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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Melt-mixed polypropylene (PP) composites with singlewalled carbon nanotubes (SWCNTs ) were used as thermoelectric materials which can convert a temperature difference between the two sides of the material into a thermovoltage. The effect of SWCNT content on Seebeck coefficient (S), electrical conductivity, and power factor was studied. In order to enhance these values for p-type composites, several strategies were applied. These involve (a) variation of the SWCNT modification, (b) incorporation of a high S copper oxide, (c) variation of melt-mixing conditions, and (d) addition of an ionic liquid. To generate n-type composites, additives like polyethylene glycol (PEG) and a non-ionic surfactant polyoxyethylene 20 cetyl ether were simply added during the melt-mixing procedure, inducing a switching from positive to negative S values in the pressed films. Finally, two prototype thermoelectric generators using both, p- and n-type PP based materials, could be manufactured.
We test whether the electrical conductivity of copper-polystyrene composites can be improved by adding a metal solder alloy during blending. Copper-in-polystyrene composites prepared by melt-blending have poor electrical conductivity. Addition of a flux (a compound commonly used in soldering) during blending is found significantly to improve the conductivity. A further large increase in conductivity was obtained by adding molten solder during composite preparation. The mechanism of this improvement is that the solder bonded the copper particles together into large aggregates that percolated throughout the sample. We examined the effects of the volume ratio of solder to copper particles on electrical conductivity and the composite morphology. If sufficient solder was added, the copper particles become welded together by the solder to form a self-supporting metal network, and a conductivity of ~500 S/m was realized at a metal loading of only 20 vol%. With insufficient solder, large but non-percolating structures of solder-bound copper particles appeared, and the corresponding blends had lower conductivity. While most of the samples were prepared by hand-blending, we verify that the same approach of improving conductivity can be applied using a Brabender batch mixer.
This paper will first address the general challenges of dispersing discrete multiwall carbon nanotubes in polymers followed by detailed morphological and tensile deformation studies of polyvinylidene fluoride blends with carbon black and discrete carbon nanotubes, commercially available as MOLECULAR REBAR®. The specific carbon nanotubes employed here are about 13nm in diameter and about 900nm in length. In thermoset, or materials which fail in a brittle mode, the discrete carbon nanotubes show improved crack initiation and propagation resistance via a crack pinning mechanism. In ductile, or elastomeric materials the tubes are seen to align with the principal stretch direction. In semi-crystalline materials the carbon nanotubes may act as crystal nucleators, but are small enough to be able to be excluded from crystal domains as they form. This crystallization behavior with discrete nanotubes results in quite complex structures, highly dependent on fabrication processes. The ability to control the structure and placement of discrete carbon nanotubes creates new opportunities for advanced materials.
The use of a self-sterilizing package that can sterilize its contents ‘on-demand’ when triggered by specific stimuli (such as ultraviolet energy (UV)) can provide a novel method for medical device sterilization that is faster, safer and more cost-effective than conventional methods in use today. We describe the development of a self-sterilizing package which can release ClO2 gas as a sterilant when triggered with UV light to sterilize medical devices packaged inside. We discuss the scheme of operation of such a package, gas release characteristics, sterilization efficacy, post-sterilization residuals and material-sterilant compatibility. We demonstrate that a sterilization assurance level of 10-6 can be achieved within such a package.
In an effort to become more “green” in the plastics world, engineers are developing unique products by adding biomass materials to create bio-friendly plastics. The biomass additives may have a different aspect ratio, size, compressibility or density than the pellets and powders but they all must come together in a uniform, consistent, reliable flow into the extruder. Understanding the implications to the handling of adding a new biomass material to a blend is critical for the success of the product. Taking a scientific approach to understanding the flowability of a component and blend is critical to ensuring a successful outcome. Often, this approach results in either making a change to the equipment that the material is handled in to support the new blend, or to making a change in the material or blend (or the conditions at which it is handled) to flow through the existing equipment.
The gaining importance of sustainability in recent years has also led to a closer look on lightweight materials such as fiber reinforced plastics. However, these materials usually pose a challenge in application. Purposeful virtual engineering and prediction is part of it. A new approach allows the reliable prediction of discontinuous fiber reinforced plastics based on integrative simulations while taking local fiber orientation and local fiber length into account. The results obtained with this method already show an improvement in prediction of simple part geometries. Further gain in quality is expected by complex parts where fiber orientation distribution and fiber length distribution spread more widely.
Vehicles confront damages and breakdown caused by various factors under working condition. The most common type of the failure is scratch. External particles such as small pebbles pop up and cause physical damages on the surface of the vehicle. It is not desirable in the aesthetic point of view. Clear-coat layer, which is on the top of the painted surface, is directly affected by scratch. To evaluate the scratch characteristics of the coatings of passenger vehicles, we conducted scratch tests using ASTM D7027 standard. Through the experiments, we obtained scratch properties of various coatings. Using the results, scratch-resistant clear-coat will be developed.
