SPE Library
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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Conference Proceedings
Automotive Composite Fuel Cell Bipolar Plates: Hydrogen Permeation Concerns
Richard Blunk, September 2005
At present Proton Exchange Membrane (PEM) performance levels and fuel cell stack operating conditions a plate area specific resistance of less than 30 mohm cm2 and a plate thickness of less than 2 mm are required to meet the vehicular volumetric power density target (> 2 kW/l). Unfortunately it is difficult to meet these targets and simultaneously obtain good mechanical properties and low through-thickness hydrogen permeation rates when using polymeric plate materials. Polymers are brittle at the high conductive filler concentrations (e.g. > 50 v/o graphite) required for high conductivity and are more likely to generate high convection-driven H2 permeation rates at a high graphite loading and at a thin plate thickness. As a result high scrap rates are realized during plate manufacturing and stacking operations and excessive permeation rates are anticipated in pressurized stacks. This study addresses H2 permeation concerns associated with using thin highly-filled composite plates and investigates factors affecting permeation such as plate temperature thickness graphite loading and aging.
Low Cost Light Weight Single Material Solution for Soft Touch Vehicle Interior Substrates
Jesse Hipwell, September 2005
The use of low-density glass-mat thermoplastic (LD-GMT) materials in automotive interior applications has increased over the last 4 years. Nearly 20% of all headliners produced in North America are molded from LD-GMT. Its popularity and use has also begun to spread to other soft-touch applications and to other global regions. The superior mechanical properties ease of tailoring performance efficiency of processing and adjustable thickness capability makes the AZDEL SuperLite LD-GMT product a versatile material solution for both structural and non-structural interior applications. This paper is divided into 4 sections and will present the basic composition manufacturing process and properties of LD-GMT applications of LD-GMT and the benefits of its' use LD-GMT performance when subjected to severl generic interior standards and design capabilities and the forming processes for LD-GMT.
An Integrated Automotive Roof Module Concept: Plastic-Metal Hybrid and Polyurethane Composite Technology
Doug Stratton, September 2005
The implementation of metal stampings combined with injection molded 30% glass fiber reinforced polyamide type 6 (PA6-GF30%) for commercial passenger car and truck front end modules has grown in the automotive industry over the past five years. This patented Plastic-Metal Hybrid (PMH) design technology has proven its ability to enable the automotive original equipment manufacturer (OEM) to engage a flexible assembly strategy decrease capital expenditures and reduce labor hours required to manufacture a vehicle. The roof module is an opportunity to further develop content by combining adhesives coatings film and reinforced polyurethane (PUR) composite materials with PMH technology. The powerful combination provides the OEM a component ready to assemble. Technical and economic benefits to the value proposition include: weight reduction compared to glass design and styling freedom from a box shaped hard top In-mold features like brackets bosses and attachment points Different color options Removable or open/close window design Safety improvement due to lowered center of gravity and benefits in the event of a rollover crash Water management and flush finish with the body exterior This paper presents a roof module concept that utilizes PMH to create a roof frame welded to the body-in-white (BIW) structure that is capable of going though on-line electro-static coating (E-coat) processes. The frame becomes a common footprint upon which a variety of roof modules constructed with PUR composites protected by coating and film can be attached to the vehicle with adhesive. A roof frame design concept for a generic medium sized vehicle is presented. The concept includes single double or triple modular panel versions. Each version can be used to manufacture three variations: a base roof sunroof or panoramic roof module.
Feasibility of Continuous-Fiber Reinforced Blanks for Automotive Applications
Andrew Burkhart, September 2005
Recent developments in the rapid processing of continuous-fiber reinforced thermoplastics (CFRTP) offer a method for automakers and suppliers to manufacture high-performance structures that meet automotive cost performance and volume requirements. Benefits of thermoplastic composites include rapid processing high toughness ease of recycling long shelf life and multi-stage processing. CFRTP tailored blanks are flat net-shape preforms comprising aligned continuous reinforcing fibers in a thermoplastic matrix. These tailored blanks can vary in thickness fiber orientation material composition and shape based on part requirements. Main benefits include material efficiency low scrap and low weight. This paper investigates the feasibility of stamp forming CFRTP tailored blanks. Experimental results are presented showing effects of forming on consolidated tailored blanks and the potential for a high quality surface finish.
