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
Effective Subtraction Before Additive Manufacturing: The Art Of Leveraging Constraints
For highly engineered components, the topological shapes that are generated based on the loads and boundary conditions, can be impacted by the many choices of constraints that are set. Over the years Altair’s Optistruct has developed the broadest set of constraints, and has recently introduced ‘overhang’ constraints for 3D printing so the resulting structure is grown to avoid a specified overhang angle (example: of 45 degrees typically), to minimize areas requiring support. Before embarking on creating a topological shape it is necessary to identify the direction of print, which is a sensitive variable by itself. With a variety of constraints available to a designer, a holistic approach needs to be developed wherein the entire process of manufacturing the part, including post processing operations, are carefully considered including the entire geometry that is printed along with the support structure. A fine balance between the interplay of choosing the right constraints, defining design & non-design space, and the right penalty factors, are critical for generating optimal topological shapes that accommodate, for example: areas for holding the 3D printed part for post-processing; or effectively evacuating the powder in plastic printing; or remove supports in metal printing. In this presentation, examples will be highlighted to showcase how to leverage the latest computational methods to efficiently subtract as much before additively manufacturing components, with a goal to develop an effective and repeatable product design strategy.
Material Selection, Testing And Validation Of Additively Manufactured Components
In order to successfully develop a structurally loaded component via additive manufacturing it is necessary to include several vital aspects. Currently, most attention is given to the geometrical reproduction of a design with as little deviation as possible. While for parts produced purely for aesthetic reasons or display this may be sufficient, it can lead to poor results for components used in structural or medical applications. Therefore, a careful material selection, rigorous testing and validation have to accompany the whole process, from the idea to the final component. This work presents an overview over the most important aspects that have to be considered for the material selection and testing in extrusion-based additive manufacturing of structural parts.
Structure And Property Relationships Of Additively Manufactured Polyphenylene Sulfide With Carbon Fiber Reinforcement
The objective of this work is to investigate the microstructure of carbon fiber (CF) reinforced polyphenylene sulfide (PPS) resulted from extrusion-based large-scale additive manufacturing (AM) process. This study attempts to establish a fundamental understanding on the role of AM process in transferring a set of intrinsic material properties to the macroscopic properties of the final part. Questions on development of morphology focus on polymer crystal orientation and carbon fiber alignment in proximity to the interface of successive layers. Our findings demonstrated that PPS at the interface has lower crystal perfectness compared to the layer region; the carbon fiber shows higher level of preferred orientation at the interface. Successive layers along the building z-direction present lower storage modulus as it is demonstrated in the dynamic mechanical analysis (DMA).
Critical Capillary Number In A Hyperbolic Converging Nozzle For Polymer Based Additive Manufacturing
Use of immiscible liquids in a polymer based additive manufacturing method is explored. A scaled up version of a converging hyperbolic nozzle is built, and the deformation seen by a droplet of Silicone oil in a bulk fluid of Castor oil is observed. Two different droplet injection positions in the channel are explored. Simulation studies showed the existence of pure extension along the centerline and a combined shear and extensional effect in the offset position. Non-dimensional plots of deformation measures vs. Capillary number showed an asymptotic trend towards a critical Capillary number for the centerline experiments. Offset deployment experiments resulted in a large degree of droplet stretch. These results advance our understanding of immiscible liquid behavior in hyperbolic converging nozzles for additive manufacturing applications
Rheological Characterization And Quality Assessment Of Commercial Abs Filaments For Fused Deposition Modeling
Acrylonitrile-butadiene-styrene (ABS) is the most commonly used thermoplastic used for Fused Deposition Modeling (FDM) due to its low cost and good properties. The viscoelastic behavior of five commercial ABS filaments was investigated and compared to quality features of a two-piece printed part. The results that the commercial ABS filaments differ not only with respect to viscosity, but also to relaxation time, recoverable deformation, morphology/composition, and thermal stability. Filaments with lower recoverable deformation tend to present better surface finish regardless the viscosity and relaxation time. Filaments with lower viscosities and faster relaxation times resulted in tight fit due to disproportional variations in the critical dimensions of the printed part.
Process Impact Of Elliptic Smoothness And Powder Shape Factors On Additive Manufacturing With Laser Sintering
As of today, polyamide 12 covers approximatively 90% of the commercially and industrially relevant Laser Sintering (LS) materials. To ensure a reasonable growth of the LS market, new materials must be developed to enlarge the material portfolio. However, the design of novel LS materials is critical as they need to fulfil several criteria. Besides suitable intrinsic properties of the polymer like correct thermal, rheology and optical behaviour, the constitution of the powder and the particles are decisive for a successful processing. This article presents the advances done in the field of particle form characterization for LS powders and their impact on LS processability. By using a trio of form factors, the powder flowing behaviour can be accurately predicted and hence enables to screen potential LS materials on a reproducible and reliable way.
Strength Analysis Of Fused Filament Fabricated Continuous Carbon Fiber Composite Test Samples
With the use of the Ansys® Workbook program, Markforged® Mark Two fused filament fabrication (FFF) composite samples were subjected to three-point flexural testing, using ASTM D790 standards. The results of flexural testing and the provided data of the mechanical properties of the composite materials were used to develop finite element analysis (FEA) models. The samples were composites of Markforged’s proprietary continuous carbon fiber filament and nylon filament. In comparison between the test results and the FEA models, both composite model methods and isotropic FEA modeling methods resulted in stronger and less flexible mechanical attributes if the proprietary material specifications were used. Through the development and analysis of micrograph samples of the Markforged’s carbon fiber filament (CFF), found that the CFF was only composed of 22.31% a fiber volume content (FVC). With the new FVC data, a more accurate model was possible for a limited range of flexural displacement.
