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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Profile Extrusion Die Balancing Using Polymer Extrusion Simulation Software
The design of an extrusion die has been evaluated utilizing a 3-D polymer extrusion simulation software for optimal flow. The flow pattern, pressure, temperature, and shear rate are simulated in the software. The post-die extrudate shape is also simulated to show the improvement by balancing flow velocity in different sections. The combination of 3-D modeling and simulation decreases the time and difficulties for tuning the die during manufacturing.
Reverse Engineering and Failure Analysis of Materials and Polymers Using Infrared and Raman Spectroscopy
Failure analysis and reverse engineering can greatly expedite product development. Infrared and Raman spectroscopy is the among the most powerful tools for this application because each molecule has a unique infrared and Raman signature. Infrared and Raman microscopy was successfully used to identify foreign particles on elastomers and to depth profile multilayer polymer film. Details of the measurement techniques are discussed.
Use of Gradually Changing Profile Shape in Extrudate Sizers for Simplification of Die Design
Simulation of the flow and extrudate deformation in two extrusion dies with gradually changing profile shape in successive sizers is presented. The change in the profile shape in sizers is used to employ a simpler die geometry and then deform the extrudate in sizers to the required final product shape. Effect of non-uniform exit velocity, cooling shrinkage and shape of sizer profiles on extrudate deformation is included in the simulation. The predicted extrudate shape and layer structure is found to match accurately with those in a coextruded product.
Bio-renewable Polyester/Graphene Nanocomposites
Bio-based polyesters are a new class of materials that are expected to replace their fossil-based homologues in the near future. In this study, nanocomposites of bio-renewable poly(ethylene 2,5-furandicarboxylate) (PEF) are reported with thermally reduced graphene (TRG) via melt blending method and compared with fossil-based PET/TRG nanocomposites. TRG was prepared from graphite oxide by simultaneous thermal exfoliation and reduction method and characterized. TRG was dispersed in PEF and PET via melt blending, and the nanocomposites were characterized for their thermal and morphological properties. The TRG exhibited strong interactions with PEF, increasing onset of thermal degradation by ~50°C and thermal degradation temperature by ~17°C. A strong nucleation was observed in both PEF and PET with the inclusion of TRG.
Bottle-to-Bottle Recyclability for Barrier Packaging Enabled by Surface Modified HDPE
Ellen McArthur Foundation’s bold vision for The New Plastics Economy is one where plastic goods can be recycled and reused in a closed loop, a “Circular Economy”. A key hurdle to enabling closed loop recycling is the deterioration of polymer properties due to raw material contamination in the recycle stream. Mixed polymer systems, i.e. co-extrusion/multilayer packaging, use barrier materials such as EVOH or Nylon, creating significant issues during recycling. In contrast, having monolayer packaging enables the highest recyclability. Fluorinated HDPE enables monolayer barrier packaging solutions. To further understand its impact on recyclability, Inhance Technologies investigated the inclusion of fluorinated HDPE in the regular HDPE stream. Fluorinated HDPE and regular HDPE were blended at different ratios, re-extruded and pelletized. Following pelletization, bottles were molded from the regrind blends and their properties were evaluated. At all blend ratios, thermal-mechanical properties, chemical fingerprint, and sortability match those of virgin HDPE. The results demonstrate that fluorinated HDPE can be recycled as regular HDPE within the existing recycling infrastructure.
Characterization and Processing of Thermally Conducting Thermoplastic Elastomers For A Microclimate
A commercially available grade of thermally conducting TPE was characterized and processed into tubing for use in a microclimate cooling system. This paper details the material characterization, extrusion of the resin into tubing, and the evaluation of tubing properties. A series of extrusion trials was conducted to establish a relationship between processing parameters. It shows there is a weak relationship between draw ratio and tensile properties. At last, future work is proposed to further improve the thermal conductivity of this material.
