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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This keynote lecture discusses the use of biodegradable polymers as tissue engineering scaffolds. The basic principles of tissue engineering are addressed, going from scaffolds processing to some brief information on biological studies. These topics are introduced in a way that an audience composed by plastic engineers can easily became aware of the importance of the field and understands its complexity, as well as the role of biodegradable polymers on its success.
A.J. Dawson, H.S. Rajamani, R. Collis, L. Owen, D. Owen, P.D. Coates, May 2002
Growing concern for ecological issues, including international standards agreements such as ISO14001, demonstrate a clear requirement to conserve energy for both environmental and cost issues. Energy measurements on injection moulding machines both in the laboratory and in industry demonstrate the potential of process energy measurements in the development of a systematic management approach to the environmental concerns of an organization. The data gathered can also provide useful information to both the processor regarding the performance of the machine in question, and the power companies regarding the specification of supply equipment.Detailed energy measurements during the injection moulding cycle provide data regarding the energy consumption of specific machine components and/or phases of the injection moulding cycle, providing valuable data for machinery manufacturers and processors.
Chlorinated polyethylene (CPE) has been demonstrated to be an effective compatibilizer for dissimilar materials in various mixed-polymer or recycled-polymer systems. In this paper the use of chlorinated polyethylene to compatibilize polymer/natural fiber composites is discussed. Examples of applications in PVC/wood flour composites are given.
In this paper, an engineered material made from paperboard and powdered polypropylene is examined. A wet, paper process was chosen for converting paperboard waste into an engineered, cost effective composite material. Using a fourdrinier, a 30 inch wide continuous sheet of paper/plastic stock was produced for subsequent thermal molding. Tensile modulus and strength of 6,000 and 50 MPa, respectively, were obtained for a material having just less than 30 percent polypropylene. Additionally, moisture content and water absorption was examined. Testing and failure analysis indicate that increasing the percent of polypropylene will improve the mechanical properties.
Ioan I. Negulescu, Roger K. Seals, Simioan Petrovan, May 2002
The overall goal of the paper is to develop recycled plastic lumber products with improved mechanical properties using inorganic filler consisting of Louisiana residuals, such as phosphogypsum, in conjunction with recycled plastic resins. Blends have been established and samples have been prepared by mixing polyethylene derived from detergent bottles with inorganic fillers in the inner chamber of a Haake rheometer. Reactive mixtures have been made in the same way using maleic anhydride in addition to polyolefin and inorganic filler. The actual composition of blends has been calculated from thermogravimetric data. Tensile properties have been determined for each composition using both an INSTRON machine and a dynamo-mechanical spectrometer.
There continues to be a need for additional uses of recycled plastics. A significant portion of recycling applications require outdoor exposure including use in aqueous applications. This paper covers the effects of water on the properties of recycled plastics under tensile loads. The paper also covers long term creep effects.
Klementina Khait, Erin G. Riddick, John M. Torkelson, May 2002
It is well known that reprocessability of plastics is essential during both manufacturing and consequent recycling. Post-consumer materials, and in particular a five component blend of high- and low-density polyethylene, polypropylene, polystyrene, and polyvinyl chloride representing American film waste, have been successfully reprocessed multiple times by solid-state shear pulverization on a laboratory scale pulverizer. A processing cycle included pulverization, injection molding and conventional grinding. Physical properties such as notched Izod impact strength, elongation at break and flexural properties remained unchanged after four cycles. No change in color or surface appearance of the injection molded test specimens was observed.
Neat resin bonded single-lap composite joint has been extensively used in composite structures. Lower strength and longer fabrication time have been identified as technical barriers in practice. In order to increase the joint strength and reduce the fabrication time, two types of prepreg composites were used to bond composite single-lap joints. Test specimens were prepared per ASTM D 3165-95 standard. Accelerated conditioning was conducted to investigate the environmental resistance of specimens. The shear strength of various specimens was obtained using tension tests. Compared to control specimens, prepreg bonded samples exhibit higher tensile strength, higher environmental resistance, and shorter fabrication time.
Daisuke Watanabe, Hiroyuki Hamada, Kiyotaka Tomari, May 2002
The sandwich injection molding technique can be used in wide ranges of engineering applications for recycle. In this study, flow behavior of core material in sandwich injection molding with sequential and simultaneous injection was investigated. Flow behavior of materials in sandwich injection moldings revealed to divided into four regions (Primary injection region, core advance region, core expansion region and break region). The flow length of core expansion region was increased with increasing of simultaneous injection time of skin and core material. And it is revealed that the core layer was formed as wide and thin structure with increasing of simultaneous injection time.
Three types of specimens of a polyester-amide and a poly-hydroxybutyrate have been tensile and tensile-impact tested. Important geometrical parameters for these specimens are wall thickness and gate dimensions, as well as a weld line in one specimen type. Explanation of the combined influence of geometry and injection molding settings on tensile behavior was in agreement with tensile-impact results. This influence was maintained after 20 months of storage in closed boxes but minor embrittlement was found for all specimen types and both materials. The beneficial effect of annealing on strain at break for all poly-hydroxybutyrate specimens was also shown.
The growth of the plastics recycling industry was spurred by increased resin prices and the landfill crisis of the 1980's. Many of the recycling companies that started in the 1980's and 1990's quickly learned that economic recycling of plastic waste was a difficult and challenging task. For many of these companies, the problems were overwhelming and they went out of business. Those that survived into the 21st century are a unique group of entrepreneurs. The bulk of the survivors are small companies with sales under $20 million.In this study, 36 plastic recycling companies in the U.S. and Europe were evaluated to determine the elements that aided their survival. Three elements that were present in the majority of these companies were: an ability to develop and maintain their own technology, financial or technical support from external sources, and strong leaders who were determined to make the business survive. These companies are the models for their industry. The stories of these companies could be of particular value to the emerging automotive and electronic post-consumer plastics recycling industry.
