicals. The plasticizers most commonly used in PVC formulations are a family of chemicals called phthalates. Because of recent concerns regarding implications of chemical leaching and health effects of phthalates on infants, it's important to investigate the methods for measuring phthalates in PVC. Phthalate plasticizers are di-esters of phathalic acid and long chain alcohol and are vegetable oil-like liquids. This study focuses on the effects of three different particle sizes on extraction of phthalates from consumer product formulations. Hexane is the solvent chemical used as the extractor.
Predicting insulating values in foam plastics have been difficult because of variations in process, variations in geometry, and general lack of understanding in heat transfer. With this research, an attempt will be made to develop a systematic method of characterizing foam injection molded parts so that the parts can be designed to withstand thermal-mechanical loads that they would not be able to survive in normal operating conditions. Finite element analysis techniques will be used to help map actual heat transfer results. These results will then be compared to those measured through heat transfer experiments.
Shear rate is an important part design and processing consideration in injection molding. Excessive shear rates can cause polymer chains to break and degrade, but actual limits are currently unknown. Four materials (polycarbonates and polypropylenes) were processed through specially designed runner inserts that varied shear rate. Each material was processed through each insert three times by regrinding and reprocessing. The resulting material was evaluated for mechanical and rheological properties. The mechanical tests showed an insignificant change in properties. Rheological tests showed a progressive decrease in viscosity as shear rate and shear duration was increased.
A hopper is a device whose purpose is to direct the flow of material from a larger cross-sectional area to a smaller cross-sectional area in a uniform fashion. They are used on numerous plastics processing machines, including injection molding machines. Hoppers are constructed in a wide variety of shapes, such as: asymmetric, conical and rectangular. The flow of resin through a gravity-driven hopper has been an area of great study for several years. This paper will discuss research done at the Plastics Lab at the Erie campus of Penn State University to determine if, in fact, height does have an effect on a molding process.
Polycarbonate resins are utilized in many high tolerance engineering applications and can be purchased with many different fillers. One additive that may not commonly be considered a filler would be the colorant. In going from prototype to production, the resin usually goes from being 'hand-colored' by the manufacturer to 'pre-colored' by the supplier. Generally, the hand-colored resin and the pre-colored resin are considered to be the same. However, in this conversion, some specific properties may not transfer exactly. This research will study the mechanical properties in a typical molding application involving polycarbonate resin, and determine which properties, if any, are subject to significant variances during this material transition to production.
The objective of this study is to use the results of a blow molding simulation package to perform FEA stress analysis of blow molded bottles. The bottle geometry generated from the simulation package will be used for the bottle geometry in the FEA package. The results from this study will be used to develop a correlation between simulated FEA results and actual results from laboratory tests. The study is being done to supply information to the part designer in determining the accuracy of the stress analysis from simulation software. With accurate simulation results a designer can predict the effect of design changes in the blow molded product before hard tooling is cut. Changes in the part design at the CAE level gives the engineer a greater insight in the cause and effect relationship design modifications have on the final part.
This paper is a study to determine the value of BlowView simulation software in the preform design phase of stretch injection blow molding. The software will be used to evaluate different preform designs in an attempt to optimize the design. The blow molding industry will benefit from this study by having an effective design tool to aid in the design phase of a product. This software may be able to reduce design time and reduce production problems. This study will examine one bottle and several different preform designs. The software will be used to evaluate a preform design and determine its efficiency to produce a high-quality bottle. Another preform will then be designed with the intent of improving the previous design and producing a more uniform bottle.
The industry standard 1D beams used in current state of the art injection molding simulation software does not pick up the shear-induced imbalances created in branching runners. This imbalance requires the use of 3D simulation software, which is in its infancy, when used for injection molding. As none of the commercially available injection molding simulation programs currently provide the required solution, use of general purpose 3D flow analysis and 3D extrusion software is evaluated. This paper provides information on the accuracy of these 3D programs against actual molding.
James Kopchick, Jody Vanderhoof, Eric Moore, May 2001
The final or ultimate mechanical physical properties of a molded plastic article are difficult to determine. As a plastic article will age, it will see several temperature excursions, which can take it momentarily above its crystalline melting point. Upon cooling, the article could possibly recrystallize in a different state that has more or less crystals. Those final properties will be determined by this second more stable crystalline level. The purpose of this paper is to conduct a controlled experiment with crosslinked or potentially crosslinked high-density polyethylene (PEX) and determine the recrystallization long-term stable mechanical properties for these types of molded articles.
Numerical techniques have made significant progress over the years in predicting various plastic properties. The permeation of small molecules through the organic polymer membranes is one topic that has not been successfully modeled. Using simple approximations between mass transfer type equations and heat transfer equations similarities can be made and comparisons drawn. This paper will attempt to show the comparison between permeation predicted based on numerical simulation techniques per heat transfer and the technique of actually measuring the small molecules permeated through. Correlation will be determined.
Di-2-ethylhexyl phthalate (DOP) has been own to be used as a plasticizer in rubber industries but because of the abundance of soyabean seeds in the world, it has become imperative to study how its oil can be used as a plasticizer in place of the conventional one. From the results epoxidezed soyabean oil has a higher plasticization effect on Nitrile rubber than DOP. An equal plasticization can be achieved by using a ratio of 1:2 soyabean oil epoxide and DOP respectively. Increase in the plasticizer concentration reduced the specific gravity hardness, viscosity, tensile strength, modulus, minimum and maximum torque. However the higher the concentration of the epoxidized soyabean oil, the more the elongation at break.
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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
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.