Bonded Hybrid Automotive Front End Carriers
Samar Teli, September 2005
The front-end carrier (FEC) refers to the part of a car that supports most of the cooling package headlights latch and various other components. It also ties the upper and lower longitudinal rails and plays a role in the global and local structural stiffness of the car. The trend is to use such a FEC in a module that is supplied for assembly after the engine is mounted. FECs are currently a combination of plastics to give form and various functions and metal to withstand mainly crash loading. Methods such as mechanical fasteners or over-molding are being used to form the hybrid plastic-metal part. Dow Automotive offers a new solution that combines its application development capability and materials R&D. This concept consists of an injection-molded plastic (LGF-PP) bonded to an e-coated metal reinforcement using BETAMATE3 LESA adhesive. This approach enables a closed-box profile with a continuous joint between the metal and the plastic that is not possible using traditional methods. The result is a significant increase in the stiffness/weight ratio as well as reduction in package space utilization. It also offers better design flexibility compared to other hybrid solutions and provides better bending and torsional stiffness. This paper will outline a prototype development demonstrating the technology as well as developments related to current programs.
Embedded Attachments for PU-Based Sandwich Composites
Ignasio Osio, September 2005
Attachments are critical for the performance of sandwich composites in automotive components. In this paper we continue our investigation on attachments techniques [a] and focus on a procedure to embed and test attachments for polyurethane (PU) based sandwich composites. In developing reliable attachment techniques and methods for evaluation and design we open new application possibilities for this family of composites in the automotive market. Embedded attachments are particularly suited for PU-based sandwich composites as the two-component polyurethane mixture allows intimate interlocking of the different sandwich “ingredients”. We discuss the performance of different attachment designs and configurations for applications where extra functionality can be added to this type of structures.
Long-Fiber Thermoplastic Injection Molded Composites: From Process Modeling to Property Prediction
Ba Nghiep Nguyen, September 2005
Recently long-fiber filled thermoplastics have attracted great interest within the automotive industry since these materials offer much better structural performance (e.g. higher elastic moduli strength and durability) than their short-fiber analogues and they can be processed through injection molding with some specific tool design. However in order that long-fiber thermoplastic injection molded composites can be used efficiently for automotive applications there is a tremendous need to develop process and constitutive models as well as computational tools to predict the microstructure of the as-formed composite and its resulting properties and macroscopic responses from processing to the final product. The microstructure and properties of such a composite are governed by i) flow-induced fiber orientation ii) fiber breakage during injection molding and iii) processing conditions (eg. pressure mold and melt temperatures mold geometries injection speed etc.). This paper highlights our efforts to address these challenging issues. The work is an integrated part of a research program supported by the US Department of Energy which includes the development of process models for long-fiber filled thermoplastics the integrating process modeling and property prediction models as well as developing new constitutive models to perform linear and nonlinear structural analyses experimental characterization of model parameters and verification of the model predictions with forming experiments.
Fiber Reinforced Dimensional Capability of Carbon Fiber Reinforced Epoxy Exterior Automotive Products
Donald Lasell, September 2005
As automakers continue in their efforts to reduce overall vehicle mass light weight high strength materials such as composites figure to gain wider acceptance for use in mainstream high volume vehicles. Vermont Composites Inc. (VCI) has partnered with General Motors to implement the automotive industry’s highest known volume usage of carbon fiber reinforced exterior body panels. VCI is the exclusive supplier to GM for the carbon fiber reinforced front fenders utilized on the 2006 Corvette Z06. The fenders are constructed of uni-directional carbon fiber reinforced epoxy resin with a nominal thickness of 1.2mm and a nominal mass of 3.5 pounds (before paint). Dimensional topics to be discussed include a general overview of the part-dimensioning scheme gage design the process of validating gage repeatability (Gage R) and gage repeatability and reproducibility (Gage R&R) and inspection techniques. This paper will summarize the work performed to date in the design and development process with respect to dimensional capability of the fenders. Product design topics such as localized product cross-section fiber orientation balancing symmetry and localized reinforcing will be discussed. Impacts of these various design and development items will be addressed using information collected during ongoing product inspection capability studies.
