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.
Halloysite Nanotubes (HNT TM) provide a new avenue for the preparation of nanocomposites. Halloysite is a naturally occurring member of the kaolin family of aluminosilicate clays. Its uniqueness is that it exists predominantly in a tubular form with lengths of up to 10 microns and diameters of up to 400 nm rather than the layered platy form of essentially all other clays. Well-behaved dispersions of HNT in nylon-6 polypropylene TPO and several varieties of polyethylene have been obtained by standard melt processes. In all cases impr oved physical performance has been realized for molded parts. The result is a molded part that is more durable and lighter than a glass fiber reinforced counterpart. In addition injection molded HNT-containing composite parts exhibit improved surface appearance and reduced extrusion and molding cycle time relative to glass fiber containing composites. HNT have also been dispersed in polymer latexes and dispersions at quite high loadings. These polymer and clay dispersions have been coated and produce coatings with a tenfold increase in strength while maintaining transparency.
In the face of dwindling resources rising energy prices and increasing environmental pollution reductions in consumption and emissions are topics of increasing importance in all fields of technology. To achieve these goals specifically in the automotive industry new engine concepts are needed in connection with thorough-going implementation of lightweight construction. Whereas weight-optimized plastics components are already utilized in many vehicle subsystems and components steel and/or aluminum structures are usually used for load-bearing structural elements. This statement also applies fundamentally for the engine mounting subsystem. In this area plastics components have been used previously only for subordinate moderately loaded semi-components. Now for the first time a mechanically highly-loadable torque reaction mount has been conceived as a plastics structural part and implemented in the series production of a vehicle with a transverse-mounted engine. In addition to weight reduction it also helps create a more advantageous load distribution on the axles. Load reduction on the front axle has positive effects on driving dynamics and safety. The paper begins by stating fundamental requirements for components of engine mounting systems. The principle procedure in developing load-bearing plastics components includes the topics of integrative simulation laboratory component tests and in-vehicle testing.
The Automotive Composites Consortium is a joint program between General Motors Ford and Chrysler to develop structural automotive components from composite materials. A current Focal Project is a structural composite underbody capable of carrying crash loads with mass reduction of the vehicle structure a primary goal. Phase 1 of the project is the selection of a material and process system (M&P system). Three systems were evaluated each with several subsets. The selected M&P system is compression molding of sheet molding compound (SMC) with a vinyl ester matrix and predominately glass fabric reinforcement with some chopped glass. A high elongation core may be used to increase the integrity of the underbody after a crash event. This selection was based on mass and cost considerations including a technical cost model manufacturing feasibility and material properties of initial plaque moldings. CAE-based design methodologies were developed to achieve acceptable performance for full frontal frontal offset deformable barrier side and rear offset impact load cases. Body-in-white (BIW) static and modal stiffness and vehicle level crash performance and mass assessments were completed. Our current intent is to use weld bonding as the means to join the composite underbody to the steel passenger compartment. In support of this we have completed a CAE study of the weld bond model including an initial performance sensitivity study of joint geometry. Phase 2 of this project is underway with the goal of providing a full design of the underbody including design for durability and feasible scenarios for component manufacturing and vehicle assembly.
Machine Augmented Composites (MAC) have small simple machines embedded in a matrix. MACs might provide materials with advantageous properties or new functions. Example properties are materials with increased damping or negative Poisson’s ratio. New functions might include the ability to change shape or to adjust stiffness. In the MAC material studied here the matrix is a soft polyurethane elastomer and the embedded machine is a nylon hourglass-shaped element. The desired improvements should give the composite material the ability to change shape and perform useful work. The hourglass core elements elongate as they are pressurized which actuates the structure. The elastomer matrix which is nearly incompressible aids the expansion. The commercial code ABAQUS was used to study the MAC’s deformation and to predict its response. Potential applications for this research in the automotive industry are in energy absorption and dissipation. Sandwich panels that change shape could increase driver and passenger safety by adapting the automotive body shell to road conditions or by damping noise and vibration. These panels might deploy like an air bag to absorb energy around passengers during an accident. Machine augmented composites are a promising field with potential to produce materials that serve as both structure and mechanism.
Polypropylene and glass fibre (PP/GF) based Long Fibre Reinforced thermoplastics (LFT) are nowadays established as state of the art materials for semi-structural applications in the automotive industry. However PP/GF LFT materials are limited for producing automotive components for use in general assembly. The use of LFT based components for structural applications and their implementation directly into the body in white assembly is still a challenge for the automotive industry. In order to develop LFT materials for such applications a feasibility study to investigate the e-coating process sustainability of LFT materials was conducted. The current article addresses the developed LFT formulations and their basic mechanical properties. For this purpose polyamide / glass fibre (PA/GF) based LFT materials were thoroughly investigated. The change of mechanical performance of the LFT materials due to applied temperatures of the e-coating process was investigated by benchmarking of non-temperature-treated against tempered LFT specimens. In addition the combined influence of temperatures and chemicals on the LFT properties was evaluated by running the LFT specimens through the actual painting line that included e-coating and subsequent painting and drying processes. Finally it was found that it is possible to manufacture LFT parts capable of withstanding the e-coating process without causing major changes in the performance of the LFT materials.
