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Conference Proceedings
Effects of Clay Loading on the Structures, Mechanical, Rheological Properties of Microcellular Foams of PLA/MMT Nanocomposites
Shyh-shin Hwang, Ching-hsin Hu, May 2013
This study investigated the effect of clay loading on the properties of conventional/microcellular injection molded Poly-Lactic-Acid (PLA) nanocomposites. The results showed that addition of MMT decreases the tensile/impact strength of PLA/Clay nanocomposites. The XRD results showed that with the addition of clay which increased the crystallinity of the PLA/MMT nanocomposites. The thermal properties results showed with the addition of clay which increased melting temperature, degradation temperature and thermal conductivity of the nanocomposites. The clay helps the nanocomposites on having small size cell on the foamed nanocomposites. For the rheological test, with addition of clay into PLA which decrease the viscosity of the nanocomposites. The decreased tensile strength and viscosity is caused by the degradation of the PLA/MMT nanocomposites.
Preparation And Characterization Of LDPE/ Clay Nanocomposites
Boniface Y. Antwi, Johannes A. Awudza, Victor N. Berko-Boateng, May 2013
Low Density Polyethylene/clay nanocomposite is a thermoplastic polymer matrix, that has nanometer scaled organoclay fillers dispersed in it. The characteristic structure of the material enhances its properties. This work therefore reports the preparation of Low density polyethylene filled with nanometer scaled octadecylamine modified Ghanaian clay particles, and determines the structure of the material formed. Commonly known clay samples from Mfensi community in the Ashanti Region of Ghana was used. Octadecylamine modified clays were incorporated into the LDPE matrix by melt mixing route. Structure of the LDPE/ clay nanocomposites was determined by Fourier Transform Infrared spectroscopy, (FTIR), x-ray diffractometry (XRD) and crosslinking density determination. Swelling index measurement was employed in the crosslinking density determination. Complete dispersion of clay fillers in LDPE matrix were best observed at very low modified clay loadings. The low density polyethylene molecules did not intercalate into the clay galleries. Modified clay contents increased the C-H vibrational motions of the LDPE/ clay nanocomposites. Also crosslinking densities of the nanocomposites decreased with increasing clay contents. We believe that dispersion of the polymer, (LDPE) in the clay matrix can be increased by applying high shear. Improving the dispersion will lead to increase of the LDPE loading in the clay composite.
Homogenization of Film Thickness in the Stretching of Polycarbonate
Andrea Wibbeke, Volker Schoeppner, May 2013
In order to study the homogenization of film thickness in the production of self-reinforced polycarbonate through stretching, it is first of all necessary to find appropriate methods for characterizing this homogenization. Different means of doing this are analyzed in this paper, and initial results presented. One way of characterizing the homogenization of the film thickness is through a double logarithmic plot of the true stress over the stretching ratio. Polycarbonate films are deformed in stretching investigations, employing different stretching ratios, stretching temperatures and stretching speeds and, in the course of this, the force versus the deformation is recorded. It is seen here that the degree of hardening is highest for the lowest stretching temperature in each case, and only at this temperature does homogenization of the film thickness occur that is independent of the stretching rate and the stretching ratio. This is also clear from the initial modeling results. The homogenization of the film thickness through deformation can be depicted by the finite difference method. Optical analyses using the 3D laser microscope allow the surface quality of the polycarbonate films to be analyzed before and after stretching.
Effective Blending of Ultrahigh Molecular Weight Polyethylene with Polythylene Via Solid-State Shear Pulverization
Mirian F. Diop, John M. Torkelson, May 2013
Blending ultrahigh molecular weight polyethylene (UHMWPE) with high-density polyethylene (HDPE) via conventional processing methods is challenging; as a result of the vast viscosity mismatch between UHMWPE and HDPE, blends prepared via melt processing contain UHMWPE agglomerates dispersed in HDPE. We demonstrate the utility of solid-state shear pulverization to effectively blend 20 wt% UHMWPE with HDPE. Using rheology, differential scanning calorimetry, and tensile testing we studied the effect of UHMWPE composition on blend properties.
Post-Curing Effects on Thermo-Mechanical Properties of Injection Molded High Performance Phenolics
Martin Hoeer, Gerrit Huelder, Sascha Englich, Michael Gehde, May 2013
Constantly increasing temperature requirements for automotive applications take thermoplastic materials to their limits. Due to their excellent thermo-mechanical properties, which can be enhanced by an additional post curing step, injection moldable thermosets have a high potential as an alternative to high temperature thermoplastics or aluminum. In the scope of this paper the influence of post curing conditions on the thermo-mechanical properties, such as glass transition temperature as well as stiffness or tensile strength are examined.
