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Various topics related to sustainability in plastics, including bio-related, environmental issues, green, recycling, renewal, re-use and sustainability.
Structural BioComposites from Natural Fibers and Biopolymers
Lawrence T. Drzal, A.K. Mohanty, M. Misra, May 2004
BioComposites are emerging as a viable alternative to glass-reinforced composites. Natural fibers have advantages over man-made fibers (e.g. glass and carbon) in areas such as low cost, low density, competitive specific mechanical properties, reduced energy consumption, carbon dioxide sequestration, and biodegradability. The combination of bio-fibers like kenaf, hemp, flax, henequen and sisal with polymer matrices from both non-renewable and renewable resources to produce composite materials that are competitive with synthetic composites requires special attention to the biofiber-matrix interface, and its resulting adhesion, as well as to the processing methods used to produce these materials. The development of useful biocomposite materials also requires that water-based sizings or dry coupling agents be used to improve fiber-matrix adhesion.. Through bio-fiber surface treatment, biopolymer modification, and adequate processing techniques, novel bio-composites can be designed and engineered so as to substitute/supplement glass fiber composites in various applications.
Structural Design of Polypropylene Stormwater Chambers
Phillip A. Sharff, Jesse L. Beaver, Timothy J. McGrath, May 2004
Environmental Protection Agency requirements for control of stormwater runoff are increasing the need to provide on-site stormwater storage as part of site development projects. Underground stormwater storage is one solution to this need. Open bottom thermoplastic chambers make use of profile design theories established for thermoplastic pipe and allow maximum area at the bottom for natural seepage of the stored water into the ground. This paper reports on analysis and testing of archshaped, open bottom, corrugated polypropylene stormwater storage chambers that have spans of 1270 mm (50 in.) and are supported on a flat, turned-out foot. Computer analysis included finite element, soil-structure interaction models of chambers with 450 mm (18 in.) and 2440 mm (8 ft) of fill with AASHTO HS20 design axle load. Field-testing included chamber installations at shallow cover from 150 mm (6 in.) to 600 mm (24 in.) with vehicle live loads and at deep cover with 3500 mm (11.5 ft) fill. Design calculations were based on the new AASHTO procedures for profile wall thermoplastic pipe. Using prescribed installation procedures, the factor of safety is greater than the required AASHTO factor for thermoplastic pipe of 1.95.
Sustainable Polymers: From a Glorious Past to a Bright Future
Brian E. Ralston, Tim A. Osswald, May 2004
In the coming decades it will become increasingly difficult to cheaply satisfy society's thirst for petroleum-based polymers. Additionally, the problems associated with disposal of non-renewable, non-degradable petroleum based polymers will drive the search for agriculture based plastics that do not sacrifice cost or performance. Although agriculture based plastics have been around for over a century, they were largely forgotten after the advent of synthetic, petroleum based polymers. This paper revisits the literature left to us by early twentieth century engineers who made protein based plastics from casein and soy protein on an industrial scale. In recent years, there has been a resurgence of interest in this type of material. This paper reviews current research on biopolymers such as casein and soy protein based plastics as well as polylactide acid, or PLA.
The Effect of Absorbed Moisture on the Elevated Temperature Properties of Polyetherimide
Michael P. Sepe, May 2004
The effects of moisture absorption on products molded from polyamides are well documented. However, other high-performance materials such as polyetherimide and polyethersulfone also absorb significant amounts of moisture from the atmosphere. Early tests suggest that this moisture absorption influences the glass transition temperature of these polymers. This has implications for short-term elevated temperature service as well as creep resistance and fatigue resistance at lower temperatures. This paper quantifies the effects of absorbed moisture on the elevated temperature properties of polyetherimide and characterizes rates of moisture gain and loss at different environmental conditions.
The Effect of Composition on Properties of Blends from Recylced Rubber and Polypropylene
N. Jain, C. Barry, J. Mead, D. Robertson, May 2004
Incorporation of waste (ethylene propylene diene rubber) EPDM into polyolefins has emerged as a new recycling technique that is eco-friendly and cost effective. The purpose of this study was to recycle EPDM, as well as to develop new impact modified blends. This study, which involved reactive blending of waste EPDM and polypropylene (PP) in a co-rotating twin screw extruder in the ratio range of 10/90 to 60/40, determined the effect of t-butyl hydroperoxide compatibilizer, low and high MFI grade of PP and ethylene-propylene impact copolymer on the mechanical properties of the blends. Formulations were injection molded and subsequently tested for tensile, flexural and impact properties. It was noted that the peroxide and the impact copolymer significantly improved the tensile elongation at break and impact resistance, but resulted in a decrease in the modulus. The approach of this investigation was to determine the optimum blending ratio of the components to achieve a balance in the flexural modulus and impact strength.
