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.
Epoxy-based adhesives for bonding aluminum substrates have gathered significant interest in recent years. Yet, more work is needed to learn how epoxy adhesives withstand creep and exposure to various environmental conditions. In this study, both experimental and modeling work (using Ngai's Coupling) has been conducted to predict creep behavior of epoxy adhesives under moisture exposure.
Research objective is to establish manufacturing-related design rules and procedures for engineering design of injection molded thermoplastics parts, and to investigate application of novel materials to support development of design for sustainability. Thorough analysis of a large number of mechanical test results has led to a better understanding of factors influencing mechanical performance in tensile and tensile-impact. Among the noteworthy conclusions is the importance of shear rates and temperature gradients in the surface layers during molding.
Poly(lactic acid) (PLA) is being investigated vastly due to its biodegradable and biocompatible nature. However, the degradation of PLA is slow, often leading to a long life-time in vivo. The major objective of this research is to modify PLA film surfaces with the ultimate aim of making a bioactive surface that will show faster degradation. The PLA film was solvent cast and the film surfaces were grafted with poly(acrylic acid) (PAA) using a UV induced photopolymerization process. The films were incubated in different pH solutions, viz., pH = 4, 7, and 10, for a specified time period. The film resulting from each treatment was analyzed using Transmission-FTIR spectroscopy and Atomic Force Microscopy (AFM). The molecular weights of the films were measured using gel permeation chromatography (GPC). Results established that faster degradation of the PLA film when incubated in different pH solutions could be achieved by surface modification of the PLA film by grafting PAA.
This report will include the way to design, fabricate, and assemble a Polymer Electrolyte Membrane Fuel Cell (PEMFC) to maintain a low voltage source, near one volt, that runs at operating temperatures near 80 degrees Celsius. Creating a stack of cells will provide an energy solution that is more efficient than the system in place today. The PEMFC runs off of pure hydrogen and air (oxygen) and will provide a power source that is non-pollutant and renewable since hydrogen is readily available through the electrolysis of water. The problems with this experiment are maintaining moisture control on both the cathode and anode and the other problem is in controlling the hydrogen gas supply since hydrogen is very explosive when combined with oxygen. With these problems taken into consideration the PEMFC could be the energy source for the future.
This paper addresses the possibility of using recycled thermoset plastic powder as filler. With budget issues in the academic setting, using recycled thermoset powder as filler could have a positive impact. Recycled powder has been successfully used in a university plastics lab for rotational molding, thermoforming molds, and for composite tooling dough. Three practical lab exercises will be given in the paper.
The most common commercial processes for manufacturing pre-pregs for electronic boards use solvent-based resin systems. Solvents are environmentally unfriendly and contribute to voids in the pre-preg and laminate. The resin impregnation process is done in an open resin bath. This low-pressure impregnation is conducent to voids in the prepregs. Voids cause product variability, which is a major source of scrap in board shops. To eliminate the above mentioned drawbacks, a solventless process, based on the concept of injection pultrusion, is developed. The impregnation is done in a die under pressure to minimize voids.In previous work, chemo-rheological and kinetic measurements were used to identify a potential epoxy-based resin system. In addition, flow visualization using model fluids was used to establish the basic flow mechanism. Here, we use the previous results to develop a mathematical model for the B-staging process. Based on the mathematical model, three potential alternatives to produce prepreg are developed and analyzed. A prototype B-staging die is built and used to verify the mathematical model. The result shows that the model agrees well with the experimental data for low pulling speed and slightly under predicts the high pulling speed runs.
Critical items in designs of plastic products are joints. The paper will deal with a number of design aspects about designing reliable plastic products. It will combine the results from our research in the field of stress concentrations, orientation and weld lines around holes, embrittlement of polymers, adhesion and environmental stress corrosion. A number of failures in practice will be presented.
Laura Luna, Yomilka Marcano, Maribel Marrero, Rosestela Perera, May 2004
In this work, the process of recycling high-impact polystyrene, both post-consumer and post-industrial, was studied. Blends of recycled/virgin materials were made and their MFI, mechanical properties and processability (thermoforming) were evaluated. Few differences in the behavior of the materials were found and their use as thermoformed packaging was ascertained.
