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Conference Proceedings

Effect of Fiber Orientation and Process Parameters on Shrinkage in Injection Molding of Thin-Wall Parts
Davide Masato, Jitendra Rathore, Sorgato Marco, Giovanni Lucchetta, Simone Carmignato, May 2017

Injection molding of high quality thin-wall parts is a challenge due to the high values of the shear stress in the melt flow, which affect the morphology of the moldings and their consequent shrinkage and warpage. In this work, the effect of the injection molding processing conditions on the dimensional accuracy of thin-wall fiber-reinforced parts was studied. The reduction of the shrinkage was taken in consideration analyzing how processing parameters affected the final dimensions of a specifically designed part. Moreover, the relation between the distribution of short glass fibers within the part and its dimensional accuracy was investigated by means of X-ray micro computed tomography. The experimental results showed that a selection of high values for both melt temperature and packing pressure allowed the minimization of the dimensional difference between the mold and the final parts. The analysis of the cross sections of the thin-wall parts, obtained from the micro computed tomography scans, allowed the observation of the `skin-shear-core' morphology indicating that the thickness ratio between the shear and core layers is affected in particular by the injection speed.

Effect of Compounding Approaches on Fiber Dispersion and Performance of Poly(Lactic Acid)/Cellulose Nanocrystal Composite Blown Films
Laurent M. Matuana, Sonal S. Karkhanis, Nicole M. Stark, Ronald C. Sabo, May 2017

This study was aimed to identify the best approach for incorporating cellulose nanocrystals (CNCs) into a poly(lactic acid) (PLA) matrix by examining two different CNC addition approaches. The first approach consisted of melt blending PLA and CNCs in a three-piece internal mixer whereas the second method involved the direct dry mixing of PLA and CNCs. The prepared compounded materials were then blown into films and compared in terms of fiber dispersion, optical, thermal and barrier properties. The experimental results indicated that the extent of fiber dispersion was not influenced by the CNC addition method, i.e., good dispersion was achieved by either method. However, the melt blended PLA/CNC films thermomechanically degraded during the melt blending process. Consequently, the melt blended PLA/CNC films had inferior properties than their direct dry blended counterparts. Thus, the direct dry blending process appeared to be the best approach of incorporating CNCs into the PLA matrix.

TUBALL™ Single Wall Carbon Nanotubes: A New Additive for Thermoplastics
Christian Maus, May 2017

TUBALL single wall carbon nanotubes (SWCNT) is a new SWCNT product developed by OCSiAl and produced at an industrial scale. It exhibits unique characteristics making it an excellent candidate to enhance material properties and to impart electrical conductivity to plastics. SWCNT allow the formation of a conductive network much more efficiently than other conducting fillers. A network of nanotubes can be established at very low additive dosages which results in a minimal influence on the other material characteristics. Investigations have been conducted to determine the possibility to prepare composites based on SWCNT using standard melt mixing equipment, such as twin screw extruders, to enable large scale adoption. This paper is primarily focused on polyolefins and demonstrates that a two-step compounding approach involving an initial masterbatch preparation enables compound development showing very low percolation thresholds. A range of parameters related to process conditions, including the effect of process temperatures, screw speed and profile or feeding conditions, have been investigated to determine their influence on the final performance. This study indicates that SWCNT can be considered as an additive for superior conductive performance for the masterbatch and compounding industry that will support the growth of high performance materials.

Melt Extrusion and Injection Molding for the Development of Pharmaceutical Mini-Tablets – Case Study Using Clotrimazole
Ethan McCarthy, Stephen Johnston, Maria Barsom, James DiNunzio, May 2017

Injection molding and hot melt extrusion are well developed plastic forming processes that have recently been garnering more attention in the pharmaceutical industry. The use of these thermal processing techniques reduces the need for hazardous solvents in order to create amorphous solid dispersions, which can improve the efficacy of poorly soluble drug compounds through increased solubility and bioavailability. This article describes the application of hot melt extrusion and injection molding to create pharmaceutical doses using clotrimazole in hydroxypropylcellulose.