The Effect of Injection Speed on the Weld Line Properties of Jute Fiber/Poly (Butylene) Succinate Biodegradable Composites
U.S. Ishiaku, Y.W. Leong, O.A. Khondker, A. Nakai, H. Hamada, May 2004
This presentation focuses on effects of injection speed and weld line on the properties of PBS/Jute fiber composites. It was found that toughness especially elongation at break is sensitive to the presence of weld line while tensile modulus and flexural properties are little affected. The presence of jute fibers improved toughness i.e. retention of EB and impact strength across the weld line. Ultrahigh speed injection facilitated the recovery of EB and hence toughness. Morphological studies with SEM revealed that some of the jute fibers were aligned across the weld line.
The Rheological and Mechanical Performance of Commercial uPVC Formulations
W.C. Yap, A.C. Ruddy, K. Halliwell, G.M. McNally, W.R. Murphy, May 2004
Rheological and mechanical analysis of a range of virgin, recycled, and pigmented uPVC formulations used in extruded profiles for conservatory roofing applications is reported. The shear viscosity, tensile properties and dynamic mechanical thermal properties of the various formulations were shown to be dependent on stabiliser type, thermal processing history and pigment concentration. Lead stabilised uPVCs were shown to have better impact properties than Ca/Zn stabilised compounds and slight differences in Tgs, storage modulii (E’) were recorded for all formulations.
Ultra-Low Permeation Test Method for Fuel System Applications
P. Delbarre, V. Aadam, B. Bonazza, May 2004
The new and more stringent regulations due in the USA by 2004 call for technical development on both fuel barrier structures and on innovative fuel system designs. They also require new techniques to evaluate emissions from such high performance systems. An experimental technique is described which can measure permeability factors on material samples such as films or plates. In-depth analysis of the technique reveals significant benefits, which makes it a powerful tool to evaluate and compare complex system components such as sub assemblies or large parts such as fuel tank shells. When combined with a gas chromatography, this tool offers an additional advantage of being able to determine the hydrocarbon types permeating from the system. This can be an advantage in developing green" for fuel systems which can control the emissions of toxic and reactive hydrocarbons.
Use of Natural Fibre as Reinforcing Agent in Biodegradable Foamed Packaging Materials Made from Wheat Flour
P.R. Hornsby, Y-G. Kang, J. Song, K. Tarverdi, J. Zhou, May 2004
The use of packaging materials is expected to increase annually on average by about 5 percent in the foreseeable future, but the technology for reusing and recycling of packaging waste is lagging behind. This paper considers the evaluation of an alternative packaging material, derived from renewable resources, which is economical to use, biodegradable and recyclable by composting. In this paper consideration will be given to the preparation, characterisation and properties of starch-based materials derived from wheat flour. A range of techniques, used to characterise these materials will be discussed, including image analysis, SEM, thermogravimetric analysis, compressive strength, impact and recovery measurements.
Use of Recycled Polymer Modified Asphalt Binder in Asphalt Concrete Pavements
Ioan I. Negulescu, Codrin Daranga, Zhong Wu, William H. Daly, Louay M. Mohammad, Chris Abadie, May 2004
Since polymer modified asphalt cements (PMAC) have been employed for a decade, the lifetime and wear on of some of these roadbeds are reaching a stage where resurfacing will be necessary. This paper considers the potential problems associated with recycling of polymer modified asphalt cements, PMAC's, in particular blending aged PMAC with tank PMAC. A standard PMAC was selected and characterized using typical asphalt binder qualification techniques, i.e., the Superpave Strategic Highway Research Protocol. Procedures were developed to separate the PMAC into its asphalt resin and polymer additive components as well as to characterize the relative concentrations of each component. Infrared and chromatographic techniques were used to identify changes in the components as a result of aging. The impact of the extraction and recovery process on binder properties has been ascertained and found to be minimal.The standard PMAC was aged under accelerated aging conditions in a Pressure Aging Vessel (PAV) that produced a material equivalent to 5-8 years in the field. The aged PMAC was then reanalyzed both chemically and rheologically and all changes in its properties due to aging were noted. Finally blends of the PAV aged PMAC with fresh PMAC, as well as blends where the PAV aged PMAC was replaced with road-aged binder, were prepared and analyzed. Our initial results indicate that aged PMAC can be blended successfully with fresh PMAC. Thus we anticipate that resurfacing of aging PMAC roadbeds can proceed, but further tests will be required to establish the precise conditions necessary to conduct this process.
UV Degradation of Recycled Photo-Degraded Polymers
I.H. Craig, E. Loyd, W. Stevenson, J.R. White, May 2004
The ultraviolet (UV) degradation of molded bars containing recycled polymer has been studied to determine whether products of photo-degradation act as pro-degradants. Recyclate that had been photo-degraded prior to recycling was mixed with virgin granules to mold new bars. Bars were also prepared from a mixture of virgin polymer with recyclate that had not been photo-degraded.Bars made from blends of virgin and recycled polymer were photo-degraded in the laboratory. For exposures of less than a month, the mechanical properties of both polystyrene and polypropylene were inferior when previously photo-degraded material was included. After extended exposure, the effect of including photo-degraded material diminished but by this time, the properties of the materials were unacceptable.
