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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Fiber Orientation Prediction of Long Fiber-Reinforced Thermoplastics: Optimization of Model Parameters
The simulative prediction of the fiber orientations for Short Fiber-reinforced Thermoplastics (SFT) has become state of the art in the last decades. Recently numerical models became available in commercial filling simulation software that allow predicting the fiber orientation in Long Fiber-reinforced Thermoplastics (LFT) parts. Especially for LFT the Anisotropic Rotary Diffusion - Reduced Strain Closure-model (ARD-RSC-model) promises an improved prediction of fiber orientation. The ARD-RSC-model is available in commercial software today, but obtaining material specific parameters is almost not possible for the user. Hence, most users are working with the default parameter set.
In this paper an automated optimization procedure is presented allowing to obtain a material specific set of model parameters of Fiber orientation-models implemented in the commercial filling software Moldflow, Autodesk Inc., San Rafael, CA, USA. This is done by comparing the simulation with experimental data. In order to determine the Fiber Orientation Distribution (FOD) experimentally, selected part sections are examined by means of Computed Tomographic (CT) analyses. The fully three dimensional measurement of the FOD is then performed by digital image processing using grey scale correlation.
Optimized sets of model parameters are determined for different flow conditions using two different kinds of test specimens. The optimization leads to an improved prediction of fiber orientation in the certain specimen. A validation of the found parameter set is conducted by transferring the parameters to another test specimen. Still an improvement in predicting the fiber orientation compared to the default parameter set can be observed.
Development of an Automated Additive Preforming Technology for RTM-Parts
The Institute of Plastics Processing (IKV) in Industry and the Skilled Crafts at RWTH Aachen University, Germany, developed the 3D Fiber spraying process. The 3D Fiber spraying process enables a high volume capable preforming for 3D shaped structural RTM parts. A key element of this process is a fiber guide unit, which allows for the orientation of the chopped reinforcement fibers. Using this process technology, RTM-parts with a fiber volume content of 40 % and an anisotropy ratio of the flexural strength of up to 2.8 : 1 can be produced at present. This is possible at a high productivity. The 3D Fiber spraying process enables an throughput of up to 150 kg/h. Furthermore, the usage of a special binder yarn, a combination of a thin glass fiber and Copolyamide binder, enables a high productivity for the preform production without a clogging of the necessary suction, as it is typical for binder particles.
Mold Design for Reduction of Offline Assembly & Secondary Operations
As OEMs seek to reduce costs to manufacture and improve part/component quality, they are looking to the mold manufacturer to provide them with creative and innovative solutions to these challenges. Mold technology has enabled better and more efficient molding processing via mold designs that incorporate multiple parts into a single molded component, thus eliminating multiple molds and multiple operations, including offline assembly, and other secondary operations that add cost and risk qualilty problems downstream. Some of the latest mold technologies include in-mold assembly, in-mold labeling and decorating, two-shot and three-shot molding, overmolding, and insert molding. This paper will provide examples of how mold manufacturers can design molds that offer OEMs creative ways to reduce costs and improve quality through innovative mold technology.
Evaluation of Nitrogen As a Co-Blowing Agent in Nanocellular Foam
The effect of nitrogen (N2) on the properties of carbon dioxide-blown acrylic nanocellular foams is evaluated in a solid-state batch foaming process. At constant partial pressures of carbon dioxide (CO2), foam porosity tends to decrease with increasing N2 amounts, but there is no significant effect on cell size and nuclei density. Because the addition of N2 is predicted to decrease the solubility of CO2 in the polymer at constant partial pressure of CO2, the properties of the foams produced with the blowing agent mixtures can be compared to foams blown with only CO2 at lower pressure (and therefore depressurization rate) but comparable dissolved CO2. Such a comparison provides a route to decouple the effects of dissolved CO2 from those of total pressure and depressurization rate. Analysis suggests that the porosity is controlled by the amount of dissolved CO2 but not the depressurization rate, while average cell size and nuclei density are mostly impacted by total pressure and/or depressurization rate.