Three different thermoplastic polyester materials were evaluated to investigate the connection between the structure of the materials and their properties. Three materials representing distinct characteristic structures were selected to contrast the results. The resins evaluated included polycarbonate, with carbonate ester functionality; poly(ethylene –co- 1,4-cyclohexanedimethylene terephthalate), a poly(ethylene terephthalate) copolymer; and poly(ethylene naphthalate), with two condensed aromatic rings. The characteristics tested as part of this work included tensile properties to illustrate the short-term mechanical attributes, glass transition temperatures to represent the thermal response of the materials, and creep modulus to demonstrate the time dependency.
Prepared by Franklin Associates for the American Chemistry Council, this study expands upon the 2014 substitution analysis that used life cycle assessment methodology to assess the energy consumption and greenhouse gas (GHG) emissions of six general categories of plastic packaging produced and sold in North America relative to alternative packaging. The updated analysis includes other life cycle impacts - including but not limited to solid waste generation and consumptive water use, as well as updated energy and GHG results. This presentation will answer the question: if plastic packaging were replaced with alternative types of packaging, how would life cycle impacts, such as energy consumption, water use, and waste generation, be affected?
Polyvinylidene fluoride (PVDF) is a non-toxic, conformable, and low-cost alternative to traditional piezoelectric ceramic in sensors and actuators. While fabrication methods such as mechanical stretching are commonly used, a combination of non-isothermal processing and supercritical carbon dioxide (ScCO2) processing has been used to successfully promote the electroactive phase (i.e., α, β, and γ phases) of PVDF. In this paper, this processing method was further analyzed by decoupling the manufacturing process into individual steps to elucidate the processing-to-structure properties and mechanisms that affect the crystallization behaviors of the electroactive phases. Differential scanning calorimetry, scanning electronic microscopy, and infrared spectroscopy were utilized to study the crystallization of the polymorph phases. Experimental results further supported our findings on the formation of γ crystal phase and its inverse relationship to β crystal phase. The results were revealed to be comparable to the mechanical stretching method with a maximum electroactive crystal phase of 72.2%.
Large-scale biomimetic organic/inorganic hybrid nanocoatings with a nacre-like microstructure were prepared via a facile co-assembly process. Different from conventional polymer nanocomposites, such nanocoatings contain a high concentration of nanosheets, which can be well aligned along the substrate surface. Moreover, the nanosheets and polymer matrix can be chemically co-crosslinked. As a result, the nanocoatings exhibit exceptional mechanical properties (high stiffness and strength), barrier properties (to both oxygen and water vapor), and flame retardancy, but meanwhile, they are highly transparent (maintaining more than 85% of their original transmittance to visible light). The nanocoatings can be applied to various substrates and regular or irregular surfaces (e.g., films as well as foams). Because of their excellent performance and high versatility, such nanocoatings are expected to find widespread application.
Liquid crystal polymers (LCP’s) make up a class of performance materials that derive favorable mechanical, chemical, and electrical characteristics from their long-range molecular ordering. This unique microstructure gives rise to anisotropic bulk behavior that can be problematic for industrial applications, and thus the ability to model this directionality is essential to the design of manufacturing processes for isotropic material production. Previous efforts to model LCP orientation have typically been restricted to structured grids and simple geometries that demonstrate the underlying theory, but fall short of simulating realistic LCP manufacturing methods. In this investigation, a methodology is proposed to simulate the director field in practical LCP process geometries for the prediction of the bulk material orientation state. The polymer flow is first simulated using a commercial CFD software and the rheological results are input into post-processing calculations of the polymer directionality. It is shown that the model predicts the expected change in anisotropy as the mold cavity thickness is changed for an LCP injection molding process.
The influence of annealing on the viscoelastic behavior of poly(ether-ether-ketone) (PEEK) was investigated. The effect of annealing at different temperatures on the crystallinity of PEEK was characterized using differential scanning calorimetry. This effect on the viscoelastic behavior of PEEK was further studied using dynamic mechanical analysis. The master curves were generated for creep and stress relaxation measurements at temperatures below Tg and subsequently a physics-based model was employed to predict the long-term viscoelastic behavior of PEEK within this temperature window of interest. The results indicated that annealing increased the degree of crystallinity and increased the activation energy of β-relaxation (Eβ), which correlates to the molecular motions below Tg and explains why the creep and stress relaxation slowed down after annealing. The modeling results also suggested a higher degree of restriction on the molecular mobility, which is consistent with Eβ results obtained from DMA.
In this study, vacuum assisted bubble free casting was used to prepare and test Polydimethylsiloxane (PDMS) with varying crosslinking densities. Tensile tests and Shore D hardness tests were performed to determine tensile strength and hardness of PDMS. PDMS with concentrations of 2.5:1, 5:1, 7.5:1, and 10:1 wt/wt silicone resin to curing agent were fabricated for uniaxial tensile testing and hardness testing. Fourier transform infrared (FTIR) spectroscopic analysis revealed that there is a strong correlation between tensile strength and hardness with respect to absorbance spectra of carbon Silicone-Oxygen-Silicone (Si-O-Si) bonds.