Weld Lines Behaviour in Melt Blended and In-Situ Polymerised Nylon 6 Nanocomposites
J. Tung, R.K. Gupta, G.P. Simon, G.H. Edward, May 2004
Nylon 6 nanocomposites containing organically-modified montmorillonite made either by the melt blending or in-situ polymerised routes are investigated. Both nylon 6 nanocomposites are examined in X-ray diffraction and Transmission Electron Microscopy, to verify the level of intercalation / exfoliation of the organoclay layers in the nanocomposites. The materials are injected into tensile specimens either with single or double end-gated (with a weld line). Neat nylon 6 and single end-gated samples are used as a control, allowing comparison the performance of nylon 6 nanocomposites when weld line is present. The results show that the tensile strength and strain-to-failure of the neat nylon 6 exhibits little variation when comparing the single and double end-gated samples and thus no weld line behaviour is seen clearly. The melt blended nanocomposites show a greatly reduced in strain-to-failure for both single and double end-gated samples although the tensile modulus is increased significantly. In contrast, the in-situ polymerised nanocomposites show more ductile behaviour at single end-gated, compared to the double end-gated samples. Both nanocomposites show brittleness when the weld line is present. The fracture tensile surfaces are examined using Environmental Scanning Electron Microscopy and the results show that much larger micron-sized organoclay entities exist in the melt blended nanocomposites and that these, rather than nano-sized individual layers, cause the final behaviour. Whilst the dispersion is much finer for the in-situ polymerised than that of the melt blending nanocomposites.
Welding of Recycled Thermoplastic Lumber for Structural Components
David Grewell, Avraham Benatar, Prabhat Krishnaswamy, May 2004
This paper reviews experimental work on welding of reinforced recycled thermoplastic lumber for the fabrication of structural components. Recently the use of thermoplastic lumber has become more accepted due to the materials longevity. However, because of extrusion difficulties, such as shrinkage holes and long cooling times, plastic lumber has not been widely used for structural components, such as pilings and supports. In order to solve some of these issues, it has been proposed to extrude standard, relatively small cross sectional components, such as 2x4 and 2x6, and join these components into larger structural components, such as 6x6 to 10x10 or engineering components such as I-beams. This work evaluated a wide range of welding processes, including; hot plate, vibration, IR and non-contact hot plate welding as well as adhesive bonding. Star design of experiments was conducted for each process and relevant parameters. Process optimization was preformed for each process in order to minimize cycle time and maximize weld strength. In addition, flexural tests of selected samples were performed. It was found that welding could produce joints as strong and as stiff as the base material.
Decorative Laminates For Thermoforming and Insert Molding Processes
Dennis Northrop, September 2003
Decorative films laminated to plastic substrates have been used for many years but the recent wave of technological advances and increased competition offer more variety in design colors materials and performance properties than previously available. This offers part designers and plastic processors the option to use decorative laminate technology for more applications while reducing costs eliminating environmental concerns conversion from non-plastic materials and improving product performance.
Bio-Based Epoxy/Clay Nanocomposites as a New Matrix for Carbon Fiber Reinforced Composites: Thermophysical and Mechanical Properties Evaluations
H. Miyagawa, A. K. Mohanty, M. Misra, L. T. Drzal, September 2003
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.
Biobased Poly(trimethylene terephthalate): Opportunity in Structural Composite Applications
A. K. Mohanty, W. Liu, L. T. Drzal, M. Misra, Joseph V. Kurian, Ray W. Miller, Nick Strickland, September 2003
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.
Carbon/Epoxy Composites for the Lamborghini Murcielago
Attilio Masini, Paolo Feraboli, September 2003
Development of the carbon/epoxy body panels and structural components of the Lamborghini Murcièlago is discussed while use of aerospace grade technology and materials is justified for this particular application. Laminate design and stacking sequence is reviewed and the use of woven fabrics over directional tape is motivated. Engineering solutions for tooling operations in order to achieve class A surface certification are analyzed. Design for environmental aging as well as accelerated degradation tests are described. Hybrid adhesive bonding as sole method of joining the composite body components to the tubular steel chassis is reviewed.
Renewable Source Materials Phase II
Peter W. Vaccarella, September 2003
In phase I soy-based polyesters were introduced in the form of sheet molding compound (SMC) to be used in farm equipment such as combines. In phase II soy-based polyester will be evaluated in the spray- up infusion and resin transfer molding (RTM) processes for similar types of application. Each system was evaluated at room temperature and 120 ° F for surface quality cure and molding ability. This paper will discuss shrink control for room temperature cured parts and surface quality as compared to automotive standards. Physical property data will also be compared to standard polyesters and SMC used in these fields.
Impact-Tolerant SMC Resins for Demanding Structural Applications
Sean P. Walsh, September 2003
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.
"Green" Bio-Composites: Moving Towards More Eco-friendly Structural Automotive Parts
L. T. Drzal, September 2002
PowerPoint Presentation at ACCE 2002.

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