Characterization of Impact Toughness of Thin Plastic Films
We investigate the role of film/dart friction on the results of dart impact test used to characterize toughness of plastic films against impact (biaxial loading) at a high speed (~3 m/s). Utilizing an instrumented dart impact (IDI) capability, impact tests were conducted for plastic films exhibiting a wide range of dart impact values under standard conditions. Steel and PTFE dart heads were used with the former representing a high-friction interaction and the latter a low-friction one at the film/dart interface. Our results indicate that differentiation between films on the basis of their measured impact toughness may change dramatically depending on friction. Load-displacement curves obtained from the IDI tests, a simplistic analysis of forces, failed samples, finite element simulations, and high-speed tensile tests help us rationalize our findings about the effect of friction on measured impact toughness of films.
Characterization of Polycarbonate – Using Thermogravemetric-Rheology Analysis
The objective of this work is to study the rheological characteristic of the formulations and the processing of plastic production. In this work, introduced two polycarbonate resins were melt blended using two different twin-screw extruders, targeted to investigate the PC blends on the characterization behavior of the grade. Formulation and processing parameters showed an excellent effect on controlling the viscosity. The research aims to identify the underlying science by conducting a systematic study of two stages. First, the polycarbonate 30/70% (Grade-3) was chosen from historical data mining extracted in our project as was showing a high number of adjustment; the material was melt-blended using (Coperion) a Co-rotating twin-screw extruder (SB). The two polycarbonate resins (PC1/PC2) were PC1 content (30wt%-pph) of MFI (25gm/10mins) and PC2 content (70 wt.%-pph) of MFI (6.5gm/10mins). The grades also included four different color pigments and three additives. The second stage, the same material was included the same composition were blended in steps of eleven in a Thermo Haake Mini Lab II twin-screw micro compounder (ML). The steps (%PC1/%PC2) were (100%/0%), (90%/10%), (80%, 20%)… (0%/100%). This resulted in eleven batches. The rheological behavior of the compositions with pigment (WP), without pigments and additive (WOP) at 280 0C have been characterized through experimental measurements. The viscosity measurements of Variation PC blends of (30-70%) and at (0%, 30%, and 100%) were characterized at certain processing of (SB) and (ML). Thermogravimetric analysis (TGA) was performed under the effect of heating rate, Glass transition temperature (Tg) for PCs blends was measured and related it is affected by the minute variation blends, viscosities, and the various interactions indicated a significant effect on color changes.
Vibration Welding of Agave Fiber Biocomposites
In this study, the welding of several formulations of injection molded agave-fiber filled biocomposites were studied. A 240Hz vibrational welder was used and weld pressure, amplitude, and weld time were varied to determine their effects on lap shear weld strength. Strength testing was performed with a universal testing machine. The morphology of the weld zones was also analyzed to gain insight into the mechanics of the welding.
Characterization of the Non-Uniform Compression Behavior and the Internal Morphology in Flexible Polyurethane Foams Using Digital Image Correlation and X-Ray Micro-Tomography
In this work, digital image correlation was performed during compression testing of twodifferent flexible polyurethane foams to obtain full-field strain maps and understand the non-uniformdeformation the foams exhibit. In addition, X-ray micro-tomographywas performed on the foam samples at different locations through the thickness to obtain micro-tomographs of the foams’ microstructures. Measurements and statistical analysis from these micro-tomographs made it possible to quantify the cell size distribution and their variation through the thickness, as well as identify differences in the microstructures of different foams.It was found that observations from compression tests with digital image correlation are in good agreement with observations from X-ray micro-tomography analysis.
Chemical Resistance Testing of Polycarbonates and Blends With Hospital Disinfectants and Cleaners
We tested an array of hospital surface disinfectants and cleaners for compatibility with several polycarbonate-based thermoplastic materials commonly used in healthcare equipment. To assess compatibility, we exposed tensile specimens to cleaners while under flexural strain, and then checked for cracking and tensile property retention. The results illustrate which cleaners are the harshest and which materials are the most chemically resistant. We also observed that periodic wiping and drying is frequently more damaging than the traditional test method of continuous wet exposure.