The relationship between the resin and fiber properties in Polypropylene Long Fiber Thermoplastics is presented. The effects of glass content Maleic anhydride grafted polypropylene additives (coupling agent) and melt flow of the resin are presented. Various samples of Polypropylene Long Fiber Thermoplastics pellets (PP GLFT) were compounded with various coupling agent loadings and using different melt flow homopolymer polypropylene resins. The glass content of the pellets was varied from 30% to 50%. The pellets were then molded and tested for normal mechanical properties. The results of the study are presented.
Polyamide-6 is widely used in many mechanical applications also in automotive replacing more and more traditional materials such as metals thermosets and elastomers. Good process ability along with outstanding physical properties also long term stability under tough conditions and a high value recycling ability make this thermoplastic material also commercial interesting for new demanding machinery parts. A broad variety of materials is achieved by producing PA-6 “in situ” by anionic polymerisation of Caprolactam which can be performed on extruders on RIM machines or in different casting processes. Nano-Clay or Glass fiber reinforced granules short or long-glass fiber reinforced molded parts glass-mat reinforced manhole covers or wind turbine blades are some examples of Brüggemann’s AP-Nylon® Material applications completed by NYRIM® the wide range impact modified grades. This paper gives an overview of the new developments in this field we were involved in during the last 2 years.
With climate change and the current situation regarding energy and environmental policy dominating the agenda car manufacturers are faced with the complex problem of drastically lowering the fuel consumption of their vehicles in order to reduce CO2 emissions. One way of tackling the problem is to pursue a consistent strategy of lightweight construction. Self-activated as well as thermally activated rigid integral polyurethane foams from BaySystems can help to realise reductions in weight. They are ideal for use in structural parts. The presentation covers some of their state of the art solutions and techniques followed by a vision of a new composite design for roof modules which combines the aforementioned polyurethanes and their processing technologies with a sprayed polyurethane barrier layer.
Current and future changes in the automotive industry present an increased opportunity for thermosets. Bio-based materials in SMC present an opportunity to help automotive manufacturers in the US to meet the 2020 Freedom Car weight and 14.9 km/L (35 mpg) CAFÉ requirements as currently mandated by the federal government. Developments in the industrial bio-technology sector are also leading to knowledge to provide opportunities to use bio-based materials to provide solutions using SMC to lower costs and weight. The National Composite Center is leading collaborative efforts in the development of biobased resins fillers and reinforcements. The result of these collaborations in both biobased materials and the interface of nano technology are presented. The opportunities exist for the development of biobased materials to produce a lighter weight SMC.
It is a well established fact that Conventional Sheet Molding Compound (SMC) manufacturer/ SMC parts manufacturer uses steps such as resin mixing blending sheet manufacture rolling or festooning maturation & transportation before actual molding. Often times the sheet manufacturing and the molding operations are in two different locations. While it offers some flexibility in isolating sheet manufacturing from molding it also leads to challenges in planning logistics storage and maintaining quality through out the process steps. These factors are some motivation for the industry to develop a process that combines “In-line compounding” with molding operations. The potential for cost savings is large but raw material properties at each step needs calibration and control.
Over the last 7 years Gurit has continued to develop advanced composite materials to address the needs of the niche automotive market with a proven track record as a innovative Tier 2 supplier. In 2006 the decision was taken to strengthen this position with the investment and move to a Tier 1 role. Through close collaboration with Aston Martin Gurit successfully introduced its Class A composite body system CBS 96 onto their premium vehicle DBS establishing our first 20000 sq. ft. advanced composite manufacturing facility. This presentation aims to establish the production route for these OEM quality components and the evolution of the manufacturing processes over these critical 18 months. The presentation will detail how cycle times have evolved through on line and off-line processes the analysis of Quality trends including 'Right First Time' and reject causes and finally to draw trends from the analysis and establish the future opportunities for Gurit's range of innovative advanced composites in this market.
