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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Melt Rheology of in-situ Polymerized Polyamide 6/Cellulose Whisker Nano-Composites
Polyamide 6 composites reinforced with various cellulose nanocrystal (CNC) contents were prepared by in-situ polymerization technique. Melt rheological properties of these composites were studied in both linear and non-linear viscoelastic regimes. The results showed that incorporation of cellulose nanocrystals even at low loadings results increased storage and loss modulus, complex viscosity and development of elastic properties in the melt. The composites showed shear thinning behavior especially at higher CNC loadings. The low frequency linear viscoelastic region showed the onset of the formation of percolated network structures of CNCs within the polymer matrix. The structure break-up and recovery tests further confirmed the evolution of CNC agglomerates and development of elastic properties, as well as, high shear-rate dependency of the filled samples.
A Method for Creating Internal Geometries in Injection Molded Parts Using Water Soluble Polyvinyl Alcohol (PVOH) Inserts
In this study, we experimented with using water solu?ble polyvinyl alcohol (PVOH) patterns to create internal geometries within injection molded parts. By overmolding sacrificial PVOH patterns with a ? shell, and subsequently dissolving the inserts, diverse internal features were fabricated with traditional injection mold?ing equipment. Metrological study perform?ed on the components has shown that precise control of the internal dimensions is possible over a wide range of processing temperatures and conditions. White light interferometry analysis conducted on the surfaces of the PVOH patterns and shell materials show that the process is capable of replicating microscale features and decora?tions onto the internal surface of the molded components. It is suggested that, in the modern global market, compa?nies differentiate on the basis of innovation and speed of development. This process can help develop and mass-manufacture complex parts with internal geometries and undercut features faster and more economically than the industrial alternatives.
A New Perspective of Surlyn? Modified Polyamides: Expanding the Role of Surlyn? from a Modifier to a Blend Partner for Polyamides
Technologies that enable ionomers to be blended with polyamides in high loading for attaining synergistic effects of both components are explored. A new ionomer that contains reactive functional groups forms blends with nylon 6 of nanoscale morphology with particle size of 60-90 nm and almost monodispersed size distribution. Nanoscale morphology is observed in all blend compositions, which enables to make nylon 6 blends possessing properties similar to nylon 11 and nylon 12. Poor ZnCl2 salt resistance is known to be a deficiency for short chain polyamides, such as nylon 6 and nylon 66. Nylon 6 modified with Na/Zn ionomer at a loading of 35 wt. % or higher was found to exhibit excellent ZnCl2 stress cracking resistance. The discovery opens a new avenue to manage salts resistance for developing flexible polyamides based on lower cost polyamides.
When Permanent Really Means Permanent. Polyfuze, the New Heat Fused Graphic for Polyethylene, Polypropylene and Other Olefin Resins
The intent of this paper is to demonstrate the truly permanent nature of a new patent protected heat fusion process for the transfer of graphics to polyethylene, polypropylene and other olefin products. As stated in Wikipedia, ?Heat fusion (sometimes called heat welding or simply fusion) is a welding process used to join two different pieces of a thermoplastic. This process involves heating both pieces simultaneously and pressing them together. The two pieces then cool together and form a permanent bond. When done properly, the two pieces become indistinguishable from each other. Dissimilar plastics can result in improper bonding.?
This paper will:
Explain the difference between the new Polyfuze Graphic and other labeling processes such as In-Mold Labels (IML), Hot Stamp (Foil), Screen/Pad Printing and adhesive backed stickers.
Define the environmental significance of each of these decorating methods vs. heat fused graphics.
Colorant Solutions to Meet Global Packaging Regulations
Colorant Solutions to Meet Global Packaging Regulations
Sharon Ehr, Technology Manager
Uniform Color Company
Today?s packaging regulations are confusing at best. Compliance with global food contact and cosmetic regulations has become standard practice rather than the exception.
Identifying the proper regulation for a specific application and geographic area can be challenging. Food and cosmetic packaging regulations can vary drastically from country to country. Often times regulations are ambiguous and in some cases conflict with each other.
Proper colorant and additive selection depends on defining the final application, how that package may be used and the product inside the package which may come in contact with the plastic part. Clear understanding of these parameters can provide end users assurance that the proper colorant package is used for the appropriate application while offering the broadest possible colorant palette.
A Method for Determining the Seven Coefficients of the Cross-WLF Equation
Commercial simulation software employs mathematical models to simulate the plastics flow and to provide useful guidelines on the process set-up. One such model is the well applied Cross-WLF viscosity model. With seven material coefficients, the model is able to predict the viscosity as a function of temperature, shear rate, and pressure. However, to the best knowledge of the authors, there is no readily accessible methodology for determining these seven coefficients, which presents a challenge for users pursuing such information. In this work, we present a methodology on determining such coefficients using thermal and rheological data generated for a polylactic acid. The methodology presented is expected to be robust at least for amorphous plastics.
Inline Detection of Material Storage Effects on Processing Behavior of Rubber Compounds
Due to the chemical activity of rubber compounds, storage temperature and -time of the material prior to processing do have a significant influence on the processability of rubber compounds in injection molding.
