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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Bart Van Mieghem, Bart Buffel, Marijke Amerijckx, Martijn Hamblok, Frederik Desplentere, Albert Van Bael, Jan Ivens, May 2015
Process insight in thermoforming is a critical factor to secure the production of high quality parts. In thin gauge thermoforming, different tools exist to monitor this complex process and to gain insight. In heavy gauge thermoforming, this is not yet the case. The current paper demonstrates by means of three applications how in situ digital image correlation (DIC) can be used as a tool to acquire in depth knowledge of the ongoing process. In the first application, it is used as a 3D reconstruction tool. The second describes how full fields wall thickness distribution can be retrieved. The third application combines the previous two and demonstrates how the effects of asymmetric heating can be quantified. The technique makes it possible to visualize in a simple and straightforward way the amount of thinning of the sheet in every step of the process. In all three cases, the main goal is to provide more process insight, making it easier for the thermoformer to master his process, reduce the setup time for new products and control the process parameters.
The polymers synthesized by living radical polymerization (LRP) have a wide potential application in various areas. The recent progress of research has enabled the polymerization method to be scaled up for commercial production. Organotellurium-mediated living radical polymerization (TERP) using an organotellurium compound as a promoter is one of the new living radical polymerization methods. Compared with the conventional living radical polymerization, TERP has a wide monomer compatibility (applicability) from acrylates and styrene to?non-conjugated vinyl monomers, along with a molecular-weight controllability even in a high molecular-weight range over 100,000. Utilizing these characteristics, we have introduced the materials for the pigment dispersants and pressure sensitive adhesives. TERP enables us to choose the best structure of block A and B for each dispersion system from a broad range of monomers and molecular weights. TERP block copolymer has the ability to maintain small particle size even with the reduced dosage compared to existing commercial products.TERP enables us to control molecular weight and its distribution to reduce oligomer that leads to excellent contamination resistance. Due to the well-defined structure of random copolymer and homogeneity of the polar functional group in one polymer chain, cohesion strength of PSA prepared by TERP become stronger. Therefore the PSA prepared by TERP demonstrates good heat resistance, good durability, and adhesive residue free. Here we report on the reduced adhesive residue of the PSA prepared by TERP compared to FRP products.
Very High quality and safety standards of modern automotive industry, imply highest demands on all the materials used.
The driving force behind the decision, whether a plastics part or a part made of a classic construction material such as steel and aluminum is used, is beside the sharp rise in the price of metals in particular the ease of processing and design freedom of plastics.
In the presentation, the development and production of a safety-relevant part made of a filled thermoplastic material (battery support) will be discussed. In addition to the criteria for the selection of filled thermoplastic material, the injection molding process, subsequent processes such as welding and laser marking, as well as the necessary qualification tests are presented.
Location and function of the battery support: The battery support is installed in front of the front wall and the left engine sub frame.
Generally, there are three versions that are used in vehicles from the premium manufacturer and these versions must be produced in very high quantities with consistent quality. The fixing and temperature isolation of the battery is the main task of this support.
A major advantage of plastics is their easy processability in injection molding process and the resulting possibility of production of highly integrated components and complete modules, finished in few process steps. In comparison, to the production of many different parts and then assembled.
This advantage of plastic processing and designing has been consistently applied in the realization of this battery support. Beside the main tasks mentioned above, it was possible within the the space specified by the OEM to include further functional parts such electronic control unit carrier, AGD, and brake vacuum line.
For material selection, especially the availability of material data (velocity and temperature) was impo
Injection moulding is an important process to manufacture complex polymer parts. However, in injection moulding of elastomers almost entirely solid parts are produced. In contrast, functionalised complex hollow parts, e. g. for the conduction of media, are usually manufactured in cost intensive multi-step extrusion processes. The projectile injection technique (PIT) as a special injection moulding process offers a new approach of processing elastomeric, fibre-reinforced hoses in a single-step process. This paper discusses the requirements on impregnation of fibre preforms with elastomers and presents investigations on the effect of varied process parameters on part properties.
In this work, a continuum mechanics model is developed to simulate the expansion process of expandable polystyrene (EPS) microspheres both in air and in partially cured epoxy resin. The model is formulated to take into account various kinetic and dynamic parameters involved in gas bubble nucleation and growth in EPS, including nucleation rate, bubble number per EPS microsphere, rate of bubble radius growth, and bubble pressure drop. For expansion in air, the model is able to quantitatively predict the actual experimental growth rate of EPS microspheres. For expansion in partially cured epoxy resin, the model prediction shows that the retardation effects on EPS expansion only becomes significant in the late stage of the expansion process.
Co-extrusion enables the combination of attributes of different polymeric resins to create films having unique and tailor-made properties. Besides the resins used in the film structure, the properties of co-extruded films depend upon factors such as film gauge, layer ratios, amount of blend component used in the layers. We developed an easy to use model with MS Excel interface to predict physical and optical properties of three layer co-extruded films. The model uses Design of Experiments (DoE) approach, and the regression coefficients obtained from each of the responses are used to model the film properties. The model enables designing film structures to optimize film properties and material cost.