Industrial designers have problems imagining how their designed plastic products might fail.The paper illustrates how our students are educated about the specific structure related properties that might cause failures.A specific course about designing for reliability of plastic products is outlined. Case studies showing failed products are important.Students must be aware of failure causes like: stress concentrations, low mass and/or mould temperatures, highly stressed weld lines, faulty ribbing and incorrect joining.The course deals also with typical failure mechanisms of plastics like: creep and stress relaxation, stable crack extension, chemical attack and environmental stress - cracking.
Carbon dioxide is widely recognized as an environmental-friendly blowing agent for foam extrusion. However, it is also more difficult to process than other gases because of its low solubility and high diffusivity. In order to improve processing, it might be suitable to use additives. The aim of this work was to study the effect of such additives on the solubility and diffusivity of carbon dioxide in the solid state and to validate their effectiveness in a foam extrusion process.Three “CO2-philic” additives were added to polystyrene and sorption experiments were conducted to measure the solubility and diffusivity at room temperature. Results show that all three additives had a small but measurable effect on gas solubility, which was a consequence of the free volume increase in the polymer blend and in some cases, due to the specific interaction of carbon dioxide with the compounds. Diffusion was also affected depending on the concentration of additive.
The ratio of a polymer's craze strength to its yield strength is an excellent measure of toughness. It can be used to quantitatively compare materials and to predict how the ductile-brittle transition will change as a function of a variety of environmental and material variables.
C. Daly, D. Leonard, F. Buchanan, J. Orr, N. Dunne, May 2004
The small punch test is a useful technique in the mechanical testing of polymers where limited material is available. This investigation focuses on the latest developments in the small punch test design, including integrated temperature control and environmental conditioning and its use in analysis of polymethyl methacrylate (PMMA) bone cement.
J. Yu, Y. Hu, B. Risch, A. Hiltner, E. Baer, May 2004
The effect of an environmental stress cracking agent on slow crack propagation in creep and fatigue of polyethylene resins was studied. At 50°C, fatigue and creep behavior of polyethylene in Igepal solutions followed the same stepwise mechanism as in air. The fatigue to creep correlation was probed by increasing Rratio (defined as the ratio of minimum to maximum stress in the fatigue loading cycle) from 0.1 to 1.0. Unexpectedly, 10% Igepal CO-630 solution, an ASTM standard environmental stress cracking agent, retarded fatigue crack propagation at R-ratio 0.1 but accelerated crack propagation at increasing R-ratios, in comparison with experiments in air. In contrast, fatigue and creep experiments in another longer chain Igepal solution, Igepal CO-997, showed no appreciable effect on crack propagation kinetics at different R-ratio compared to air.
J. Lou, K. Schimmel, A. Shahbazi, V. Harinath, C. Rutkoski, May 2004
Filled biodegradable polymer samples were prepared and exposed to simulated composting environment and the degradation kinetics was characterized. Particularly, the influence of the fillers on the biodegradation kinetics was investigrated.
Yasuo Hashimoto, Tsujii Tetsuya, Kitagawa Kazuo, Machiko Mizoguchi, Yasuhiro Fujita, Hiroyuki Hamada, Umaru S. Ishiaku, May 2004
The heat-sealing machine is a vital tool in plastic bag manufacture. Processing conditions such as heat-sealing temperature and pressure greatly affect mechanical properties of the heat sealed part. In this study, the mechanical properties of the heat sealed part of a biodegradable plastic film were examined. Based on the results obtained from peeling test, circular notch tensile test and DSC measurement, the optimum heat sealing was established at 130-135 °C. The mechanical properties of the heat seals decreased with increasing heat sealing temperature.
M.S. Huda, A.K. Mohanty, M. Misra, L.T. Drzal, E. Schut, May 2004
Green composites were made from poly (lactic acid) (PLA) and cellulose fibers by extrusion followed by injection molding processing and their physico-mechanical properties were evaluated. The properties of PLA reinforced with varying amounts of wood pulp-based cellulose materials were studied. These composites possess superior thermal and mechanical properties based on the strong interaction between the PLA matrix and the cellulose fibers. It was found that the wood pulp-based cellulose fiber could be a good reinforcement candidate for the high performance biodegradable polymer composites.
