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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Biobased Poly(trimethylene terephthalate): Opportunity in Structural Composite Applications
Injection molded composite materials as fabricated from chopped glass fiber and poly(trimethylene terephthalate) PTT are evaluated through their physico-mechanical and thermo-mechanical analysis. The fiber-matrix adhesion in composite is studied through environmental scanning electron microscopy (ESEM). The tensile and flexural properties including impact strength of virgin polymer improved drastically on fiber reinforcements. Simultaneous improvement of both stiffness and toughness of composite materials show strong potential in structural applications. The high heat distortion temperature HDT (>220 degree C) of such composite materials possess strong promise in automotive and building product applications.
Bio-Based Epoxy/Clay Nanocomposites as a New Matrix for Carbon Fiber Reinforced Composites: Thermophysical and Mechanical Properties Evaluations
The thermophysical properties of bio-based epoxy nanocomposites reinforced with organo-montmorillonite clay and the mechanical properties of carbon fiber reinforced plastics whose matrix is the bio-based epoxy/clay nanocomposites are reported. A novel sample preparation scheme was used to process the organically modified clay in the glassy bio-based epoxy network resulting in nanocomposites where the clay was homogeneously dispersed and completely exfoliated in the bio-based epoxy network. The storage modulus of bio-based epoxy at room temperature which was below the glass transition temperature of the nanocomposites increased approximately 0.9 GPa with the addition of 5.0 weight percent of exfoliated clay platelets. The glass transition temperature Tg decreased with addition of the organo-clay nanoplatelets. To understand the role of clay platelets in the bio-based epoxy nanocomposites the microstructure of clay platelets were observed using transmission electron microscopy (TEM) and wide angle X-ray scattering (WAXS). Carbon fiber reinforced composites (CFRP) were processed using the bio-based epoxy/clay nanocomposites. No difference in elastic modulus and flexural strength was observed regardless of the use of different matrices. It was observed that the interlaminar shear strength of CFRP with bio-based epoxy was improved with adding 5.0 weight percent intercalated clay nanoparticles.
Impact-Tolerant SMC Resins for Demanding Structural Applications
Composite materials have penetrated the transportation market where their lower total component cost and lighter weight have made them the material of choice. As designers and engineers become more comfortable with the use of composites they are being specified in more demanding load-bearing applications. Structural thermoset resins combine high modulus the ability to efficiently translate reinforcing fiber properties with the elasticity to withstand the high stresses and strains of load bearing applications. A new generation of impact-tolerant structural thermoset resins has been developed that have the high modulus critical to achieving maximum structural properties yet exhibit the toughness of thermoplastics. These tough thermosetting resins absorb high transient loads without suffering micro-structural damage that can propagate to failure after repeated mechanical chemical and environmental exposures. Cast resin properties and reinforced composite properties show the potential of these materials as a cost-effective option for transportation applications. Efficiency of reinforcing fiber utilization allows weight reduction without sacrificing structural performance. These new impact-tolerant materials can be processed with standard techniques at the production rates typical of high volume processes such as SMC at very low scrap rates. Composite formulation latitude allows tailoring the mechanical dimensional and appearance properties that typically make composite materials an economically attractive choice.
Cost Effective Use of Carbon Fiber SMC
Viper demonstrated the capability of carbon fiber SMC and the benefit it offers high performance vehicles. That was an important and necessary first step for the broader use of carbon reinforced composites in the automotive industry. The next critical step for carbon fiber SMC (CFSMC) is to make it cost competitive. Only then can CFSMC move beyond high performance vehicles and into the broader automotive market. In the broader market with lower performance requirements CFSMC is not cost competitive. However there is a great deal of work being done all along the supply chain to address the key cost drivers for CFSMC. Once the competitive cost targets are reached CFSMC will be able to compete with glass reinforced SMC as well as Aluminum. In the mean time there is a cost effective approach for using CFSMC in current parts and new applications that need increased stiffness. The key is to use CFSMC where it provides the maximum benefit at the lowest cost.
Structural RIM Choices for Today's Automotive Design
Bayer Polymers has been engaged in extensive development of Structural RIM (SRIM) polyurethane materials for over two decades. Out of these developments two traditional plus one new composite technologies have evolved. These afford the automotive designers as well as the engineers to capitalize on the composite advantages that are increasing with the demand for lighter weight cars and trucks. This paper discusses these three composite technologies. Historically SRIM composite have enjoyed interior applications such as door panels roof modules instrument panel retainers sunshades spare tire covers etc. Additionally SRIM materials have enjoyed exterior applications such as seat frames bumper beams truck boxes midgates and tailgates. Recent Bayer SRIM developments have brought about another composite technology choice. This technology combines traditional reinforcing materials with honeycomb cores. The result is a lighter weight composite than ever before with exceptional load bearing properties. Since a variety of manufacturing processes and/or equipment are involved to produce SRIM composites some process descriptions are discussed. Finally real production applications in use today are provided as typical examples.
