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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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.
A TriSEC and 3dTREF Approach to Polymer Blend Design
Polyolefin technology has made remarkable progress in the last four decades. The market is expanding and the technical challenges today remain high. New products are being developed with new catalysts or by the blending processes. New resins are needed to meet the requirements of high-speed fabrication machines, and market expansions into high-tech applications. A successful resin development either by blending or by optimizing catalyst and reactor condition requires a strong polymer characterization support in determining the polymer microstructures. To this end, we have made considerable upgrade of our polymer characterization capabilities using GPC and TREF. Our approaches are the following. First, we have focused on obtaining the best precision we could out of these techniques. We then added the triple detector capabilities to the systems and take a hybrid approach of analyzing the polymer microstructure results. We generated a polymer microstructure plot" that contains both the triple detector GPC and TREF results in one chart. We find the results presented this way are very effective in comparing products or defining blending conditions for resin design."
The Case against Oxidation as a Primary Factor for Bonding Acid Copolymers to Foil
Oxidation is often used in the extrusion-coating industry to enhance the adhesion of LDPE to polar substrates such as aluminum foil. Previous investigators have suggested that oxidation plays a key role in the adhesion of acid copolymers to foil; the most direct evidence for this is the observed increase in peel strength with increasing time in the air gap (TIAG). The results of new experiments, however, suggest that oxidation may not be responsible for this behavior. Acid copolymers that have been ozone treated, loaded with antioxidants or processed at temperatures well below the expected onset of oxidation still show the characteristic increase in adhesion with increasing TIAG. Measurement of peel strength in the MD and TD show that the TD peel strength is not influenced by TIAG and peel strength correlates with % elongation of the coating. This suggests that stress and orientation may play a role in the observed behavior. A practical implication of this work is that acid copolymers will generally adhere more strongly to foil than LDPE, even when the acid copolymer is processed at lower temperatures. This reduces the potential for taste/odor, processing and other problems associated with high-temperature processing.
A New mLLDPE for Extrusion Coating Applications
Metallocene polyethylenes are well known for providing superior toughness, heat sealing, and clarity versus conventional polyethylenes. Their unique attributes have been employed for almost a decade in the manufacture of many different high-performance blown and cast films for numerous end-use applications. Lower density metallocene plastomers have also found use in specialty extrusion-coated and laminated structures where good puncture and tear resistance along with excellent hot tack and heat sealing performance are required. An extrusion coating study has shown that a similar set of attributes can be obtained using a new mLLDPE. For the best extrusion coating performance, the mLLDPE should be blended with small amounts of LDPE.
Joining of Thermoplastics with Friction Stir Welding
Friction stir welding is a process that is used for joining aluminum and its alloys. It requires only relatively simple tooling, and is extremely safe. There are no arcs, fumes, or other emissions. Early attempts to use the process for joining plastics were unsuccessful, but newly developed tooling has made it possible to weld many thermoplastic materials using a modified FSW process. This paper reports the tooling and operating parameters used to join a variety of materials, as well as the strengths of the resulting joints. Weld properties in ABS, PP, and HDPE exceeded 90% of the base material strength using the new tooling developed.
Visual Color Evaluations: Problems and Solutions
In this era of high-powered computers and spectrophotometers, the human eye-brain combination of a trained observer is still commonly used as a tool to evaluate color differences. This paper is written in hopes of pointing out some of the potential areas for problems with visual observation, and how these can be overcome to allow this wonderful tool to be used effectively. To start with the basics, there are three things necessary to have color-a light source, an object, and an observer. If you remove any of these, color no longer exists. What is equally true but perhaps less obvious is that if you change one of them, the color changes. Change the object, and the color changes-this is quite evident. Change the light source and the color changes-perhaps less evident, but still true. What is the least evident is that if the observer changes, the color changes. This is due to the nature of the way the eye works.
Development of a Continuous Thermal Separation System for the Removal of PVC Contamination in Post-Consumer PET Flake
Differences in thermal properties of plastics such as their softening and melting points can be exploited to separate mixed post-consumer plastic flake. This form of separation can be most effective if differences in melting or softening points of the two plastics are large. For example polyvinyl chloride (PVC) and polyethylene terepthalate (PET) differ in their softening points by ~ 60°C, (i.e. PVC becomes tacky at 200°C and PET at 260°C. This article examines the development of a rotary thermal separating system for the removal of PVC flake from a stream of post-consumer PET flake.
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