Controlled Drug Delivery of a Hydrophilic Drug Model from a Fibrous Elastomeric Compostie with Shape Memory Properties
Creating plastic biomaterials with a goal of mimicking healthy tissues continues to be a major challenge, particularly when the material is tasked with multiple functionalities. We present a novel elastomeric polymeric construction capable of localized, long-term tunable drug release that also exhibits shape memory properties. This assemblage is fabricated using an electrospinning process to produce a micro-fibrous framework. These fibers are doped with a hydrophilic drug model, Rhodamine B, and embedded within a siloxane based elastomeric matrix to form a composite, which is critical to regulating water transport from the environment to the fibers to release the drug. In vitro drug release studies were conducted in PBS under physiological conditions to evaluate the effect of the siloxane matrix and varying the drug concentration. We found that the integration of this elastomer can control the initial burst release commonly observed in many drug delivery devices and extend drug release while exhibiting thermally triggered shape memory.
Relationship between Moisture Absorption, Crystallization and Rheological Property of Recycled PET Filled Pellets with Talc and Glass Bead
Talc, glass bead and poly(ethylene glycol) (PEG) were used for developing moisture absorption and improving crystallization of recycled poly(ethylene terephthalate) (RPET). RPET and fillers were compounded in twin screw extruder with using air drying along the conveyer to yielding high crystallinity of the compounds. The effect of additional fillers and PEG on intrinsic viscosity, moisture absorption, crystallization and rheological behavior was investigated. The incorporation of fillers and PEG slightly decreased intrinsic viscosity and yielded lower moisture absorption rate than neat RPET. Crystallization kinetic parameters indicated that RPET compounds were faster crystallization, which resulting in higher crystallinity than RPET. Rheological properties of RPET compounds decreased at higher talc contents and the addition of PEG. It can be noted that RPET compounds were lower moisture contents, higher crystallinity and better rheological properties at lower shear rate, which would improve mechanical properties of talc and glass bead filled RPET compounds.
A Numerical Verification and Experimental Validation of the Multi-Jet Cooling System for the Blown Film Application
In a previous work, the assignment of task concerning the development of a numerical based procedure for the optimization of a blown film cooling system was successfully achieved. With this procedure a realistic bubble behavior, with respect to the cooling configuration and the proper initialization data, can be computed. Based on this numerical procedure a novel cooling system was developed, called Multi-Jet. In this paper, the development stages of the numerical procedure and the first experimental results will be presented. Furthermore the experimental data and the cooling-effects will be discussed with regard to the pre-optimization of the new cooling system.
The Effects of High Solvating Plasticizers on the Processing Properties of Polyvinyl Chloride Plastisols
High solvating specialty plasticizers are very polar molecules that enhance the final properties of fused plastisols, as well as decrease the time and energy necessary for fusion. In this evaluation, plastisols were prepared with various concentrations of plasticizers, one general purpose and two high solvating benzoate plasticizers. Viscosity aging was monitored at both room temperature and at 40øC to determine the effect of heat on storage stability. Based on the results obtained here, an extended study was performed on plastisols with higher concentrations of pure high solvator to determine how much must be added to maintain viscosity stability at high temperature. Gelation and fusion characteristics were measured and used to demonstrate the benefits of adding high solvators to a formulation to help reach optimum processing and storage properties.
A Comparison of PVC/Plasticizer Interaction Parameter and Plastisol Processing Characteristics with High Solvating Plasticizers and Plasicizer Blends
There has been an increased need for PVC formulators to find substitutes for phthalate type plasticizers without sacrificing compatibility, processing properties, and performance. This work compares the Flory-Huggins interaction parameter (?), a theoretical test for compatibility, to plastisol compatibility through an examination of roll compatibility, gel/fusion temperatures, and viscosity aging stability of new high solvating plasticizers and blends with general purpose type plasticizers. Results show that by blending plasticizers with low compatibility with high solvating plasticizers compatibility and processing characteristics can be improved, providing a viable substitute for traditional general purpose phthalate plasticizers.
Effect of Degree of Crosslinking on Ultrasonic Decrosslinking of Peroxide Crosslinked High Density Polyethylene
Decrosslinking of peroxide crosslinked high-density polyethylene (XHDPE) of different degrees of crosslinking by means of an ultrasonic single-screw extruder (SSE) is investigated. Barrel pressure and ultrasonic power consumption during extrusion are recorded. Swelling test, thermal analysis and tensile test are used to elucidate the structure-property relationship of decrosslinked XHDPE. It was found that a more intensive rupture of the crosslinked network occurs in XHDPE of higher degree of crosslinking. Analysis based on the Horikx function shows that the type of preferential bond breakage during decrosslinking of XHDPE of various degrees of crosslinking is not determined by the bond energy alone but also influenced by structural characteristics of the network. The thermal and tensile properties of the decrosslinked XHDPE are greatly affected by the type of preferential bond breakage. A significant improvement in the mechanical properties of decrosslinked 2% peroxide cured XHDPE is achieved due to the occurrence of a highly preferential breakage of crosslinks during ultrasonic decrosslinking.
