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
Monitoring Of Injection Molding Process With Piezo-Electric Sensor
Injection molding is one of the most popular techniques for global plastic production. With this automation technique, the plastic products can be manufactured at low cost with a complex geometrical shape. A manufacturing process with high productivity of an injection molding machine depends on optimized injection molding parameters. Injection molding pressure and temperature inside the mold cavity are the most critical parameters. However, cavity pressure transfer is not used due to cost and maintenance issues. During this research, an experimental procedure is performed to determine a process monitoring system using asynchronous data acquisition, through the incorporation of a wired piezo-ceramic sensor to acquire pressure of the injection molding system. This piezoelectric sensor is designed in such a way that, a Bluetooth device can be connected with a sensor and can take live data reading of parameters from the running molding machine.
Deformation Analysis Of Mold Cavity With Sla Conformal Cooling Channel Insert
Injection molding is the process of injection molten plastic into a mold to form desired shape of part and it’s widely used process for mass production of plastics over the world. This process is not complete without the mold as it is the most critical part of the process. The cost of producing mold is huge due to manufacturing process and technique, tool material and cost of labor. The more effective the mold, the more efficient the process and the more profitable to the business. A critical factor is the cooling time, and a well-designed mold can achieve even cooling in the shortest period, which leads to increased productivity and higher quality of molded parts. In this research, an alternative core design was employed, to achieve these goals during the molding process. The core has 2 parts: the core and core insert. The core insert was produced using SLA technology to achieve the conformal cooling while the core was machined, and the deflection was studied using finite element analysis.
A Recycle Stream In The Reactive Extrusion Process For Preparing Lignocellulosic Thermoplastic
Processes needing to extrude biopolymers can be challenged by the poor flow properties often exhibited by this class of materials. Lignocellulose is one such material that is very attractive to the future polymer industry as a potential engineered biopolymer suitable for structural applications. To convert the poorly processable lignocellulose pulp into a flowable thermoplastic, the chemistry of both cellulose and lignin need to be modified, and to do so economically, attention is turned towards reactive extrusion. A reactive solution is required for the modification but also, to simply allow the lignocellulose to flow through the extruder. This study examines the novel idea of a recycle stream in reactive extrusion to reduce the normally high concentration of reactive solution needed. The goal behind the recycle stream was to produce an exiting product requiring minimal recovery of the unreacted solution without the introduction of a contaminant into the process to aid lignocellulose flow. The results showed that a comparable thermoplastic product could be produced with ~50% less reactive solution by recycling 25% of the exit stream back into the process, The recycled polymer was an effective plasticizer for the lignocellulose pulp, lowering the reliance on the reactive solution to offer this function in addition to acting as the modifier.
Experimental Studies Of High Density Polyethylene Exposed To Chlorine Dioxide Media With Various Concentrations And Temperatures
High density polyethylene (HDPE) is one of the most widely used materials in the pipe industry because of its several advantages such as low price, excellent productivity, light weight and high resistance to chemical degradation. For potable water pipes, their lifespans are supposed to be over 50 years, so it is essential to check their long-term performance in certain service conditions. The point is that potable water contains disinfectants including chlorine or chlorine dioxide which shortens the service time of water pipes. In addition to disinfectant, environmental conditions like internal pressure and temperature of media inside also cause deterioration of properties of plastic pipes. To understand the degradation mechanism by potable water, we focused on two parameters, the concentration of disinfectant and the temperature of the solution. In this study, specimens obtained from HDPE pipes were artificially degraded in 5 different kinds of chlorine dioxide solutions with various concentrations and temperatures. Micro-tensile tests were conducted to study the variation of mechanical properties of HDPE specimens. The Fourier transform infrared (FTIR) spectrometry and the gel permeation chromatography (GPC) analysis were also conducted to study the variation of chemical properties of HDPE according to exposure time to chlorine dioxide solutions.