Sayantan Roy, Vipul Mathur, Anil K. Sadana, May 2015
A reactive blending of two immiscible thermoplastic polyarylene derivatives namely, poly (p-phenylene sulfide) [PPS] and poly (phenyl sulfone) [PPSU] was accomplished in presence of compatibilizing agents.
The blend of a semi-crystalline polymer, PPS, and an amorphous polymer, PPSU, can be turned into entirely amorphous material with finely dispersed discrete domains in the matrix phase. The cured composite obtained by further heat treatment of melt-mixed PPS/PPSU blend exhibits a single glass transition temperature (Tg).
The cured polymer blend thus developed extends the application potential as downhole backup ring and sealing application over the application range of the component polymers (ò400F).
Creep behavior of polymers and polymer composites as structure materials used in load bearing applications is of considerable interest to the design engineers. This paper presents short-term creep behaviors of three polymer blend systems: unreinforced compatibilized blend, glass fiber reinforced blend, and miscible blend. The long-term creep behaviors of these blends were predicted based on the time-temperature superposition principle. The applications of this principle to the polymer blends that contain more than one phases were discussed. The benefits of creep behavior to plastic parts designers, builders, and operators were revealed.
Vicki Flaris, H. Siccardi, I. Banerjee, Joseph W. Hartnett, May 2015
Abstract Various surface energy models were applied to amino acid-triazole based conjugates, each blended with polymers such as polyethyleneglycol diacrylate (PEG), t-butyl acrylate (TBA) and diethylene glycol (DEG). The Zisman model and the Owens/Wendt model, among others, were evaluated to determine the surface energy of the various amino acid and polymer compounds. In some cases the biofilms were grown in the presence of the amino acid conjugates as well as polymers to determine the extent of its antimicrobial activity.
Previous research has shown that multilayer film/foam structures can be developed by co-extrusion technology. This paper discusses the strategy to achieve good layer integrity as well as high deformability in polyethylene based film/foam systems. In order to improve the layer stability during processing, a viscosity contrast between film and foam layer is maintained. Three different LDPE grades having different melt flow indices have been used. Film/Foam systems with up to 32 layers have been produced. High viscosity film layer and low viscosity foam layer in each film/foam system contributed to good layer integrity even with high foam content. Moreover, each film/foam system exhibits high failure strain in tensile mode. In addition, increasing layer number also improved the tensile modulus and strength of each film/foam system.
Kezhen Yin, Zheng Zhou, Joel Carr, Donald Schuele, Lei Zhu, Andrew Olah, Eric Baer, May 2015
High energy density dielectric film capacitors require polymer films having advanced dielectric and breakdown properties. Using nanolayer coextrusion technique, multilayer film capacitors were produced with poly(ethylene terephtahlate) (PET) and poly(vinylidene fluoride-co-hexafluoropropylene) [P(VDF-HFP)]. Dielectric properties of the polymer multilayer films were improved by adding poly(methyl methacrylate) (PMMA) as tie layers and biaxial orientation. Layer uniformity of PET/PMMA/P(VDF-HFP) films was confirmed using AFM and a diffused interphase was found with PMMA as a tie layer. From biaxial orientation, the c-axes in P(VDF-HFP) crystals oriented parallel to the layers. With interphase modulation and biaxial orientation, PET/P(VDF-HFP) films exhibited a 33% enhancement in breakdown strength and 150% improvement on energy density
This paper describes overmolding processability and performance of wide range of polyester elastomers with varying hardness over commercially important hard substrates. Such combinations are judiciously selected to achieve required performance for excellent grips, aesthetics or improve impact strength. While the soft components vary from 60 Shore A to 55 Shore D; hard components are selected based upon the relative polarity and cover a broad variety of engineering thermoplastics used for structural applications. New low hardness (60 Shore A to 80 Shore A) thermoplastic copolyester elastomers (TPE-E) are also tailored to achieve good adhesion on difficult to bond substrates such as polyacetals. These elastomers deliver excellent mechanical properties, such as low-temperature flexibility, cold temperature impact strength, tensile elongation greater than 700%, and work well at a broad range of temperature and humidity conditions. These recyclable elastomers can be processed via injection molding, blow molding and extrusion.
The impact resistance of film is a critical property for many applications. The Falling Dart (or Dart Drop Impact, DDI) test is an industry standard for gauging the strength of films subjected to a relatively high speed impact event. The test is based on a ?staircase? methodology and requires a minimum of 20 drops to obtain a single strength value. An alternative test, the Spencer Dart Impact test, uses a pendulum mounted impactor and measures the energy required to break a stationary film. This has an advantage over the Falling Dart test in that each impact will give a strength allowing for better statistics. We examine here the variability of the dart strength within a blown film and how ?robust? the dart test is in determining the true strength of the film using experimental and modeling data.
Forced assembly multilayer coextrusion through a series of layer multiplying elements has enabled the production of films containing tens to thousands of alternating continuous layers with individual layer thicknesses down to the nanoscale. A multilayered triple shape memory material, polyurethane (PU)/ethylene vinyl acetate (EVA)/polyvinyl acetate (PVAc), with 257 alternate micro- or nano-scale continuous layers, was investigated. The triple shape memory behavior of PU/EVA/PVAc multilayered film was studied by thermomechanical cyclic test, and its triple shape memory mechanism was also discussed.