LFI-PUR®: The Process for High Quality Long-Glass-Fiber-Reinforced Polyurethane Parts
Tim Donovan, September 2005
Krauss-Maffei's LFI-PUR® technology can be used to reinforce both light-weight and solid PU parts with long-glass-fibers. In a LFI-PUR® system glass fiber from a roving is chopped into filaments which are wetted with the PU reaction system. The mix is discharged into the open mold the mold is closed and the part is formed under pressure causing the glass filaments and the PU matrix to bond into a high-strength composite. The unique process technology benefits of LFI-P UR® can boost a company’s competitive advantage in the production of glass-reinforced PU components. The process can be used to produce foamed or solid parts with high-quality surfaces. Additional benefits are high stiffness and low thermal expansion.
Hemp Fiber Reinforced Sheet Molding Compounds for Automotive Applications
Ellen Lee, September 2005
Natural fibers have been steadily gaining interest for use as a mechanical reinforcement material in place of fiberglass for thermoplastic and thermoset composites. In addition to their lower cost and lower density natural fibers are a renewable material and are less energy intensive to produce (grow) than glass fibers. In the current study hemp fiber reinforced SMCs (sheet molding compounds) were prepared and compared to conventionally reinforced glass SMC for cost density and mechanical properties. Continuous hemp fiber (in the form of twine) non-woven hemp mats fiberglass and hybrids (fiberglass/continuous hemp twine mixture) were examined. Severl commercial resins were screened for copatibility to the various fiber formulations and the effect of added compression during the compounding process was studied. In addition to mechanical performance moisture uptake measurements were performed for the hemp glass fiber reinforced materials. Selected SMC composites were evaluated against typical desired properties for automotive applications. Results show that certain formulations are currently close to target values. Next steps for additional optimization of composite formulation fiber dispersion fiber compatibility and moisture resistance will be discussed.
Wood Fiber Composites from Recycled Polyolefin
Minh-Tan Ton-That, September 2005
Wood composites based on recycled polypropylene (PP) were fabricated by melt processing. Different formulations involving two different types of coupling agents two different types of reactive additives and an impact modifier (IM) were used. The reinforcements were in the form of wood sawdust. The mechanical performance of the resulting composites was evaluated before and after conditioning in water for 1 and 7 days. The composites show superior mechanical properties when compared with the pristine matrix and resist humidity very well. The results also demonstrate the effect of formulations on the performance of the recycled composites.
Role of Fiber Adhesion in Natural Fiber Composite Processing for Automotive Applications
James Holbery, September 2005
The prediction and characterization of the adhesion between fiber surface treatment and polymer is critical to the success of large-scale natural fiber based composites into automotive semi-structural applications. The two primary limiting factors in natural fiber composites are in large part dominated by fiber moisture uptake due to fiber structure and limits in high-temperature processing. In this study we have developed several fiber surface modification techniques and analyzed the fiber-polymer adhesion to more clearly understand the critical parameters controlling moisture uptake swelling and structural degradation due to interface degradation. We will present preliminary surface modification findings on hemp fiber sources and attempt to resolve the role that fiber interface adhesion characterization plays in understanding and predicting fiber performance within polymer matrices.
Wood Fiber Reinforced Poly(lactic acid) Composites
M.S. Huda, September 2005
Natural fiber-reinforced composites are increasingly being used in applications in the automotive furniture or building industry. The processing and physical properties of these composite materials are the very important parameters in respect to the design layout and product guaranty. This paper presents the results of the study of processing and physical properties of environmentally friendly wood fiber reinforced poly(lactic acid) (PLA) composites that were produced by a micro-compounding molding system. Wood fiber-reinforced polypropylene (PP) composites were also processed and compared to PLA/wood fiber composites. The mechanical thermal-mechanical and morphological properties of these composites have been studied. PLA/wood fiber composites have mechanical properties of sufficient magnitude to compare with conventional thermoplastic composites. The tensile and flexural properties of the PLA/wood fiber composites were significantly higher when compared with the virgin resin. The addition of 20 wt % of wood fibers in PLA/wood fiber composite improved the flexural strength of PLA by 19 % the flexural modulus by 115 % and the tensile strength