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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A New Self-reinforced Polypropylene Composite
A novel 100% polypropylene material has been developed which creates a new class of thermoplastic composites. In a patented process high-modulus polypropylene tapes are compacted to form a self-reinforced thermoformable polypropylene sheet. The recently commercialized material exhibits a unique set of properties including: low density good tensile strength outstanding impact strength (even at low temperatures) and recyclability. This performance positions the composite between isotropic thermoplastics and highly structured glass reinforced composites. Work with OEM's and Tier 1 suppliers suggests these composites have significant advantages in a range of interior and exterior applications. The material is under evaluation for a number of upcoming models.
Injection Molding Compounders: A Revolution in Injection Molding
Direct compounding combines the continuous preparatory process with the cyclic or discontinuous injection-molding process. Everything involved in turning the individual components (polymer colorizer fillers and so on) into a homogeneous melt takes place in a single heat cycle. The co-rotating intermeshing twin-screw extruder is never shut down during production so the quality of the melt at the machine’s nozzle always remains consistent. The constancy of the recipe is sustained for all individual components by a continuously operating gravimetric feeding system. This “one heat” process allows better material properties for a substantial lower price.
Economical Production Technology for Low & High Volume 3-D TPC Parts
When thermoplastic composite materials first appeared a great effort was made to allow the materials to be 3 dimensionally formed by existing molding processes such as compression molding and thermoforming. As those materials have matured and new materials have become available the demand for more flexible and economical molding technology has arisen. By exploring the use of diaphragms in the molding process technology has been implemented to form 3-D thermoplastic composite parts on an industrial level. Evaluating the costs of current molding processes such as compression molding or thermoforming reveals an economical deficiency for thermoplastic composite parts with annual volumes from 1000 up to 100000. With a significant number of potential product applications increasing proportionate to a decrease in annual volumes diaphragm molding technology can generate a competitive market for thermoplastic composite materials for low and high volume production applications. Throughput tooling costs capital costs for molding equipment and what the market will bear all generate the viability of materials and manufacturing. Diaphragm molding assists in creating new economic targets for the market for a given application. This paper will overview the diaphragm molding process analyze and compare the economics of traditional molding processes for thermoplastic composites and discuss how this new technology can be applied to automotive applications.
Electron Beam Processing for Automotive Composites Applications
Electron beam (EB) processing has been used for many years to modify polymers for a number of important industrial applications. More recently a significant amount of research and development effort has been directed at electron beam curing of advanced composites primarily for aerospace applications. An overview of potential uses of this technology for automotive applications including curing of SMC and RTM /VARTM components filament wound components large body/chassis components adhesive bonding of composite components composite resins and thermoplastic composites as well as some important non-composite automotive applications is presented.
Using Computer Aided Engineering to Design Better Thermoset Composite Parts.
This paper focuses on the effects of fiber orientation anisotropies on the structural performance of thermoset composite parts. The most important factors to consider when predicting fiber orientation are gate or initial charge location as well as part geometry. The structural performance of the part is greatly affected by the amount of fiber orientation. Taking an automotive headlamp housing and a truck front bumper as examples this paper presents the structural effect that gate and charge location as well as choice of injection and/or compression molding have on performance of the final part. First a mold filling computer simulation is performed for each case. Then fiber orientation is computed and used to model the structural performance of the part under load. Results are compared to structural performance modeled without taking into consideration fiber orientation. The results show up to 100% difference on the final stress when fiber orientation is taken into account. These results demonstrate the importance of considering fiber orientation when modeling structural performance to design better composite parts.
Influence of Consolidation and Forming Parameters in the Molding of Continuous Fiber Reinforced Thermoplastic Composites
Continuous fibre reinforced thermoplastic (CFRTP) composites offer many advantages over thermoset composites and metallic materials especially their resistance to corrosion their recycling possibilities and their high specific stiffness. The shaping of these materials into complex forms however requires a good knowledge of the combined behaviour of the molten thermoplastic matrix and of the fibres because of the high intra and interlaminar shear deformations involved during the forming process. In this paper the influence of laminate consolidation parameters on the microstructure and mechanical properties of the laminate are first presented. Next the deformation mechanisms induced in the laminate in typical forming conditions are presented and discussed in regard to their influence on the physical and aesthetic properties of the moulded part. Numerical moulding predictions obtained from a commercial code are finally presented.