Latest Developments in TPO Stabilization for Automotive Applications
Emilie Meddah, May 2017

In the past few years started a race for performances in TPO compounds for Automotive applications. Lighter, stronger, more durable, better aesthetics, more sustainable, less smell, a large amount of requirements for a given part in vehicles is making new developments more and more demanding and challenging. Clariant Business Line Polymer additives, specialized in polymer stabilization, is introducing new solutions which provide most of the current performances requested by the OEMs and beyond. Heat and light stabilization, low odor, surface appearance, low/no blooming are some of the qualities provided by this new range of products dedicated to Automotive TPOs under the AddWorks terminology. Specific AddWorks have been developed for Interior, Exterior and Under-the-Hood applications, and will be presented here.

Strain Analysis of HDPE Butt Fusion Joint in Side Bend Test
Xiangli (Shawn) Meng, May 2017

The standard practice ASTM F3183-16 (F3183) has been developed for conducting a three point side bend test to evaluate the ductility of a polyethylene butt fusion joint, but our understanding of the bending strains that are applied across the specimen during the test is far less than desired since there are no test values provided by the practice. In this paper we perform the strain analysis through grid method to investigate the strain level applied to the specimen. The present paper provides the results of strain levels at different bending angles for various selected combinations of loading nose radius and specimen thickness and then compares them with the estimated strain from pure bending theory. The experimental results show the strains increase with the bending angle and are higher than the estimations when the bending angle is larger than 60°. In addition, we conduct the side bend tests in three different temperature conditions to address the effect of temperature on the strain levels applied to the specimen at a given bending angle. The test results show that the higher strains are applied to the specimens at a lower temperature. In general, the present work will be a good resource to assist in the employment of the standard practice F3183 and advance our understanding of the process of the side bend test.

Processing of In-Plant Mechanically Recycled PA-12
Tino Meyer, Paul Sherratt, Andy Harland, Barry Haworth, Chris Holmes, Tim Lucas, May 2017

The increasing public awareness and demand for a more sustainable handling of the earth’s resources has led to the idea/ concept of a circular economy. Within this concept materials will be re-used in a closed loop system rather than being down-cycled or inappropriately managed (disposed via landfill) at the end of their life-cycle. Based on previous research, Polyamide 12 (PA-12) is a promising material candidate in the sports and leisure sector and its ability for being reprocessed via injection molding has been investigated. While other PAs tend to show a decrease in impact properties on mechanical recycling, PA-12 is shown to be able to overcome these problems when reprocessed at a higher melt temperature, yielding samples with improved impact properties compared to the primary material.

Injection Moulding Pilot Production: Performance Assessment of Tooling Process Chains Based on Tool Inserts Made from Brass and a 3D Printed Photopolymer
Michael Mischkot, Guido Tosello, Daniel K. Y. Nielsen, David B. Pedersen, Yang Zhang, Thomas Hofstätter, Lucas Herbin, Hans N. Hansen, May 2017

Additive Manufacturing is becoming a viable option for the production of injection molding inserts in pilot production settings. This work compares an insert made from brass using conventional machining with an insert made from a proprietary photopolymer using Digital Light Processing (DLP) through the application of precision injection molding. The performance of the inserts is analyzed focusing on design, metrological aspects, tool lifetime, and thermal performance. In the experiment, a disk-shape geometry (diameter 41.5 mm, thickness 3.5 mm) was injection molded in Low-Density Polyethylene in a two-cavity mold. The inserts as well as selected injection molded parts were analyzed with an optical 3D micro-coordinate measuring machine. It was found that additive manufacturing technology can lead to a significantly more cost effective pilot production, both in terms of development time and investment. DLP technology enables fast production of micro-features, however insert production with DLP is less reliable than milling e.g. when considering process repeatability. Photopolymer and brass inserts lead to differences in optical surface appearance on the injection molded parts. The lifetime of the photopolymer inserts is challenging to predict reliably. Depending on how many parts need to be produced, the use of several photopolymer inserts instead of one brass insert is a means to overcome the shorter lifetime and can represent a cost-effective alternative to machined inserts. In order to exploit the advantages of using additive manufactured injection mold inserts, specific tool design rules have to be applied.

