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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Filament winding as a composite process for fabricating highstrength reinforced thermoset hollow structures is well documented. Traditionally cure was accomplished in a convection oven and this cure sequence was the most time consuming portion of the overall process as well as the least predictably controlled. This paper will define and detail a new method for curing filament-wound composites. Here a closed-loop controlled heatpipe thermally enhanced mandrel heated by induction heating replaces a cure oven allowing for very-rapid cure and permitting the escape of volatiles and water vapour that normally are trapped interstitially.
A primary goal in automotive structures is reduction of weight while maintaining or improving other desirable attributes. Composite materials offer solutions to weight reduction in comparison to metal structures and thermoplastic composite materials offer the added benefits of improved cycle times high impact resistance cost-effective solutions and a path for sustainability. Developments in the area of injection over-molding of structural inserts produced from continuous-fiber-reinforced thermoplastics (CFRT ®) are an example of this and combine the advantages of injection molding with CFRT properties. Typical applications are in seat structures airbag housings front-end modules and crash beams that take advantage of the excellent strength and impact characteristics of the materials. A seat back application produced with injection over-molding of CFRT inserts is used as a demonstration case study.
The resin transfer moulding (RTM) process is well established for low-volume manufacturing and has recently gained interest for manufacturing higher volumes particularly in automotive to produce lightweight composite structures. However the process is currently limited by the low-volume production capacity of the preforming processes long impregnation times and lack of robust processing equipment all of which limit RTM’s use for continuous manufacturing of components. This presentation addresses recent developments in the RTM process and RandD strategies of a trilateral collaboration working to address these issues.
Stamped steel body structures set a benchmark for construction and aesthetics that any alternative including carbon fiber body structures must meet. The challenge to carbon fiber body structure manufacturers is to achieve the traditional body structure standards while maintaining the most competitive possible per part manufacturing costs. Fortunately for these manufacturers there is a great deal of accumulated experience in composite manufacturing including the finishing and trimming processes that can be among the most challenging to automate. This paper will discuss some of the robotic technologies that have been adopted from other composite finishing and trimming processes to meet the needs of carbon fiber body structure manufacturers. Specific examples will be discussed including robotic sanding of Class A surfaces and abrasive waterjet cutting of holes and features on various carbon fiber body structures both of which are or will soon be in full production. For abrasive waterjet cutting this paper will elaborate on a unique approach that was developed using robots to manipulate parts while secondary robots manipulate the abrasive waterjet media.The paper will also discuss the advantages of these robotic solutions vs. other approaches including lower running costs and the flexibility to quickly adapt to product or model changes.
This presentation discusses issues that must be addressed by engineering software tools currently used for metal structures and based primarily on geometry so that engineers can efficiently make the tradeoffs required to design mixed-material vehicles. Engineering software must help identify optimal combinations of materials assembly methods and joining technologies by allowing engineers to efficiently conduct tradeoffs. These tradeoffs include assembly complexity vs. part complexity the appropriate mix of material (metals plastics composites) the impact of alternative joining methods and assessment of part manufacturing and assembly alternatives while concurrently conducting an integrated design cost and performance assessment as design features are changed.
This presentation will showcase some examples of the current market for low-density sheet-molding compound (SMC) and will provide a brief history of weight reduction initiatives and benefits in the automotive industry. One specific development program will be described in detail. This program focused on improving stiffness-to-weight ratio maximizing the benefit of microsphere technologies and creating a paint-ready surface suitable for high-appearance applications. The result was a new low-density SMC with an industry-leading density of 1.18 sp.gr. — 9% lower than the previous industry best. The discussion concludes with a peek at future opportunities for thermoset composites in this specific marketplace.
Fiberglass-reinforced epoxy (FG/epoxy) and carbon fiber-reinforced epoxy (CF/epoxy) composite components are known to be produced in high volumes using the compression-molding process. This same molding technology can reasonably be expected to produce high volumes of CF/epoxy automotive body structure and chassis components. The author discusses unique epoxy chemistry forming and molding processes possible due to the thermoplastic stage-of-cure referred to as the epoxy “B-stage.” B-staged epoxies are discussed and then compared to what is commonly referred to as a B-staged sheet molding compound (SMC). A progression-molding assembly line concept similar in configuration to existing automotive sheetmetal forming lines is discussed. This conceptual molding operation would be capable of producing complex CF/epoxy structural composite components at a rate of at least 120 / hour.
New pressures and regulations in the transportation and commercial and residential construction industries intended to improve “interior” air quality are spurring new research in additive technologies to reduce emission of volatile organic compounds (VOCs) odors and fogging for polymeric materials. Much work has already been done to help reduce VOCs odors and fogging by addressing coupling-agent purity. Unfortunately there are many pathways for the release of VOC emissions and in cases where they cannot be eliminated at the source in components of the masterbatch a third strategy is needed. One such approach described in this presentation has studied the use of adsorbents and stripping agents during extrusion compounding of the masterbatch to capture and flashoff (in the case of stripping agents) or permanently bind up (in the case of adsorbents) VOCs and fogging or odor causing emissions.
The presentation differentiates the high-pressure processes from the standard resin injection molding (RTM) processes and discusses the latest R&D results regarding the development of high-pressure RTM of high-performance fiber compounds. The focal point is set on the innovative production processes suitable for high volume as well as on the industrialization of the so-called RTM process within the high-pressure compression RTM (CRTM) process --from preforming to the final component. The compression process is of special focus. Various process parameters and their influence on part quality are highlighted and a serial process run is demonstrated.
Thermoplastic oil pans are an up and coming metal-to-plastic application. With the need for light-weighting vehicles for improved fuel economy and reduced emissions thermoplastic oil pans and oil pan modules that incorporate the windage tray and oil pickup tube are under investigation at a majority of the global OEMs. At present there are 7 serial product thermoplastic oil pans most of which have just launched in the past 18 months. This presentation will provide a brief overview of OEM concerns by global region and outline the component design challenges. The focus will highlight the CAE analysis methodology used on current productions plastic pans and provide a comparison of plastic pan performance relative to aluminum or stamped steel.
Applying the direct-long-fiber-thermoplastics (DLFT) process to recent composite product launches outside of automotive has given a fresh perspective on how to create more effective products and efficient launches for future DLFT applications. Recent expansions of DLFT into markets such as agricultural construction personal watercraft recreational vehicles and trailers brought unique challenges that fit the flexibility of the DLFT process. Combining common materials such as glass and polypropylene with more unique materials such as wood block and recycled polymers led to a unique over- molding solution for one high-volume molding application with aggressive material cost targets. Other lower volume applications benefited from new predictive-modeling techniques of long-fiber compression molding to ensure the proper tool design of a compression molded part that weighed 40 kg and that had a length of 2.7 m could achieve a 99.9% accuracy in its length from the first shots of the tool.
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.
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.
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.
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
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 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.
Hugo Renkema, Bart Hofstede, Menno Claase, Marcel Schutte, Paul Vercoulen, September 2013
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.
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Brown, H. L. and Jones, D. H. 2016, May.
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