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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Crystallization Kinetics of Poly(Ethylene Terephthalate) Based Ionomer Nanocomposite Materials
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.
The Effects of Regrind Loading Levels and Heat History on the Properties of Selected Engineering Polymers
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.
The Effect of Pack and Hold Parameters on Part Cooling in Injection Molding
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 Sensitivity of Notch Radius on the Izod Impact Strength of Polycarbonate and the Effects of Blending with ABS
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.
Properties of Nanofiber Reinforced Polymer Composites with Intercalated Copper Particles
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.
Automated CAE Assisted Process Setup Versus Conventional Process Setup Methods
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.
Effects of Particle Size and Solvent Chemicals on the Extractions of Phthalate from Polyvinyl Chloride
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.
The Effect of High Shear Rate and Shear Duration on the Properties of Injection Molded Plastics
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.
Effects of Material Height in a Hopper on Part Weight
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.
The Effects of Color Additives on Polycarbonate Resins
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.
Verifying the Accuracy of Internal Stresses from Blow Molding Simulation Software Used for FEA Stress Analysis
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.
Case Study of Simulation Software in the Production Design Phase
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.
Effects on Physical Properties of Recrystallized Crosslinked Polyethylene on Molded Articles
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.
Computer Simulation of Small Molecules Permeation through Polymer Membranes
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.
Production of Plasticizer (Lubricant) from Soya Bean Oil for the Rubber Industry
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.
Design of Experiment: Determining the Effect of Process Parameters on the Weld Line Strength of GPPS & SBC
This study evaluated the effect of melt temperature, injection velocity, and holding pressure on the weld line strength of general-purpose polystyrene (GPPS) and styrene-butadiene copolymer (SBC). Specifically, double gated tensile bars were molded according to the runs required for a three factor, two level ANOVA. The tensile and impact testing results were then analyzed to determine which parameters were significant to the weld line strength. The results show that the tensile data for GPPS were affected by melt temperature only and that the impact results were not affected at all. On the other hand, the tensile results for SBC were influenced by melt temperature, injection velocity and holding pressure while the impact results were affected by melt temperature and injection velocity.
An Investigation of Cavity Pressure Transducer Position when Used for Velocity to Pressure Transfer with Various Injection Molding Process Strategies
The use of cavity pressure for velocity to pressure transfer during the injection phase of the molding process is generally considered to be the most repeatable method. This study looked at the effect of cavity pressure transducer location and the velocity at which transfer occurs for three different process strategies: 1) transfer before the melt front hits the last place to fill, 2) transfer during the pack phase with the screw going relatively fast, and 3) transfer at the end of pack with the screw going relatively slow. This experiment found that, as long as an inflection point is seen in the cavity pressure curve, it does not matter which cavity pressure transducer location is used when considering process consistency.
Hydrogel Contact Deposition of Polymeric Multilayers
We are pursuing a novel processing method for the rapid processing of polymeric multilayers with spatial resolution for such applications as polymeric photovoltaic devices and microfluidics. Toward this end, hydrogel contact deposition offers a quick and efficient procedure for producing multilayer polymeric structures by combining aspects of both electrostatic self-assembly (ESA) and contact stamping. We are studying the influence of the hydrogel's physical properties on such a process. For the present study, uncharged hydrogel applicators, swollen by two different solutions of polymers (positively and negatively charged), were used for controlled growth of multilayers via cyclic contact. The resulting coating structures were characterized.
Using Crosslinked Polyethylene to Stabilize Metal Injection Molding Feedstock
Shape retention of Metal Injection Molding (MIM) parts throughout the debinding and sintering stages of production is a common problem throughout the industry. Slumping of parts often causes distortion and diminishes surface detail. Challenges in development of a binder system include powder compatibility, wetability, and polymer compatibility. A mix of coupling agents, surfactants, anti-oxidants, plasticizers and compatibilizers must be determined. The proposed polyethylene based binder system will eliminate the distortion phase encountered by traditional systems. Feedstock must not cure during compounding or injection molding. Sample batches will be compounded and molded. Successful candidates will be tested for shape retention and mechanical properties.
An Experimental Study of the Flow of an Encapsulated Polymer Melt through a Unique Blown Film Die
Many polymers are extruded through blown film dies to produce monolayer and multilayer films. The most popular style of die in use today to produce blown films is the spiral mandrel die. This type of die can be used effectively for many polymers but cannot easily be used with thermally sensitive materials due to long flow paths and large surface areas that can lead to polymer degradation. This paper will discuss a new, unique blown film die technology in which a thermally sensitive polymer is encapsulated with a less sensitive material and processed into a blown film. Experimental data will be shown on the viscosity of encapsulated melts and the unique flow patterns in the die.
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