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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Simulation of Droplet Breakup Using a Lattice Boltzmann Method
Droplet breakup in homogeneous shear flow at super critical Capillary numbers and a viscosity ratio of unity is studied using a lattice Boltzmann method. We find that the total number of child drops that form from an isolated super critical drop scales according to a power law relation (n = 3.5). The child drops that form are all below critical, but not wholly uniform in size, and the distribution appears to be log-normal at high drop numbers. It is also found that for large ratios of the Capillary number to its critical value, the total strain required to break up a drop into N sub-critical entities tends to a constant value.
Drop Breakup Mechanisms in Polymer-Polymer Systems
The deformation and breakup of a single viscoelastic polymer drop inside a viscoelastic polymer matrix at high temperatures under simple shear was visualized in a specially designed transparent Couette mixer. The polymer systems studied were polyethylene matrix/polycarbonate drop (PE/PC) with viscosity ratios between 2 and 8. Aside from the “erosion” mechanism, which has already been reported (1, 2), three other distinct breakup modes were observed: (a) “parallel breakup” – the drop breaks after being stretched into a thin sheet or sausage parallel to the flow direction; (b) “tip streaming” – streams of small droplets are released from the tips of a pointed drop in the flow direction; and (c) “perpendicular breakup” – the drop breaks after being elongated in the vorticity direction.
Polymer Dispersion Visualization in a Couette Flow Cell
Dispersion mechanisms in high viscosity ratio polystyrene/polyethylene (PS/PE) and ethylene propylene rubber/polypropylene (EPR/PP) systems under relatively high shear rates and temperatures up to 230°C have been investigated in a transparent Couette setup. Through the in situ visualization, two non-Newtonian breakup mechanisms were revealed. The first one was the droplet elongation perpendicular to the flow direction followed by droplet shattering when the ends of the elongated droplets get slightly off axis with the stationary plane. The initial elongation has been associated to elastic normal force buildup in the droplet. The second non-Newtonian mechanism consisted in erosion at the drop surface.
Time-Scales of Coalescence in Polymer Processing: Study on Polypropylene/Polyamide-6 Blends
The effects of shearing time, volume fraction, shear rate, and viscosity ratio on coalescence of isotactic polypropylene (PP) and polyamide-6 (PA6) blends were studied in simple shear flow. A simple model for coalescence developed to provide characteristic times in coalescence in polymer processing operations was used to analyze experimental results. The pre-coalescence droplet morphology was created by melt blending the polymers in a twin-screw extruder at several compositions and was subjected to a simple shear flow in a cone and plate rheometer at low shear rates (0.1 and 0.5 s-1). The rheological data was analyzed after removing the effects of viscosity mismatch to leave only the interfacial effects on coalescence.
Morphology Transitions in Multilayer Polymer Melts Due to Growth and Interaction of Holes
Chaotic advection has been used in prior work to create melts containing a large numbers of very thin individual layers among polymer components. Morphology changes in the layers occurred due to hole growth and interaction. Because the process was amenable to control, a wide variety of blend morphologies were obtained in extrusions. Modeling of these morphological transitions has been carried out with the aim of improving process control in envisioned smart blending machines where blend morphology can be specified via a computer keyboard. The lattice Boltzmann method (LBM) was used to study the interactive growth of various hole patterns in layers in a periodic three-dimensional domain. It was demonstrated computationally that hole growth can lead to numerous thin and oriented fibers, single and dual phase continuous morphologies, and very fine droplets. The advantages of obtaining these and other structures via controllable multilayer formation and breakup are discussed.
Laminar Morphology of Extruded HDPE/PA-6 Blends Controlled by Flow Fields
Ribbons were extruded from two high-density polyethylene (HDPE)/polyamide-6 (PA-6) blends with different melt shear viscosity ratios (VRs) of PA-6 to HDPE. Three different screw configurations, one metering and two mixing screws, and three screw speeds were evaluated to investigated their effects on the morphology of extruded ribbons. The scanning electron microscopy (SEM) observation showed that the blends with different VRs need different screw shearing intensity to yield a thin, overlapping, and discontinuous laminar PA-6 phase, which results in enhancing permeability barrier properties. The screw speed also played a distinct role in controlling the morphology of the blend. By controlling the flow fields, through appropriately combining the screw configuration with screw speed in this study, a well-developed laminar PA-6 phase with an aspect ratio of about 100 was obtained.
Interfacial Chemistry and Morphology of Blends of Polybutyleneterephthalate and Epoxide-Containing Rubber
Of the various ways in which polybutyleneterephthalate (PBT) can be toughened, the addition of epoxidecontaining rubbers is one of the most effective. The interfacial chemistry (dissolution and fractionation experiments) and morphology (transmission electron microscopy) development in blends of PBT with ethylene-(methyl acrylate)-(glycidyl methacrylate) rubber (E-MA-GMA) has been studied as a function of the mixing time for batch kneaders and of the length along the axis of a co-rotating twin-screw extruder. First, a physics-controlled mixing regime occurs with a very fast dispersion of the rubber to the ?m level. Subsequently, a chemistry-controlled regime occurs, where the interfacial area is covered with PBT/E-MA-GMA graft copolymer, which prevents coalescence and, thus, results in further refinement of the morphology to sub-?m level. The occurrence of cross-linking of the rubber phase in some cases limits optimum blend dispersion.