Innovative Process Technology LFT-D-NF Offers New Possibilities for Emission Reduced Long-Natural Fiber-Reinforced Thermoplastic Components
Automotive components manufactured by using long- fiber reinforced thermoplastics have been firmly established for years for the purpose of large-scale production of semi-structural automotive components. In particular the LFT direct processing method using glass reinforcements has increasingly achieved its objectives due to its cost saving potential and excellent material characteristics and it is the base of operation for the processing of natural fibers. As a manufacturer of LFT and GMT processing plants Dieffenbacher GmbH & Co. meets the high requirements regarding material quality in order to guarantee a process for safe part production including an acquisition and evaluation system (SPC) of process data. The North America Division Dieffenbacher DNA offers this solution to the American market. The process modifications as well as some material properties will be introduced and discussed in this paper.
Compounding with Pushtrusion" Technology "
Pushtrusion"™ is a new technology that combines continuous fiber reinforcement with molten polymer creating fiber reinforced compounds during the molding process. The continuous reinforcing fibers are cut to specified lengths to create short fiber compounds long fiber compounds or even continuous fiber reinforced materials. The "Pushtrusion" technology can be used with many part forming processes including injection molding compression molding extrusion and filament winding. "Pushtrusion" is a patented process developed by Woodshed Technologies Inc. The process is licensed to end-users. Equipment is manufactured to use existing molding machines (retro-fit) or for new molding machines with pushtrusion technology integrated by licensed OEM machine manufacturers. "
Advanced Technologies for Design and Fabrication of Composite Automotive Components
Structural composites are available in various forms and functionality providing the designer a tremendous amount of flexibility to develop innovative compostie design solutions. But these advantages often cannot be realized without novel manufacturing methods that can accommodate hererogeneous parts of complex shape. Today new manufacturing methods allow the designer to satisfy specific local strength criteria by judicious selection and placement of materials. At the same time the freedom of complex component geometry provides the added benefits of combining multiple components/operations into a one-piece compression molded component. These new material combinations and manufacturing techniques provide a vast and comprehensive set of new opportunities for novel design solutions that exceed previous performance overcome previous limitations and stretch the limits of previous engineering design intuition. In order to take full advantage of these new materials and manufacturing techniques advanced automated design optimization technologies can be used to discover creative solutions. These methods dramatically improve the relevance and speed of complex manual design processes truncating them from months to days or even hours. They concurrently explore hundreds of design parameters and their relationships in product and process design scenarios and intelligently seek optimal values for parameters that affect performance and cost. These design tools have been used in the development of several FRP structural programs solely focused on replacing traditional materials like steel aluminum and cast iron. In this paper a new composite manufacturing method and a new design optimization technique are discussed briefly. Several example applications to real automotive composite components are described to illustrate the benefits of combining advanced manufacturing and design methods to realize novel composite solutions at a fraction of the weight of equivalent metallic parts.
Energy Absorption in Thermoplastically Stamped Composite Grid Structures
This paper summarizes results from an analytical/experimental study of the energy absorption characteristics of grid-stiffened composite structures under transverse loading. Tests and finite element simulations were carried out for quasi-static loading of isogrid E-glass/polypropylene panels in 3-point bending. Test panels were fabricated by using a thermoplastic stamping process and co-mingled E-glass/polypropylene yarns. The results of the tests and simulations show that these types of structures have excellent energy absorption characteristics and that most of the energy absorption occurs beyond initial failure. Results for isogrid panels loaded on the skin side will be compared with similar results for loading on the rib side and conclusions regarding design of such structures for energy absorption will be offered.
The Effect of Surface Energy of Boron Nitride on Polymer Processability
Fluoropolymers have long been used as processing aids for surface melt fracture treatment of polyolefin extrudates. Recent developments have shown that a small amount of Boron Nitride powder successfully eliminates surface melt fracture and also delays the onset of gross melt fracture. Study of surface energy helps in understanding the different mechanisms of these two processing aids in eliminating extrudate melt fracture.