Multilayer EVOH/HDPE Packaging in Processing and Performance of Recycled HDPE
Jon Mitchell, Didier Houssier, Geert Herremans, Edward Kosior, Kelvin Davies, May 2017

Kuraray, EVAL Europe N.V. (EE) produces Ethylene Vinyl Alcohol copolymers (EVAL™), which are used in multilayer structures in a combination with a wide range of materials such as High Density Polyethylene (HDPE) to produce multilayer bottles to provide superior barrier properties to gases, flavours or bring functional barriers against external contaminants such as mineral oils (MOSH,MOAH). Bottles are typically made by Co-Extrusion blow moulding (Co-EBM) technology and are used for beverage packaging such as dairy products and specialty milk and other packaging applications for sauces or dressings or for the packaging of medical products for which the Water Barrier of HDPE is of added value. The objective of the study was to investigate if multilayer EVOH/HDPE rigid packaging material, which is a percentage of the post-consumer recycling stream, can be effectively sorted with the HDPE stream and decontaminated back to food grade approved for use as Post-Consumer Recycled (PCR)-HDPE into food packaging applications. Multilayer rigid food packaging found in the post-consumer recycling stream has been represented in the design of materials guides and recycling guides as ‘may be suitable’ for recycling. The present work investigates the recyclability of EVOH barrier packaging due to the growing trends of multilayer rigid food packaging and more importantly, as recovery systems strive towards a better circular economy. The steps taken to produce food grade rHDPE with analysis included; Audits of the HDPE fraction at Viridor MRF, testing on automated NIR sorting equipment at Tomra (Titech), compounding in a low pressure, elevated temperature, food-grade decontamination process and overall migration testing conducted by Smithers-Pira. The evaluation showed that post-consumer HDPE (rHDPE) material containing at least 0.25% EVOH (equivalent to 5% multilayer EVOH/HDPE packaging) can be “super cleaned” to food grade quality without any significant impact on the process performance or physical properties compared to rHDPE only. The results showed that at the levels of multilayer EVOH packaging typically found in the recycled HDPE stream, the rHDPE can be processed and utilized in a full range of applications, without impact on migration characteristics or physical properties compared to rHDPE alone.

Back Injection Molding with Additive Manufactured Mold Inserts Using All-Inkjet Printed Substrates
Thomas Mitterlehner, Christoph Beisteiner, Hannes Rieger, Peter Dunzendorfer, Georg Steinbichler, May 2017

Back injection molding is a well-known process in the plastics industry. For example, the fabrication of decorated interior parts in the automotive industry is one of many fields of application. In the last few years, the additive manufacturing process rapidly expanded in injection molding. For instance, it is used for producing injection mold inserts made of metal or plastic. This technique is called Rapid Tooling. The aim of this paper is to investigate the back injection molding process with additive manufactured mold inserts made of Fullcure RGD 720 and to verify if this technique is feasible. Therefore, a substrate with all-inkjet printed conductor traces was placed in the mold insert. The injection molding was done with a standard injection molding machine. The conductive traces were printed with a standard inkjet printer manufactured by Epson. To generate additional information about the additive manufacturing material Fullcure RGD 720 a differential scanning calorimetry (DSC) was done.

Influence of Long-Term Annealing on Residual Stress Distribution and Quasi-Brittle Failure Properties of Talcum Reinforced Pipe Grade Polyproyplene
Omar Mohammed, Florian J. Arbeiter, Gerald Pinter, Andreas Frank, May 2017

In this study a polypropylene material with talcum reinforcement used for sewer pipes has been subjected to an annealing procedure at 80°C, roughly 60°C above the actual application temperature, in air for a time period of 18 months. As expected, examination of the material showed no significant decrease in mechanical or fracture mechanical properties due to the temperature exposure. However, samples stored at higher temperature showed better resistance against quasi-brittle failure in fatigue tests compared to unconditioned samples. This could mainly be attributed to the decrease of residual stress in the pipe wall. Even though pipes have been annealed for very long times above Tg, residual stress could not be totally relaxed within 18 months.

Creep Deformation Behaviour of Pc-Abs Parts Processed by Fused Deposition Additive Manufacturing under Different Extrusion Parameters
Omar Mohammed, Syed Hasan Masood, Jahar Lal Bhowmik, May 2017

Fused deposition modeling (FDM) is a complex process for many additive manufacturing practitioners as it involves selection of a large number of intervening process conditions to produce quality products to meet customer needs and achieve competitive advantages. Understanding the effect of operating conditions on the mechanical properties of FDM printed parts is an important task as they influence the functionality of the products. The growing demand for use of Polycarbonate /Acrylonitrile-Butadiene-Styrene (PC-ABS) alloys in the production of automotive components led to the need for understanding the creep deformation performance of processed material and product under various processing parameters. This study investigates the effect of FDM process conditions on creep deformation behaviour. A systematic study through definitive screening design and statistical analysis was carried out in order to correlate the FDM processing parameters with the performance of PC-ABS alloys. In this study, the regression model was developed for the calculation of the processing parameters in FDM of PC-ABS products and gives technical information for the determination of which process parameters are the best to use for practical purposes.

