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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Hemp Fiber Reinforced Sheet Molding Compounds for Automotive Applications
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
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
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
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
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
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
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
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
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
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
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.
Polyurethane Structural Composites: An Innovative Process using In-Mold Decorating Films for Exterior Vehicle Parts
The Woodbridge Group continues to progress with innovative composite technologies for high performance applications encompassing its extensive expertise in the PU fields as well as its growing experience in composites. This paper presents a novel fabrication technology of PU Composites applicable for vehicles. The novel technology is based on an open mould pouring process that allows the usage of relatively low cost tooling low tonnage presses as well as a high level of component integration and process automation for the production of performance products. The process eliminates the need of in-mold or post-painting of the finished part by integrating in the composite structure a high performance film as a decorative exterior layer that provides a high quality surface resistant to environmental factors. The new process allows the fabrication of relatively thin lightweight structural composite with flexural modulus in the range known in other technologies as Polyurethane Structural Reaction Injection Moulding (PU-SRIM) and Sheet Moulding Compound (SMC) with Coefficient of Linear Thermal Expansion (CLTE) compatible with the In-Mould Decorating (IMD) films. The specific gravity of the part dependent on composition is lower than for similar strength products manufactured via PU-SRIM or SMC. End-product performance easily matches or exceeds the requirements of general transportation or other similar applications.
In-Mold Decoration for Structural Weatherable Applications
A method has been developed to produce unpainted high surface quality weatherable thermoplastic composite parts. This process utilizes aspects of both traditional compression molding and large part in mold decoration (IMD) and requires minimal secondary operations. The multi-layer system consists of a LEXAN* SLX film reinforced by AZLOY* laminate a polycarbonate based glass mat thermoplastic (GMT) produced by Azdel Inc. The process consists of first thermoforming the weatherable film trimming and compression molding the composite to for the final part. Applications which may be a fit for this technology include those which require a higher modulus and which have aesthetic and/or weatherable requirements such as automotive exterior panels hoods trunk lids fenders boats and personal watercrafts outdoor vehicles snowmobiles and tractors.
Exterior Long Glass Fiber Polypropylene System for Automotive Applications
Long glass fiber technology is used to reinforce both polyolefins and engineering thermoplastics. There is a large potential for growth in polypropylene (PP) and opportunities for LGF-ABS automotive applications. There are two primary processes for introducing long glass fiber into composite systems which are used in the industry today: direct and pellet processes. The direct processes include new extrusion-compression and injection molding equipment whereas the pellets are formed via pultrusion type processes. These processes can be used in applications where design and material are optimized for metal replacement or other material substitution opportunities. Potential benefits include part consolidation and weight reduction as well as improved economics. In this work a long glass fiber composite material was developed for use in the direct extrusion compression process which met stringent part performance needs including molded-in-color aesthetics customer weathering specifications mechanical properties and impact performance. Application requirements were achieved by the use of functionalized masterbatches in conjunction with olefinic base resins in a materials system approach.
Development of a New Composite Material with Improved Structural & Acoustical Properties for Automotive Interiors
The use of thermoplastic composites is growing rapidly in the automotive interiors segment. Headliner systems are getting more modular and use of audio-visual and other electronics is increasing. With the introduction of the FMVSS 201 requirements for head impact the conventional substrate technology used today is becoming costly. In this paper we present the development of a new type of thermoplastic composite material with enhanced acoustic and semi-structural properties. This new substrate material of glass/PP is manufactured using a proprietary process and is available at various weights and glass contents. The material can be molded to shape and the special re-lofting characteristics of the composite allow parts of varying thicknesses to be molded in a single shot. This allows greater design flexibility as both stiffness and acoustics can be controlled to meet today’s changing requirements in automotive interiors. This new composite is usually made in three weights—800 1000 & 1200 gsm although it is possible to make it in both heavier and lighter weights if required. The composite is usually supplied with a scrim on one side and an adhesive film on the other. Headliners made from the composite have a much simpler structure than conventional polyurethane headliners.
Development of Lightweight Hybrid Steel / GMT Composite IP Carrier to Meet World Crash Requirements on Passenger Vehicles
A new 2-piece hybrid steel / glass-mat thermoplastic (GMT) composite instrument panel (IP) carrier reduces weight noise / vibration / harshness (NVH) and cost while simultaneously improving parts consolidation and assembly vs. traditional steel-intensive multi-piece systems. In fact for the first time ever in a single carrier design this IP retainer meets or exceeds all world crash requirements. The award-winning design is currently featured on 6 IPs in 12 vehicles from Ford Volvo and Mazda. This paper will discuss design development and testing of this common carrier plus the technology breakthroughs that helped make it possible.
Composites in the Trucking Industry
Over the years the transportation industry has incorporated more and more composite materials into its vehicles. The automotive industry has used composites for exterior body panels e.g. hoods fascias hatches and doors as well as under the hood and structural reinforcements. The truck industry followed by introducing composites for hoods doors roofs bumpers and fairings. This paper will focus on the advancements made in composite materials from hand-spray up open molded parts to the various improvements in sheet molding compounds to liquid molded resin materials. It will concentrate on parts used in the trucking industry and how quality especially in cosmetic and surface properties has improved over the years.
Automotive Composites Consortium B-Pillar Molding Program
The Automotive Composites Consortium is conducting a program to develop a design and manufacturing strategy for a composite intensive body-in-white (BIW). This BIW is to have 60% mass savings compared to a corresponding steel structure meet all structural requirements and be manufactured at 100000 units per year at cost parity to current processes. A key element of this design was to use a liquid molded chopped carbon fiber reinforced composite with a fiber volume fraction of 40% for the body side component of this structure. This process has the advantages of producing variable section thickness to optimize the structure at minimum mass while each element in the process has been demonstrated to have a 4 minute cycle. Preforming and molding tools representing the B-pillar portion of the body-side design were designed and built. These were used to investigate the processing of high fiber content chopped fiber composite in the shape of the main contours of the body-side. The first phase of this program was to develop the basic preforming and molding with glass fiber roving. Once this is accomplished the program will move to carbon fiber. This paper reports the development of preforming molding bonding and testing in the initial phase of the B-pillar program.
Seating Structures and Other Structural Applications with Locally Unidirectional Reinforced Thermoplastic Composites
A new mass production process combining unidirectional continuous (endless) and long fiber thermoplastic (E-LFT) allows the product ion of highly loaded structural components. This one-shot production process is a combi nation of the well-established LFT process and a new process for unidirectional continuous fibers which enables low cost mass production of complex structural lightweight parts. The continuous unidirectional fiber tapes (EF) provide excellent mechanical characteristics and can be inserted three-dimensionally following exactly the paths of load. Serial production will start by the end of 2006.
Mechanical Recycling of Injection-Molded Wood-Thermoplastic Composites
Wood-thermoplastic composites are usually processed by extrusion, and therefore an attempt has been made to study their suitability for injection molding. The experiments were made to study the behavior of the wood flour-polypropylene composite during injection molding, and to what extent the mechanical properties deteriorate after several processing cycles, i.e. mechanical recycling.
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