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 During Materials Extrusion Based Additive Manufacturing Of Polycaprolactone
Filament-based additive manufacturing processes extrude molten polymer through a printer nozzle at high shear rates (> 100 s-1) prior to cooling and crystallization. Although the phenomenon of flow-induced crystallization is well-known in general, the effect of nozzle flow on the crystallization kinetics of polymers are unknown for extrusion based additive manufacturing. In fact, there is no method available to quantitatively measure crystallinity during the AM process. To address this issue, we demonstrate that fiber optic probe based Raman spectroscopy can be used to conduct in situ measurements of the crystallinity kinetics of extruded polycaprolactone during additive manufacturing. We then quantify crystallinity as a function of distance away from the nozzle.
3D Printed Tooling Solutions
Additive Manufacturing is a fast emerging disruptive technology that has potential to redefine the conventional manufacturing processes and supply chain management globally in the future. The fundamental principle of this technology is to build the three dimensional objects directly from the 3D computer models in a layer by layer additive manufacturing process. This technology can be leveraged to create prototypes, functional parts, tools and to produce production end user parts in plastic and metal materials.This technical paper will discuss the potential of AM technologies for polymer processing industry and the new space it provides for innovative thinking in plastic application development and the related tooling, without having to worry about any of the conventional manufacturing constraints. At SABIC, printed metal tools for cavities and cores with innovative conformal cooling designs have been utilized for efficient tooling and to improve cycle time. By going one step further additive tooling is integrated with heat & cool processing technology to achieve thin-wall and better quality parts. We will show an example of how such additive tooling was designed and printed, along with the impact on the final part quality.Furthermore, two SABIC resins, ULTEM 9085 resin and ULTEM 1010 resin have widespread adoption in the AM industry. Many customers are installing machines, which run true engineering thermoplastics such as these, and using them to print parts ranging from prototyping, jigs and fixtures, robotic end effectors, and tooling all the way to end use components. We will discuss the use of ULTEM in 3D printed tooling for the polymer processes such as injection molding and thermo-forming. Also, we will review our internal capabilities in design & simulation techniques to optimize tooling for minimum material, less printing time and lower system cost with couple of examples.
Structure-Property Relationships Of Microporous Membranes Produced By Biaxial Orientation Of Compatibilized Pp/Nylon 6 Blends
In this study, microporous membranes were fabricated from polypropylene/polyamide 6 blends compatibilized with polypropylene grafted maleic anhydride. Biaxial orientation of these blend films within a narrow composition range yielded through-pore membranes with adjustable pore size and porosity. The morphologies of the through-pore membranes were characterized by scanning electron microscopy. The effects of composition, draw ratio, and initial film thickness on porosity, and water permeation were evaluated. The blend film thickness was found to be the major variable upon membrane properties where higher thickness yielded lower density and smaller pores. These blend membranes were employed as the filtration media to separate Latex microbeads in aqueous solutions. It was discovered that the blend membranes could achieve >99% filtration efficiency using 100 nm Latex microbeads.
Investigation Of Droplet Behavior Under Real Mixing Conditions
Plastics gain higher impact strength when they contain a certain amount of a soft-phase. In case of incompatible blending components, the properties of the final product depend usually on the soft-phase’s droplet size distribution. Therefore, many research activities address the prediction of the droplet sizes during plastic processing. However, the investigations are done under laboratory conditions usually and often representative polymeric model fluids are used instead of real plastic melts.In this work a novel experimental setup was constructed, which allows to research the droplet behavior under real operating conditions with plastic melts. Experiments were carried out and the droplet size distribution was evaluated under several conditions. In the next steps a simulation model for prediction of the droplet size distribution will be developed.
Influence Of Processing And Formulation On The Properties Of Pp-Pet-Blends
The aim of this work was to investigate the effects of the composition and processing on the properties of PP-PET blends with and without compatibilisation. As the processing routes blend production via a co-rotating twin screw extruder as well as single screw extruder were chosen. We found, that it is possible to compatibilize PP-PET blends via the addition of maleic anhydride grafted PP. This effect can be seen from the morphology of the samples as well as from mechanical properties. In twin screw extrusion, the application of vacuum degassing shows additional property improvement due to the condensation of PET. The compatibilizer is also effective in single screw extrusion, but the effect is lower due to the missing degassing options. Nevertheless, the compatibilized blends are stable and the results show, that such mixed plastics, which can also be found in waste streams, can be reused when being properly processed.