The aim of this work is to quantify storage-induced material changes in the laboratory as well as to evaluate how these changes affect the injection molding process. Furthermore, two key process indicators (KPIs) are presented which allow the evaluation of the material condition inline.
Therefore, a batch of a NBR model compound filled with carbon black was produced to be used for injection molding experiments in its fresh state as well as for repetitive experiments after a storage period of three months at cooled ambience. This is generally the maximum storage period for commercially processed rubbers.
Several process settings were varied systematically to identify the most important parameters regarding the processing stability of the compound. Simultaneously to the injection molding experiments, the material was characterized in the laboratory for its changes in rheological, thermodynamic and curing behavior in dependence on the storage time.
While a significant viscosity increase with storage time was observed, the incubation time of the rubber decreased which diminishes the possible processing window. The results of the injection molding experiments clearly show that the material changes observed in the laboratory can also be monitored in the injection molding process. With two KPIs based on machine signals, the inline evaluation of the material storage condition is possible and allows timely triggering of counteractions to ensure process stability as well as the estimation of expectable part quality.
Extrudate Swell of HDPE Melts with Application to Manufacturing of the New Generation Fuel System (NGFS?)
The axisymmetric and flat sheet extrudate swell is studied with application in the optimization of a New Generation Fuel System (NGFS?) manufacturing process for the automotive industry. A series of extrudate swell measurements for HDPE melts are carried out using an optical micrometer attached to the capillary rheometer in order to study the effect of die geometrical characteristics, temperature (isothermal and non-isothermal) and gravity on extrudate dimensions. It is found that temperature plays a significant role in the extrudate swell when isothermal measurements are performed; i.e. temperature of exit is maintained equal to temperature in the die. As a single value cannot characterize the extrudate swell, the whole profile of the extrudate at the exit is determined and reported. The ultimate extrudate swell that corresponds to the swell when all stresses have been relaxed was also studied, and this can be significantly different from typical extrudate swell values measured at the die exit.
Extrudate Swell of High-Density Polyethylene Using Integral and Differential Constitutive Equations
The polymer extrudate swell phenomenon is studied to understand the effects of parameters such as past deformation history, die design characteristics, viscoelastic characteristics and process conditions. Accurate prediction of extrudate swell is very crucial in applications such as blow molding, extrusion and fiber spinning. The integral K-BKZ and differential PTT constitutive models are used to simulate the extrudate swell phenomena of a high molecular weight HDPE in capillary extrusion, under various geometric and operating conditions. The simulated swell results were further compared with experimental observations. It was found that the K-BKZ model overpredicts and the PTT model slightly under-predicts the experimental measurements. An attempt has been made to explain the discrepancy between swell predications using K-BKZ and PTT models by studying various material rheological functions using these rheological models.
Biocomposites and Bioblends Based on Engineering Thermoplastics for Automotive Applications
This paper presents innovative solutions concerning the utilization of engineering polymers in bioblends and biocomposites designated for automotive applications. The studied biomaterials have lower-cost, lower-weight, and at least same performance comparing with the current engineering thermoplastics used in automotive parts. Polyamide (PA6) and acrylonitrile-butadiene-styrene (ABS) were formulated using different types and concentrations of cellulosics, polylactic acid (PLA) as a bio-sourced polymer, and in a combination of cellulosics and PLA. These biomaterials were characterized in terms of morphology, mechanical properties, and heat deflection temperature. The extruded biocomposites, foamed in injection molding process, presented similar properties as the unfoamed and reference counterparts while being around 25-30% greener, lighter and less expensive.
Effect of Pigments Compounding on Product Performance
As global leader in custom colored engineering thermoplastics SABIC is committed to investigating sustainable methods in process and analytical techniques. SABIC has long history partnering with customers to differentiate their products by developing desired looks and aesthetics for unique branding. SABIC and its COLOREXPRESSTM is therefore, capable in handling complex color matching, formulation to meet product performance and utilizing expertise in delivering long term product performance regardless of lot size.
Processors commonly use color concentrate or master batch for product coloring during molding or extrusion. This process involves modification of screw design or feeder for optimal product quality. Custom compounders such as SABIC use pigments with various polymers and additives, with optimized formulation, screw design, and feeding methods. Therefore providing customers with convenience and superior product performance than color concentrate or master batch.
General concerns include pigments dispersion, its effects on engineering thermoplastics properties and surface appearance. Theory behind agglomerate break-up and its effects on experimental molded samples are discussed in the paper.
For this study samples were produced using different pigment feeding methods including standard pigment compounding method and use of color concentrates. Also, SABIC?s proprietary method was compared. It is critical that pigments be evenly dispersed and distributed in the polymer matrix while maintaining consistent viscosity and optimal mechanical properties.
