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Conference Proceedings
Durable Bond of Originally Incompatible Materials by Using the InMould-Plasma Process
Elmar Moritzer | Frederik Mühlhoff | Erhard Krampe, April 2021
Continuously increasing demands on the component functionality as well as the demand for efficient production processes are causing a change of multi-component injection molding from a special process to a key technology in plastics processing. However, the possibilities of the process are limited due to the complex interactions in adhesion. Innovative product solution ideas are limited by limiting material factors or by excessive process costs due to necessary process steps. The use of the atmospheric pressure (AP) plasma process can extend the compatibility of polymer materials. Nevertheless, a complete integration into the injection molding process has not yet been achieved. With the development of the InMould-Plasma treatment a process has been developed which integrates the plasma activation of plastic surfaces into the injection molding cycle. In this study it is shown that original incompatible materials, like polypropylene (PP) and thermoplastic polyurethane (TPU), have a long-term stable bond under different aging conditions, by using the InMould-Plasma technology. Due to their relevance in the automotive sector, the aging conditions are based on test standards of German car manufacturers. These include aging in an oven up to 120 °C, cold storage down to minus 40 °C, water storage and climate change tests. For testing the bond strength, the samples were peeled apart according to the standard VDI 2019. The influence of the aging of the individual components was supplemented by tensile tests. The test specimen are tensile rods according to DIN EN ISO 3167 and were subjected to the same conditions as the composite. It is shown that the InMould-Plasma process enables a long-term stable bond between originally incompatible materials and withstands the aging conditions in accordance with test standards of German car manufacturers.
Failure Analysis of Products with Plastic to Metal Threaded Connections
Gaurav Nagalia | Anand R. Shah, April 2021
Many products and assembled systems of different products require the use of threaded plastic to threaded metal connection to provide the mechanical integrity required for the service application. While there are design guidelines and industry acceptable standard specifications related to the design of the different thread profiles used in the connection of plastic to plastic or connection of metal to metal threaded components, there is very limited information available for designing a plastic to metal threaded connection. Generally, designing a mechanical connection between a plastic threaded component and a metal threaded component is discouraged. However, in some applications this cannot be avoided and as such the lack of understanding related to plastic to metal threaded connection leads to product failures when such connections are made or designed improperly into products. This paper reports two case studies of product failures where plastic to metal threaded connections contributed to product failure that caused either personal injury or personal property loss. A failure analysis investigation was conducted to evaluate the thread design in two products in which plastic to metal threaded connections were involved in the product failure. In the first case-study, the thread connection was found to be insufficient in the mechanical strength and in the second case study the root cause of failure was determined to be excessive tightening of the female threaded plastic component onto a male threaded metal component.
Fiber Orientation Measurements for Large Additive Manufactured Parts Using Optical and SEM Imaging
Rifat Ara Nargis | David A. Jack, April 2021
Acrylonitrile Butadiene Styrene (ABS) is widely used in additive manufactured part production due to its widespread availability and ease of manufacturing, but unfortunately its structural and thermal performance limits its use in industrial applications. The addition of fiber reinforcements, specially chopped carbon fiber to the ABS matrix has the potential to enhance its structural performance while simultaneously reducing dimensional variations during thermal changes. The quantification of the fiber orientation in the processed ABS bead is important to understand its correlation to the mechanical and structural properties of the processed thermoplastic. This study presents the sample preparation and acquisition of images of fiber orientation and void measurements through optical and scanning electron microscopy of an additive manufactured bead with 13% by weight carbon fiber reinforced ABS. The images are then analyzed, and the fiber orientation is measured using the method of ellipses. The method of ellipses poses a problem of ambiguity for the direction of fiber orientation. With the SEM images the ambiguity problem can be solved using an electrical shadowing technique and the orientation of the fibers in the ABS matrix can be determined. The results for the orientation from the two methods are contrasted, and a discussion is provided on the impact the fiber orientation has on the final part performance. The results also indicate the presence of voids caused by the deposition process that is unique to the currently employed additive manufacturing process which will hamper the final part performance.