and tensile modulus by 5 wt % and 77 % respectively. The flexural modulus (8.9 GPa) of the PLA/wood fiber composite (30 wt % fiber content) was comparable to that of traditional (i.e. polypropylene/wood fiber) composites (3.4 GPa). Incorporation of the wood fibers in PLA resulted in a considerable increase of the storage modulus (stiffness) and a decrease in the tan delta values. The addition of the maleated polypropylene coupling agent (MAPP) improved the flexural and Izod impact properties of the wood fiber reinforced composites. The morphology as indicated by scanning electron microscopy (SEM) showed good dispersion of wood fiber in the PLA matrix. Microstructure studies also indicated a significant interfacial bonding between the matrix and the wood fibers. The specific performance evidenced by the wood fiber reinforced PL
Processing Methods and Physical Properties of Native Grass Reinforced Biocomposites
Wanjun Liu, September 2005
Big blue stem grass fiber (BBSGF) reinforced thermoplastic biocomposites were fabricated with both extrusion followed by injection molding and sheet-molding compounding (SMC) followed by compression molding. The physical properties were evaluated with dynamic mechanical analysis (DMA) mechanical properties testing and microscopy observation. It was found that compression molding could achieve similar modulus values to injection molding forgrass reinforced high density polyethylene (HDPE) composites. The stiffness of compression-molded specimens is related to the consolidation state of the samples which depends on compression molding conditions such as temperature pressure and mold type. Compression molded specimens exhibited a higher heat deflection temperature (HDT) and notched impact strength compared to injection-molded samples. Grass fiber reinforced cellulose acetate butyrate (CAB) biocomposites from SMC processing had similar physical properties with grass fiber reinforced HDPE composites which indicates that natural fiber reinforced CAB biocomposites have the potential to replace polyolefin based composites for automotive applications.
Fabrication and Characterization of Clay / Epoxy Nanocomposite
Yuanxin Zhou, September 2005
In the present investigation we have developed a novel technique to fabricate nanocomposite materials containing SC-15 epoxy resin and K-10 montmorillonite clay. A high intensity ultrasonic liquid processor was used to obtain a homogeneous molecular mixture of epoxy resin and nano clay. The clay s were infused into the part A of SC-15 (Diglycidylether of Bisphenol A) through sonic cavitations and then mixed with part B of SC-15 (cycloaliphatic amine hardener) using a high speed mechanical agitator. The trapped air and reaction volatiles were removed from the mixture using high vacuum. DMA TGA and 3-point bending tests were performed on unfilled 1wt. % 2wt. % 3% and 4wt. % clay filled SC-15 epoxy to identify the loading effect on thermal and mechanical properties of the composites. The flexural results indicate that 2.0 wt% loading of clay in epoxy resin showed the highest improvement in flexural strength as compared to the neat systems. DMA studies also revealed that 2.0 wt% doped system exhibit the highest storage modulus and Tg as compared to neat and other loading percentages. However TGA results show that thermal stability of composite is insensitive to the clay content.
Nanoclays: Multi-Dimensional New Nano-Tools in the Polymer Development Toolbox
Karl Kamena, September 2005
Layered smectite nanoclays particularly of the montmorillonite type have interesting structural characteristics making then suitable for converting the planar surfaces from hydrophilic to hydrophobic thereby rendering them more suitable for incorporation into organic polymer matrices. Since surface areas of these clays are very large on the order of 750 m²/gram a small percentage of the clays when fully dispersed and exfoliated can saturate the host polymer (or monomer) system. Nanoscopic phase distribution can impart enhanced stiffness and strength with substantially less inorganic content than conventional mineral fillers. Furthermore additional properties such as improved barrier properties abrasion resistance and modified flame retardancy can result. Traditionally the focus has been on the development and preparation of nanocomposites with nanoclays being the principal non-polymer ingredient. Increasingly however we’re seeing the development of polymer systems combining a variety of modifier agents combining to generate the desired properties and cost/performance characteristics. Nanoclays are demonstrating unique multi-dimensional capabilities to synergistically enhance overall polymer system performance and constitute a powerful new nano-tool in the polymer development toolbox. Thermoplastic polyolefin (TPO) formulations based nanoclays are being used in exterior automotive trim applications and a variety of polyolefin-based products are being used in the interior. Nano-modified nylons have been specified for under-the-hood applications. Unsaturated polyester formulations utilizing nanoclays and microspheres are also being developed for SMC applications.