The United States photovoltaic (PV) demand has experienced exponential growth in the residential, commercial and utility segments during the past several years and this growth is expected to continue. The growth of this market is due to the drastic reduction in the cost ($/watt) of solar energy systems initiated through the Department of Energy (DOE) Sunshot program which aims to reduce the cost by over 70% by the year 2020.1 In order to achieve this aggressive goal, alternative materials such as engineering plastics are being considered more than ever before. This paper discusses the impact of engineering plastics on reducing the overall cost while increasing the performance of solar installations in the United States. This paper focuses primarily on the commercial flat rooftop segment of solar due to this segment?s traditionally strong growth and high potential for metal to plastic product conversion.
Strain Hardening of polyethylene in uniaxial extensional flow is evaluated with a focus on its strain rate dependency. The stress growth function data of LDPE and HDPE by a rheometer with dual drum fixture was evaluated with the Molecular Stress Function (MSF) Theory. The model provides evidence that the MSF fit on the data at the lowest available strain rate may be used to obtain reasonable semi-quantitative characterization of the long-chain branching content of LDPE. The rate dependent strain hardening behavior of the LDPE and HDPE samples, on the other hand, is well characterized with the maximum Trouton ratio (Tr) predicted by MSF. All three resins studied show a decreasing Tr with increasing strain rate. The rate dependence is strong when Weissenberg number Wi ó1.
Kenneth A. Holt, Alex Savitski, Hardik Pathak, Leo Klinstein, Mike Luehr, Paul Golko, May 2015
Ultrasonic welding of thermoplastics is widely used in many industries to fuse two parts together in a very short time with no additional consumables. The development of the Dukane?s iQ series Servo-Driven Ultrasonic Welder with patented Melt-Match? technology introduces unprecedented levels of control, which allow to overcome less than optimal weld joint designs, material compositions and processes, that have long been challenging to pneumatically driven welding presses. This study further investigates the capabilities of the servo-driven welder and focuses on experiments evaluating the feasibility of using round energy director (ED) designs for the ultrasonic welding process.
Vera Seitz, Markus Sch”nberger, Marc Hoffstetter, Erich Wintermantel, May 2015
Polymeric hard-soft combinations manufactured by multi-component-injection molding are a suitable way to combine strength properties of a hard thermoplastic component with an elastomer for damping, sealing or haptic functionalities. The use of multi-component injection molding has been transferred to medical applications, mostly applied for sterile products. Consequently, it has to be ascertained that necessary sterilization processes do not affect the adhesion between hard and soft component during the life cycle of the plastic part. So far, there is a lack of sufficient studies on sterilization effects within hard-soft combinations. For this reason, the adhesion strength of different polymeric hard-soft combinations after sterilization treatment was analyzed in this study. The tested material combinations are different thermoplastic elastomers (TPE) on thermoplastic substrates. Moreover, silicone rubber was combined with thermoplastic substrates after atmospheric pressure plasma treatment. Hot steam sterilization (20 min., 121øC) and gamma irradiation (50 kGy) were applied on the specimens with varied intensities. To quantify the influence of sterilization treatments, adhesion strength was analyzed by 90ø-peel testing. SEM images of the peeled off surfaces were compared for qualitative analysis of the bond strength. Hot steam sterilization was particularly critical to polar materials as e.g. polycarbonate (PC), resulting in reduced peel force, as well as to heat sensitive material combinations. Gamma irradiation can be applied to nearly all tested polymers, for some thermoplastic ? silicone rubber combinations the peel force can even be enhanced due to post-curing reactions. Beneath the influence of sterilization on adhesion, other effects as yellowing of e.g. PC and TPU or changes in mechanical characteristics have to be respected.
Kurt A. Koppi, Xiaofei Sun, Colleen Southwell, Ellen C. Keene, Diana K. Deese, Tammy K. Fowler, Hunter Woodward, Charles F. Broomall, May 2015
The focus of this study is to characterize the rheological properties of boron nitride (BN) composites. A series of boron nitride composites with varying filler loading level were prepared using two different forms of BN fillers blended with polystyrene (PS). The rheological properties of these composites were characterized using a parallel plate rheometer and a capillary rheology. The structure and thermal conductivity of these composites were also characterized. These data were used to identify structure-property relationships for PS/BN composites.
Wenyi Huang, Mark A. Spalding, Michael D. Read, Todd A. Hogan, May 2015
The continuous annealing process in conjunction with an extrusion casting line is of vital importance to reduce the shrinkage level of plastic sheets while maintaining economic competitive advantage. Therefore, it is crucial to accurately predict the temperature profile of plastic sheets during the annealing process to facilitate process design and operational control. In this paper, a heat-transfer model was developed to predict and optimize the continuous annealing process. Through mathematical modeling of the infrared heating process using a finite-difference analysis (FDA) program coded with FORTRAN language, we successfully mapped the temperature profile of plastic sheets. The numerical simulation results were validated and consistent with experimental data.
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