3D Printing Sustainable Biocomposites From Recycled PLA and Micro-Crystalline Cellulose
Akhilesh K. Pal | Erick O. Cisneros-López | Arturo U-Rodriguez | Feng Wu | Manjusri Misra | Deborah F. Mielewski | Alper Kiziltas | Amar K. Mohanty, April 2021
The motivation for this work was to increase the economic life of recycled poly(lactic acid) (rPLA) (30 wt%) by utilizing it with virgin PLA (70 wt%) in the presence of a fiber-based reinforcing filler, micro-crystalline cellulose (MCC) and an epoxy-based chain extender. A conventional melt extrusion technique was used to fabricate the strands with and without MCC and chain extender in the PLA/rPLA blend matrix. It was observed that the complex viscosity of rPLA was improved significantly after the addition of the chain extender, which resolved the issue related to excessive polymer flow during processing and hence made it possible for use in fused deposition modeling (FDM)-based 3D printing. The addition of the chain extender improved the impact strength of 3D the printed PLA/rPLA specimens. The voids in the 3D printed material contributed to the reduced weight of the developed sustainable composites. The modulus and tensile strength of the 3D printed sustainable biocomposites were improved significantly, and impact strength increased by ~10% by reinforcing the blended matrix with 5% of MCC.
Depolymerization Kinetics of Recycled Polyethylene Terephthalate During Melt Mixing
Akanksha Patel | Shawn Martey | Margaret J. Sobkowicz, April 2021
This article shows the effect of melt mixing parameters such as temperature and time on the macromolecular chain structure of Recycled Poly(ethylene terephthalate) using a batch mixer. The objective was to develop a pretreatment of PET to reduce molecular weight and crystallinity in preparation for microbial degradation. A depolymerization kinetic model was built to understand the irreversible structural changes caused via melt processing of RPET. Chain scission reaction occurred faster at higher temperatures, as evidenced by molecular weight calculated from intrinsic viscosity measurements.
Advances in Extrusion Blow Molding of Post-Consumer Resin
Ian P. Query, April 2021
Demand for increased recycled content in various applications has driven innovation toward incremental step change in recycled material quality. In pursuit of increasing recycled content usage in extrusion blow molding applications, considerations must be made for the preservation of mechanical properties via the prevention of thermal and oxidative degradation during both the recycling and molding processes. In order to understand the importance of timely implementation of solutions like stabilizer blends, a set of experiments was run on extrusion blow molded articles to illustrate the rate of performance decay that occurs between the recycler and the molder. This analysis proposes pathways to improve upon current recycled content utilization while simultaneously improving end-use properties.
Scratch Resistant Coatings: High Performance, Economic Solutions for High Quality Low Gloss Finishes
Robert Randant, April 2021
Low gloss finishes (≤2 GU at 60°) are a demand across a variety of industries. These low gloss finishes must provide scratch, mar, and burnish resistance to maintain physical and visual integrity over the lifespan of a product. This can present unique challenges within interior automotive, where low gloss finishes are expected to provide luxurious aesthetic characteristics as well as support the need for anti-glare application for driver safety. The high traffic of automotive cabins requires the low gloss finishes to be highly resistant to chemical and abrasion resistance throughout the lifetime of the vehicle. Continuous evolution in the methods used to evaluate interior automotive materials has led to the development of new, innovative coating technologies that exceed previous scratch and chemical resistance expectations for interior finishes. The performance capabilities of new coating technologies and the supplemental benefits they bring enable designers to achieve low gloss, quality finishes that exceed Original Equipment Manufacturer (OEM) testing demands for performance and quality while remaining cost-effective.