Investigation Of Selective Laser Sintering Parameters On The Tensile Properties Of Polyamide-11
Selective laser sintering (SLS) is a rapid developing additive manufacturing process. It produces parts by selectively sintering powder together in a layer-by-layer mode. SLS processing behavior was investigated with a desktop printer (equipped with a 2W UV laser) on a commercial polyamide-11/carbon black (PA11/CB) powder. By systematically increasing the laser energy received by powder (by varying laser speed and laser hatch spacing), we successfully mapped out the laser settings needed to print parts with a reasonable amount of strength and ductility. Therefore, our low power 2 watt UV-laser successfully sintered PA11/CB tensile specimens. These PA11/CB specimens yielded at 53 MPa and elongated up to 65% before fracturing.
Investigation Of A Novel Additive Manufacturing Technique “4D-Rheoprinting” For The Manufacture Of Enhanced Polymeric Products
This paper discusses a novel additive manufacturing technology called “4D-RheoPrinting” and its application in spatial control of the material properties of additive manufacturing products. The technology was designed and developed to allow precise control over shear rate that a polymer strand undergoes during the 3D printing process, thereby inducing customizable molecular orientation of an individual printed “road”. This ability provides an added dimension to the conventional dimensional accuracy goal in 3D printing. Molecular orientation and crystallinity have shown to significantly influence mechanical, optical, thermal, and biodegradation properties of polymeric materials [1]. This work focuses on manipulation and control of shear rate using the RheoPrinting technique in order to print parts with tunable thermal, mechanical and biodegradation properties.
The Opportunity With Direct Digital Manufacturing
3D printing is often thought of only during the prototyping phase of product development, but designers and engineers should expect more from the additive technologies and materials available today. By embracing a direct digital manufacturing (DDM) strategy, companies are driving greater innovation, mitigating risk, lowering costs, and gaining agility. DDM enables design freedom, reduces lead times, and allows for more decentralized production, which will have significant impacts on communities across the globe. Ultimately, less rigid development and manufacturing means that more optimized, customized, and specialized products suddenly become viable as the barriers of scale are torn down. In this session, FATHOM will discuss why companies are opting for tool-less manufacturing for end-use products with real world application examples.
The Influence Of Melt Flow Rate And Nozzle Temperature In Fused Filament Fabrication
This study investigated the influence of the melt flow rate of acrylonitrile butadiene styrene (ABS) and nozzle temperature used in fused filament fabrication (FFF) on layer adhesion and printability. Prediction of the mechanical properties of printed parts, and the optimal process parameters for each material, is an area of continued difficulty. Test specimens were printed using four ABS filaments (representing a range of melt flow rates) at three different nozzle temperatures. Ultimate tensile strength, dimensional accuracy, bridging performance, and surface roughness were investigated using designed experiments. In general, low nozzle temperatures correlated to lower layer adhesion, but higher dimensional accuracy. Build plate position was not a significant factor for horizontal specimens but was for vertical specimens. Bridging performance and surface roughness were not affected by the melt flow index or nozzle temperature.
Mechanical Properties Of 3D Printed Polylactide/Microfibrillated Polyamide Composites
Fused deposition modeling (FDM) as the most common type of additive manufacturing (3D printing) is experiencing rapid growth. FDM employs thermoplastic-based materials to create complex and three-dimensional objects layer by layer. To expand the applications of FDM for end-use structural and functional products, novel printable materials with enhanced properties must be developed. Polylactide (PLA) has been well established as one of the most common feedstock materials in FDM 3D printing. However, PLA suffers from brittleness, narrow service window, and relatively poor mechanical properties. In this work, we report a printable PLA-based filament reinforced with microfibrillated polyamide-6 (PA6) in an attempt to enhance the mechanical properties of PLA-based prints. The microfibrillated PLA/PA6 fibers were produced by melt mixing followed by a hot stretching process. The filament feedstock was then prepared using a plunger-type extrusion process. Tensile test samples were then 3D printed and tested. The introduction of microfibrillated 3wt.% PA6 resulted in the improvements in the tensile modulus (~35%), tensile strength (~60%), and strain-at-break (~38%), compared to those of the neat PLA samples. The results of this work are highly applicable in developing high-performance printed materials.
Improving The Electrical Conductivity Of Pc/Abs Printing Filament For Fused Filament Fabrication Using Carbon Nanostructures
A study was conducted to show the effect of polyurethane coated carbon nanostructure (CNS) loading on the electrical volume resistance of polycarbonate (PC) and acrylonitrile butadiene styrene (ABS) blends. Formulations containing estimated 0.5, 3, 4 and 5 wt% CNSs were created using twin screw extrusion at various screw speeds and an efficient, repeatable method for characterizing electrical volume resistance was developed to compare the resistivity of manufactured samples. Screw speeds of 400 rpm, a material feed rate of 7.11 g/min and an actual CNS loading of 4 wt%, filament samples exhibited an average volume resistance of 74 ohm.
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.
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