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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Precision Waterjet Cutting in the Composites Industry Utilizing Robots for High Quality Accurate Machining
This paper discusses the coupling of 5-axis Gantry robots and 6-axis articulated-arm robots to abrasive waterjets for a range of cutting applications primarily in the composites market. The use of ultrahigh pressure waterjets and their technical advantages over conventional mechanical cutting tools are covered as well as the succesful adaptation of advanced software packages typically used in the aerospace industry. A few case studies are also presented that address composite trimming for wing skins used in aircraft and wind turbines small airframe composite parts glass trimming for high efficiency solar panels and three-dimensional machining of relatively small parts used in jet engines.
Melt-Mastication for Polyolefin Nanocomposite Dispersions
Polyolefin-exfoliated graphene nanoplatelet (xGnPTM) nanocomposites were prepared by a new process called melt mastication (MM) in which the polymer nanocomposite undergoes a mastication process that allows for enhanced breakup of larger clusters of xGnP. This presentation will present comparative results from different polyolefin- xGnP fabrication strategies including conventional melt mixing in-situ polymerization methods and MM. Improved dispersion quality with MM was confirmed using differential scanning calorimetry (DSC) and visualization of sample films by optical microscopy (OM). The nanocomposites prepared by MM showed the smallest agglomerate sizes and best xGnP dispersion followed by conventional melt mixing and finally in-situ polymerization.
Nanographene Reinforced Carbon-Carbon Composites
Carbon-carbon composites (CCC) have applications in under-the-hood and friction applications in automobiles where high heat is generated. In this study CCC was produced by using nanographene platelets (NGP) as nanofillers. Different weight concentration (0.5 wt% 1.5 wt% 3 wt% 5 wt%) NGPs were introduced by spraying the NGPs during the prepreg formation. The nanographene reinforced CCC was characterized for effect of NGP concentration on microstructure porosity inter laminar shear strength (ILSS) and flexural strength. It was found that flexure properties and ILSS increased whereas porosity decreased with addition of NGP.
Energy Absorption Characteristics of Automotive-Type Beam Structures in High-Speed Crush Testing
As part of a larger study on automotive lightweight materials / low - carbon vehicles the University of Warwick's WMG evaluated the energy - absorption characteristics of a n automotive - type U - beam structure in 3 - point bending and high - speed crush testi ng . Variants evaluated include thermoplastic composite ( laminates produced from unidirectional (UD) tapes of 60% fiber fraction by weight E - glass - reinforced polyamide 6 (PA 6 - GF60 ) ) structural steel (DP600) and structural aluminum (AA5754)) . The composit e materials were hot stamp - molded at 100 - 150 bar in a 6 0 - sec cycle in a high - speed compression press . Owing to the higher fiber fraction and orientation of the reinforcements there was very little flow forming of the materials during the molding cycle. The thermoplastic composite laminates performed well in the crush tests with superior specific properties (notably improved strength to weight and specific energy absorption ) vs. the metallic options . Additionally failure mode for the composites was con sidered beneficial vs. that of the metals as material was removed from the crush zone once it was no longer able to absorb additional energy (rather than being folded back in the metallic beams). Although for a highly loaded structural application alternat ive polymer matrices (other than PA 6) would likely be used the beam geometry was an ideal way to evaluate high - speed crush characteristics and energy absorption of pure composite and pure metallic component s side - by - side . Further the method used to pro duce the composite beams (UD tape layup plus high - speed hot stamp - forming ) offers interesting opportunities for producing highly complex void - free composite components with high levels of design flexibility since fiber orientation can be varied greatly o n each ply. G iven the rapid mold
Carbon Nanotubes: Applications and Benefits in the Automotive Industry
Thanks to their multi-functionality carbon nanotubes (CNTs)/ polymer composites have allowed the development of many innovative parts in the automotive industry that offer improved properties at competitive costs vs. metals and filled polymers. Since CNTs do not negatively influence warpage or shrinkage neither molds nor dies need to be changed to obtain required part dimensions. The benefits of electrical and thermal conductivity chemical resistance improvements in fracture toughness and compression strength and even better paintability are leading to new innovations that improve performance save weight and replace metals without need for modifying existing equipment. This presentation will discuss examples of how nanotechnology is starting to exhibit its true potential and prove that it can improve or even impart new properties to polymers which will allow researchers and engineers to develop breakthrough materials and unprecedented new technologies.
Graphene Based Impact Modified Polypropylene Nanocomposites for Automotive Applications
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.
Using Nano-Carbon Templates to Control Polymer Matrix Micro-Structure Formation and Properties in the Composite
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.
Effect of Fabrication and Electrical Testing on the Measured Performance of Thermoplastic CNT Composites
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.
New Powder In-Mould Coating for SMC in Automotive Applications
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.
Colored Inorganic Pigmented Long Fiber Thermoplastics
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.
Thermoplastic Composites in One Step: In Situ Polymerization of Caprolactam into Fiber Glass Reinforced APA6
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.
Finite Element Modeling of Bond-Line Read-Through in Composite Automotive Body Panels Subject to Elevated Temperature Cure
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.
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.
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