A Semi-Genetic Process For Fitting Polymer Viscosities And Selecting Best Models
This paper presents a process for fitting corrected viscosity data to constituent and temperature dependent data to a range of two-equation models. The process tests different models to determine the best fit model for each. Rheometer data for polymer melts, after corrections for shear rate and entrance pressure losses, may fit one model better than another, and as such the following constituent models are reviewed in the form as they are commonly applied in commercial software today: 1) Cross Model, 2) Modified Cross Model, and 3) Carreau-Yasuda. Once the constituent model is fit, the following temperature dependent models are compared: 1) WLF, Exponential, Arrhenius, and Masuko-Magill. The differences between the models are presented in order to highlight the need to compare different models to obtain a best fit. Lastly, a solution is presented to the problem of convergent viscosities with respect to shear rate as compared across a range of temperatures as no existing model in common use today can capture this specific behavior.
Density-Based Analysis Of Polymers Using Magnetic Levitation Device Constructed By Magnet Arrays
Standard magnetic levitation (MagLev) device consists of two identical square permanent magnets with like poles facing each other. Limited by the size of the permanent magnet, standard MagLev device cannot levitate samples with large size. This paper proposed a novel MagLev device using magnet arrays, which can accommodate large-scale samples. Unlike magnet arrays in previous studies, all magnets employed herein face the same direction. The magnetic field generated by the magnet arrays is similar to that of the standard magnet. Within the magnetic field induced by the magnet arrays, the polymer can be levitated to an equilibrium position in a paramagnetic solution and the levitation height is related to its density. The equation correlating density and levitation height can be obtained according to the simulation results. Solutions of different concentrations were used to measure densities of a variety of polymers with an accuracy of ±0.0003 g/cm3. The non-destructive testing could also be used for plastic parts based on its posture (orientation) within the paramagnetic solution. The use of magnet arrays circumvents the trouble of manufacturing large magnets, realizes testing of polymers/parts with large sizes, and facilitates industrialization of magnetic levitation detection.
Analytical Method Development For Additive Analysis In Polyethylene
The overall goal of the project targets the development of a product containing a rheology modifier additive in polyethylene (PE). This product is being sold to film converters for addition to the extruders of blown-film lines together with LLDPE resins. This increases the melt-strength during processing and the shrink tension for collation shrink films, enabling reduction in LDPE content and resultant tougher films. A tougher film will allow down-gauging and hence reduce material consumption, increasing the sustainability component for customers. This study focuses on the development of an analytical method at Dow to measure the concentration of the rheology modifier additive in PE. The method was validated and implemented successfully.
Colloidal Stability And Gel Prevention Of Urethane-Acrylate Interpenetrating Polymer Network Systems
Advances in nanotechnology and surface sciences have necessitated superior polymeric coatings with novel applications. Urethane-acrylate-based interpenetrating polymer networks are one such class of ultra-tough polymers being researched actively for their wide-ranging applications from bullet-proof vests to binders for super dewetting coatings. Urethane-based systems are well-known for undergoing side reactions which could result in instability of colloidal suspensions engendering gelation resulting in significantly reduced shelf life of synthesized formulations and coating inconsistencies over time. Consequently, it becomes crucial to examine and control the factors inducing gelation. In this study, we investigate two approaches to prevent the gelation of colloidal urethane-based suspensions. In the first approach, we tune the NCO:OH ratio, and in the second approach, urea groups were formed in the presence of water. It was observed that both approaches resulted in storage stable colloidal suspensions with more than six months of shelf life. Durability assessment of coatings however indicated that urea-containing formulation resulted in notably robust coatings as compared to NCO:OH tuned coatings which can be attributed to the presence of strong hydrogen bonding arising from bifurcated hydrogens of urea.
Extraction Of Cure-Dependent Fatigue Behavior Of Filament-Wound Composites For Fuel Cell Vehicle Applications
The extraction of cure-dependent fatigue behavior under tension-tension fatigue is presented for filament-wound coupons. Displacement controlled fatigue tests are performed on tubular filament-wound coupons. The state of the tube is characterized by performing interrupted static tests in between the fatigue cycles. At the coupon level, the state of damage in the matrix is obtained using micromechanics expressions with the help of Digital Image Correlation (DIC) technique. The results show a noticeable difference between fully cured (95%) and 80% cured composite specimens.