This paper is dedicated to a realistic prediction of the deformations of advanced composite car body panels during curing. In the present work a cure-dependent viscoelastic model is used for the resin to establish the cure-dependent orthotropic viscoelastic properties of a unidirectional glass/polyester ply via micromechanical fiber/matrix models. Also the anisotropic curing shrinkage of the unidirectional ply is obtained from unit cell calculations by inserting the measured curing shrinkage of the resin. These evaluated properties are used in the finite element model of the laminate which is verified by an experimental study of the deformations of square cross-ply laminates. As an application of this effort different parts of a car body like the roof and the trunk are modeled considering various symmetric and asymmetric stacking sequences for them. Both open-mold and closed-mold curing conditions are simulated. It is concluded that the curing stresses have a viscoelastic nature which may not be modeled by using the available elastic models. The curing stresses induce significant deformations in the composite panels which cannot be avoided even if symmetric laminates are cured in closed molds. The initial curvatures and bends of the panel in the mold affect its final deformed shape.
In this study the low velocity impact behavior of three layer thermoplastic laminates consisting of woven glass fiber and polypropylene has been investigated. Panels with dimensions of 100 x 100 mm were subjected to impact energies between 4 and 16 Joules using an instrumented dropping weight impact tower. Results suggested that the woven thermoplastic composites exhibit good energy absorbing properties with approximately 73% of the impact energy being absorbed after a 16 Joule impact. The impact damaged plates were cut into 100 x20 mm coupons and tested under four point bending (4PB). The result showed a reduction in flexural strength of approximately 27% after a 16 Joule impact. Following this a simple compression molding damage repair process was applied to the low velocity impact damaged laminates. Repaired samples were tested under 4PB and results showed a significant recovery of flexural strength to approximately 98 % of the undamaged strength. These results suggest that a simple one step process could be used to successfully repair impact damaged thermoplastic composites.
Mechanistic Computer simulations of flexible fiber suspensions are developed to study the molding of fiber reinforced composites. Fibers are modeled as chains or rigid beads connected by springs. Parameters such as fiber concentration fiber length and stiffness can be modified to match specific processing conditions. Simulation results include final fiber orientations and fiber distributions within a molded part. Specific applications for this type of simulations are compression molding of Sheet Molding Compound where defects such as Fiber-Jamming and Fiber-Matrix separations are difficult to predict and still not well understood.
A novel measurement technique was developed to obtain unbiased fiber length distribution (FLD) measurements at specified locations in the thickness of the sample. This technique relies on elastic energy stored in long fiber thermoplastics (LFT) which is released during partially constrained burn-off. This release results in an increase of thickness dimension of the sample and partial disentanglement allowing sample selection and subsequent filament separation. Quantitative FLD results and the measurement technique are discussed in detail. The FLD in long fiber reinforced injection molded thermoplastics is shown to vary as a function of thickness.
Polymer-clay nanocomposites involving a blend of two otherwise incompatible thermoplastic polymers were prepared and investigated for the effects of adding organically modified clay. Linear low density polyethylene (LLDPE) and polyoxymethylene (POM) at several composition ratios (70/30, 50/50, 30/70) were melt mixed with 5% Cloisite 15A and 5% Cloisite 30B, respectively. Their blends were characterized by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The LLDPE/POM (70/30) blend nanocomposites incorporating Cloisite 15A showed co-continuous morphology according to the SEM images, while those with Cloisite 30B showed some limited levels of compatibility. Further, Cloisite 15A improved the melting temperature of LLDPE and POM while Cloisite 30B had no significant effect on the LLDPE melting temperature but increased the melting temperature of POM. As for the LLDPE/POM (30/70) blends, Cloisite 15A made the two originally incompatible phases indistinguishable, while the blends containing Cloisite 30B showed a significant decrease in the domain sizes. However, the blend samples without organoclay incorporation did not exhibit any compatibility and the dispersed phase was totally segregated. TGA results showed that addition of clay decreased POM degradation temperature but there was no significant changes detected in PE’s. The clay’s compatibility with one or both polymers is shown to make a significant difference in the blend morphology and compatibilization mechanisms of the polymer-clay nanocomposites, which are phenomenologically explained in this paper.
Simulation and design of single-screw extruder screws using the standard pseudo-Newtonian Tadmor method is known to deviate from measured performance yet many screw designers have used the method successfully for many years. The research provided here shows the conditions when the method can be used for design work and when it deviates to an unacceptable level.
Multilayer coextrusion is a process in which two or more polymers are extruded and joined together in a feedblock or die to form a single structure with multiple layers. This paper will discuss techniques for measuring experimental rheology data for monolayer and multilayer structures. These data will then be used to show the effects of multilayer rheology in the design of coextruded structures.
Differences in solids conveying screw pressure profile generation output motor energy required will vary between resins barrel temperature profiles and resin preheat temperatures on a single stage low compression barrier screw design.
The Melt Flow Index (MFI) of a polymer could be measured using MFI equipment and following ASTM D1238. Although MFI is a single point it is the most known test that uses MFI equipment. However MFI equipment could yield more information about the polymer. Principally by changing the heating temperature the dwell time and the load a whole set of information could be obtained from the MFI equipment. This paper sheds some light on some of the possible information that could be gained from MFI equipment by changing temperature time and load.
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