Small parts less than one quarter of a pellet require a complete rethink by molding engineers and mold designers. Total part cost justification becomes more challenging based upon the amount of material wasted and tooling costs. Micro machinery is helping to meet the requirements of accuracy through simplicity. There is no need for complicated multiple profile closed-loop servo controlled injection and metering functions.The two-stage plunger over plunger injection unit is capable of processing basic polyolefins to high temperature LCP materials. Shot pot injection provides accuracy of volumetric control by eliminating variation caused by slider or check ring shutoff inconsistency. The minimum number of components used in the design achieves simplicity.
The thermoforming industry has achieved a good understanding of the process, which has been in large scale operation since the 1950's. Consequently, control of machine settings such as heater band temperatures, plug position, plug and mould temperatures is quite advanced. However, to date, little work has been done to address the control of state parameters describing material behaviour during processing, such as sheet temperature and material distribution in the part. Control of state parameters is essential as material property changes, environmental factors and machine operating drifts can significantly change the dynamic operating point of the machine.
Rui A. Sousa, Rui L. Reis, António M. Cunha, Michael J. Bevis, May 2002
Conventional injection molding and Multiple live Feed Molding (MLFM) has been used to process starch based biodegradable composites aimed for load bearing bone replacement/fixation applications. Blends of starch with : (i) poly(ethylene vinyl alcohol) and (ii) cellulose acetate were studied. Both polymers were reinforced with bone-like ceramics (hydroxylapatite) in amounts up to 50 % wt.. The use of MLFM allowed for the inducement of molecular anisotropy into the moldings. However it was necessary to prevent material degradation associated to shear dissipation effects and to the longer residence times.
The need for biodegradable thermoplastics continues to grow as waste disposal remains an environmental problem. In order to meet these needs, alloying of biodegradable plastics may expand the markets in which they are used. Initial evaluation of mechanical properties of selected blends suggests that Biomax®, which is a somewhat brittle material, may be toughened by the incorporation of a low modulus copolyester, Bio® GP. Also, blends of CAPA® 6500 and Bio® GP offer a group of mid to low modulus biodegradable polymers. The suitability of blends of Biomax® and CAPA® 6500 are unknown at this time. Assessment of the mechanical properties suggests that miscibility is suspect. The addition of ECM Masterbatch Pellets® to a polyolefin is another approach for developing degrading polymers. The addition of the concentrate did not significantly change the mechanical properties of a polyolefin resin.
Automobile manufacturers are searching for ways to eliminate the traditional painting process employed in assembly plants to decorate and protect the exterior of an automobile. The entire paint facility in a typical assembly plant runs anywhere from $200 million to $600 million and can occupy 50 percent or more of the factory floor. Add to this the cost of environmental compliance, energy, raw materials and labor and it's easy to see why elimination of the paint operation can be a huge benefit to car manufacturers.GE Plastics has developed a polymeric film that can eliminate the need to paint. The film is a proprietary product of polyester carbonates based on resorcinol arylates. This film can be applied over a variety of substrates through an in-mold decoration (IMD) process to yield Class A, exterior panels and trim - that can then be assembled without the need for painting. This product generates an ultraviolet (UV) screener, which extends outdoor life. In addition to the weatherability, the material also exhibits improved scratch and chemical resistance over other thermoplastics.
Philip H. Patterson, James M. Sloan, Alex J. Hsieh, May 2002
The use of advanced lightweight materials to improve combat survivability has been of crucial interest to the U.S. Army for a number of years. The design, development, and performance testing of these advanced materials is critical for enabling Future Combat Systems and the Objective Force Warrior. Specifically, hybrid organic/inorganic polymer matrix nanocomposites show promise in providing many of the physical properties required (i.e. lightweight structure, rugged abrasion resistance, high ballistic impact strength). However, as with any polymer system, these materials are susceptible to degradation over time when exposed to various environmental (i.e. sunlight, moisture, temperature) conditions. This structural degradation (1-5) will eventually comprise the original integrity of the materials’ desired properties.Polycarbonate (PC) has outstanding ballistic impact strength, good optical clarity, and high heat distortion resistance. The Army has a continuous interest in research on PC for better chemical resistance and enhanced resistance to abrasion. The focus of our research is to exploit nano-technology through incorporation of layered silicates for property enhancement. Typical mica-like clays consist of stacked platelets with the thickness of each individual platelet on the order of 1 nm. (1-5) Because of the nanometer size and high aspect ratio characteristics, polymer-layered silicate nanocomposites with much lower volume fraction of clays exhibit properties significantly better than the conventional mineral-filled micro- or macro-composites.In this study, the impact of accelerated weathering upon newly developed polycarbonate-layered silicate nanocomposites materials was investigated. The silicate loading varied from 0-3.5 % by weight. A fluorescent ultraviolet (UV)/condensation weathering tester was selected for the exposure study. The materials were characterized by UV/VIS spectroscopy and FT-IR spectroscopy.The results reveal that the carbonate linkages
Violet Stefanovski, Syed Masood, Edward Kosior, Pio Iovenitti, Igor Sbarski, May 2002
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%.
Márcia S. Sader, Marysilvia Ferreira, Marcos L. Dias, May 2002
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.
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.
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Any article that is cited in another manuscript or other work is required to use the correct reference style. Below is an example of the reference style for SPE articles:
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