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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PREDICTING PHASE MORPHOLOGY DEVELOPMENT OF POLYMER BLEND IN CONVERGENT-STRATGHT CHANNEL
Reduced capillary number theory was used to predict the flow field-induced morphology development of polypropylene/polyamide 6 (PP/PA6) blend with a compatilizer in a convergent-straight channel. Numerical simulation was carried out to predict the flow fields in the channel. The predicted results showed that the dispersed phase featured a droplet structure and a fibrous structure near the center line and wall of the channel, respectively. The predicted results were verified by the experiments. Between the center line and wall, a clear transition of the morphology of dispersed phase was predicted. The predicted transition location was compared to the experimentally-determined result and a good agreement was obtained.
POLYMER NANOCELLULAR FIBERS VIA SUPERCRITICAL CARBON DIOXIDE BASED EXTRUSION FOAMING
The quest of novel materials for making lighter fibers for textile and non-woven fabrics applications prompts us to exploit the nanocellular fibers. Thermoplastic polyurethane nanocellular fibers were prepared by extrusion foaming using supercritical carbon dioxide as the blowing agent. Nanoparticles such as nanoclay, multi- walled carbon nanotube, and graphene nanosheets were added as the heterogeneous nucleation agents in order to achieve high-efficiency nucleating effects. Surface functionalizations on nanoparticles were conducted in order to ensure the high-degree dispersion of nanoparticle in the polymer. Optimization of processing conditions is necessary for achieving uniform foams with cell size below 1 m in the fiber having a diameter of less than 30 m. The density of nanocellular fiber was reduced by 30- 50% as compared with that of bulk polymer.
SYNTHESIS OF FUNCTIONAL GRAPHENES FOR HIGH-PERFORMANCE NANOPAPERS
Functional graphenes were synthesized from graphene oxide, which was obtained from low-cost graphite via oxidation. In order to prevent the precipitation of graphene during the reduction process, graphene oxide was partially reduced using sodium borohydride and then treated with diazonium salts having –SO3H or –COOH groups, followed by complete reduction with hydrazine. Functional graphenes were prepared in such a way that they could be well dispersed in water, and as a result, nanopapers could be obtained by flow-directed assembly of individual graphene nanosheets via simple filtration. The presence of functional groups in the graphene also allows the formation of covalent bonds between nanosheets by crosslinking with other polymers. The resulting nanopapers have high electrical conductivity with excellent mechanical properties close to those of steel. These functional graphenes are also promising for the applications in water purifications, ultracapacitors, lithium batteries, and electronic materials.
DISTRIBUTION OF SPECIFIC ENERGY IN TWIN-SCREW COROTATING EXTRUDERS USING ONE-DIMENSIONAL PROCESS SIMULATION
Specific mechanical energy (SME) is a single parameter that represents the energy transfer from the main drive motor through frictional heating for melting, mixing and die pressurization in the compounding process. The calculation of SME is performed using the extruder motor load, screw speed and total throughput to provide energy input on a unit mass basis. Use of one-dimensional computer simulation to analyze the axial distribution of specific energy reveals strategically where this energy is applied in fully-intermeshing, co-rotating twin-screw extruders as a function of screw design.
THE EFFECT OF NANOCLAY ON THE RHEOLOGICAL PROPERTY AND MELT STRENGTH OF POLYPROPYLENE/POLYAMIDE-6 BLEND
Polypropylene (PP) and polyamide-6 (PA6) blend and nanocomposite were prepared using melt intercalation technique by blending PP and PA6 by the incorporation of nanoclay. The melt intercalation of PP and PA6 blend was carried out in the presence of a compatibilizer maleic anhydride grafted polyolyaltha olfin. The rheological property, melt strength and the morphology of PP/PA6 blend and PP/PA6/CN nanocomposite were studied. It was found that the incorporation of nanoclay has positive influence on the rheological property and the melt strength of PP/PA6 blend.
SINGLE-STAGE BLOW MOLDING SIMULATION & CONTAINER PERFORMANCE PREDICTION
For the first time, an analytical computation model has been developed to design and virtually blow preforms on single-stage machines. Due to the complexity of the single stage process, this simulation has been difficult to accurately perform in the past. The model takes into account variables, such as molding temperature and conditioning, to correctly predict the preform profile before blowing. Virtual Prototyping™ software is used to simulate the container blow molding process for round- and oval- shaped containers. The sidewall thickness and mechanical property outputs that are dependent on extent and temperature of stretch are input into finite element analysis software. This enables the computational model to predict container top load and side indentation resistance. A 3L toner bottle case study will show how the computational model was used to evaluate several wide-mouth container preforms for desired thickness distribution and top load performance.