Development Of A Non-Destructive Measurement Method For Quality Assessment Of Foamed Plastic Parts
Foamed parts are being produced in ever greater quantities. This is done, on the one hand, to save weight and, on the other hand, to take advantage of the greater design freedom in the layout of foamed components. Until now, quality control of the foam structure has hardly been possible without destructive testing methods. Therefore, a test method is presented to qualitatively evaluate the foam structure of foamed components without destruction.
The Toughening Of Highly Crosslinked Epoxy Networks Using Core-Shell Rubber Particles
This work explores the effect of core shell rubber (CSR) addition on the resulting properties of a highly crosslinked bi-component epoxy resin blend. The effects of network structure and topology are explored and related to the efficacy of CSR as a toughener for rigid, high-Tg polymer networks. A combination of thermal, spectral, and mechanical testing shows that excellent toughness enhancement can indeed still be achieved, despite a modest reduction in flexural properties for a high glass transition temperature (~259°C) network.
Foaming Behavior And Property Of PMMA Nanofoam Fabricated By By Hot-Bath And Hot-Press Foaming
Nanocellular foam has attracted significant attention because of its superior physical and mechanical properties than microcellular foams. In this study, nanocellular foams were produced using the hot-bath and hot-press foaming methods. By lowering the saturation temperature (Tsat) to -30 ºC, the CO2 solubility was increased to 45.6%, and the cell size was reduced to less than 40 nm. Samples prepared by hot-bath exhibited smaller cell size, thinner solid skin, and transitional layer.
Fem Modeling On Scratch Behavior Of Micro-Patterned Polymer Surfaces
Polymers are inherently scratch sensitive due to their soft nature. Utilizing patterned surfaces while retaining transparency is a viable strategy to achieve better scratch performance. In this paper, we model the scratch behavior of micro-patterned surfaces using FEM simulation by employing a powerful coupled Eulerian-Lagrangian approach. The effect of two different pattern types on scratch behavior is studied and validated with available experimental results. Results suggest the significance of patterned surface topology in improving scratch performance.
Cyclic Olefin Copolymer Foam: A Promising Thermal Insulation Material
In the effort to alleviate climate change and energy consumption issues, thermally insulating polymeric foams can improve energy-management efficiency. we report a superior thermal insulation (~28.5 mW⋅m-1K-1) microcellular foam from ethylene-norbornene (NB) based cyclic olefin copolymers (COCs). Unlike the traditional carbon-filled approach, the incorporation of more NB segments (content from 33, 36, 51 and 58 mol %) in the COC structure greatly improved its ability to block thermal radiation without increasing its solid thermal conductivity. Using the supercritical CO2 and n-butane as physical blowing agents, we fabricated COC foams with tunable morphology. The void fraction of the foams ranged from 50 to 92%, and they demonstrated a high degree of closed cell content (>98%). In COC foams with given cellular structures (e.g. void fraction of 90%, cell size of 100–200 μm and cell density of ~107 cells/cc), their total thermal conductivity decreases from 49.6 to 37.9 mW⋅m-1K-1 with increasing NB content from 33 to 58%, which is attributed to high- NB COC’s strong ability to attenuate thermal radiation.
Diffusion-Bonded Mold Inserts Expand The Portfolio Of Injection Molding Tool Manufacture
Due to rising demands on the quality of the final plastic product, it becomes increasingly important to influence the thermal behavior of the injection molding tools. Due to this fact the geometry of heat control channels becomes very complex, leading to a change in the manufacturing strategy of large-scale tools: manufacturing of a layered structure followed by joining the complete component. Besides the influence of the surface roughness and precision of the mold making the possibility of joining non-planar surfaces is elucidated. To demonstrate and to evaluate the diffusion bonding process, a demonstrator injection-molding tool was constructed and realized by joining the nozzle side and the ejector site of the mold by diffusion bonding after the contour conformal cooling channels were integrated. The cycle time for the production of fan wheels with the finalized mold could be reduced by 10%. Moreover, the concentricity of the fan wheels could be improved.
