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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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Graphene-based nanocomposites demonstrate superior electrical mechanical physical and thermal properties. Because of this they have moved swiftly from the research laboratory into the marketplace in applications in aerospace automotive coatings electronics energy storage and paints. Based on the huge interest enhanced properties as well as ease of production and handling the European Union is funding a 10 year $1.73 billion coordination action on graphene; South Korea is spending $350 million on commercialization initiatives; and the United Kingdom is investing $76 million in a commercialization hu because many current and potential applications for carbon nanotubes may be replaced by graphene at much lower cost. The main objective of this study was to characterize the influence of exfoliated grapheme nanoplatelets (xGnP) particle diameter filler loading and the addition of coupling agents on the mechanical rheological and thermal properties of xGnP-filled impact-modified polypropylene (IMPP) composites.
For nano-materials — in particular nano-carbons — one of the most attractive uses has been to fabricate polymer- based composites that are lightweight but exhibit high strength and high modulus. While impressive properties for such composites have been found to date one major drawback for commercial usage has been the high cost of nano-carbons. Some potential solutions to this issue have included improving the production methods to increase batch sizes/quality to drive down materials cost as well as looking at alternative nano-carbons such as graphitic nano-platelets which can be derived from cheaper carbon sources (i.e. graphite) as fillers. An alternative route to achieve nano-carbon polymer-based composites that are low cost lightweight high modulus and high strength is to use the nano-fillers as templates to modify the thermoplastic micro-structures. It is well known that polymers can exhibit high modulus (>100 GPa) and high strength (>10 GPa) if the structure can be controlled. The work outlined in this presentation shows that by using low volume percents of nano-carbons (i.e. less the 1 vol%) in the polymer the micro-structure of the matrix can be modified around the nano-carbon to influence its intrinsic properties. It has been demonstrated that the modified-polymer properties are significantly higher than the bulk-polymer component. This method provides insight into processing routes that can lead to structural control in the composite. This technology may enable the production of high-performance polymer-based composites which utilize low volumes of nano-carbons that are low-cost and thereby attractive at the commercial scale.
To fully realize the performance advantages of carbon nanotubes (CNTs) in thermoplastic composites the development process must extend beyond the formulation and production of materials. Electrical performance is strongly influenced by the fabrication processes used to form these materials into application-specific parts. Furthermore the measured properties are highly sensitive to the electrical testing configuration even when common standards- based test methods are used. This study demonstrates the impact of forming and testing effects through a simple injection molding study for polycarbonate/CNT (PC/ CNT) composites. Common electrical testing techniques were applied in standard and modified configurations and compared to characterize sources of variability. This testing suite was also used to track performance changes in injection molded parts as a result of an annealing process. This study addresses the resulting implications for evaluating the electrical performance of CNT composites in real-world applications and demonstrates the opportunity to adapt standardized methods as application-driven tests throughout the development process.
This paper describes the powder in mould coating process (PIMC) in combination with sheet moulding compound (SMC). A powder coating is applied to a preheated mould to pre-gel. SMC is placed into the mould and pressed as one with the PIMC to cure together inside the mould. When the SMC is removed from the mould it comes out coated with a highly durable super smooth powder coating layer which has a strong adhesion to the SMC. The coating has good barrier properties hardness flexibility and abrasion resistance. With the unique controlled chemistry based on durable unsaturated polyester and vinylether urethane the coating properties and curing behavior can be fine tuned to automotive requirements. Rheological curing studies were conducted to investigate the curing behavior.
Long fiber thermoplastic (LFT) composites materials are one of the fastest growing materials in the polymer composites industry. Most of the thermoplastics used in automotive transportation and recreational industry are natural or black in color; and exterior painting adds to the cost of the manufacturing. Engineered plastics have higher processing temperatures that restrict the use of standard organic pigments and dyes in the processing of thermoplastics. Organic materials are not stable at higher temperatures typically above 250 degrees Celsius and degrade during processing. Alternatively inorganic particle-based pigments are acceptable for these applications because they are thermally stable to at least 800 degrees Celsius and are compatible with the polymer systems. These high performance inorganic pigments are engineered to be weather able chemical resistant and acid resistant; however in reinforced fiber composites the pigment cause fiber attrition and thereby reduction in strength. The focus of this work is on colored inorganic pigmented long fiber thermoplastic composites. The ability to integrate the color in the manufacturing steps eliminates the need for secondary painting. Pigment variables such as particle size distribution chemistry and coatings and their influence on the strength of the final part have been investigated. The paper presents the processing and performance envelopes of inorganic pigments colored LFTs in comparison to unpigmented standard LFTs.
In situanionically polymerized fiberglass reinforced composites from lactams can provide the advantages of both thermosets and thermoplastics: long fiber retention one step process short cycle times thermoformality and re-cyclability. Due to the low viscosity of caprolactam very-high glass contents can be realized which in essence makes these composites unique new engineering materials. The very strong and lightweight composites can potentially replace many existing materials in a wide field of applications.
Several studies have been conducted to investigate the ability of analytical tools to predict the surface distortion observed after adhesively bonding sheet molding compound (SMC) composite assemblies at elevated temperatures. This surface distortion has been termed bond-line read-through (BLRT). Initial studies using a finite element analysis (FEA) based approach showed good agreement with experimental observations and highlighted the importance of accounting for viscoelastic adhesive material properties. The current paper reviews the FEA-based approach and a parametric joint parameter study to provide background on key adhesive joint parameters. Next the results of a lab scale coupon study are presented in which measured curvature results are compared to FEA predictions. In this study several adhesive bead configurations are reviewed including a joint geometry with a machined groove. The results of this study indicate good qualitative and quantitative comparison between measured surface curvatures to FEA predictions. Lastly two analytical panel studies are presented to examine how complex three-dimensional panel geometry and local panel character line geometry can influence BLRT severity. The results of this study indicate that BLRT is a local phenomenon so that the overall panel geometry does not influence the local BLRT severity; however changes in local panel geometry can influence the BLRT severity.
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.
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.
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.
After evaluating mechanical properties of thermoplastics composite laminates constructed from unidirectional tape of nylon 66 / glass fiber system the author will present findings in preparing prepregs including the key factors that affect laminate quality and productivity such as resin weight glass size and “knottability” and “spreadability” of tow. Also discussed will be considerations in using these properties for a composite product design and pros and cons of two compression molding methods.
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.
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.
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.
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.
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.
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%.
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.
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.
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).
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