Interfacial Area and Rheological Measurements of Cocontinuous Poly(Ethylene Oxide)/Polystyrene Blends
Blends of poly(ethylene oxide) and polystyrene were analyzed using scanning electron microscopy with image analysis and rheological measurements to determine the region of cocontinuity. Local maxima in the amount of interface in the blends and in the elastic modulus at low frequency correspond to the boundaries of the region of cocontinuity. Annealing of the samples caused some blends near the boundaries of the region of cocontinuity to break up into dispersed morphologies, while other blends remained cocontinuous, despite dramatic increases in the size scale.
Morphological Phase Behavior of PMMA and PC in PMMA/PC Binary and PP/PMMA/PC Ternary Blends
The morphological phase behavior of polycarbonate and poly(methyl methacrylate) was studied in PMMA/PC binary and PP/PMMA/PC ternary blends prepared in a Haake batch mixer. Even though extensive research on the PMMA/PC blends has been performed, the miscibility between two polymers has not been clearly understood to date. The phase separation between two polymers has been consistently observed specifically the blends were prepared in molten state. In this paper, immiscible and miscible PMMA/PC phases were observed in PMMA/PC binary blends and PP/PMMA/PC ternary blends, respectively. Therefore, effects of the PP-matrix on the PMMA/PC miscibility were proposed in this study. In order to clarify the effects of the PP-matrix, various analyzing techniques including NMR, GPC, ICP and SEM were utilized. It was also found that the miscibility of PMMA and PC is highly affected by the processing parameters such as mixing temperature and mixing time in the presence of the PPmatrix.
Blends of Ethylene-Methyl Acrylate-Acrylic Acid Terpolymers with Ethylene-Acrylic Acid Copolymers
The effect of methyl acrylate composition in ethylene-methyl acrylate-acrylic acid (E-MA-AA) terpolymers and acrylic acid content in ethylene-acrylic acid (E-AA) copolymers was investigated in blends of these two materials. The E-MA-AA terpolymer with 8 mole percent methyl acrylate was not miscible with any E-AA material no matter what the AA content, while the terpolymer with only 2 mole percent methyl acrylate was miscible, at least to some extent, with the E-AA copolymer at high acrylic acid contents. For the E-AA polymer material with the highest acid content, there was a synergistic effect for some properties at low E-MA-AA contents; the tensile strength was 10% higher than the value for the E-AA copolymer, even though the E-AA copolymer was much more stiff.
Study on Mechanical Properties of Dynamically Cured PP/Epoxy Resin Blends
In this paper, dynamical vulcanization process which usually used for preparation of thermoplastic elastomers was applied to PP/epoxy resin blend systems. Products of crosslinked epoxy resin particles finely dispersed in PP matrix were obtained, and were named as dynamically cured PP/epoxy resin blends. Maleic anhydride grafted PP (PP-MA) was used as a compatilizer. The influences of PP-MA content, epoxy content and reaction conditions on mechanical properties of dynamically cured PP/epoxy resin blends were investigated. Experimental results show that dynamically cured PP/epoxy resin blends have better mechanical properties than that of the PP/epoxy and PP/PP-MA/epoxy blends. By increasing epoxy resin content, flexural modulus increased significantly, while the elongation at break dramatically deceased. Impact strength was slightly affected by the presence of the epoxy resin.
The Processing and Performance of Polyvinyl Chloride / Ethyl-Vinyl Acetate Copolymer Blends
Two grades of ethyl-vinyl acetate (EVA), each containing 26% (modified with 1.2% methacrylic acid) and 27% vinyl acetate (VAc) respectively, were blended at various compositions, with two grades of PVC. Mechanical analysis of these blends showed that the tensile and flexural modulus decreased and impact strength increased, with increasing EVA content. Rheological analysis for the blends showed only slight changes in shear viscosity with increasing EVA content, even at lower shear rates. DMTA showed a shift in glass transition temperatures of the PVC and EVA components within the blends, suggesting partial miscibility over the range of concentrations studied.
The Effects of Coupling Agents on the Mechanical Properties of Wood-Polymer Composites
A range of wood-polymer blends, containing 40% w/w MDF sawdust (90-150 microns) was prepared using polypropylene (MFI 1.7 g/10min) and LDPE (MFI 2.2 g/10min). The blends were melt compounded using a Killion single screw extruder with a barrier type screw design. Two different coupling agents, maleic anhydride and a titanate compound, were incorporated into the blends during compounding at concentrations of 1 and 2%. Tensile, flexural and impact specimens from these blends were prepared using injection moulding. Mechanical analysis showed improved impact strength, tensile modulus and break strength for polypropylene-wood and polyethylene-wood blends containing 1% maleic anhydride.