Lessons Learned: An Entrepreneur Using Stage-Gate? to Guide a Project
Stage-Gate? is process to manage a project to minimize the expenses of commercializing the product. Normally Stage-Gate? is used in organizations. However, using Stage-Gate? as an entrepreneur is just as effective to guide a project, control costs and make decisions to continue, modify or stop a project. This paper reviews a project to develop a pesticide to control the bighead and silver Asian carp. By understanding the project market, product requirement, risks and capabilities before the development began, the development work was focused and forced honest evaluation of the data. When the development plan was not meeting the project goals, the project were stopped, re-evaluated and a new plan implemented. The new plan resolved the lack of capabilities in the original project plan.
Making Tailor-Made High Performance Thermoplastic Polyolefin (TPO)/ Polylactide (PLA) Blends for Automotive Interior Applications by Irradiation
In order to create high performance thermoplastic Polyolefin (TPO)/ Polylactide (PLA) blend films with high heat stability for automotive interior applications it is necessary to crosslink the PLA. In this study, films of PLA and compatibilized TPO/PLA blend films were irradiated using electron beam (EB) and triallyl isocyanurate (TAIC) as crosslinking agent. The samples were irradiated with various irradiation doses. Gel fractions of the irradiated samples and FTIR spectra showed that with increasing irradiation dose mainly the crosslinking of PLA increased whereas the TPO remains in a non crosslinked state. The heat stability of the samples was tested by tensile tests at 80øC. As an indication for higher heat stability of PLA through crosslinking, 300%-Modules were analyzed. The non-irradiated TPO/PLA blend film showed 1.3 MPa as 300%-Module and the blend film irradiated with 87 kGy 2.2 MPa. Therefore the 300%-Module increased by 85% by crosslinking PLA with 87 kGy. With these studies it is proven that through crosslinking PLA films, even in a blend with TPO, PLAs heat stability and consequently the performance of the PLA blend is increased. The increased heat stability of PLA via crosslinking is helpful in expanding the applications of PLA.
Use of Pre-Hardened Tool Steel Gives Faster Mold Manufacturing
The last decades have seen a rapid development in hard-machining which has encouraged steel manufacturers to develop modern pre-hardened tool steels having leaner chemical compositions when compared with the well-established P20. Use of pre-hardened grades enables faster tool-manufacturing thanks to the elimination of the need for heat treatment (Q&T) in mold manufacturing. Traditional pre-hardened tool steel is commonly delivered in hardness of 300 HBW (P20) and Approx. 360/370 HBW (P20 HH). Today?s modern pre-hardened tool steels are delivered at nominal hardness from 300 HBW up to 450 HBW/45 HRC. Those grades have lower alloy contents than P20 giving much improved machinability. New pre-hardened tool steel grades are also suitable when molding glass-fiber reinforced components as these grades were developed to show good properties after surface engineering (Nitriding, PVD-coating etc.). The tool designer can now tailor-make the mold surface properties required in a given wear situation.
Glass Filled PBT Blends with High Bonding Strength for Nano Molding Technology
Minimizing weight and size is an important aim in today?s consumer electronics market. Recently nano-molding technology (NMT) is a newer technology wherein plastic resin is injected into metal surface. Therefore high bonding strength between the plastic and metal is important for such applications. Despite significant research and development efforts, there remains a need for blended thermoplastic compositions that effectively address the appropriate balance of properties required in the consumer electronics industry, such as blended thermoplastic compositions that are high stiffness yet have high toughness, while retaining desired color ability. In this paper, we describe a method to manufacture THERMOTUFTM glass filled PBT compounds with high bonding strength and low thermal expansion/shrinkage for NMT application.