Lifetime Prediction of Continuous Fiber-Reinforced Plastics Based on Nonlinear Damage Accumulation
Simon Rocker | Reinhard Schiffers | Lars Gerdes | Daniel Hülsbusch | Frank Walther, April 2021
Full Title: LIFETIME PREDICTION OF CONTINUOUS FIBER-REINFORCED PLASTICS BASED ON NONLINEAR DAMAGE ACCUMULATION AND FINITE ELEMENT SIMULATIONS Abstract: This paper presents an approach for lifetime prediction of fiber-reinforced plastics based on nonlinear damage accumulation. Already established damage accumulation laws, such as Palmgren-Miner, are to be modified with nonlinear parameters in order to characterize the damage evolution of fiber-reinforced plastics in a more accurate way. For this purpose, cyclic investigations were carried out on glass fiber-reinforced polyurethane with quasi-isotropic layer setup to determine basic mechanical characteristics. The stiffness-based characteristic values, recorded to develop the simulation model, are generated from hysteresis loops, which are also used to calibrate the material model. The experimentally determined stiffness degradation is converted into a damage curve by assigning the first measured value to degree of damage 0 and the failure value to degree of damage 1. Therefore, a hysteresis loop for each degree of damage between 0 and 1 is present, so that a damage dependent stress-strain ratio can be determined and transferred to the material model cali-bration. In addition, a characteristic damage development is derived from the damage curves, whereby the stress level and the influence of sequence can be taken into account for a nonlinear damage accumulation model on global level. Based on the global findings an algorithm is presented that transfers those to the local level in finite element simulations. This approach provides the fundamentals for a lifetime prediction of fiber-reinforced plastics with varying fiber orientations under cyclic loading.
Developing Photopolymerizable Acrylate Resin Formulation for Impact Modified 3D Printed Thermosets
Chinmay Saraf | Amy Niu | Alan J. Lesser,, April 2021
This contribution focuses on engineering photopolymerizable acrylate resin formulations for a superior fracture energy absorption of 3D printed acrylate thermosets. Herein, we report a polydimethyl siloxane-based block copolymer as an impact modifier, compatible with the UV curing process, which undergoes reaction induced phase-separation during the 3D printing process to form a rubbery phase sufficient for enhanced impact properties. A systematic investigation of the effect of concentration of the impact modifier on the morphology of rubbery domains and fracture toughness was conducted. Results show that at an optimum concentration of 15 wt.% and particle size of 57 nm, an order of magnitude improvement in the fracture energy release rate is realized. Fractographic analysis of the impact modified thermosets using optical microscopy indicates the presence of significant plastic deformation in an otherwise brittle material. Notably, the engineered acrylate thermosets, at an optimum concentration, exhibit similar improvements in the impact properties irrespective to the print layer thickness and independent of the crack orientation with respect to the printed interphase. Detailed investigation of the failure mechanisms for impact modified thermosets show that the block copolymer diffuses to the interphase during the 3D printing process, resulting in preferential localization of the impact modifier near the print interphase resulting in an isotropic enhancement of the fracture toughness.
Evaluation of Sub and Near Critical Carbon Dioxide for Low Processing Temperature of Medical Thermoplastic Polyurethane
Sarn-ii Baru | Laurence Fitzhenry | Siobhan Matthews | Philip Walsh | Eric Marchese | Austin Coffey, April 2021
Incorporation of thermosensitive active pharmaceutical ingredients for manufacturing multifunctional polymeric medical device is still limited as they can be deteriorated in the hot-melt extrusion process. In this study, the potential of sub and near-critical carbon dioxide used as a green plasticiser was injected to hot melt extrusion process of Pellethane thermoplastic polyurethane to decrease process temperature. Its thermal and rheological behaviour were also evaluated. The resultant extrudates were characterised using parallel-plate rotational rheometry and differential scanning calorimetry. The process temperature decreased from 185 to 160 °C. The rheology indicated that the reduction of melt viscosity to 36.36% and 40.04% at 600 and 1000 psi, respectively. The results indicate that the employment of scCO2 as a transient plasticiser is a viable aid to conventional hot-melt extrusion and offer more opportunities for thermosensitive drugs to be more thermally stable in the molten stream of Pellethane thermoplastic polyurethane.