Synthesis and Corrosion inhibition of polyurea-b-polyimide copolymer Coatings
Linqian Feng, Jude O. Iroh, May 2013
A new class of polyurea-polyimide (PUI) block copolymer coatings has been successfully synthesized and formulated for corrosion protection of Al 2024-T3. The addition of polyurea leads to a remarkable enhancement in corrosion resistance and durability of PUI copolymer coatings, characterized by direct current polarization (DCP) in 3.5 wt% NaCl solution. In terms of chemical structure, the shielding of imide group by hydrogen bond (H-bond) self-assembly with polyurea effectively protects imide ring from hydrolysis. In terms of physical structure, the established H-bonds decrease the diffusivity of coatings, resulting in outstanding barrier property.
Scientifically Designed Barrier Screw
Chan I. Chung, May 2013
Single-screw extruders are most widely used in processing plastic materials for melting solid plastic into molten state, suitable for forming into desired shapes. The performance of an extruder basically depends on the geometrical feature of the screw. Among various types of special screws developed to improve the extruder performance, barrier screws utilizing a barrier flight have been most successful. The barrier flight divides the screw channel into a solid channel and a melt channel. Only molten plastic material can flow over the barrier flight from the solid channel into the melt channel. Many types of barrier screw with different geometries have been developed and successfully utilized in practice. Advances in machining screws now allow manufacturing of screws with complex geometries without difficulty. A novel barrier screw with a complex geometry is developed which confirms to the extrusion mechanisms along the screw, eliminating the shortcomings of previous barrier screws.
Effects of a Locally Inhomogeneous Atmospheric Pressure Plasma Treatment on the Adhesive Strength
Elmar Moritzer, Christian Leister, May 2013
To improve the adhesive strength of bonds for joining thermoplastic parts, atmospheric pressure plasmas are frequently used for pretreatment. To increase the width of the treatment, nozzle designs are deployed with an eccentric orifice rotating around the central axis of the nozzle. This rotating movement of the emerging plasma can result not only in inhomogeneous jet formation but also in uneven pretreatment. To examine the effects of inhomogeneous atmospheric pressure plasma treatment on the properties of the adhesive bonds, peel tests were performed with adhesives on pretreated thermoplastic substrates. Various locally inhomogeneous surface states were achieved by the pretreatment while varying some of the parameters such as the distance between orifice and substrate, velocity, and the position and diameter of the plasma orifice. To describe the intensity distribution of the plasma on the substrate surface, a mathematical model was developed and compared with the attained bonding properties. The results of the peel test correlate well with the modeled intensity distribution of the plasma treatment. In future, this model could be used to obtain a better description of the locally different adhesive properties after atmospheric pressure plasma treatment.
Sandwidh-Structured Thermo Plastic Olefin Resin for Light Weight Automotive Bumper Facias Enables Molding by a Conventional Injection Molding Machine
Kazuhisa To, Masaaki Onishi, Chiaki Asano, Masao Hara, Kazuhiro Furuta, May 2013
A high stiffness, Thermoplastic Olefin (TPO) resin material has been developed for light weight automotive bumper fascias. Although most conventional TPO materials for automotive bumper fascias consist of three components: polypropylene, elastomer and filler, this newly developed TPO consists of 5 components: two kinds of polypropylene, two kinds of elastomer and filler. The composition in this TPO was designed to enable sandwich- structure molding by a conventional injection molding machine. This TPO has not only a much higher modulus, but also better flow-ability when compared to conventional TPO ’s. By using this TPO for automotive bumper fascias, the wall thickness can be reduced from 2.5mm to 2.0mm, while maintaining equivalent performance. The new material, with sandwich structure molding, achieves a weight reduction of approximately 20%. Moreover, in the bumper production process, the thinner wall thickness reduces cooling time for molding by about 50%. As a result, the bumper molding time can be reduced from 60 to 30 seconds, leading to major reductions in the amount of energy consumed in the production process.
Experimental Verification Of Process-Parameter-Dependent Temperature Simulation Of The Two-Stage GITBlow-Process
Elmar Moritzer, Thorsten Plugge, Stefan Seidel, May 2013
The Two-Stage-GITBlow-process is based on the idea of combining advantages of injection molding and blow molding techniques. This is achieved by producing a preform with gas-assisted injection molding, which is then inflated into a larger cavity in the same mold. In this paper the transient development of the temperature distribution in the preform is calculated via finite element method for the entire molding process. Material-specific temperature-optima are simulated and subsequently verified with experimental studies.