Circular Economy - New Styrenic Polymer Processing Concepts
Circular economy is a term describing a sustainable way to interact with all major stakeholders of the economic sphere. One basic idea is to minimize waste creation and to use post consumer waste as raw material for new products. This concept stands in contrast to the “linear economy”, based on products that end in landfill. Circular economy will play a particularly important role for all materials and goods having a short and mid-term lifetime and will have an implication on how these products are designed and recycled. Plastics food packaging are examples for goods, providing safety, protection and extended shelf-life and hence allow us to lead our modern life style. They typically have a short-term lifetime and are disposed after use. Within the challenge of “Circular Economy” however, producers of packaging, as well as upstream raw material producers are requested to provide new concepts for re-use in a true circular way, hence re-cycling rather than down-cycling or waste dumping in landfills. Plastics producers, and especially producers of Styrene-based plastics are taking up the challenge and started to “connect the dots” between municipalities, new recycling technology providers, raw material producers and customers. By promoting “chemical recycling” they are pursuing new ways to create high quality, even food grade plastics based on post consumer waste as new raw material.
Comparison of Additive and Conventional Tooling on Injection Molded Part Properties
Additive tooling can make injection molding viable for low volume production, reducing tooling cost and lead-time. This studycomparesthe final properties of injection-molded samples manufactured with a steel mold and two sets of 3D printed polymerinserts using material jetting (Digital ABSfrom Stratasys) and stereolithography(Toughfrom Formlabs). Results show thatthe Digital ABS insertsfailed after100 cycles, while the Tough insertsfailed after15 cycles. Parts producedwith steelmold and Tough and Digital ABS inserts exhibited a shrinkage of approximately3%, 6% and 9% respectively. The shrinkage and ultimate tensile strength was directly proportional to the degree of crystallinity measured using differential scanning calorimetry(DSC).
Comparison of Fiber Orientation Results of a Moldflow®-implemented pARD-RSC Model to µCT Scans
Fiber-reinforced polymers have gained popularity in various industries over the past years, as they allow the reduction of products' structural weight without compromising on performance. The material and mechanical properties of such polymer composites are mainly dependent on those of the fibers included in the polymer matrix. It is therefore crucial to be able to predict the fiber orientation in the injection-molded part during the design process. Simulation techniques offer an efficient and cost-friendly way to perform such predictions early on in the development process. However, accurate simulative predictions necessitate precise material models. Therefore, in this work, the prediction accuracy of three fiber orientation models are compared to experimental fiber orientation data obtained from high-resolution x-ray micro-computed tomography (µCT) scans for two different geometries. The models used to describe the fiber orientation in the Moldflow® simulation are a Solver API-implemented pARD-RSC model with shear-fitted parameters, an MRD model with Moldflow® default parameters and an RSC model with Moldflow® default parameters. Through the performed comparison, it was found that today’s state-of-the-art models are still unable to predict the fiber orientation for variant flow regimes and different part geometries accurately. This shortcoming was mainly highlighted for elongational flows.
Compounding Technology (Techniques and Tips) For Improved Performance and Productivity of Automotive
Ever since the first polymer applications were incorporated into the automobile in the 1960’s, OEM requirements for polyolefin based automotive compounds have pushed the performance envelope with respect to, for example, improved mechanical properties such as flex modulus, tensile strength, and heat distortion temperature; aesthetic properties such as surface quality; processing characteristics such as viscosity; and as always, cost. However, density was not a critical concern since the part being replaced was most probably made of metal. To attain required physical, esthetic and viscosity properties such as those listed above, compound formulations have become very complex. The main additives to the base polymer in early automotive applications such as a battery tray, were typically glass fiber and/or mineral filler for reinforcement. However, as manufacturers have continued to push vehicle weight reduction, they are re-evaluating specifications for current polymer-based applications/parts, i.e. bumpers, trim, etc., for future model years. In most instances, all the specified mechanical and flow properties remain the same, but density is reduced between 5 and 10%. Generally, this requires an extensive material reformulation to meet the new specifications. As part of most light-weighting reformulations, high bulk density filler content is decreased and replaced with multiple grades of polypropylene having a wide range of viscosities. These resins need to be melted and uniformly blended to provide, for example, strength from a high MW, high crystallinity component and good flow characteristics from a low MW grade. Additionally, any IM (impact modifier) needs to be dispersed and uniformly distributed. For reinforcement to be effective, fibers need to be unbundled as well as maintain a critical length during the compounding process. Minerals, depending on their structure, need to be distributed and/or distributed and dispersed. The co-rotating twin-screw compounder has long been the equipment of choice for such compounding functions. However, compounders still face processing challenges such as how to optimize the extruder set up to uniformly compound 1) diverse viscosity matrix polymers, 2) incorporate and disperse impact modifier, 3) unbundle and distribute fibers, and/or 4) feed, distribute and disperse a poor flowing, “sticky” mineral filler or possibly an easy to fluidize low bulk density talc while simultaneously maintaining an economically viable production rate. Additionally, the process can be challenged to maximize fiber length in high viscosity mineral filled formulations. This paper will review requirements for compounding automotive polyolefin compounds with an emphasis on recent innovations in Co-rotating Twin-screw technology that have enhanced product quality and productivity for these complex lightweighting material formulations.