Comparative Study of Filled and Unfilled PLA Produced Via Injection Molding and 3D Printing
Chethan Savandaiah | Bernhard Plank | Julia Maurer | Juergen Lesslhumer | Georg Steinbichler |, April 2021
This study investigates the impact of two different processing methods, Injection molding (IM) and 3D printing (3Dp), on Neat/unfilled polylactic acid (NPLA) and the short carbon fibers (SCFs) filled polylactic acid (SPLA). Furthermore, the resulting processing conditions and its influence on mechanical properties, such as tensile, flexural, notched Charpy impact test, and heat deflection temperature (HDT) along with the process-induced effects, such as fiber length distribution and voids were studied. The process-induced voids were evident in all the computed tomography (CT) scans, 3Dp specimens have higher void volume fraction compared to no visible voids in IM specimens. Similarly, the mechanical test results such as tensile, flexural and notched Charpy impact test follow the trend for 3Dp SPLA and IM SPLA. On the contrary, 3Dp 0° and ±45° NPLA tensile test results are comparable to IM NPLA, whereas 3Dp 0° NPLA has the highest impact resistance compared to injection molded NPLA and SPLA as well as 3Dp SPLA specimens, indicating the annealing effect induced by the heated 3D printing bed along with increased void volume fraction. Furthermore, the HDT study indicates the maximum serviceable temperature of both NPLA and SPLA remained comparable regardless of the processing method. Moreover, the change in fiber length distribution for SPLA injection molded and extruded filament specimens were negligible.
Failure Analysis Case Study: The Good and the Bad PVC Cable Coatings
Sergey Shilov, April 2021
Polyvinylchloride (PVC) is the most commonly used thermoplastic resin for electrical cable coatings. PVC that hardens after polymerization is not suitable for insulating and protecting wires and cables. The necessary mechanical, thermal, and electrical levels can only be reached with the addition of softeners, stabilizers, and fillers. Composition of the good and the bad PVC samples were analyzed using FTIR spectroscopy and TG analysis.  It was found that ditridecyl phthalate was used as a softener in both samples. Magnesium oxide was used as a filler in one sample. The higher amount of water that present in the sample at room temperature and evolves during the first stage of PVC decomposition might be responsible for the low heat resistance of one sample.
Effect of Filler Content on the Electrical Conductivity of Graphite Based Composites
Muhammad Tariq | Utkarsh | Nabeel Ahmed Syed | Ashique Baten | Amir Hossein Behravesh | Ghaus Rizvi | Remon Pop-Iliev, April 2021
This research work addresses the feasibility of employing thermoplastic composites as the substitute material for bipolar plates in a fuel cell. Bipolar plates are vital components of a proton exchange membrane (PEM) fuel cell assembly. Vigorous efforts are directed by manufacturers to reduce the size, weight, and cost of the bipolar plates. The carbon-based composites are comparatively cheaper, lightweight, and can easily be used for the production of bipolar plates. However, the bipolar plate material's electrical conductivity should be sufficient to conduct the electric current from one cell to another. The main purpose of this research was to study the effects of carbon content on the electrical conductivity of the composite material. The composite materials were produced by adding graphite particles into polypropylene matrix at different contents ranging from 60wt% to 84wt%. The through-plane electrical conductivity tests were carried out. While the electrical conductivity of the composites increased by increasing the graphite content. A sudden rise in electrical conductivity was also observed between 76wt% and 80wt%.