Kevin G. Cai, Charles G. Reid, Satchit Srinivasan, Norbert Vennemann, May 2004
The elastomeric properties of polyolefin thermoplastic vulcanizates (TPV) have been characterized by compression set, recoverable strain after hysteresis, and thermal scanning stress relaxation (TSSR) analysis. Unlike a thermoset rubber, a TPV is a two-phase system with highly crosslinked fine rubber particles dispersed in a thermoplastic matrix. Compression set, which was originally designed to characterize the elastomeric properties of a thermoset rubber, does not truly characterize the unique elastomeric properties for a TPV. Compression set for a TPV is not only highly dependent on the crosslinking density and structure, but also very sensitive to the orientation of the two phases in the TPV. For the same TPV with a fully crosslinked rubber phase, the compression set value can vary substantially depending on sample preparation and thermal history. Elastomeric properties can be better characterized by the recoverable strain after hysteresis and TSSR stress-temperature curve. The thermal-mechanical properties or stress relaxation behaviors provides more useful information for designing and producing all-thermoplastic parts, such as automotive seals, from TPV.
Bret H. Calhoun, Jeremy Swanson, Graham Behringer, Robert B. Moore, May 2004
Nanocomposites are materials that exhibit a change in composition and structure over a nanometer length scale. In many cases, these systems have shown remarkable property enhancements compared to traditional polymers. Recently, poly (L-lactide) (PLLA) has received considerable attention because of its “green” nature. However, the end-use properties of this biodegradable polymer typically fall short of typical petroleum based polymers. Therefore, PLLA/montmorrilonite nanocomposites have been prepared via solution blending in an attempt to enhance the properties of PLLA.
S. Chung, J. Couch, J.D. Kim, K. Oliphant, P. Vibien, May 2004
Environmental factors are known to significantly impact the oxidative failure mechanism of materials. For example, the chlorine present in potable water as a disinfectant is an oxidant that has been reported to impact the failure mechanism of materials in potable water applications. In this paper, the relationship between various potable water qualities, with different oxidative potentials, and chlorine induced oxidative failures of plastic piping materials is examined. The primary factors of potable water quality affecting oxidative strength are reviewed. Laboratory exposed pipe samples tested at various water qualities to ultimate failure are examined to determine the impact of water quality on the failure mode. The chlorine in potable water is seen to attack the inner pipe wall causing oxidation and degradation of this inner surface. The stresses on the inner wall lead to micro-crack formation in this degraded layer. These micro-cracks are seen to propagate radially through the pipe wall resulting in a brittle slit type failure. The failure mode is shown to be the same over a range of water qualities. The impact of chlorine is shown to be simply one of oxidation with the rate of degradation primarily related to the oxidative strength of the potable water. For the PEX pipe material examined, it is projected that material performance can significantly exceed the excellent performance predicted based on testing at the aggressive water qualities typically employed in validation testing, depending on the specific water quality of the end use application.
A compressed air line exploded suddenly and caused extensive damage to property, fortunately without casualties. The air line was used as part of a plant for annealing glass, and so was pressurised regularly up to about 10 bar. When the pressure was released, a blast of cold air was directed over the hot glass surfaces. Most of the pipework for the system was made of ABS pipe and solvent-welded fittings. The explosion was caused by catastrophic growth of an internal axial crack in one of the pipes of the system. The inside surface of the pipe was covered with deep cracks, and the first investigators concluded that the cracks had been caused by fatigue. However, a separate investigation of the remains indicated that traces of fluid from the oil of the air pump compressor had created environmental stress cracks.
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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:
Brown, H. L. and Jones, D. H. 2016, May.
"Insert title of paper here in quotes,"
ANTEC 2016 - Indianapolis, Indiana, USA May 23-25, 2016. [On-line].
Society of Plastics Engineers
Available: www.4spe.org.
Note: if there are more than three authors you may use the first author's name and et al. EG Brown, H. L. et al.
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