Fundamentals of Melt Fracture Elimination Using Fluoropolymer Process Aids
Fluoropolymer process aids are widely used in polyolefin blown films to eliminate melt fracture. These process aids function by depositing a thin fluoropolymer layer on internal die surfaces, and promoting slip at the fluoropolymer – polyethylene interface. The present work describes how the morphology of fluoropolymer – polyethylene blends can be controlled to increase fluoropolymer deposition rate by using a new, rheology-modified fluoropolymer in combination with an interfacial agent.
A Survey of Manifold Designs for Flat Die Extrusion
Feedblock Coextrusion is considered to have been commercialized with the Dow Chemical patents issued in 1971. As Cloeren and Nissel introduced their own Coextrusion technology, a common thread throughout all technologies was design of Coextrusion dies. For decades extrusion die manifold designs remained unchanged. The ‘90s ushered in new commercial manifold designs aimed at solving age old problems with flow uniformity, die deflection, and coextrusion performance. This paper will examine the progression of die manifold designs, their impact on extruded products, and their implications on future coextruded structures.
Blown Film Characterisation
Effects of process changes on polyethylene blown films were studied using profile analysis techniques. The relationship between process parameters, barrel temperature, haul off rate and die gap, and film properties, thickness, blow up ratio (BUR), freeze line height, consistency of bubble profile were studied. An optical analysis system was developed which allowed film characteristics to be monitored during processing.
The Effect of Orientation on the Mechanical Performance and Thermal Properties of Extrusion Cast Metallocene Polyethylenes
Cast films were prepared using a Killion single screw extruder, from a range of metallocene PEs of varied comonomer types (hexene, octene), using different haul off speeds (8-4m/min) and die gaps (700-250?m). It was found that samples with greater orientation in one direction had increased tensile strength and shrinkage in that direction. DSC analysis showed crystallinity to decrease with decreasing haul off speed.
An Investigation into the Cooling of Blown Film
The focus of this investigation was develop a relatively simple model which could be used in blown film simulation. We desired to have the model represent the major contributors to the heat transfer for blown film. Our experimental results suggested that the heat transfer coefficient went through a maximum as the the bubble expanded. We have proposed a physical model which is consistent with our experimental observations. The model is based on a 3D representation of the boundary layer of ain around the bubble.
Process Stability Enhancement by Encapsulation Extrusion Method
A film casting simulation has been used to demonstrate why the encapsulation extrusion process is so effective industrially in enhancing the stability of the extrusion. In the present study, it is intended to explain theoretically why and how the coextrusion of LDPE in encapsulation dies improves the HDPE process. The undesirable neck-in and draw resonance phenomena frequently occurring in the extrusion of HDPE are shown due to its low-melt-strength property, and consequently can be alleviated using high-melt-strength materials in the encapsulating dies.
Performance Analysis of a Variable Barrier Energy Transfer Screw
High plastication rates and high quality extrudates are often difficult to produce using single-screw extruders, especially at low discharge temperatures. A new screw called a variable barrier energy transfer (VBET) screw was recently developed to plasticate at high rates, low discharge temperatures, and with high melt qualities. The fundamental operation of the screw along with performance aspects will be presented. A comparison is made between the melting, pumping, and mixing characteristics of an Energy Transfer (ET) screw and VBET screw.
Novel Barrel Heating with Natural Gas
Normally for direct heating of barrels in plastic processing machines electrical resistance heaters are used. A newly developed heating/cooling system uses natural gas. This paper explains the design and realization of a unit where the exhaust air from a radial burner heats the barrel by convection and radiation. Integrated cooling possibility by a tangential incoming airflow also meets practical requirements. Transforming basic energy is not necessary, which leads to CO2 reduction and lower energy costs for the processors.
On-Line Visualization of PS/PP Melting Mechanisms in a Twin-Screw Extruder
The melting and deformation mechanisms of polystyrene (PS) and polypropylene (PP) blends were investigated through on-line visualization of the co-rotating twin-screw extrusion process. A sliding barrel technique was used to realize the on-line visualization with one glass window in the barrel. The axial temperature and pressure profiles along the screw channel were measured using the same sliding technique. Different melting mechanisms were found for the PP/PS (80:20) blend and PS/PP (80:20) blend.
Engineering Analysis of Devolatilization of Additives in Intermeshing Co-Rotating Twin Screw Extruders
An experimental study of various operation conditions and screw configurations was made to understand and solve devolatilization problems in intermeshing co-rotating twin screw extruders. This includes studying additives (Nonane, Hexanol, p-Xylene) of polyethylene. We describe devolatilization through a model of interfacial area and mass transfer coefficients in an intermeshing co-rotating twin screw extruder.
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