Tensile Specimen Preparation Method Impacting Failure Behavior
Sean S. Teller | Jorgen S. Bergstrom, April 2021
Sample preparation for polymer testing is an overlooked portion of the test plan and execution. Thermoplastics and thermoset materials offer multiple methods to prepare samples: injection molding, CNC machining, waterjet cutting, die-cutting, and laser cutting are all used often. We test samples of a polycarbonate (PC) material in uniaxial tension and compare results for injection molded, machined, waterjet cut, and diecut samples. All but the diecut samples showed the same stress vs. strain response, though the waterjet samples failed at a significantly lower strain. The die-cut samples showed significant damage on the edge of the specimens, and had a lower yield stress. Careful selection of specimen preparation methods is important to a well-designed test plan.
Filterability of Raven 1300 Ultra Carbon Black For Fine Denier Fiber Applications
Jun Tian | Natalie K. Harris, April 2021
Carbon blacks can offer improved performance over dyes in fiber and textile applications in polyester, polyamide and polypropylene resins. Their stringent cleanliness and superior filterability are of critical importance for successful fine denier fiber applications. In this study, the filterability of Birla Carbon’s fiber black Raven 1300 Ultra was evaluated after compounded in PET resin via twin-screw extrusion and a Farrel continuous mixer (FCM). The carbon black demonstrates excellent filterability performance via twin-screw extrusion and an FCM compounding processes. FCM was explored to make atypical PET masterbatches with higher carbon back loadings beyond 30%. However, a further study focusing on improving dispersion and filterability of highly loaded PET masterbatches is warranted to better serve the fiber application.
Novel Flame Retardants Based on Ionic Liquids for PMMA, PC and TPU Plastics
Yanjie”Jeff” Xu, April 2021
Inovia Materials LLC is positioned to develop new generation flame retardants and flow enhancers based on ionic liquids, to replace and expand the applications of traditional additives with high “green chemistry” qualities, superior performance and enhanced properties. we have developed new flow enhancers for PC, TPU, TPAE and high-performance plastics: PAR, PPA, PPS, PSU, PEI, PEEK, etc. Our flowing enhancers have superior thermal stability (400 degree C TGA), perfect compatibility (ionic liquids being tailorable), significant increase melt flow index at very low loading level, and mild effects on the physical-mechanical properties of plastics. We welcome product application opportunities from industries.
Blending Scholarly Knowledge and Practioner Know-How To Successfully Injection Mold A Complex Part
Jeremy Dworshak, May 2020
A complex piece of sporting equipment was molded to customer satisfaction, meeting critical dimensions despite complicated tooling and the use of a crystalline resin. Combining modern simulation techniques and industry expertise proved to be a winning strategy in solving this challenge. The use of post-molding, warp controlling fixtures was completely eliminated from the legacy production process, leading to improved part performance and plant efficiency.
Comparison of Longevity of PE- and PP-based TPO Waterproofing Membranes
Yushan Hu, May 2020
This study compared the longevity performance of polypropylene (PP) and polyethylene (PE) based thermoplastic polyolefin (TPO) waterproofing membranes. It was demonstrated that PE-TPO outperformed PP-TPO for both heat aging and standard UV aging in terms of tensile property retention, weight retention and resistance of surface cracking. Better longevity for PE-TPO is attributed to the lack of tertiary carbon which is intrinsic to PP and prone to chain scission.
Direct Compounding of Long Glass Fiber-reinforced Plastics in the Injection Molding Process
Marius Wittke, May 2020
Currently, only specially treated and compacted carbon fiber recycles can be fed into the twin screw extruder. In this paper, different delivery forms of fibers are characterized in terms of the product quality. The differences between the fibers for twin screw extrusion is illustrated.
Evaluation of Mesh Interface and Immersed Boundary Models For the Optimisation of Mixing Elements
Malte Schön, May 2020
Mesh interface and immersed boundary models are presented as simplifications for the simulative design of dynamic mixing elements for single screw extruders. These simplifications have great potential to cut complexity and cost in both drafting and computation. Results for distributive mixing are compared quantitatively and qualitatively to a non-simplified 3D model. It is found that good agreement with the 3D model is achieved when the simplified models’ throughputs are adjusted for mass conservation.


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