Commonly used pigments in polymers include titanium dioxide and carbon black. Typically color compounds incorporate more than one pigment which adds to the complexity. Experimental findings from the various compounding methods on mechanical properties, surface, heat/hydro aging and color appearance are presented. This paper also compares and reveals some superior pro
Lower-Cost, Ligther and Greener Polypropylene-Based Biocomposites for Industrial Applications
This paper discloses the viability of the formulation, processing, and performance of advanced biocomposites and bioblends based on polypropylene (PP) designed for industrial manufacturing. The PP was compounded with three different types of cellulosic fibers, in a bioblends with polylactide (PLA) as bio-sourced polymer, and in PP/PLA/cellulosic biocomposites. These biomaterials were characterized in terms of morphology, mechanical and thermal properties. Tensile strength, tensile modulus, and the heat deflection temperature of the bioblends and the biocomposites presented at least equivalent values comparing with virgin PP and with PP current industrial grades. The extruded biocomposites, foamed in injection molding process, presented similar properties as the unfoamed and reference counterparts while being up to 25 wt.% lighter, up to 50% less expensive, and up to 50% greener.
Importance of Processing and Fiber Orientation for Realistic Performance Prediction with Fiber Reinforced Thermoplastics
Current industrial state of the art for predictive engineering of fiber reinforced thermoplastic materials relies on isotropic material modeling. This approach gives inaccurate predictions, where orientation and length of fibers play a critical role. An innovative approach is developed in the last years with consideration of the anisotropic behavior of the material. Mechanical material modeling, which is considering correct processing and fiber orientation, can significantly improve the accuracy of mechanical predictions.
The authors follow the innovative approach of combining the processing conditions of the fiber reinforced materials with obtained fiber length and orientation in the end applications. Influence of the processing conditions and fiber orientation on mechanical properties will be elaborated. Differences between the current isotropic and innovative approaches will be displayed in chosen show case applications.
Ultrasonic Inspection of Artificially-Defected GFRP
In this investigation, we tried to evaluate how much size of the micro-defects can be detected and analyzed by using the ultrasonic inspection method and the ultrasonic microscope. Additionally, we also investigated the relationship between the detection sensitivity and the ultrasonic frequency, because the detection sensitivity of ultrasonic inspection method generally depends on ultrasonic frequency. As results, it was found that the 5 MHz transducer was suitable for the detection of larger artificial defects as compared with 1 MHz transducer. In addition, it was indicated that the detection sensitivity was improved by using the high-frequency transducer, and was also independent from the depth position of artificial defects.
Polystyrene-c-Poly (Ethylene-co-Butylene)-c-Polystyrene/Zinc Oxide Block Copolymer Nanocomposites: Rheological and Dielectric Properties
In this paper, nanocomposites of polystyrene-b-poly (ethylene-co-butylene)-b-polystyrene (SEBS) filled with different Zinc Oxide (ZnO) nanoparticles loadings are studied. An homogeneous distribution of the nanoparticles within the polymer matrix was achieved and confirmed by Scanning Electron Microscopy (SEM). Although individually dispersed nanoparticles were not observed, the average size of agglomerates was limited to the nanoscale and only few micrometric agglomerates were formed. The rheological and dielectric properties were evaluated as well and correlated to the morphology. In particular, an increase of the storage modulus G? was achieved at low frequencies while a progressive decrease of the breakdown strength was observed with increasing nanofillers concentration.
Fabrication of Films from Poly(3-Hexylthiophene) Colloidal Suspensions by Doctor Blade Coating
In this work, colloidal suspensions were prepared from electroactive polymer poly(3-hexylthiophene) using the mini-emulsion method, and films were prepared from these suspensions using a doctor blade coater. The effect of blade speed, blade height and surfactant type on film properties were analyzed by atomic force microscope (AFM), wide angle X-ray diffraction (WAXRD) and UV-visible spectroscopy. The results showed that colloids with uniform distribution in the submicron size range were produced. The morphology and thickness of films could be tuned by changing the blade height and speed. Furthermore, the crystal structure of both surfactants and P3HT could be observed in films. During the drying process, further aggregation of P3HT colloids was observed using UV-vis spectra.
Characterization of Melt Mixed PP Composites with New Nanostructured Carbon Materials
In this paper, composites of polypropylene (PP) with four different carbon based fillers are compared. These are single-walled carbon nanotubes (SWCNTs), multi-wall carbon nanotubes (MWCNTs), nanodiamonds (ND) and nanohorns (CNH). The geometry and properties of these filler and the effects on composites? properties such as conductivity and melt viscosity are correlated. In addition, changes in surface tension of polypropylene nanocomposites were investigated using contact angle measurements on compression molded plates.
The results show that there is an increase in the contact angle measured with heptane, a non-polar solvent, for the composites based on MWCNTs. Adding increasing amounts of carbon fillers to the composites results in a decrease in contact angle, indicating greater wettability. The surface tension of the composites increases slightly with filler content, except for the MWCTs where it decreases at high filler content of 10%.
Mechanism of Bubble Nucleation and Growth in High-Pressure Foam Injection Molding Using Gas-Counter Pressure
A new visualization mold was designed and manufactured to observe the foaming phenomena of thermoplastics in situ in high-pressure foam injection molding. With the aim of a fused-silica prism, mold cavity images were reflected to a camera. The melt front travel as well as bubble nucleation and growth were investigated in high-pressure foam injection molding with and without the application of gas-counter pressure. It was elucidated that the application of gas-counter pressure resulted in a faster bubble nucleation and larger size bubbles.
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.
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