Compressibility In Fused Filament Fabrication
Fused filament fabrication (FFF) is one of the most accessible and flexible additive manufacturing processes. However, it is plagued by consistency issues related to material deposition. The role of compressibility is explored with an instrumented nozzle to relate the observed printing pressure to variations in deposited road widths. Variations in road width are analyzed relative to those predicted using a double domain Tait equation (PVT model) for high impact polystyrene (HIPS). Compressibility was found a critical effect, varying the road widths by up to 50% when accelerating and decelerating. The effect of the speed of transient stress propagation was also investigated but found insignificant.
Computational Modeling of IR Heating of Composite-Material Parts
This paper explains the computational model developed in predicting the infrared heating of a composite material component. Computational Fluid Dynamics (CFD) technique is used in predicting heating behavior of a thermoplastic composite component. In-house testing facilities has been utilized to determine the radiation characteristic of the materials. The computational thermal model developed is validated by experimentally measured temperatures at key locations of sample plate during its heating. Comparisons between experimental data and numerical simulations showed good match between model & measurement. The developed model can be used as an effective tool in predicting the heater setting parameters for polymers/ composites heating in different application scenarios.
Creating A Skin-Core Structure With Foamed Phenolic Resins In An Injection Molding Process
The research of foam injection molding for thermosetting materials is still in an early stage. Recent studies focused on the process of volumetric underfilling, but open pore structures and gradients over the flow path were obtained. This paper gives an insight into a novel process variant, which makes the production of skin-core structures possible. It is shown, how an expanding mold technique enables the production of components with a solid skin layer and a foamed core in an injection molding process with phenolic resins. In an experimental design, packing pressure time and mold temperature are identified as the main influencing parameters. Their impact on the skin layer’s height as well as the surface quality of the specimen are discussed. Finally, a model description of the processes leading to the formation of these foam structures is proposed.
Degradable Plastics/Wood Hybrids For Sustainable Packaging Solutions
The costs for degradable plastics are in comparison to bulk plastics still high. To increase the market share of degradable-plastics-based products the reduction of the plastic used itself could be suitable option. To keep the degradable properties of the product suitable materials for a hybrid are wood or woodbased products like carton. In this paper, the combination of wood and degradable plastics to a hybrid material by overmolding was investigated. In this feasibility study the effects of injection molding on wood as an insert and the bonding strength between the two materials was analyzed.
Degradation Behavior of Aliphatic and Aromatic Biomass-based Copolyesters for Agriculture
This work concerns the synthesis, characterization and evaluation of enzymatic degradation kinetics in three biobased polymers: poly(hexamethylene succinate), poly(hexamethylene 2,5-furan dicarboxylate) and a copolymer containing hexamethylene succinate (HS) and hexamethylene 2,5-furan dicarboxylate (HF) units. All three comonomers are available from renewable resources, and their use in agricultural films and coatings would reduce the incidence of microplastics in soils, and could also provide functionality in controlled release applications. We find that copolymerization of the aliphatic and aromatic monomers reduces the crystallinity in the polymer, thus increasing the degradation rate.
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