Design Of Extensional Flow Static Mixers For Blending Of Ternary Nanoparticle-Polymer-Polymer Blends
In this work, static mixers were designed, fabricated, and tested that employ strong extensional flow fields to promote dispersion in immiscible thermoplastic polymer blends. Additionally, surface-treated nanoparticles were added to the blends for the purpose of compatibilizing the immiscible polymers. Several relatively simple, easily fabricated designs are discussed along with their efficacy at promoting dispersion in a blend of high-viscosity high-density polyethylene (HDPE) dispersed in low-viscosity polystyrene (PS). Several commercial grades of fumed nanosilica with various surface chemistries were investigated to study their effects on the polymer blend morphology with and without processing through the extensional flow static mixers. Some simple design rules were determined to aid in the design of extensional flow static mixers, or extensional flow cells (EFCs), based on results processing unfilled binary polymer blends, and the efficacy of ternary nanoparticle-polymer-polymer blend processing for controlling the morphology of the blend was evaluated.
Rheology of Polymer Nanocomposites
The rheological behavior of polymer nanocomposites is a field of vital importance to scientists and engineers in the plastic and rubber industry. The rheological behavior of nanocomposites is affected by type of fillers (nanoparticles, graphene, nanofibers and nanotubes) their concentration, filler-filler and polymer-filler interactions. After decades of extensive research, the theoretical description of the linear and nonlinear behavior of nanocomposites is still lacking. This presentation will discuss the rheological behavior of the polymer nanocomposites in small and large amplitude oscillatory flow (SAOS and LAOS), start-up shear flow and step-strain relaxation. Our current understanding of theoretical description of various rheological properties obtained in these flow regimes will be presented. The model parameters will be obtained from SAOS experiments. Then these parameters will be used to describe the nonlinear behavior in various flow regimes.
Investigation On The Viscosity Characterization Of The Glass Mat Thermoplastics (Gmt) In Compression Molding System
Due to its great features of lower tooling cost, better retaining fiber length and concentration, glass fiber mat thermoplastics (GMT) material has been attracting a lot of attention in modern lightweight technology development. However, some defects and unstable quality control problems are still bothering us. To overcome these troubles, people are usually applying CAE technology to assist. However, in this field, CAE is not mature enough yet due to the rheological properties of the GMT material are not measured properly. In this study, we have proposed a method to measure the rheological properties of GMT material through a compression system. Specifically, we have focused on the viscosity of the squeeze flow under the operation of compression processing. The analyzed data is further used for estimation of the rheological parameters and calculation of viscosity at various temperature settings. Moreover, the estimated rheological parameter of the GMT material is integrated into Moldex3D to evaluate the squeeze flow behavior under the compression operation through numerical simulation and experimental study. Results showed that under the higher compression speed, the loading force is increased exponentially as melt flow time is increasing. The numerical simulation prediction is consistent with that of experimental result. However, at slower compression speed, the deviation becomes more serious for simulation approach and experiment. The reason needs to be investigated later. Also, there are various conditions need to consider in the coming future.
Effect Of Molecular Weight On Dynamics Of Linear Isotactic Polypropylene Melt At Very High Shear Rates
In this work, three isotactic linear polypropylenes, with weight average molecular weights between 56 250 - 75 850 g/mol, have been characterized at 230oC over a very wide shear rate range. A low shear rate primary Newtonian plateau, a pseudoplastic region and a well developed secondary Newtonian plateau were identified for all the polypropylene melts. Flow activation energy at low (E0) and high (Einfin) shear rates was found to be 56.590 kJ/mol and 25.204 kJ/mol, respectively. For the first time, it has been discovered that the secondary Newtonian viscosity, EtaInfin, depends linearly on the weight average molecular weight, Mw, in log-log scale as EtaInfin=1.19*10^(-6)*Mw^(1.084). The observed slope close to 1 between Einfin and Mw suggests that polymer chains in the melt are disentangled at the secondary Newtonian plateau region. This conclusion is supported by the experimental observation that the high shear rate flow activation energy Einfin for given PP melts is comparable with the flow activation energy of PP like oligomer (squalane, C30H62; 2,6,10,15,19,23-hexamethyltetracosane).
Visualization Of The Flow Paths In A Tangential Internal Mixer To Optimize The Mixing Behavior
The visualization of the flow paths in a tangential internal mixer gives the opportunity to understand which kind of mixing is pronounced in dependency of process parameters. With this knowledge the mixing processes can be optimized, so that shorter mixing times and more homogenous mixing is possible. The flowing behavior between the rotor and the mixing chamber was already investigated extensively but the complex flow paths between the rotors is not well known yet. With different colored compounds, it is possible to visualize the flow paths in the mixing chamber. Hereby, the mixing process is stopped after different mixing times and the mixing chamber is completely opened to take the compounds out of it. Those compounds are sliced and photographed. The complex flow paths can be analyzed with different methods that are evaluated in this contribution. One possibility is the analysis of objects in the area between the rotors to draw conclusion on the distributive and dispersive mixing.
