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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THERMOPLASTIC COMPOSITES IN STRUCTURAL LIGHTWEIGHT APPLICATIONS–POTENTIAL OF UNIDIRECTIONAL FIBERREINFORCEMENT AND SANDWICH STRUCTURES
This work presents the investigations of process developments with injection molded components in combination with damaged and planar fiber structures. Fundamental experiments with tensile loaded structures in the first and flexural loaded structures in the second case are presented. The results lead to a better understanding of the influence of local continuous-fiber reinforcements in thermoplastic composites and their applicability in structural applications.
Tensile and Fatigue Performance of a Self-Reinforced Polypropylene
Self-reinforced thermoplastics are single polymer composites in which the reinforcing fibers and the polymer matrix are of the same thermoplastic type. The principal advantages of such materials are that they are completely recyclable and the interfacial bond between the fibers and the matrix is very strong which helps them achieve high tensile strength. Polypropylene fiber-reinforced polypropylene is the most common self-reinforced thermoplastic available today. It not only possesses high tensile strength but also high impact strength and for these reasons it is being considered for a variety of automotive applications. In some of these applications fatigue properties of the material may be of greater significance than the tensile or impact properties. In this study both tensile and fatigue tests were conducted on a self-reinforced polypropylene fabric. Fatigue performance was evaluated in terms of number of cycles endured and changes in cyclic properties occurring during fatigue cycling.
Analysis of Adhesive Geometric Effect on Fracture Behavior in Applying Rubber Filled Epoxy Materials
Epoxy is widely used in industry as adhesives and binding matrix for composite materials. By adding liquid rubber into Epoxy it is generally accepted that the toughness of the composite can be improved due to better energy absorption in fracture. This toughening effect however can vary with the adhesive thickness due to the preferred energy dissipation manner. In view of this phenomenon this study investigates the geometric effect in applying rubber toughened epoxy as adhesive. Using a combination of experimental and predictive modeling approach the effect of bonding layer thickness and application dependent (modulated thickness) for rubber-filled epoxy system has been investigated. It is observed that the adhesive bonding geome try could affect both fracture initiation and propagation. The finding from this study can be applied to different types of substrates such as bonding of laminate materials and adhesion of composite materials.
High Performance Engineered Polypropylene Compounds for High Temperature Automotive Under-the-Hood Applications
Over the years plastic composite air intake manifolds made of glass filled nylon 6 and 66 have replaced their metal counterparts. While nylon has been a suitable material for these demanding high temperature under-hood applications optimized polypropylene compounds are proving that they are able to perform equally well in these rigorous operating environments. This paper introduces a new polymer innovation a high temperature glass reinforced polypropylene compound. Key performance attributes will be compared to incumbent materials and the material’s suitability for under hood applications will be explored.
Closing the Gap Between Polypropylene and Polyamide Composites with New Silane Grafting Technology from Dow Corning
A new discovery regarding the grafting of polypropylene (PP) with silanes by melt reactive extrusion processing was demonstrated while preventing significantly the undesired |?-|scissionphenomenon. Such modified PP was then used for enabling cross linking into an injected part showing enhanced high temperature resistance for both neat PP resin and glass fiber reinforced PP composites as well as significant improvement in coupling of glass fibers versus MAgPP showing significant improvement in tensile and flexural properties as well as higher stability under heat and water. Also observed was reduction of water uptake in lignocellulosic fiber PP composites. The relevance of this work will be discussed in applications related to Automotive and the potential to replace PA with PP composites.
Near-Perfect" New Centrifugal Pump Wear Rings and Bushings"
Pump bushing or shaft wear is readily indicated by a dramatic loss of pump performance that required down time for maintenance. With all previous bushing materials in difficult applications Carver pumps were scheduled to last no more than 90 days without maintenance down time for bushings replacement and some exceptional applications required bushing replacement every week. However a new molding compound has been developed for the manufacture of pump wear bushings. Since switching no measurable wear has been detected during pre-production testing or during 2 years in the field. Furthermore no shaft wear has been found either indicating the wear problem has been solved.
Recent Case Studies of Engineering Thermosets for Under-the-Hood Applications (Part A: Overview)
Automotive engineers are looking for options to reduce weight and increase engine efficiency to comply with new CO2 emission and fuel economy regulations. As a consequence under-the-hood operating temperatures continue to increase. Engineering thermosets are an effective lightweighting alternative to heavier conventional steel and aluminum die-cast products. They combine outstanding temperature stability long-term mechanical strength dimensional stability and high chemical resistance. This presentation focuses on 2 recent automotive underhood applications where phenolic-based engineering thermosets successfully replaced traditional metals. First a thermoset water pump housing was shown to outperform cast aluminum in dimensional stability while lowering overall weight; and a thermoset vacuum pump also originally designed in die-cast aluminum provided high mechanical strength and improved dimensional stability at reduced cost and weight. Finally various recycling methods for these thermoset materials are described.