The Influence of Plastics Processing on the Biocompatibility of Medical Products
Andrea Müller, Annette Quick, Susanne Kühne, Thomas Seul, May 2017

Medical products must be biocompatible depending on application. However, numerous factors can negatively affect biological compatibility. Plastics processing can lead to degradation of polymer molecules via various process parameters such as processing temperature. These degradation products can have a negative influence on biocompatibility. The aim of these initial investigations is to explore the influence of injection molding on the biological properties of medical products. Comprehensive analyses of processing parameters, polymer degradation and its degradation products, as well as the cytotoxicity of various medical-grade plastics are presented. That processing parameters can significantly influence the final product's biocompatibility for certain materials is shown. Thus the release of formaldehyde during POM processing is demonstrated to have a cytotoxic effect on medical products.

Squeeze Performance of Oval Containers
Sumit Mukherjee, May 2017

Household cleaning agents and many salad dressings, mayonnaise, ketchup and condiments are often packaged in oval shaped containers that need to be squeezed in order to facilitate dispensing. These products are often displayed on a kitchen table or sink which means that brand owners should use containers that are both attractive and functional to support their high-visibility. Containers should not distort after use. On the store shelves they cannot appear dented—a potential byproduct of excessively thin corners or a non-optimal stacking arrangement. In a study conducted by Plastic Technologies, Inc. the many attributes of containers that make them easier or harder to dispense were investigated. The squeezing force has been recorded for a variety of 20- to 25 ounce containers in a number of product segments.The study was constructed to help brand owners understand what container attributes make them easier or harder to dispense. The force needed to dispense along with the amount dispensed per mm of indentation were tracked for different package segments. To make the comparisons fair, same size containers in a similar market segment were analyzed.

Developing a Soft Sensor Random Forest Model for the Inline Product Characterization of Polylactide (PLA) in a Twin Screw Melt Extrusion Process
Konrad Mulrennan, Marion McAfee, John Donovan, Leo Creedon, Fraser Buchanan, Mark Billham, May 2017

The melt processing of Polylactide faces challenges due to its poor thermal stability which is influenced by processing temperatures and shearing. The characterization of processed products takes place offline in laboratory environments. Typical scrap rates of a medical grade product can be up to 25-30%. This work discusses the development of soft sensor random forest models for a twin screw melt extrusion process. The resulting models can predict product end characteristics from inline data. These include mechanical properties and percentage mass change of a product during its degradation cycle. These models will act as novel inline indicators as to whether products will be in or out of specification. This will reduce manufacturing costs and minimize waste as well as accurately predicting future performance and behavior of products.

Polypropylene-Rich Blends with Ethylene/a-Olefin Copolymers Compatibilized with Intune™ Polypropylene-Based Olefin Block Copolymers
Jeff Munro, Yushan Hu, Ray Laakso, Lisa Madenjian, Steve Werner, Gary Marchand, May 2017

Polypropylene (PP) is one of the most commonly used thermoplastics due to its low cost and excellent properties, such as stiffness and heat resistance. However, PP is a relatively brittle material and is frequently modified with elastomers and other thermoplastics to impart toughness. Ethylene/?-olefin copolymers, including ethylene-propylene rubbers produced in the impact copolymer polypropylene (ICP) process and polyolefin elastomers (POEs) made in a solution process, are commonly used to impact modify isotactic polypropylene. While blends of polyethylene (PE) and polypropylene often have poor properties due to the incompatibility of the two resins, INTUNE™ Polypropylene-based Olefin Block Copolymers (PP-OBCs) were recently introduced as a means to compatibilize PE and PP resins. The design flexibility of these novel OBCs allows for a variety of ethylene-based polymers to be compatibilized with PP, from high-density PE (HDPE) to low density POEs, such as ethylene-octene elastomers. As with any immiscible blend, controlling the dispersion of the minor phase is critical to achieving the desired mechanical properties. Compatibilization can reduce the size of the domains in the blends and improve properties. Three cases of PP-rich blends will be used to illustrate the capability of novel PP-OBC compatibilizers to improve the dispersion and properties of ethylene-based copolymers dispersed in a PP matrix: injection molded ICPs, injection molded thermoplastic polyolefin blends (TPO – PP/POE/talc blends), and slow-cooled compression molded PP/POE blends.