Rheological Method Development: Polymer Designs For Blow-Molded, Automotive Seatbacks
Extrusion blow-molding of very large parts such as those used in the automotive industry can exceed the melt strength limits of the polymer or polymer blend of choice. This study was undertaken to define new rheological tests capable of defining the maximum parison weight a material can maintain in the blow-molding process at a given die dimension and temperature. In addition, this is balanced with 1) measurements of the extent of shear thinning as it relates to shear heating that reduces melt strength and 2) measurements of strain recovery that add to the parison weight required to achieve a given length. These rheological measurements are combined with the mechanical properties required to meet specific automotive material specifications as responses in a design of experiments approach to polymer development. Compositional factors associated with PC/ABS blends were defined to successfully produce a model predicting both the ability to fabricate a part from a 30 lb. parison as well as have the mechanical properties necessary to meet the requirements of the European Luggage Retention impact standard for a seatback.
Molecular Weight Distribution Prediction Of Rheology Against Gel Permeation Chromatography For Film Grade Polypropylene
General purpose isotactic polypropylene (iPP) grades are not very suitable for processing operations subjected to sever elongation flow field due to their tension thinning behavior and low melt strength of their essentially linear nature. Yet, by some modification in their structure, or even changing the shaping process design, they may be readily be used in processes such as blow molding, fiber spinning, BOPP processing, etc. In this work, suitability and molecular structure requirement of two commercial PP homo-polymer film grades for slit-die extrusion were investigated. Molecular weight distribution (MWD), as the main parameter to describe the molecular structure of a linear polymer, of these resins were evaluated through measurements of GPC and rheology. From their dynamic shear data the relaxation spectra, h(τ), were calculated from which MWD was estimated using molecular viscoelastic theories and then compared with the GPC results. Generally good agreement, but with narrower MWD rheology curves was found. Exception was observed for the grade for which rheological data predicted bimodal distribution curve comprising a small shoulder of high MW, not seen in the corresponding GPC curve. A higher value of the generalized mixing parameter than that of the double reptation model which was found for this bimodal grade was attributed to an increase in the number of entanglements and better network connectivity.
Effect Of Salt Addition On Dynamic Mechanical Properties For Poly(Methyl Methacrylate)
The effect of the addition of a metal salt compound with low molecular weight on the glass transition temperature Tg was investigated using poly(methyl methacrylate) (PMMA). Lithium trifluoromethanesulfonate was found to be miscible with PMMA and thus the blends show excellent transparency. Furthermore, the Tg shift to high temperature as well as the modulus enhancement in the glassy region were detected by the addition of the salt. The electrostatic interaction between PMMA and the salt is responsible for the phenomenon. Furthermore, it was found from the oscillatory shear modulus measurements beyond Tg that rheological terminal region is clearly detected in the blend without a secondary plateau.
Synergistic Absorption Of Microwave Radiation In Pvdf Hybrid Nanocomposites Containing Multiwall Carbon Nanotubes And Ferrite Particles
This study presents absorption driven attenuation of microwave radiation in polyvinylidene fluoride (PVDF) nanocomposites facilitated by conducting multiwall carbon nanotubes (MWNTs) and ferrite particles. Electromagnetic interference (EMI) shielding was achieved via a large dielectric loss arising from electrical conductivity (associated with networks of MWNTs) and magnetic loss stemming from ferrite particles. Two different types of ferrites (i.e., nickel ferrite and cobalt ferrite) were synthesized and employed for absorption of microwave radiation. When ferrite particles along with MWNTs were incorporated in PVDF matrix, cobalt ferrites depicted the highest shielding effectiveness. Moreover, the effect of network formation of fillers in PVDF matrix was analyzed by rheology and the correlation of rheological properties with microwave attenuation was studied. The underlying mechanism of microwave absorption in these nanocomposites was systematically assessed with the help of complex permittivity and permeability in X-band frequency, as the X-band frequency range is essential for major commercial applications.
Modification Of Rheological And Crystallization Properties Of High Performance Polymers For Thermoplastic Composite Applications
Continuous fiber reinforced thermoplastic composites offer many advantages over thermoset composites, including longer shelf lives of raw materials, faster processing times, design freedom, and the ability to recycle. High performance resins offer high use temperature and excellent mechanical properties in composites, however they present the challenges of high processing temperatures and melt viscosities. Polyhedral oligomeric silisesquioxane (POSS) nanostructured chemicals offer the opportunity to enhance melt flow and increase crystallization rates in polymer systems when they can be dispersed at the nano-level. We describe the rheological and crystallization performance of POSS blends with PPS and PEEK resins.
