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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Failure Analysis of a Fractured Polyamide 6 Shock Absorber Housing
A polyamide 6 shock absorber housing on a jogging stroller fractured completely during service. A range of techniques were utilized in the failure analysis, including DSC, TGA, FTIR, ICP-OES, SEM-EDS, and mechanical testing. Lithium grease, calcium, and chlorine were detected on and near the fracture surface. Fracture morphology observed by SEM suggests chemical interaction played a role in initiating the fracture. The combination of mechanical stress and the presence of known environmental stress cracking (ESC) agents in CaCl2 and LiCl is suspected to have led to time-dependent crazing, cracking, and eventual fracture of the housing.
Comparison of Compounding Approaches for Wood-Derived Cellulose Nanocrystals and Polyamide 6
A simple, water-assisted approach to compounding cellulose-nanocrystal-reinforced polyamide 6 was investigated and compared to solvent blending using formic acid and melt compounding using freeze-dried CNCs. The watter-assisted approach did not result in any apparent degradation of the CNCs during compounding and dispersion improved in the following order: freeze-dried compounding < water-assisted compounding < solvent blending. Improved dispersion resulted in less thermal degradation during injection molding and improved tensile properties. Future work to improve both the processing and performance of these composites is suggested.
Improving the Dispersion of Ionic Liquid-Modified Montmorillonite in Poly(Ethylene Terephthalate)
A two-step centrifugation method was applied to remove large particles from commercial montmorillonite (MMT) and provide nanoclays with smaller particle size distributions. Both centrifuged clay (CMMT) and MMT were modified with thermally stable imidazolium- and phosphonium-based ionic liquids. Thermal gravimetric analysis results indicated that clays modified with thermally stable ionic liquids degraded above 300 §C and could survive PET processing temperatures. X-ray diffraction, and Transmission electron microscopy revealed an improvement in the dispersion of centrifuged nanoclays (modified with both imidazolium and phosphonium ionic liquids) into the polymer matrix compared to non-centrifuged modified MMT with larger particle sizes. PET/clay bottles prepared with ionic liquid-modified clay showed a significant improvement in mechanical and barrier properties compared to those prepared with unmodified clay, and to PET bottles.
Low Gloss PC/ASA Blends for Automotive Interior Applications
A new low gloss acrylonitrile-styrene-acrylate (ASA) impact modified polycarbonate (PC) blend is developed to address product performance needs for the low gloss finish in automotive interior applications. To provide inherent matte and/or low gloss surface finish properties, low gloss additives were added in the PC/ASA blends. A direct comparison of the product performance between the optimized formulation and the existing commercialized low gloss PC/ASA material revealed improved low gloss characteristics of the resulting new product with enhanced heat and impact properties. The custom solution technology for the new low gloss PC/ASA product presented here enabled the new business development in automotive interior applications and is highly translatable across the automotive industry.
In-Situ Saxs Study of Phase Segregation and Morphology of Styrenic Block Copolymers
The equilibrium morphologies of the styrenic block copolymers have been studied extensively [1,2,3], however the structural developments in dynamic regime are virtually unknown. In-situ Small Angle X-ray Scattering (SAXS) measurements were performed on a series of thermoplastic elastomers at the synchrotron light source at Brookhaven National Laboratory. The results from the scattering experiments were compared to different structural models. It was found that the styrenic blocks segregate very rapidly at high temperatures (200oC ? 250oC). It was established that the molten polymers start from the disordered state at high temperatures and on cooling, rapid phase segregation with significant phase fluctuations occurs. The hard block segments segregated into hexagonally packed cylinders before leaving the spinneret of the extruder. The rapid segregation is followed by a slower process of 3-D spatial ordering, which could take up to two weeks for completion depending on the annealing conditions.
Lignin Powder as a Filler for Thermoplastic Automotive Lightweight Components
Lightweight design is an essential part of the overall Volkswagen strategy reducing the CO2 emissions. The use of lignin as a filler for thermoplastic materials offers an enormous lightweight potential. Here, a Lignin-PP compound filled with up to 30% Lignin powder offers a 20% weight reduction compared to traditional filled PP compounds assuring the same mechanical performance. Furthermore, in comparison to unfilled thermoplastics a potential cost reduction potential of up to 30% by using lignin as filler seems possible. Today, the use of lignin as filler for thermoplastic materials in automotive components in mass series applications is unknown.
Key aspects for the investigation of novel lignin based fillers are: the examination and quantification of lignin, the optimization of the manufacturing processes, the characterization and quantification of the mechanical properties of the novel lignin filled thermoplastics within an established material pre-validation process and a final economic efficiency and sustainability analysis.
Furthermore, the process ability of the products and demonstrators as well as the suitability for high volume production of the developed processes are investigated as main issues for successful implementation in future lightweight vehicle concepts.
Conversion of Lignin: Sustainable and Cost-Effective Carbon Fibers Usable within the Automotive Industry
Lightweight design is an essential part of the automotive strategy for reducing the CO2 emission. The use of carbon fiber reinforced polymers (CFRP) offers an enormous lightweight potential in comparison to aluminum, enabling a weight reduction, if a load-adapted (unidirectional) CFRP-design is used, of up to 60% in automobile parts without a degradation of the functionalities. Today, the use of CFRP is limited in mass series applications of the automotive industry by the cost of the conventional carbon fiber precursor Poly-Acrylic-Nitrile (PAN). Fifty percent of the cost of a conventional carbon fiber already belongs to the cost of the PAN precursor.
The analysis of lignin as an alternative precursor shows clearly a significant reduction in the cost of CFRP and reduction of CO2 emission during carbon fiber production. This fact is essential to make carbon fibers ready for a mainstream use within the automotive industry.
For qualifying Lignin as a precursor for automotive carbon fiber a detailed chemical understanding of the material is necessary. Lignin, which was used for carbon fiber production, is analyzed with the help of nuclear magnetic resonance spectroscopy and infrared spectroscopy in this paper, and the major chemical reactions during conversion process are highlighted.
On the Potential of Stereo Digital Image Correlation in Thermoforming
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.
Advanced Polymer Materials Synthesized by New Living Radical Polymerization Method (TERP)
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.
An Effective Material Concept for a New Generation of Battery Supports within Premium Class Cars (Melanie Mennigke, Invista Engineering Polymer Solutions; Di Werner Posch, Dr„xlmaier Group)
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
Manufacturing of Fibre-Reinforced, Elastomeric Parts Using the Injection Moulding Process
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.
Numerical Simulation of Expandable Polystyrene Microsphere Expansion
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.
Predicting Physical and Optical Properties of Co-Extruded Blown Films Using Design of Experiment Based Model
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.
Compatibilizing and Toughening of an Immiscible Polyphenylene Blend via Reactive Mixing
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 Polymer Blends and Long Term Prediction
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.
Layer Integrity in Polyethylene Based Multilayer Film/Foams and Their Properties
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.
Effect of Interphase Modulation and Orientation on Dielectric Properties of PET/P(VDF-HFP) Multilayer Films
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
Injection Overmolding Performance of Thermoplastic Polyester Elastomers (TPC-ET)
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.
Understanding Blown Polyethylene Film Dart Strength Variability
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.
Triple Shape Memory Materials Fabricated by Forced Assembly Multilayer Film Coextrusion Technology
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.
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