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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Recycling

Various topics related to sustainability in plastics, including bio-related, environmental issues, green, recycling, renewal, re-use and sustainability.

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.

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.

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.

"Green" Bio-Composites: Moving Towards More Eco-friendly Structural Automotive Parts

L. T. Drzal, September 2002

PowerPoint Presentation at ACCE 2002.

Bio-based Thermoset Resins and Their Composites

M. Misra, September 2002

PowerPoint Presentation at ACCE 2002.

Growing and Processing Natural Renewable BAST Fibers for Natural Fiber Composites

Hugh S. McKee, September 2002

PowerPoint Presentation at ACCE 2002.

Soy Biobased Materials for Automotive Applications

Professor Richard Wool, September 2002

PowerPoint Presentation at ACCE 2002.

Influence of Consolidation and Forming Parameters in the Molding of Continuous Fiber Reinforced Thermoplastic Composites

Gilbert Lebrun, September 2002

Continuous fibre reinforced thermoplastic (CFRTP) composites offer many advantages over thermoset composites and metallic materials especially their resistance to corrosion their recycling possibilities and their high specific stiffness. The shaping of these materials into complex forms however requires a good knowledge of the combined behaviour of the molten thermoplastic matrix and of the fibres because of the high intra and interlaminar shear deformations involved during the forming process. In this paper the influence of laminate consolidation parameters on the microstructure and mechanical properties of the laminate are first presented. Next the deformation mechanisms induced in the laminate in typical forming conditions are presented and discussed in regard to their influence on the physical and aesthetic properties of the moulded part. Numerical moulding predictions obtained from a commercial code are finally presented.

The Use of UV Light for Surface Cleaning for Painting and Adhesive Bonding of Composites and Metals

Michael J. Rich, September 2002

Contemporary vehicles utilize a mix of materials in their construction consisting of metals plastics and composites. These materials must possess suitable surface properties to achieve desired performance when these parts are adhesively bonding or painted for field service. Surface preparation methods now in place oftentimes use solvents or caustics an increasingly unacceptable approach in an era of mounting environmental regulations. New methods of surface preparation are called for that are environmentally benign and economically feasible while meeting the stringent quality standards of the automotive industry. The use of energetic ultraviolet light is emerging as a promising technology to compete with the old methods of surface preparation. This paper reports the utility of using energetic UV light to generate appropriate surface chemical composition on plastics composites and metals for subsequent painting or adhesive bonding operations. UV treatments have the potential to replace the old methods of treating assorted materials used in the automotive industry in an environmentally responsible and cost-effective manner.

A Plasticating Screw Design for the Reprocessing of Multi-Layer or Multi-Material Plastic Formulations

Robert Malloy, Anthony Filip, Mark Colella, May 2002

Recycling or reprocessing of “multi-layer” or “multi-material” plastic products is a particular problem for plastic compounders or recyclers. Examples of multi-layer plastic products include painted or coated plastic items, such as automotive body panels, or multi-layer plastic packaging, such as that used in high barrier applications. In each of these cases, the coating or multi-layer structure is utilized to enhance either the product's overall performance or appearance. Unfortunately, the presence of other material layers will generally have a negative impact on the recyclability of the primary thermoplastic material as they often act as incompatible contamination. For example, most of the paints or coatings used in the automotive industry are thermosetting in nature and act as solid particulate inclusions in the recycled matrix material. Methods to remove coatings from coated plastic parts have been developed, but are not always cost effective. As an alternative, these complex material constructions can sometimes be effectively recycled if the contaminating layers can be reduced in particle size and effectively mixed into the continuous thermoplastic matrix material. A single screw mixing or “grating” section has been designed and evaluated experimentally in this study. Experimental trials were conducted using reground, painted thermoplastic olefin automobile bumpers. The reground bumper scrap was extruded using a single screw equipped with this grating sections, and several more conventional extrusion screw designs. The paint flake size distribution of the extrudate, and the physical properties of samples molded from the extrudate were evaluated for each screw design, both with and without melt filtration.

Application of Thermoplastic Elastomer Material Testing Data for Automotive Body Seal Analysis

Linhuo Shi, May 2002

Material recycling requirement gradually opens the automotive body sealing market to thermoplastic elastomers (TPE), which is primarily dominated by EPDM thermosetting elastomers. Due to special material behaviors of elastomers, careful attentions should be taken when analyzing the body seal performance using material testing data, especially for TPE materials. This paper will address some of the issues by analyzing body seal products using TPE materials. The general guidelines for body seal analysis and result evaluation will also be discussed.

Acrylate Elastomer Modified Polyolefinic TPEs

Nisha Patel, Satish Sharma, May 2002

Soft polyolefinic TPEs are increasingly being favored over PVC based TPEs for automotive interiors. The major drivers for this change are the recycling and environmental aspects of PVC. Some strengths of polyolefinic TPEs are good low temperature performance, retention of properties after exposure to sunlight and high temperatures, low fogging, and little or no odor. The challenges in switching from PVC to polyolefinic TPEs involve attaining the desired melt processing characteristics and the mechanical and aesthetic properties at a relatively low cost. This paper will discuss Eliokem's use of a specialty acrylate elastomeric modifier in designing polyolefinic TPEs for automotive interiors and other applications

Analysis of Carpet Recycle Streams Using Differential Scanning Calorimetry, Thermogravimetric Analysis and Gas Chromatography

John J. Tria, Kanda Kumar Balasubramanian, Michael K. Goodin, May 2002

In order to make an injection moldable product with consistent properties from recycled carpeting, quantitation of the polymeric and non-polymeric components of the carpet feed stream is required. Feed mixtures containing nylons, polypropylene and PET as well as latex and calcium carbonate from backing material have been studied. A combination of DSC and TGA measurements is shown to provide compositional data on both polymeric and non-polymeric components in a rapid and inexpensive manner. More exact determination of polyamide components is accomplished using hydrolysis and derivatization to prepare samples for gas chromatography.