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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Various topics related to sustainability in plastics, including bio-related, environmental issues, green, recycling, renewal, re-use and sustainability.
Pipes from Recycled High Density Polyethylene Blends
This paper presents the results of the development of recycled HDPE blends with improved SCR for low pressure pipe containing the maximum possible portion of post consumer recycled HDPE. A post consumer recycled High Density Polyethylene (R-HDPE) was blended with virgin Medium Density Polyethylene (MDPE), over the composition range of 0-100%. The recycled HDPE has limited post-consumer applications due to its poor stress crack resistance (SCR). Resistance to SCR of the compositions was determined by the Notched Constant Tensile Stress Test (NCLS). Results indicate that there is potential to incorporate the use of Post consumer HDPE in low pressure pipe applications at composition greater than 50%.
Poly(3-Hydroxybutyrate) Porous Structure for Tissue Engineering Applications
Biodegradable polymeric supports (scaffolds) have been used in tissue engineering in order to regenerate damage or lost tissue and organ structures.In this work scaffolds of poly (3-hydroxybutyrate) (P3HB), a natural polyester produced by bacterial fermentation process, were prepared by solvent - casting / particulate - leaching where the polymer was dissolved in organic solvent and mixed with salt particles of different sizes, followed by controlled solvent evaporation and water dissolution of the salt.The interconnected pore structure was evaluated by Scanning Electron Microscopy (SEM). Differential Scanning Calorimetry (DSC) was used to determine the thermal properties of P(3HB) / salt. SEM micrographs revealed the presence of interconnected pores for all ranges of salt particles. Thermal analyses showed that the degree of crystallinity for the porous structures was higher for lower salt particle size compared with P(3HB) dense film.
Processing and Characterization of Recycled PC/ABS Blends with High Recycle Content
In order to develop a polycarbonate (PC)/ acrylonitrile-butadiene-styrene (ABS) product with a high content of recycled PC, a low molecular weight virgin PC was added to recycled PC to minimize batch-to-batch property variations in the compounded product. Six PC/ABS blends were prepared on a twin screw extruder by mixing 50 wt% virgin ABS and 0-25 wt% low molecular weight virgin PC with 25-50 wt% high purity recycled PC recovered from end-of-life electronics. These blends were characterized rheologically and mechanically. Results showed that this strategy could yield consistent quality resin blends with a high recycle content.
Reactive Blending of Poly(Ethylene Terephthalate) and Ionomerfor Recycling
The reactive blending in melt state of poly(ethylene terephthalate) and sodium and zinc ionomers based on ethylene-methacrylic acid copolymers was investigated using a torque rheometer. The components were blended in mixer during 90 min for recycling simulation. The torque increases with processing time according to typical profiles depending on the metal type. Torque changes were attributed to chemical reactions between components generating high molecular weight species. In addition to PET degradation, the ionomers react with PET carboxyl or hydroxyl end groups forming graft copolymers and crosslinked species identified by multiple internal reflection (MIR) FTIR technique.
Recyclability of Crosslinked Polyethylene Based on Creep
Crosslinking of polyethylene greatly improves the material's properties. The crosslinking process causes problems with the material's ability to be recycled. It prevents the material from remelting, making it nearly impossible to process in an injection molding machine.The crosslink density has an effect on both the material's ability to creep and on its ability to be recycled. Creep data was studied to determine the effects of increasing crosslink density on an injection molded polyethylene part. This data will be used as a baseline for how parts made from 25% recycled crosslinked regrind compares with the original crosslinked part. This paper will focus on recycling crosslinked polyethylene (PEX) determined by its creep data.
Reliability Assessment of New Polymer Products with Environmentally Driven Failures
A methodology is presented for the reliability assessment of new product offerings, where product failures are driven by environmental conditions. The methodology is valid for the case of limited related product field data and understanding of underlying environmentally driven failure mechanisms. The methodology uses reliability theory in concert with failure mechanistic models to provide high resolution models which can be used to forecast liability exposure of new product offerings. The methodology has been successfully demonstrated for evaluation of Vinyl based products. The quantitative results generated suggest environmental region risks, overall new product risk, and risk relative to existing related products.