Twin Screw Extrusion of TPVs Made from Devulcanized Tire Rubber Crumb and Polypropylene
Prashant Mutyala, C. Tzoganakis, M. Meysami, S. Zhu, May 2017

Blends obtained by dispersing devulcanized tire rubber (DRT) in thermoplastic polypropylene (PP) matrix were earlier studied by our group with the mixing carried out in a batch mixer. In order to obtain useful properties for these blends, the use of curatives was found to be essential. It was also realized that in order to facilitate the commercialization of this material, scaling up from a batch operation to a continuous one was necessary. This paper describes the work done to produce thermoplastic vulcanizates (TPVs) in a continuous manner using a twin screw extruder. Experiments were carried out at different conditions and samples were tested for tensile properties, hardness, compression set and their morphology was characterized using scanning electron microscopy (SEM).

Improved High Temperature Molding with Montan Waxes
Frank Neuber, Christian Lechner, May 2017

With the increase in demands for light-weighting and rapid, economical production of automotive and equipment parts, polymers which can withstand the high temperatures of under the hood applications have been replacing metal. In order to produce these parts rapidly and consistently, molders have reported needing the following to produce such parts consistently: easier flow, better mold release, consistent color without black specks, a “resin-rich” surface in filed polymers, faster cycles times, maintenance of physical integrity, reduced mold cleaning and reduced vent plugging. This paper provides data which shows how these improvement targets may be reached with montan waxes as the major process lubricant.

Computer Aided Output Improvment of a High Capacity Blown Film Extrusion Line
Benedikt Neubert, Johannes Wortberg, May 2017

For improving the output of high capacity blown film extrusion lines usually, the limiting factor, namely the air-cooling ring, is substituted or modified. Therefore, the production process has to be interrupted which is time and cost intensive. Primarily the major disadvantage of this experimental strategy is the uncertainty about the outcome. In detail, not all the thermodynamic and fluidic phenomena caused by the changing cooling configuration, and their impact on the formation of the bubble, are predictable in advance. To overcome these problems and to understand all the effects, which take place inside the bubble formation zone a numerical procedure has been developed and validated in previous works [1, 2, 3]. The so-called Process Model is capable of simulating the formation of the bubble with regard to changing cooling configurations and rheological behavior. According to industrial concerns, the modeling procedure was adapted to fulfill the requirements for simulating a high capacity blown film process [4]. In this paper, the first results for the numerical optimization of an industrial high capacity blown film process, using the adapted Process model, will be presented. Furthermore, a developed evaluation strategy for the CFD-results will be used to point out the positive effects of the modified cooling configuration. Based on the simulation results, the experimental validation will prove the applicability of the computer-assisted designing and optimizing strategy. For this purpose, the best virtual outcome will be manufactured and transferred to the current high capacity blown film line. It will be shown that output improvements of approximately 10% are achievable without neglecting the quality of the final film product.

Virtual and Experimental Comparison of Different Dynamic Mixing Devices for Single Screw Extrusion
Bastian Neubrech, Gregor Karrenberg, Johannes Wortberg, May 2017

Depending on the application, the demands on mixing devices in extrusion processes vary. The most common tasks can be summarized by providing a thermally and materially homogeneous melt for the downstream processes and mixing in additives or color master batches. Anyhow, the requirements increase due to increasing reachable screw speeds and the processed materials. Besides the named tasks the final plasticizing becomes relevant, as residence times inside the extruder decrease or a higher energy input is needed for the material. The major problem of implementing mixing devices is the increasing shear stress in combination with the rising melt temperature. Higher screw speeds intensify the problem of inadmissible high melt temperatures and material stressing even further. Nevertheless, the use of mixing devices is often indispensable, in order to meet the melt quality requirements. The consequence is the need of improved mixing devices as well as the development of new mixing device geometries. The aims of these improvements have to be an sufficient melt homogeneity and less material stress, leading to lower melt temperatures. For this development, the flow situation and the geometric influences of mixer geometries on the shear rate have to be analyzed. This paper deals with a numerical and an experimental comparison of two variants of an Improved Quality - Dynamic Mixing Ring device. The different designs are verified by CFD simulations and at the end validated by experimental data.

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