Evaluation Of Shear Modulus Using Destructive Shear Test And Non-Destructive Ultrasonic Shear Waves
The material properties of fiber reinforced plastics are highly directional and the final fiber orientation can usually only be determined after the manufacturing process by time-consuming and cost-intensive sample preparation. The determination of the mechanical properties usually requires destructive testing. Compared to conventional methods, the method of ultrasonic birefringence presented here allows a non-destructive determination of the shear moduli G13 and G23. Furthermore, it allows the determination of the fiber orientation without the need of a complex specimen preparation. The difference in shear modulus measurement between the two methods is less than 1%.
Experiment And Simulation Of 1D Flow And In-Plane Permeability Validation Considering Fabrics Orientation Effects In Resin Transfer Molding
The purpose of this research is to develop measurement devices and verify whether the permeability values obtained by different experimental devices and theoretical models are correct through Moldex3D RTM simulation tool. The experimental mold dimension and process parameters are established in Moldex3D for verification, such as one-dimensional flow and radial flow. From the results, it is known that the experimental and simulation results are highly consistent. Therefore, Moldex3D simulation software can be used as a verification tool to compare the permeability and flow front.
Turnkey Solution For 3D Metal Printed Conformally Cooled Injection Mold Inserts
Background: In Spring of 2020, Instaversal was contracted to test our newly developed conformal cooling technology, CoolTool™, against existing production benchmarks for a plastic injection molded Pipe Bracket Adapter. The Product Innovator was going through a period of elevated demand where the current cycle time of the existing injection mold tool prohibited them from meeting their demand. When cooling cycles were sped up this led to higher scrap rates due to sink marks. This left the Product Innovator with two options: delay delivery of the product to their top customer with the risk of losing the sale and potentially losing the customer or to invest in additional injection mold tools to double production capacity. To meet the customer’s demand, 100,000 parts needed to be produced in a 60-day time period. This request created conflict with the contract manufacturer. They were being asked to absorb the cost of additional molds to meet the timing or run full 24-hour (Monday-Friday) shifts over the 60-day period which would create losses in revenue by eliminating other clients’ scheduled jobs.
Zirconium Dioxide As A Thermo-Insulating Coating For Molds In Plastic Injection Molding
Effect of the thermal barrier coating (TBC), deposited on the mold for plastic injection molding was investigated. The mold cavities were coated by yttrium stabilized (YSZ) and phosphorous doped (PDZ) zirconium dioxide as multilayer film using chemical vapor deposition (CVD) method. It was found that films deposited at higher temperatures have better thermo-insulating properties than films deposited at lower temperatures. Growth rate and film porosity increase as deposition temperature increases. It was observed that the TBC slightly affects the flow length of the plastic melt but improves the filling ability of poorly vented molded part areas.
Relative Humidity Effects on Accelerated Aging of Medical-Grade Polymers: Should ASTM F1980 be Revised to Recommend Constant RH Instead of Constant Moisture Content?
ASTM F1980 provides a methodology for accelerated aging of sterile barrier systems for medical devices, and is also widely used as the definitive guide for accelerated aging of medical devices and pharmaceutical packaging. ASTM F1980-16, as well as previous versions going back to 2007, emphasize that when increasing temperature to accelerate aging, it is preferable to decrease relative humidity so as to maintain an approximately constant moisture content. However, there is a revision under consideration by the ASTM F02.50 committee that would dramatically change this guidance to indicate a preference (although allowing for other options) to keep relative humidity approximately constant. This change is based on somewhat limited test data and literature review published recently by Thor et al. In this paper, we perform a study looking at eight resins (PP, COC, ABS, PC/PET, Copolyester, PBT, PA66gf, PUR) that have been aged at 60C and three different RH levels to evaluate the impact on aging. Our findings to date indicate that: (i) yes, it is likely that RH should be held constant when increasing temperature in order to keep moisture constant in the resins at a similar level; and (ii) for the medical-grade resins evaluated here, RH level does not significantly impact the physical aging mechanism. We also recommend that further accelerated aging studies are performed to more thoroughly evaluate the impact of moisture content on Q10 factors, corrosion rates, and other endpoints before this dramatic change is made to the ASTM F1980 standard.
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