Separation of Polyphenylene Ether from its Additives
Polyphenylene ether (PPE) is a high cost material, starting at three times the cost of polypropylene, with the price only increasing as fillers are added. Plastic parts made of PPE with the additives carbon, talc, and mica could be reused as pure PPE if the additives were removed. A process was developed to separate the PPE from the additives, using a solvent that dissolves the PPE and leaves the additives as tiny particles. The mixture was filtered, allowing the dissolved PPE to pass through but retaining the additives. The reclaimed PPE can be sold for a profit and used to make new parts. Recycling the PPE saves millions of pounds of material from being dumped into landfills each year.
Solid State Polymerization of Recycled Poly(Ethylene Terephthalate) - The Influence of Process Conditions in the Increase of Molecular Weight and Thermal Properties
The solid state polymerization (SSP) of recycled PET from 2L bottles was investigated. The bottles were ground, washed, dried, crystallized and processed in a reactor under heating and nitrogen flow. The material was feed in the reactor as flakes and not in pellet form, so an extrusion step was eliminated. A systematic study of the influence of process conditions, like crystallization temperature, SSP temperature, reaction time and nitrogen flow rate was carried out. The weight-average molecular weight of the recycled PET were measured by SEC. Thermal properties and crystallinity were determined by DSC.
Surface Cleaning of Mold Release Compounds from Metals and Non-Metallic Materials
Mold release compounds can be transferred to molded parts and interfere in downstream painting, decorating, and bonding operations. These agents also accumulate on tool surfaces necessitating periodic cleaning which disrupts productivity and can involve the use of caustics or solvents. This study reports the promising results of using short duration exposures to UV irradiation to remove mold release compounds from both metals and non-metallic materials, such as plastics and polymer composites. In this study assorted materials were intentionally contaminated with heavy amounts of industrial mold release agents. The surfaces were rapidly and efficiently cleaned following exposure to high intensity UV light as demonstrated by a significant reduction in the water contact angle. UV treatments provide an environmentally benign alternative means to remove mold release compounds from tool or molded part surfaces.
The Effect of Additives on the Processing and Physical Properties of Recycled Polyethylene Terephthalate (RPET)
This paper describes the effect of individual additives that are present in masterbatch formulations, and the role they play in modifying physical properties and processability of blends based on RPET. Additives such as titanium dioxide, carbon black, linear low-density polyethylene and polyethylene wax are often incorporated in masterbatch compositions. The blends based on these additives have been analysed for shifts in thermal transition points, levels of crystallinity and physical properties such as tensile and impact strength. The results show that at the addition rates used, some additives had significant effects on processability and crystallinity, negligible effects on physical properties and antagonistic effects were noted when additives were combined.
The Effect of Orientation on Mechanichal Properties of Recycled PET
The use of plastic products is becoming more prevalent in society. Scrap from plastics processing is reground and reused by plastics manufacturers. When the percentage of reground plastic becomes higher than 30% a decrease in mechanical properties is seen. No research has currently been found to encourage runner, vent, or gate modifications to enable manufactures to use a higher percentage of recycled material. The objective of this investigation determine if pin point, standard, or fan gates have an effect on the molecular orientation of virgin, 30%, and 80% recycled PET. Molecular orientation can be evaluated by performing mechanical property testing such as yield strength, tensile modulus, percent elongation, and hardness testing. Tensile bar inserts will be machined with pin point, standard, and fan gate styles. The resulting bars will be subjected to the mechanical tests of yield strength, tensile modulus, percent elongation, and hardness. By using a 2k factorial designed experiment, the results will be analyzed to determine which, if any, gate causes the mechanical properties of the recycled plastic to be similar, within 10%, of the virgin material.
The Effects of Multiple Heat Histories on the Mechanical Properties of High-Impact Polystyrene
The plastic materials that make up consumer items are most often discarded after use. However, thermoplastics can be subjected to several recycle histories before they are disposed of in a landfill. Many studies have shown that mechanical recycling can cause some level of degradation of polymer properties. However, few studies have looked at the effect of repeated recycle histories on the properties of plastics. In this study, the effects of multiple recycle histories on the mechanical properties of high-impact polystyrene were determined in an attempt to show that plastics can be quite recyclable even after a large number of recycle histories. In this study, the high-impact polystyrene was reprocessed a total of thirty (30) times. Melt flow rate, tensile properties, and impact properties were determined for these multiple recycle histories. In most cases, the change in properties was relatively small, even for the large number or recycle histories studied.