Fabrication and Evaluation on Nano-Phased Unidirectional Carbon Fiber Reinforced Epoxy
Yuanxin Zhou, September 2005
In the present investigation we have developed a novel manufacturing technique to fabricate unidirectional nanophased carbon prepregs using solution impregnation and filament winding methods. Siliconcarbide nanoparticles (? -SiC) were first infused in a high-temperature epoxy through a high-frequency ultrasonic cavitation technique. The loading of nanoparticles was 1.5% by weight of the resin. After infusion nanophased resin was used to impregnate a continuous strand of dry carbon fiber tows in a filament winding set up. As the process continued excess resin was squeezed out and the prepregs were run through a heater to partially cure the resin and evaporate out the solvent used for dissolving the resin. In the next step prepregs were wound onto spools. The same filament winder was then used to wrap the nanophased prepregs over a cylindrical mandrel of Marcore foam especially built for this purpose. Once the desired thickness was achieved the prepregs on the cylinder was longitudinally cut opened into a rectangular flat sheet and cured in a compression molding machine. Test coupons were then prepared from these rectangular panels. In parallel control panels were also fabricated in identical manner from the neat resin without any particle infusion. Extensive thermal and mechanical characterizations were performed to evaluate the performances of the neat and nanophased systems. Thermo-gravimetric analysis (TGA) results indicated that by incorporating nanoparticles the thermal decomposition temperature increased by about by about 7-80C due to enhancement in the cross-linking of the polymer. This enhancement in cross-linking was also substantiated by the differential scanning calorimetry (DSC) tests. Significant improvement in flexural properties of nanophased laminates was also observed when compared to the neat system. Improvement in strength and stiffness was observed to be around 32% and 20% respectively over the neat system. Failure mechanisms fiber orientations an
Graphite Nanoplatelet-Polypropylene Nanocomposites
Kyriaki Kalaitzidou, September 2005
Exfoliated graphite nanoplatelets (graphene sheets ~10nm thickness ~1?m diameter) a new material developed in our lab is used as nanoreinforcement in polypropylene. Exfoliated graphite nanoplatelet (xGnP) olypropylene (PP) nanocomposites are fabricated by (i) solution method and (ii) melt mixing and their thermo-mechanical and electrical properties are determined. Comparison of xGnP-PP nanocomposites to composites made using other carbon-based electrically conductive fillers indicates that xGnP is a multifunctional reinforcement that enhances the overall performance of polymers. Results include thermal (coefficient of thermal expansion and thermal conductivity) and mechanical properties (flexural strength modulus of elasticity and impact strength). In addition the electrical conductivity and the percolation threshold of the xGnP-PP nanocomposites will be determined as a function of the xGnP's aspect ratio and the processing method used.
Biobased Nanocomposites from Toughened Bacterial Bioplastic and Titanate Modified Layer Silicate: A Potential Replacement for Reinforced TPO
Amar K. Mohanty, September 2005
Biobased ‘green’ nanocomposites are the materials for the 21st century. Polyhydroxybutyrate (PHB) a bacterial bioplastic is recently highlighted because of its renewable resource based origin and its potential to replace/substitute petroleum derived non-biodegradable plastic like polypropylene (PP). The major drawback of PHB is its brittleness. This work investigates toughening mechanisms for PHB via incorporation of elastomeric components. Maleated polybutadiene with high grafting and low molecular weight was identified as the compatibilizer. The toughened PHB was characterized through their thermo-mechanical rheological and morphological analysis. The resulting toughened PHB showed ~440% improvement in impact strength over pure PHB with only 50% loss in modulus. The loss of modulus was recovered to permissible extent through incorporation of titanate modified montmorillonite clay. The hydrophilic clay was modified by titanate-based treatment to make it organophilic and compatible with the polymer matrix. The toughened PHB on reinforcement with 5 wt.% titanate based modified clay gave ~400% improvement in impact properties and 40% reduction in modulus over virgin PHB. The novel toughened bioplastic nanocomposites show potential as a green replacement/substitute of specific TPO for use in structural applications.
RIM PUR on Vacuum Formed Foils: The Right Choice for Aesthetic Structural Parts
Barry Pile, September 2005
An innovative solution is presented for the production of finished structural and aesthetical parts based on the synergies between the polyurethane foaming and the vacuum forming technologies. Reaction injection molded parts are created by back-foaming a PVC or PET film with standard or reinforced PU in a single working station. Cost reduction low weight excellent mechanical properties and elimination of painting are driving the expansion of this process making it extremely suitable for a wide range of industrial applications: external body parts for earthmovers and agricultural vehicles household appliances bathroom showers television cabinets etc.
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