Pigments for Food Packaging – A Regulatory Journey
Understanding the U.S. FDA requirements for pigments or colorants in plastic food packaging involves a long journey. You’ve heard that the longest journey in the world begins with one step, and through this presentation you will take this first step in understanding FDA requirements. Few other food-contact substances have endured the regulatory twists and turns as experienced by colorants since the Food Additives Amendment of 1958. To prepare for such a journey, you first should be equipped with a background of the Federal Food, Drug, and Cosmetic Act, interpretations of the law and certain regulations, and an understanding of concepts and doctrines observed by the FDA. We will travel and see how the concepts of interstate commerce, adulteration, and misbranding govern the enforcements of FDA. We will define foods and food additives, as well as exemptions such as GRAS, prior sanctions, and housewares. We will continue our journey and travel through the history and regulations for colorants and color additives. We will finally visit the processes used to obtain new clearance through the threshold of regulation and food contact notifications.
Nanocolorants - More than Colored Nanoparticles
Recently we have developed a novel class of colorants combining the advantages of both classical pigments and dyestuffs, the so-called NanoColorants. By nature these are nanocomposites consisting of hydrophobic dyestuffs molecularly dispersed and immobilized in highly crosslinked nanosized polymer particles prepared by a modified miniemulsion polymerization process. Whereas our initial development activities were focused primarily on a proper understanding of the basic polymerization process itself, and the incorporation of highly oleophilic dyestuffs, we have now extended our work to a number of other functional additives, ranging from optical brighteners and UV absorbers via copolymerizable fluorophores to all-organic opacifiers.
Using the Internet to Calibrate Color Spectrophotom Eters Back to a Traceable NIST: A Revolutionary Patented Technology for Color Control
The Internet changes the way we conduct business strategically and on a day-to-day operational basis. For those managing color throughout a supply chain, the Internet offers revolutionary capabilities to improve your process and speed-to-market.Whether you’re a technician, lab manager, or quality control engineer, or whether you are responsible for color control within a multi-site enterprise, your challenges have several common denominators. First and foremost is that color makes a difference. It’s used as a litmus test for quality, which is compounded by extended supply chains around the world, increasingly compressed cycle times, and limits on resources and expertise in the field of color measurement and management.Another denominator is consumer demand for variety. To meet this demand, designers of apparel, toys, automobiles, consumer electronics, appliances and all types of household and office furnishings are increasing the number, frequency and complexity of their creative endeavors. While the products may be comprised of different raw materials (i.e. pigments, textiles, resins, metals, etc.), they do have one common denominator – color. Although color quality may be the ultimate discriminator, it’s often last on the list of priorities for designers, brand managers and manufacturing managers.
Color Matching Software from the Colorant Producer’s Perspective
The field of color science and color matching using mathematical models has come a long way in the past two decades. Today a number of companies can claim to have expertise in this field; each demonstrates this expertise in similar fashion by offering the coating, ink and plastic industries with colorimetry software targeted to make color matching and quality control accurate and faster. Still, however, issues remain. One’s ability to achieve accurate color matches can be compromised by differences in the type of substrates being measured, the form of the sample, the surface type and ultimately limitations of the colorant libraries themselves.In this paper, we will review the attributes of a colormatching program that was internally developed by a colorant producer. It will show that this software can be used as a predictor for application performance in the areas of heat stability and weathering. Lastly, the importance of accurate colorant libraries will be reviewed including an elaboration on issues associated with pigment dispersion.
Understanding the Effects of a Compounding Process on the Production of Co-Extruded Vinyl Sheet through the Utilization of Design of Experiments
There are many ways to add color to the windows of your home. Methods include painting, powder coating, and use of capstock materials. One window manufacturer utilizes a co-extruded polyvinyl chloride (PVC) sheet, vacuum formed over a wood frame to provide a durable, low maintenance, and weatherable exterior. The market need for expanded color options has placed a need for understanding the key variables of success for this particular process. This paper will discuss the results of a Design of Experiment program conducted to determine the variables for successfully optimizing the production of the PVC sheet used in vacuum forming applications.
Perylimide Fluorescent Dyestuffs - Specialty Colorants with a Brilliant Future
Fluorescent colorants based on the perylene chromophore are well known for their exceptionally high photo-and thermostabilities, thus enabling their use in a number of demanding outdoor plastics applications. In this paper, chromophore design strategies leading to novel perylene based fluorophores covering additional coloristic regions, their unique property profiles, as well as recent advances in the development of state-of-the-art plastics applications are presented, ranging from emissive color filters for large scale LCD displays to fluorescent retroreflective sheets and films for traffic safety applications.
Degradation of Rubber Networks during the Ultrasonic Treatment
The ultrasonic treatment of vulcanized rubbers under controllable conditions softens the rubber and creates a considerable amount of sol that makes possible a further reprocessing of the rubber. This paper demonstrates that a unified approach can be applied to analyze the numerous experimental data on structure of various unfilled and filled rubber vulcanizates ultrasonically treated under the continuous (with flow) and static (no flow) conditions. This approach is based on a model, which describes degradation of rubber network as a random scission of crosslinks and main chains due to the thermo-mechanical action of ultrasound.
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