The Effects of Power Ultrasonic Wave on In-Situ Polymerization and Formation of PMMA-Clay Nanocomposites
Several methods have been used to synthesize polymer-clay nanocomposites. In-situ polymerization with clay belongs to a classical way to develop nano-structured materials, while melt intercalation is being recognized as another useful approach due to its versatility and environmentally benign character.In this research, we prepared polymer-clay nanocomposites based on the poly (methyl methacrylate) and organically modified montmorillonite via two-stage sonication process. According to the unique mode of power ultrasonic wave, the sonication during processing led to enhanced breakup of the clay agglomerates and reduction in size of the dispersed phase. Optimum conditions to form stable exfoliated nanocomposites were studied for various sonication times, sonication ratios, addition of initiator and different kinds of clay.It was found that a novel attempt carried out in this study yielded further improvement in the mechanical performance of the nanocomposites compared to those produced by the conventional melt mixing process, as revealed by DMA, XRD and TEM.
Thermal and Mechanical Studies of Recycled HDPE, PP and PET from Blow- Extruded and Blow -Injected Bottles
This work examines the melting point and crystallinity behavior applying differential scanning calorimetry; mechanical properties by tension and Charpy-impact behavior and Melt Flow Index of recycled High Density Polyethylene, Polypropylene, and Polyethylen terephthalate used in blow-extruded and blow-injected bottles from post-consumer and post-industrial scrap. Some of the DSC results indicate a small decrease of the melting point for HDPE and a lower super cooling for the materials tested. Mechanical properties suffer minor deteriorations making possible the use of these recycled polymers in some industrial applications with reduction of cost.
Upgrading Recycled Waste Stream Polyethylene by Modification with Nanoscale Clay Hybrids
Recycled polyethylene (RPE) - clay hybrids (RPECHs) were prepared by melt mixing of RPE with modified montmorillonite clay using maleic anhydride grafted polyethylene oligomer (PE-MA) as a compatibilizer. Electron microscopy and X-ray diffractometry revealed that dispersion of hydrophilic clay in the highly hydrophobic polyethylene matrix increased with increasing PE-MA content. The highly dispersed RPECH nanocomposites provide substantially enhanced mechanical properties over neat RPE. The results of experimental parametric studies are reported and applied to new value-added applications for this inexpensive and plentiful polymer resource.
Using Recycled Concrete as a Filler in Polyethylene Resins
Adding concrete fillers to base plastic materials can increase mechanical properties such as tensile strength, flexural strength, and hardness. This can be done through the addition of fillers to a virgin and recycled plastic material. By increasing these properties, plastics can be used in applications where they were not previously used.The effects of compounding concrete filler with polyethylene were studied. Two different percentages of the concrete fillers were added to test different properties against a NEAT (nothing extra added to it) sample of both recycled and virgin polyethylene.
Viscosity Characterization of Bulk Molding Compounds
Viscosity variations in bulk molding compounds have long been a concern. The reactive nature of the polymer, response to thickening agents, high filler and glass loading, all contribute to this variance. Additionally, environmental factors such as storage temperatures and humidity affect the viscosity of these compounds.Confounding the issue is the often forgotten about gage variation. There have been many test methods developed in an attempt to characterize the viscosity of bulk molding compounds. Most of these contribute, as much, if not more to the total variance.This study examines viscosity characterization methods for bulk molding compounds
"Green" Bio-Composites: Moving Towards More Eco-friendly Structural Automotive Parts
PowerPoint Presentation at ACCE 2002.
Bio-based Thermoset Resins and Their Composites
PowerPoint Presentation at ACCE 2002.
Growing and Processing Natural Renewable BAST Fibers for Natural Fiber Composites
PowerPoint Presentation at ACCE 2002.
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