Modeling of the glass fiber length distribution in the compounding of short glass fiber-reinforced thermoplastics
Volker Schoeppner, Philipp Kloke, Tobias Herken, Peter Heidemeyer, Johannes Rudloff, Karsten Kretschmer, Martin Bastian, May 2013
The use of short glass fiber-reinforced thermoplastics for the production of highly stressed parts in the plastics pro-cessing industry has experienced an enormous boom in the last few years. The reasons for this are primarily the improvements to the stiffness and strength properties brought about by fiber reinforcement. These positive characteristics of glass fiber-reinforced polymers are governed predominantly by the mean glass fiber length and the glass fiber length distribution. It is not enough to describe the properties of a plastics component solely as a function of the mean glass fiber length. For this reason, a mathematical-physical model has been developed for describing the glass fiber length distribution in compounding. With this model, it is possible on the one hand to optimize processes for the production of short glass fiber-reinforced thermoplastics, and, on the other, to obtain information on the final distribution, on the basis of which much more detailed statements can be made about the subsequent properties of the molded part. Based on experimental tests, it was shown that this model is able to accurately describe the change in glass fiber length distribution in compounding.
Integrative approaches for the mechanical mold design in injection molding
Christian Hopmann, Ivo Erler, May 2013
The injection mold faces a number of different loads during the injection molding process of plastic parts. The effect on the mechanical behavior of the mold, inserts and adjacent processes can be complex and may cause bad final parts. By using an integrative simulation approach it is possible to take the process influence into account when calculating the solid body behavior of the mold in a structural simulation. A newly developed approach at IKV uses the advantages of the integrative approach and extends it by an automatic back coupling of deformation results during the filling simulation. This way the interaction of the melt flow and the deformation of inserts or mold components can be considered during the filling phase.
Creating Sustainable Growth by Incorporating Sustainable Development Behavior in Supplier Selection
Larry Nitardy, May 2013
As we work to make our companies more sustainable, it’s necessary to evaluate not only ourselves but also those we select to help us achieve an improved “triple bottom line”. Our vendors and suppliers today will need to be collaborative partners tomorrow if we want to achieve more impactful financial, societal and environmental results. To evaluate a potential sustainable collaborator, consider a teachable, measurable and repeatable process that outlines the questions and judges the responses; then look for potential suppliers that have an observable culture of sustainable development and continuous improvement. You should be able to witness their culture in action when dealing with company officials and representatives. There are clear signs for companies with sustainable development cultures. When they are combined with a set of stewardship behaviors that drive sustainability, they make great suppliers. We have identified seven distinct stewardship behaviors that can be broken down into contributors to the Triple Bottom Line aspirations of every company focused on their on sustainable growth. For the environmental bottom line, consider “touch”; for societal goals, consider the behaviors such as “teach, treat and tout”; and for the profit driver, focus on behavior resources such as “time, talent and treasure”. These seven behaviors have attributes that can, and should be evaluated and measured as we chose our suppliers. In our presentation, we take a look at each separately to give us insight into the complete value a supplier can deliver.
Ultrasonic welding of hygroscopic materials - influence of moisture on the welding process
Christian Hopmann, Anika van Aaken, May 2013
The welding of hygroscopic materials such as polyamide can lead to unstable conditions during the welding process. Due to changing material properties the ultrasonic welding process is influenced largely by the moisture level of the welding parts. To achieve stable welding processes and high weldline qualities it is necessary to learn more about the influence of moisture on the material properties and the ultrasonic welding process. To perform a scientific examination of the influence of moisture on the ultrasonic welding process, the interactions between the material properties and the welding process are determined in relation to the moisture content. With the aid of welding tests, it can be shown that with constant welding parameters the attainable weld strength decreases with increasing moisture load. With recommendations on optimum moisture contents and a process-integrated control of the actual moisture content, poor-quality welds can be avoided. Through a direct control of the actual condition it is possible to dispense with complete predrying, which has until now been seen as the only way to ensure reliable welding of hygroscopic materials.