Nonlinear Viscoelastic Fluid Models With Fractal Time Derivative
In this paper, we present a viscoelastic fluid formulation containing fractal time derivative. We demonstrate that the inclusion of fractality allows one to model multiscale effects of typical viscoelastic fluids, overcoming undesired stationary predictions and reducing or even eliminating multiple modes in data fitting. The linear version of the fractal model is scaled up to large deformation by incorporation of objective rotation in the constitutive formulation. The resulting model having five model parameters (one for degree of fractality, two for linear viscoelasticity, one for straining, and the last one for rotation) is able to fit startup shear viscosity of a high molecular weight polystyrene solution in high accuracy, and yet using only a single mode.
The Effects Of Metal Stearates On The Rheological Properties Of Powder Injection Molding Feedstocks And Resulting Molded Green Parts
The effects of adding metal stearates to a powder injection molding (PIM) feedstock prepared with a wax based binder system and silicon powder was investigated. The rheological properties and molding properties of the feedstocks were characterized. Predictive viscosity models were developed for each feedstock. The zero-shear viscosity was constant with the introduction of metal stearates while, the yield stress was seen to decrease. The molded green parts were produced with a traditional injection molding process. The surface quality of the molded green parts did not seem to change. The quality through the thickness changed as vacuum voids started to form with the introduction of the metal stearates.
A Mechanistic Model For Nanocavity Filling
In this paper, we present an analytical study on the influences of different competing factors on the nanocavity filling process. Particularly, various dimensionless groups are defined to gauge into the size effects in nanocavity filling. A mechanistic model for nanochannel flow is formulated on the basis of disentanglement between molecular layers. The focus was placed on determining the major enabling factors for achieving cavity fill in an extremely short imprinting period on the order of 1 second. It is found that a high-energy mold surface is necessary in roll-to-roll imprinting where the contact time is extremely short and a high imprint pressure is difficult to apply. Additionally, in-mold solidification must be incorporated in precision replication, suppressing shape distortion caused by elastic recovery.
How Plastics Helps To Conquer The New Challenges Of Vehicle Electrification
How plastics helps to conquer the new challenges of vehicle electrificationbyMelanie Mennigke; LG Chem - Key Account ManagerWerner Posch; Dräxlmaier Group - Material ManagementThe need for zero emission solutions is steadily increasing and OEMs are currently developing battery electric vehicles with a focus on providing emission-free transportation, combined with lowest total cost of ownership. The main challenges for these vehicles include: range; cost and weight.Electric vehicles are no longer a trend but an established fact. In order to make the correct decision on which technological approach – BEV (battery electric vehicle) or REEV (range extended electric vehicle) - best meets the requirements of the market, the manufacturers specific boundary conditions and economic aspects have to be balanced with a multidisciplinary approach. The development of alternative drive vehicles is driven by both consumer and government demand. Consumers want fuel-efficient, low-emission vehicles, but they do not want to pay a premium to drive a more sustainable car. Governments want improved fuel economy and low emissions, and go as far as using manufacturer tax credits and consumer write-offs to incentivize alternative drive vehicle development. However, for a solution to be truly sustainable, it must be economically feasible, as well as environmentally sound.As the market grows for hybrid-powered and electric vehicle technology, plastics play an ever more important role to help reduce carbon emissions and dependence on petroleum. The challenges of using plastics in electric vehicle technology are: • Use of plastics instead of aluminum and steel for weight reduction• Use high-performance polymers and elastomers to integrate components and functions — this miniaturization reduces space and improves packaging.• Improve battery pack performance with flame-retardant and thermoplastic materials.• Prevent electrical arcs and sparks in connectors with thermoplastic materials that meet 650-volt system requirements.• Provide electromagnetic compatibility (EMC) The presentation includes proved plastics solutions for challenges described above. Examples of developed and already in serial production electric power trains (High-voltage battery systems, power electronics,...) to identify the right plastics for design and serial production which fulfil requirements such flame resistance, EMI shielding, weight reduction,... So that automakers can build hybrid and electric vehicles that meet consumer and environmental needs.
Connecting Rheology Of Polyolefin Elastomers To Dispersion In A Polypropylene Matrix Via Modeling And Experiments With Simple Flow Fields
Controlling the dispersion of polyolefin elastomers in polypropylene is critical for applications requiring low temperature impact toughness, such as for automotive TPO compounds. To better understand the role of polyolefin elastomer design and rheology on dispersion in polypropylene resins, a computational fluid dynamics model was developed to study the effect of viscoelastic behavior on particle breakup in simple flow fields. This model was applied to breakup of polyolefin elastomers with different rheological features in a high flow polypropylene matrix. Experiments were conducted with similar blends under comparable simple flow fields to validate the results of the model. The learnings were then applied to a simple TPO compound produced with typical twin screw extrusion and injection molding, demonstrating the benefits of a particular elastomer rheology on dispersion and impact toughness properties, and validating the utility of the computational fluid dynamics model to help guide polyolefin elastomer resin design.
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