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.
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.
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.
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.
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.
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.
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.
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 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 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.
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.
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.
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.
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 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
Natural/Bio-fiber composites (Bio-Composites) are emerging as a viable alternative to glass fiber reinforced composites especially in automotive applications. Natural fibers which traditionally were used as fillers for thermosets are now becoming one of the fastest growing performance additives for thermoplastics. Advantages of natural fibers over man-made glass fiber are: low cost low density competitive specific mechanical properties reduced energy consumption carbon dioxide sequesterization and biodegradability. Natural fibers offer a possibility to developing countries to use their own natural resources in their composite processing industries. The combination of bio-fibers like Kenaf Hemp Flax Jute Henequen Pineapple leaf fiber 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 i.e. biofiber- matrix interface and novel processing. Natural fiber reinforced polypropylene (PP) composites have attained commercial attraction in automotive industries. Needle punching techniques as well as extrusion followed by injection molding for natural fiber–PP composites as presently adopted in the industry need a “greener” technology-- powder impregnation technology. Natural fiber–PP or natural fiber–polyester composites are not sufficiently eco-friendly due to the petro-based source as well as non-biodegradable nature of the polymer matrix. Sustainability industrial ecology eco-efficiency and green chemistry are forcing the automotive industry to seek alternative more Eco-friendly materials for automotive interior applications. Using natural fibers with polymers (plastics) based on renewable resources will allow many environmental issues to be solved. By embedding bio-fibers with renewable resource based bio-polymers such as cellulosic plastic corn-based plastic starch plastic and soy-based plastic are continuously being developed at Michigan S
A resin that utilizes 25% grain-derived organics has been developed. Ethanol and soybean oil are reacted with other materials to produce a durable polyester resin capable of equal or better performance than current polyester resin systems. Utilizing the sheet molding compound (SMC) molding process this unique renewable-source polyester resin has successfully produced large combine parts for use in the agriculture industry. The transportation industry is investigating this resin for use on upcoming vehicles.
The development in the field of composites has been spurred by the need for lightweight fuel-efficient automobile that is environmentally friendly and affordable. A low density light weight GMT composite containing long chopped fiber strands was developed by AZDEL Inc. for use in headliner and other automotive applications. The low density GMT (LD-GMT) is available in grades ranging in basis weight of 600 to 2000 g/m2. This paper presents development of this LD-GMT material for automotive interior and structural applications. This thermoformable material has several advantages over other traditional materials like steel and thermoset composites. The LD-GMT offers design flexibility low weight high rigidity excellent energy absorption characteristics faster cycle times and an environmentally friendly manufacturing process. The design flexibility and application of these LD-GMT composites in automotives and the advantages of applying these composites over the other materials in interior structural and modular applications will be discussed.
The number of colors or colorants used in your operation takes on a life of its own, ever growing in size and complexity. There are valid reasons for the growth; to better match colors, satisfy a key customer, gain more heat or light stability, improve cost or processing properties, more reliable supply or to provide a specialty product. At the time each one is introduced we are typically under some driving force to satisfy a tactical need, what the heck its just one more item, and we lack the time to take a more strategic view. Next thing you know the number has grown from 80 - 100 items to 300 or more! So, do you really need that many colors? If you had fewer colors, your operations would be much simpler and simplicity implies better, less costly more reliable operating. So why not do the job with 50 colors. Well why stop there, why not 20 or maybe 16, shucks the rainbow only has 7, ROYGBIV. You know, we see all the colors on a TV screen or CRT & they are made from just Red Green & Blue, why not 3 colors? This paper will deal with the issue of what is the right number of colors, how you can go about getting there (and maybe staying there) and finally some of the benefits you might expect.
This paper describes the development of blends of recycled polyethylenes suitable for rotational molding. The blends consist of recycled post-industrial polyethylene resins and polyolefin plastomer impact modifiers, produced by single-site (metallocene) catalysts. The rheological properties of the blends were found to be favorable for rotational molding. Rotomolded parts provided satisfactory low temperature impact strength and good tensile properties.
The most common commercial processes for manufacturing pre-pregs for electronic applications use solvent-based epoxy systems. Solvents are environmentally unfriendly and contribute to voids in the pre-preg and laminate. Voids cause product variability, which is a major source of scrap in board shops. In this paper, we use chemo-rheological and kinetic measurements to identify a potential epoxy-based resin system for a solventless process, based on injection pultrusion. DSC and rheological data show that the candidate system does not react appreciably without catalyst to temperatures of 170°C or with catalyst at temperature below 110°C. The system solidifies below 105°C. It was found that the overall viscosity of the resin system is dependent upon the temperature, degree of cure, and filler content. Kinetic rate and viscosity rise expressions to be used in process modeling and optimization have been developed. A preliminary process window for the process has been established.
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