Influence of self-bias on barrier and elongation properties of barrier coatings deposited on flexible PET films
Christian Hopmann, Karim Bahroun, Henrik Behm, Florian Winkler, May 2013
Polymers gain more and more market shares due to their favorable properties such as lightweight, flexibility and transparency which makes them suitable for food packaging, organic light emitting diodes (OLED) and flexible solar cells. Nonetheless, due to their macromolecular structure plastics do not offer sufficient barrier functionality against oxygen and water vapor permeation, which is a key demand in a variety of applications. A common solution in plastics processing is the deposition of thin silicon oxide layers using microwave (MW) excited plasma processes. Unfortunately for some applications silicon oxide layers do not fulfill requirements concerning elongation properties especially when deposited on flexible plastic films. It is known that because of the brittle behavior of the coatings, induced strain of 1 – 2 % results in a cracking of the deposited thin coating and therefore a loss in barrier properties. Adaption of the self-bias using a radiofrequency (RF) source is one possible way to enhance barrier properties due to deposition of coatings with a higher density. When deposited on flexible substrates, a possible impact on elongation properties has to be taken into account. Since a variation in self-bias leads to a change in surface structure, the mechanical properties of the films have to be taken into consideration.
Development of a Process Technology for High Volume Production of Thermoplastic Composites Based on Hybrid Rovings
Christian Hopmann, Roman Schöldgen, Arne Böttcher, Marco Pöhler, May 2013
Continuous fiber reinforced thermoplastics are increasingly used for lightweight construction parts due to their relatively easy processing. Yet, a cost effective use for structural components is still limited due to the absence of an appropriate and economic high volume production technology. Therefore, a new process technology for the production of lightweight parts within short cycle times is being developed at the Institute of Plastics Processing (IKV) at RWTH Aachen University. This paper presents first results of the research on the process technology based on fiber spraying and consolidation of preforms made of chopped hybrid rovings.
Recycling of Polylactide for Packaging Applications
Christian Hopmann, Sebastian Schippers, May 2013
Polylactide (PLA) is a bioplastic which has a high potential for packaging applications. Due to a high raw material prize and a limited availability the usage of PLA is limited apart from some niche products at the moment. Nevertheless, the number of applications is increasing. At the Institute of Plastic Processing (IKV) the recycling behavior of PLA is evaluated. Recycling helps to cut the raw material consumption and lowers material costs. Additionally, it improves the ecological balance. Following the industrial praxis different recycling strategies are analyzed. This paper gives a review about the multiple processing of PLA and the processing with melt degassing.
Continuous Extrusion of Physically Foamed Silicone Rubber Profiles
Christian Hopmann, Sarah Sitz, May 2013
The foaming of rubber products offers saving potential with respect to component weight, material consumption and costs, while damping properties can be improved. For foaming of high-temperature vulcanizing (HTV) silicone rubber, the use of chemical blowing agents is state of the art. Physical blowing agents such as inert gases have ecological, economical and process-engineering advantages. This paper presents results of a current research project focusing on the development of a continuous process for the physical foaming of solid silicone rubber using nitrogen as blowing agent. The main aim is the achievement of a constant process in order to produce homogeneously foamed rubber profiles and the identification of quality-determining parameters.
Interdependency of Machine Settings and Temperature Profiles - An Experimental Study on Extrusion Embossing for the Replication of Microstructures
Christian Hopmann, Stephan Eilbracht, Ralf Morgenroth, May 2013
Replicating microstructures for functional surfaces in a fast and economic way is crucial for many technical applications. In this paper an experimental study on the variothermal extrusion embossing is presented. Polyethylene and polypropylene grades are used to manufacture hydrophobic films. Microstructure geometries as well as static and dynamic surface behavior in contact with purified water are analyzed. A theoretical approach to estimate the distinctive temperature profile that is generated according to processing conditions (e.g. haul-off speed, temperature of the embossing roll, etc.) is verified experimentally. Thus, the assumption is confirmed that a set of processing conditions (responsible for a specific replication accuracy) can be transferred to another set of conditions while keeping the replication quality constant.
Piezo-Based Mold Design for Injection-Compression Molding of High Precision Plastics Lenses with Minimized Centering Error
Christian Hopmann, Paul Walach, May 2013
Centering errors in the alignment of the surfaces of optical lenses lead to aberrations. In spite of very precise molds and processes, a lateral offset between the two mold halves and therefore between the optical inserts occurs and leads to centering errors in the replicated optical components. A newly developed mold design with integrated piezo-actuators allows the adjustment of the die-sided optical insert and with it the minimization of the centering error. Therefore it is possible to influence and reduce the geometrical error and raise the optical performance of plastics lenses without a machining of the mold.


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