Numerical Simulation of Reinforcements Forming: The Missing Link for the Improvement of Composite Parts Virtual Prototyping
Composites draping simulation is introduced. There are basically two methods: the geometric approach and the mechanical approach. The possible results that can be obtained using these methods are illustrated by an example. This type of simulation can be used not only to optimize the fabrication process but also to improve the mechanical performance calculations and more generally speaking the composite parts design. For example the influence of the preforming operation on resin injection for processes like resin Transfer Molding (RTM) is demonstrated on a numerical example
New Developments in Co-Rotating Twin-Screw Extrusion for Production of Long Glass Fiber Composites
Long fibre reinforced thermoplastics have excellent mechanical properties and stiffness-weight ratio which is of particular interest to the automotive industry. The new Inline-Compounding processes for long fibre materials offer users more flexibility as they are able to both compound and process such materials in accordance with their own formulation and also use ready-made compounds. The following process combinations are possible: E-LFT; In-Line-Compounding and Direct Extrusion to Profile or Plate D-LFT; In-Line-Compounding and Compression Moulding S-LFT; In-Line-Compounding and Injection Moulding
FiberSIM: Advanced CAD software for composite engineering from racing to production automotive
The principal challenge in applying composite materials to automotive vehicles is to provide structural performance that allows for significant weight reductions over conventional materials such as steel. However the automotive market is quite different from the proven aerospace composite arena. Aircraft parts are typically produced in low volumes with few requiring very complex surface shaping. The automotive industry by contrast produces a variety of products comprising hundreds of basic structural forms. Dramatic changes in fiber orientation can occur inducing large thickness changes loss of laminate stack-up symmetry and balance. All of these issues can have a considerable effect on the behavior of the final part. This paper describes how the FiberSIM suite of software tools supports the entire composite engineering process by using a unique material simulation technology that predicts how composite material conform to complex surfaces. Engineers can quickly visualize ply shapes and fiber orientations and identify manufacturing problems during the design phase. Designers can also create and automatically update drawings and related manufacturing data directly from the master CAD model thus reducing opportunities for errors and delays on the manufacturing floor. Practical case studies from automotive highlight how composite engineering can be improved and risk can be reduced by the use of these new integrated simulation-driven tools.
Analysis of Resin Flow under Flexible cover in Vacuum Assisted Resin Infusion
Techniques to simulate resin infusion using classical RTM simulation software are investigated. The difference in the filling behavior between “rigid” and “flexible” molds is evaluated and explained. A model describing the evolution of permeability with pressure is developed for flexible moulds. This model takes into account the changes in thickness of the cavity following deformations of the mold cover as well as the compressibility of the reinforcement. The model is validated by comparison of numerical simulations for a complex automobile part manufactured by resin infusion with actual test results obtained at the factory
No Postcure RRIM for Automotive Exteriors
Reinforced reaction injection molding (RRIM) has reemerged as an important method in automotive exterior applications. Presently composite applications demand higher productivity and improved part performance. Stability at higher heat to endure E-coat oven bake improvements in fillers yielding easier processing at high loading improved toughness at high modulus and higher productivity have already been realized with RRIM in Europe and NAFTA. Now the kinetics of one new material Bayflex 190 is such that reaction is essentially complete at demold. In the past RRIM molded parts were required to be baked at 120oC and above to complete chemical reactions attain complete physical properties and de-gas parts prior to painting. In current E-coat applications postcure of 190oC is typical. Elimination of postcure means significant savings in energy increased productivity decreased handling and lower capital expense. Bayflex 190 polyurea attains virtually all properties at demold. After molding parts can be washed and primed directly. Dynamic mechanical analysis shows that further heating to 200oC anneals and strengthens the composite. Several very sensitive analytical methods have been employed to characterize the degree of cure at demold. Differential scanning calorimetry (DSC) shows no exothermic chemical reaction up to 200oC. Thermal gravimetric analysis (TGA) shows no CO2 loss from unreacted isocyanates. And Fourier transform infrared spectroscopy (FTIR) scans indicate no free isocyanate in freshly molded samples. Parts painted in production exhibit no defects associated with elimination of postcure.
Designing for Durability Using an E-Glass Reinforced SRIM Urethane Composite
The durability of a SRIM Urethane composite are evaluated and the results are used to develop a design guide to aid in the use of this material. Test methods for static fatigue creep and impact testing are described in detail. The Oak Ridge National Laboratory developed these methods for durability testing. The raw test data from an earlier study are summarized and generalized in the form of design equations. The scope and limitations of these design equations are discussed. This material evaluation and data summary process provides a means for designing for durability using an E-glass reinforced SRIM Urethane composite.