Addition of functional components into polymers is the important route for preparing polymer functional composites. For economic cost increase and mechanical properties decrease in the presence of functional fillers, we are all exploring the good functional performance at the lowest content of fillers. Here tailoring the structure morphology of the composites will play the important role. Laminating is one of preferred structures. In general, the polymer composites with multilayer structure have good balance of toughness, stiffness and strength. In this paper, the morphology development of polymer in the confined space of micro- and nano-layers and layer interfacial contribution to properties enhancement will be reported. We can develop a series high damping and sound-proofing polymer composites through multi-layer structure : high damping materials, high noise shielding, high electromagnetic waves shielding materials, high flame retardant materials and high Conductive materials.
Commercial applications of polymers have always included circumstances of impact, but it has been consistently difficult to measure the high rate response of thermoplastics, thermosets, elastomers, and foams. Designers require this information to properly prototype and ensure the impact resistance of products, yet the suite of characterization techniques remains incomplete. This paper presents various methodologies to evaluate the high strain rate (impact) properties of polymeric materials. The discussion examines the applicable range of strain rates by material and methodology, and discusses which techniques provide information within constraints of accuracy, repeatability, and ease of testing.
The cell structure of a mattress foam influences a number of foam physical properties which are important to the thermal comfort of a sleeping person. An interconnected model was developed to quantify these relationships with the following model components: 1) semi-empirical sub-models to relate foam structure to foam properties, 2) finite element analysis to simulate transport of heat and moisture within a foam mattress, and 3) lumped-parameter model to quantify human thermal response to external environment. This paper presents the results of numerical simulations using the combined model, in which important structural parameters are traced to their ultimate effects on thermal comfort.
Microcapillary film (MCF) membranes offer a promising new media configuration for water purification devices. A 50 mm wide microcapillary film die was designed and constructed, allowing a fluid to be injected at 42 separate locations within a molten polymeric film as it exited the die. MCF membranes were prepared using this die by profile extrusion of a polyvinylidene fluoride (PVDF) based formulation, which was rendered microporous via Thermally Induced Phase Separation (TIPS) and dissolution of a dispersed nano-calcium carbonate porogen. Air was used as the bore fluid to form the microcapillaries. Analysis of the membranes prepared by this technique using scanning electron microscopy showed surface porosity and an interconnected, porous interior morphology that was uniform from the outside surface to the capillaries on the interior. These MCF membranes can be formed into spiral wound modules, useful for ultrafiltration applications or, when coated with an ion-rejecting top layer, for desalination of aqueous feed streams.
High temperature thermoplastic polymers are continuously evaluated as options in a multitude of applications, including aerospace, medical, oil and gas exploration, and other high demanding applications. The fundamental understanding of their structure and its effect on their expected performance in critical environments is of high importance for the development of new technologies and complex processing techniques. Commercial efforts have recently focused on the development of high performance materials for specialized and highly demanding applications. In this regard, due to their superior properties, poly(aryl ketones) or PAEKs have gained significant attention. Their exceptional behavior at high temperatures, along with their superior chemical resistance, mechanical properties, excellent abrasion resistance, and natural flame retardancy make them suitable for a multitude of growing applications and markets. Among the PAEK family, poly(etherketoneketone) (PEKK) offers a unique chemical structure, favoring precise manipulation of its polymer microstructure and key properties. PEKK resins offer very high melting and glass transition temperatures, a wide range of crystallization rates and degrees of crystallinity, superior mechanical properties, chemical resistance and low flammability. Because of their extremely high thermal properties and polymorphic crystalline nature, PEKK polymers offer also clear advantages in powder applications over traditional high-performance thermoplastics and other aromatic polyketones [1-3].This study provides a detailed evaluation of the performance of PEKK polymers in rotomolding applications. The results presented here offer a general overview of the changes in physical properties and macroscopic morphology observed in PEKK parts when processed at elevated temperatures. This study also describes the development of an optimized rotomolding process to produce parts with improved performance capable of satisfying highly demanding requirements for specialized applications such as aerospace, medical, and oil and gas exploration among others.
The Fluted (aka Maddock) or Spiral Fluted (aka Egan) mixers are commonly used on single screw extruder screws to help disperse particles and homogenize polymer melts. However, these devices are generally added with some “standard” dimensions or designs and are often not optimized for the particular polymer or process conditions being used. A poorly designed mixer can adversely affect the performance of the extruder and create more problems that it is supposed to solve. There are also some design variations that make manufacturing easier but also adversely affect the performance. This presentation will propose some optimization criteria that should be applied to the design of a fluted mixer that can help avoid some problems, which will also be presented.
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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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