Unpainted Visible-Surface LFT Parts for Auto Interiors
Recently LFRT materials have been used in the automotive interior to incorporate structural requirements while delivering a first-surface appearance thereby eliminating secondary operations such as painting plating or fastening. The key technical requirements in many of these applications is impact strength surface abrasion resistance and color uniformity. Added benefits of using LFRT materials are superior dimensional stability even in thin-wall parts. With proper tool design warpage can be significantly reduced while reaping the weight reduction benefits of lower specific gravity LFRT PP materials.
High Duty Lightweight Polyamide Engine Mounts
Engine mount components are the key link between the engine transmission unit and the body or the chassis and are designed to secure the power unit in the engine compartment and suspend it so that by damping impacts due to road irregularities and isolating engine vibrations the power unit does not come into contact with the body. Such load-bearing structural components are primarily made from steel or aluminum. but their high weight not only affects vehicle mass and thus fuel consumption but also axle load distribution. This paper will discuss the development of heavy-duty fiberglassreinforced polyamide structural components for motor vehicle engine mounts which yielded weight savings of up to 50%.
Polyurethane Environment Friendly Sandwich Structure Load Floor
Dow Automotive and Magna International have developed a polyurethane-based system to enable a novel sandwich structure that includes extensive use of environment friendly materials. This system addresses two significant challenges in the automotive industry: weight reduction and incorporation of renewable materials. An ideal application for this technology is the load floor an interior component located in the rear of the vehicle immediately above the floor pan. This paper will review the performance requirements for a load floor the alternative materials and the development of a novel sandwich structure solution which gives the best mass to load performance with the capability to tailor shape requirements and includes the use of environment friendly materials.
EFFECT OF RUNNER AND GATE CONFIGURATION ON THE PERFORMANCE OF D-LFT COMPOSITEPARTS
This presentation deals with the hypothesis that the differences in the geometry of the flow channels for 2 composite moulding approaches affect the length dispersion and distribution of reinforcing fibres in the polymer matrix. It has been well documented in literature that fibre length affects the mechanical properties of the composite material while dispersion and distribution affect the uniformity of these properties. A systematic analysis of composite parts produced with the 2 processing methods was carried out results of which are reported here.
INTEGRATED SEMI-CONVERTIBLE SUNROOF SYSTEM IN GLASS-REINFORCED SMA/ABS RESIN
This presentation discusses the first very-large thermoplastic sunroof module for a serial (production) cabrio (semi-convertible) vehicle. Industrial partners combined their efforts to reduce weight and optimize systems cost. The large innovative tool that was developed molds both sunroof and rear window frames at one time. The part uses glass-reinforced styrene maleic anhydride/acrylonitrile butadiene styrene (SMA/ABS-GR) resin and meets all the OEM’s requirements for precise dimensions weathering resistance good aesthetics and adhesion to other substructures. This paper will detail the development process tooling considerations and benefits vs. other materials (e.g. metals and thermoset polymers).
Multi-Scale Modeling of Failure of Continuous Carbon Fiber Composites Application to Coupon Tests
In the steady quest for lightweighting solutions continuous carbon fiber composites come down to the ground serving now not only the aerospace but also the automotive industries. This category of carbon fiber-reinforced plastics (CFRP) has recently taken a step in car body structures for its high stiffness and strength. Continuous carbon fiber composites are much more complex than metal with respect to failure in particular. This presentation will cover the application of micro-mechanically-based progressive failure models to simple demonstrator structures such as coupons.
A FORMULATION STUDY OF LONG FIBER THERMOPLASTIC POLYPROPYLENE (PART4):THE EFFECT OF MOLDING CHANGES ON MECHANICAL PROPERTIES OF PP LFT PARTS
In Part 4 of this multiyear study the relationship between the polypropylene long-fiber thermoplastics (PP LFT) and the processes used to mold are presented. Parts are formed by injection molding compression molding and plunger tool using the same formulation in the PP LFT part. The effects of glass-fiber diameter sizing and changes in molding conditions were explored. Prior work showed significant differences between injection molding and compression molding. The use of the plunger tool has given a unique opportunity to evaluate the effects of molding conditions and fiberglass products on the final part performance.
Progress on Simulating Orientation of Long Glass Fibers in Composites Molding
The bulk properties of long (> 1mm) fiber-reinforced composite materials are highly governed by the orientation of the embedded fibers within the matrix which depends on processing conditions and mold design. Modeling the orientation of long fibers in molding processes is typically carried out using the Folgar-Tucker equation for rigid rod-suspensions which is a modification of Jeffery’s equation for suspensions of prolate spheroids. In the first part of this paper we report our efforts to extend the traditional method of ellipses for measuring fiber orientation to systems of long glass fibers. In the second part we evaluate an alternative model for predicting the orientation in long fiber composite materials which allows the effect of bending to be taken into account during processing in both shear and shear-free flow fields. Simulation of fiber orientation in injection molding using the new model is compared against experimental data showing significant improvement in the predictions relative to those based on using the conventional model for rigid fibers.