The Use of UV Light for Surface Cleaning for Painting and Adhesive Bonding of Composites and Metals
Contemporary vehicles utilize a mix of materials in their construction consisting of metals plastics and composites. These materials must possess suitable surface properties to achieve desired performance when these parts are adhesively bonding or painted for field service. Surface preparation methods now in place oftentimes use solvents or caustics an increasingly unacceptable approach in an era of mounting environmental regulations. New methods of surface preparation are called for that are environmentally benign and economically feasible while meeting the stringent quality standards of the automotive industry. The use of energetic ultraviolet light is emerging as a promising technology to compete with the old methods of surface preparation. This paper reports the utility of using energetic UV light to generate appropriate surface chemical composition on plastics composites and metals for subsequent painting or adhesive bonding operations. UV treatments have the potential to replace the old methods of treating assorted materials used in the automotive industry in an environmentally responsible and cost-effective manner.
Enhanced Bonding of Polypropylene to Polypropylene and other Materials with Novel Thermoplastic Heat Activated Adhesives
It is commonly accepted that bonding polypropylene to itself or other adherends is difficult and the options available for cost-effective bonding using adhesives are very limited. The aim of the presentation will be to describe a new range of heat-activated adhesives recently developed in our research laboratories and their applications. These adhesives which are now commercially available offer numerous advantages for the rapid manufacture of composite materials in addition to promoting new or improved assembly methods in a wide range of market sectors. e.g. automobile aerospace construction textiles footwear and packaging to mention but a few. The main focus of the presentation will be to outline various ways in which the film strand or pellet forms of the new adhesives may be used to solve a variety of industrial problems. The range of materials to which polypropylene can be successfully bonded (e.g. to itself to many metals and to a range of other materials notably cellulosics) will be outlined together with their associated manufacturing methodologies such as hot compression lasers and induction heating. An indication of the mechanical bond strengths which can be achieved at various temperatures will also be outlined.
Electrochemical and Stack Evaluation of Composite Bipolar Plate Materials
Composite plate materials for use as bipolar plates in a fuel cell stack must meet certain performance criteria namely high surface and through-plane electrical conductivity very low gas permeability and chemical resistance to both coolants and reactants. In addition to these performance criteria it is necessary from a cost viewpoint that the bipolar plates are easy to manufacture. One category of materials being used for bipolar plates are carbon composites where carbon additives are mixed with a thermoset resin for net-shape compression molding of bipolar plates. A study of the corrosion resistance (via electrochemical testing) helium permeation stack performance and electrical conductivity of a variety of composite materials designed for bipolar plate applications will be presented.
Polymeric Composite Bipolar Plates for Vehicle Applications
At present membrane electrode assembly performance levels and stack operating conditions of PEM fuel cells a plate area specific resistance of less than approximately 20 mohm cm2 and a plate thickness of less than 2 mm are required to meet the vehicular volumetric power density target (> 2 kW/l). It is however difficult to meet these aggressive requirements and simultaneously obtain good mechanical properties when using polymeric plate materials. Polymers become brittle and break frequently at the high conductive filler loadings (e.g. > 50 v/o graphite) required for high conductivity. This study investigates a potential approach for obtaining high plate conductivity at low conductive filler loadings thus enabling high volumes of thin and ductile plates to be manufactured at low scrap rates.
3D FEM Simulation of Feed-Block Profiling for Flat Die Coextrusion
This paper presents the results of a 3D FEM analysis of some layer spreading experiments performed on flat die with a coextrusion feed-block. The complete feed-block and die assembly was simulated using a commercially available 3D FEM software package and a path-line analysis was used to determine the interface position and the degree the of layer spreading. The results obtained were in good agreement with the experimental data. The simulation also provided a better insight into the flow development within these types of systems.
Adhesive Bonding of Polymers and Composites with Microwave Mode-Switching Method
Microwaves provide rapid, selective and volumetric heating in processing polymers and polymer composites. A variable frequency mode-switching method was studied to uniformly bond two polymer composites with an epoxy-based adhesive. Results were compared with thermal process. For one substrate, microwave method reduced the bonding time and enhanced the bonding strength significantly. For the other substrate, microwaves reduced the bonding time and achieved equal bonding strength as that in thermal process.
Advances in the Stabilization of Flexible PVC Using a Liquid Calcium-Zinc Technology
The global market for liquid mixed metal stabilizers is migrating toward heavy-metal-free products. Historically, these systems have not been performance and cost competitive. High efficiency calcium-zinc stabilizers have the potential to replace heavy-metal-based products. The intrinsic value of non-phenolic lubricating calcium intermediates and calcium-zinc stabilizers are discussed within the following report.
AFM Study of Ultrathin Tri-Block Copolymer Films on Tailored Grafted Polymer Layer
AFM was used to study the morphology of ultrathin poly[styrene -b- butadiene -b-styrene] copolymer (SBS) films deposited on polystyrene brushes. The grafting density and molecular weight of the grafted polymer layers were varied to reveal the relationship between the parameters of the brush interface and the structure of the film. We found a strong effect of the underlying brushes on the formation of the SBS films.
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