Piezoelectric Foams Based on Cyclic Olefin Copolymer
The preparation and characterization of a new type of highly efficient pseudo-piezoelectric materials (ferroelectret) based on porous cyclic olefin copolymer (COC) is reported in the study. The quasi-static piezoelectric coefficient of the ferroelectrets can reach exceptionally high level ~1100 pC/N, and the materials retains the high piezoelectric activity for temperature up to 170oC. The sample preparation procedures can be divided into three steps. First, patterns on COC film were prepared using laser cutter. Then CO2 bonding was used to bond different layers together. Finally, contact charging was implemented to obtain desired piezoelectricity. The piezoelectricity was characterized by quasi-static piezoelectric coefficient. Moreover, thermally stimulated discharge was selected to study the thermal stability of the ferroelectret. And hysteresis loop measurements were used to study the charge build up process inside the artificial void. The critical breakdown voltage of the 50?m artificial void sample is about 2500V and agrees with the value calculated from the simplified model. Such material have applications on sensing, actuating and energy harvesting and many other fields.
Effect of Particle Dispersion on the Rheological Behavior of LLDPE/CaCO3 Composites
The dispersion effect has a direct influence upon the rheological behavior of filled blends. This paper aims to study the steady and dynamic rheological properties of different CaCO3 dispersions in LLDPE. A rheological model was chosen to fit the steady viscosity curve. Then the relationship between the dispersed forms and the rheological properties was investigated in order to describe the different filler dispersions via changing the parameters of the equations and consolidating the theoretical support for evaluating the effect of different dispersions based on rheological tests.
Processing and Characterization of Exfoliated Graphite Nanoplatelet and Carbon Nanotube / Polylactic Acid Nanocomposite Films
A two-step, scalable melt compounding method is used to fabricate carbon nanotube (CNT) / polylactic acid (PLA) and exfoliated graphite nanoplatelet (GNP) / PLA nanocomposite films. The CNT or GNP is dispersed in the PLA melt using a twin-screw microextruder and melt spun fibers are compression molded into films of approximately 110 ?m thick. Fiber & film morphology, investigated using scanning electron microscopy (SEM), shows that the fibers are continuous with a diameter in the range of 60-70 ?m. The thermal and mechanical properties are examined using differential scanning calorimetry (DSC), tensile testing, and dynamic mechanical analysis (DMA). Electrical properties of the films are investigated using impedance spectroscopy.
Study on Worm Melt Fracture of Blow Molding Process Using Capillary Rheometer
During the blow molding process of large size drums, string-like defects, which are called worm melt fracture, can be observed on the extrudate surface. Such string-like defects are observed in the capillary extrusion at high shear rate range after the slip-stick transition. It is proposed that the cohesive slip layer which is a failure within the polymer melts inside the die could emerge out as the sting-like defects on the extrudates. The resin having more small chains and lower plateau modulus can be easier to have such an internal failure and consequently exhibit more ?worm? defects.
Modelling the Rheolgocial Behavior of Blowing Agent Laden Melts That Simulates the Foam Injection Molding Process
Currently a new approach for simulating the foam injection molding process is being developed at the Institute of Plastics Processing (IKV) Aachen, Germany. As existing simulation software for foam injection molding works with restrictions and assumptions, especially for the nucleation phase of the foam injection molding. Simulation results often do not correspond with practical tests at the injection molding machine.
In the new approach the influence of the blowing agent on the PVT- and rheological behavior is measured with two injection molds directly on the injection molding machine. The characterization of the material behavior is than prepared as input data to the injection molding simulation software.
In this paper the approach for modeling the rheological behavior of blowing agent loaded melts for simulating the foam injection molding process is described. Step one is to measure the effect of a blowing agent on the viscosity of a polymer melt at different melt temperatures and blowing agent concentrations through an online rheometer. Afterwards the measured data is adjusted, optimized and inputted into the injection molding simulation software.
Preparation of Micro and Nanocellular Tpu-Graphene Nanocomposite Foam by Supercritical Co2 Foaming
Thermoplastic polyurethane (TPU) possesses many special characteristics. The flexibility, rigidity, and elasticity can be adjusted by controlling the ratio of soft and hard segments. Additionally, the chemical properties of TPU can be varied by using different starting monomers. Due to its versatile physical and chemical properties, TPU is commonly used in transportation, construction, and biomaterials. The technique of foaming TPU by CO2 is still under investigation. To avoid the effect of additives that are found in commercially available polymer, we synthesized TPU ourselves using a pre-polymer method. In addition, graphene was added as the nucleation agent. The synthesized TPU was foamed by batch foaming using super critical CO2 as the blowing agent, and the effect of saturation temperature on the cell morphology of TPU foam was examined. The average cell size of TPU foam decreased from 1.8 ?m to 800 nm, after only 0.1 wt% of graphene being added.
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