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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Compatibilization of Nylon 6 Nanocomposites/ABS Blends Using Functionalized Metallocene Polyolefin Elastomer
The impact behaviors of nanoclay filled Nylon 6 (Nano-Nylon 6) blended with poly (acrylonitirile-butadiene-styrene) terpolymers (ABS) prepared through a twin screw mixing process were investigated here using metallocene polyethylene grafted maleic anhydride (POE-g-MA) as compatibilizer. It is found that impact strength increases slightly for Nano-Nylon 6/ABS blend system with the addition of compatibilizer, but increases remarkably for the conventional Nylon 6/ABS case. These discrepancies could be attributed to a different degree of available reaction sites from amine group on Nano-Nylon 6 and Nylon 6.
Compatibilisation Studies of Blends of Nylon 6 with Metallocene Linear Low-Density Polyethylenes
Polymer blends of polyamides and polyethylenes are immiscible and highly incompatible. These blends are characterised by high interfacial tension, a two-phase morphology and poor physical characteristics due to reduced interaction across the phase boundaries. The compatibilising agent, maleic anhydride-grafted-LLDPE, is physically miscible with the polyethylene phase and has a chemical functionality with the polyamide phase. The use of a new generation mLLDPE (ENGAGE ™ by Dupont) was studied to investigate its suitability as a modifier for the polyamide grade. The influence of the composition of the blends and the effect of the addition of the compatibiliser were both investigated for their effect on the mechanical properties. Increased mLLDPE content was shown to slightly decrease the impact values but significantly increase the modulus values. The addition of the compatibiliser improved the properties of the blends.
Nano-Composites Derived from Melt Mixing a Thermotropic Liquid Crystalline Polyester and Zinc Sulfonated Polystyrene Ionomers
A nanocomposite consisting of rectangular prism-shaped liquid crystalline polymer nano-crystals dispersed in a thermoplastic polymer matrix was produced by melt mixing blends of a thermotropic liquid crystalline polyester (TLCP) and the zinc salt of lightly sulfonated polystyrene ionomers at 300 °C. The conversion of a macroscopically dispersed LCP phase to nano-particles during melt mixing was analyzed directly by torque measurements during melt-mixing and indirectly by wide angle X-ray diffraction and transmission electron microscopy of the resulting blends. Salts other than zinc did not induce the formation of the TLCP nano-particles, so it appears that the formation of the nano-crystals involved a specific interaction of the zinc sulfonate groups with the TLCP. The specific nature of the interaction, e.g., physical or chemical is not yet known.
New Miscible Blends of Nylon 6 and Polyhydroxyaminoether Resins
Nylon 6 (PA-6) was found to form fairly miscible blends with certain types of polyhydroxyaminoether (PHAE) resins as evidenced by microscopy and DSC techniques. Such miscibility between a nylon and a non-nylon polymer is rather rare and novel. However, the observed miscibility and phase behavior was found to depend on both the nylon and the PHAE resin structures. For PA-6, the miscibility was found to occur only when the PHAE contained sufficient amounts of resorcinol moieties and ethanol amine moieties. Other nylons such as PA-66, PA-6I/6T, PA-MXD6 and PA-12 showed an increasing tendency for phase separation and immiscibility.
In Situ Block Copolymer Formation during Solid-State Shear Pulverization: An Explanation for Blend Compatibilization via Interpolymer Radical Reactions
Interpolymer radical coupling leading to block copolymer formation is demonstrated for the first time in the solid state and in the absence of diffusion using solid-state shear pulverization. Fluorescence-detection gel permeation chromatography detected interpolymer reaction in high-molecular weight polystyrene (PS)/pyrene-labeled PS and high-MW poly(methyl methacrylate) (PMMA)/pyrene-labeled PS blends. Proof of interpolymer radical coupling supports prior pulverization studies demonstrating compatibilization, i.e., stability of dispersed-phase to long-time annealing, of PS/high density polyethylene and PS/PMMA blends.
Compatibilization of PC-SAN Blends by Ultrasound-Assisted Melt Mixing
In this study, high intensity ultrasound was employed to induce mechano-chemical degradation during melt processing of polymeric materials. It was expected that generation of macroradicals in polymer mixture can lead to in-situ copolymer formation by their mutual combination, which should be an efficient path to compatibilize immiscible polymer blends and stabilize their phase morphology in the absence of other chemical agents.Ultrasound-aided degradation of PC and SAN was practiced during melt processing of the polymer in a sonicated mixer. We investigated the changes in the morphology of PC/SAN blends for various viscosity ratios of PC and SAN and improvement of mechanical properties of sonicated blends was evaluated.
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.
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