Dry Fiber Preforming Methods - Pros and Cons
This presentation will discuss the various dry fiber preforming methods that can be used with the many iterations of liquid composites molding processes (e.g. resin transfer molding (RTM) vacuum-assist RTM (VARTM) liquid compression molding high-pressure injection molding etc.). The evolution of dry fiber processing methods will be shown as will the changes in binders the importance of binder selection and the evolution in mechanization of preforming. Many photos will be shown of the various types of preforming equipment with discussion of each dry fiber preforming method process options and how they relate to the types of reinforcing materials applications properties and production rates achieved. It will be shown how application material and production requirements drive selection of the dry fiber preforming process. The pros and cons of each dry fiber preforming process will be discussed to provide guidance for process selection based on the design requirements of an application material selection and production requirements. For structural applications complex dry fiber preforming will be shown for complex laminate schedules with mixtures of reinforcing materials such as engineering fabrics woven materials and unidirectional fabrics in complex fiber alignments. The use of inserts and core materials with complex dry fiber preforms also will be shown and discussed. Last the pros and cons of the need for net-shape dry fiber preforms for high volume applications and structural applications will be discussed with examples and pictures.
Predicting the Tensile Strength of Short Glass Fiber Reinforced Injection Molded Plastics
The tensile strength of a composite is dependent on the properties of the fiber the properties of the matrix resin the fiber content the geometry and orientation of the fibers and the interfacial strength between the fiber and the matrix. We have found we can successfully model the strength with knowledge of the fiber length distribution the average through-thickness fiber orientation and the stress / strain curve for the unfilled resin. Surprisingly accurate strength predictions (within 10%) have been validated for both flow and cross-flow directions which can greatly simplify analysis and allows for a quick estimate of the strength values of any reinforced plastic using material data that is generally available.
Superior Resistance to Thermo-Oxidative & Chemical Degradation in Polyamides & Polyphthalamides
DuPont™ SHIELD Technology allows polyamide and polyphthalamide resins to be used at higher temperatures than could be previously achieved. This SHIELD Technology combines several innovations including a new polymer backbone polymer modifications and a special set of additives to enhance performance. The resistance to thermo-oxidative damage and chemical degradation is highly superior to standard polyamide polyamide and polyphthalamide resins. Examples of improved performance include: Improved air oven aging-retaining >50% of initial mechanical properties after at least 1000 hours at 210°C Improved fluid aging resistance-maintaining >75% of its impact strength after 5000 hrs at 150°C in hot oil. Improved CaCl2 resistance resisting cracks three times the number of cycles of standard glass-reinforced nylons.
Automotive Sunroof Systems & Frames in Xiran® SMA/ABS
Automotive sunroof systems which have become a must-have for the added comfort and styling to today's cars increasingly rely on engingeering plastics functionalities to replace mtals. Structural and semi-structural sunroof module components sunroof frames in particular typically need to meet a wide range of technical requirements with a clear focus on the integration of functions safety cost and weight reduction. The glass-reinforced materials thermoplastics and thermosets currently used for sunroof frames are mostly based on PBT/ASA PBT PA PP and unsaturated polyester SMC. These products are not a perfect match for the application needs of today and the future. Glass-reinforced SMA/ABS on the other hand offers an ideal unique combination of properties required in sunroof frames and systems. SMA/ABS-GF compounds such as Polyscope's Xiran SG grades have clear technical and commercial benefits such as; high dimensional stability and precision very large warpage compliance to mold cavity shape good performance at low wall thickness high creep resistance excellent adhesion without surface treatment low density high economic value good chemical resistance and easy recylability with efficient waste streams.
The First Generation of Vinyl Composites with Long & Continuous Fibers
To date the only types of fibre-reinforced PVC composites were made of short fibres mixed with PVC dry blend before being extruded but that process cuts the fibres giving limited properties to the finished products. New technologies have been developed that allow long and continuous fibre lengths to be maintained in PVC composites via processes without shearing. The first technology consists of a rigid impregnation of the fibres by a water-based PVC dispersion followed by drying gelation by hot air and calendering. Reinforcement can be unidirectional (UD) fibres (e.g. fiberglass) to produce tapes or in the form of fabrics to produce prepregs especially in flax fibres. The second technology consists of a dispersion of PVC powder into a network of fibres by an alternative electrostatic field followed by a gelation in a flat calender. The plates obtained present isotropic properties and an excellent ratio of rigidity to impact toughness. The presentation shows the outstanding properties obtained with these composites by keeping the original length of the fibres and the possibilities offered in term of applications.
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