MINERAL REINFORCED IMPACT MODIFIED POLYCARBONATE BLENDS: EXPLORING SPECIFIC FILLER SURFACE INTERACTIONS FOR PROPERTY ENHANCEMENTS
Incorporation of nano to micron scale mineral reinforcements in impact modified polycarbonate blends provides a potential route for achieving high stiffness dimensionally stable blends which are an attractive engineering thermoplastic solution for automotive exteriors and body panels. Designing such blends has traditionally focused on optimizing the flow-impact-stiffness balance. The toughness and impact properties of such reinforced blends are to a large extent dictated by the reinforcing agent characteristics, loading, particle size etc. to name a few. Modifying the surface chemistry of the mineral reinforcements for achieving exceptional toughness and impact properties is the focus of the current paper. The results shall focus on how the interfacial chemistry between the engineering thermoplastic blend and the mineral reinforcement is a key enabler to push the boundaries of flow-impact-stiffness balance in these systems.
A STUDY ON THE PERCOLATION AND DEFORMATION MECHANISM OF POLY(BUTADIENE ADIPATE-CO-TEREPHTHALATE)-LAYERED SILICATE NANOCOMPOSITES
Poly(butadiene adipate-co-terephthalate) (PBAT) is a biodegradable polymer that is used in film applications due to its exceptional elongational properties. Nanoclays such as organically-modified layered silicates are used in an increasing number of applications to improve mechanical, thermal and barrier properties of films. This work aims to elucidate the deformation mechanism and the effects of incorporating a modified MMT clay into PBAT at various clay loading through viscoelastic and tensile measurements, XRD and TEM imaging.
LAYER MULTIPLYING COEXTRUSION OF POLYLACTIC ACID AND POLYVINYL ALCOHOL CAST FILMS
Layer multiplying coextrusion was utilized to produce a films containing polylactic acid and polyvinyl alcohol for food packaging applications. Control films and films containing 9, 25, 73 and 145 layers were produced. The emphasis of this study was to investigate the processability, morphology, barrier, mechanical and biodegradability properties of these multilayer films. The films showed stable layers, high oxygen barrier and mechanical performance that could all potentially be used in a food packaging applications.
VALIDATION OF PREDICTIVE MODEL FOR COMFORT IN POLYURETHANE FOAMS USED FOR AUTOMOTIVE SEATING APPLICATIONS
High resiliency polyurethane (PU) foams are used to provide superior comfort in automotive seating. An existing industry need is to reduce the foam thickness in the seat in order to improve passenger head space and seat weight. In order to maintain the current level of comfort while reducing seat thickness, the underlying physical mechanisms that provide comfort must be well understood. Previously, we presented a method to evaluate dynamic comfort based on a modified Voigt viscoelastic model, and the use of a servo-hydraulic frame to generate model parameters . In this paper, we report the validation of the method and model. Two comparative evaluations were carried out: (1) The transmissivity and damping characteristics of high resiliency (HR) foams were measured by the industry standard Japanese Automobile Standard (JASO) method and compared with the new dynamic oscillatory hysteresis analysis method (DOHA) reported in this paper. (2) Evaluation of the role of foam thickness on dynamic comfort using the new DOHA method. The results showed that the DOHA method compared well with the JASO method for predicting comfort in PU foams. Thus a simple and easy to implement servo-hydraulic method can be quickly leveraged to obtain comfort characteristics of any given foam. A comparison between actual JASO and DOHA predicted transmissivities show good match in terms of shift to higher resonance frequency and amplitude with decreasing foam thickness. Hence DOHA method is an effective tool for studying effect of foam thickness.
TRANSIENT PARTICLE FLUX DURING INJECTION OF COMPOSITE POLYMER COMPOUNDS AND THE RELEVANCE OF SUBSEQUENT MANIFESTATIONS IN MULTI-CAVITY TOOLING
An experimental analysis of the degree of particle diffusion is conducted and analyzed, focusing on multi-cavity tooling. Highly reinforced composite resins are injected into multi-cavity tooling and subsequently analyzed by thermal and mechanical approaches to uncover the degree of shear-induced particle diffusion manifesting under varying injection velocities, mold temperatures, and primary runner aspect ratios. Results indicate that shear induced diffusion is occurring in the length and time scales employed, yet the imposed environments, favorable to particle diffusion, show relatively low influence on cavity-to-cavity gradients in particle concentrations with net migrations occurring opposite to theoretical notions under molding environments. A significant local migration is found to occur radially within the melt delivery. Mechanical properties exhibit a dependence on the rheological history of the polymer in.
MOISTURE RESISTANT TECHNOLOGIES FOR WOOD COMPOSITES
Synthetic fiber reinforced thermoplastic composite materials have become staples for automotive, construction, defense, aerospace and consumer products. Most of these composites are derived from glass or carbon fiber reinforced engineering thermoplastics. However, polyolefin based composite materials are being applied in cost sensitive applications that demand higher performance. Examples include glass reinforced polypropylene (PP) composites and natural fiber reinforced polyolefin composites. Wood composite based products (WPC’s) have rapidly penetrated non-structural wood applications because they offer the consumer low maintenance attributes and durability. However, the best wood composites on the market today are ½ the strength, twice the weight, and as much as five times the cost of pine and cedar! Additionally, there is a need for composites to have improved resistance to moisture and the elements. This work describes new interfacial modifiers for natural fiber and wood filled polyolefin composite materials that have been recently developed by Interfacial Solutions.
SUSTAINABILITY AND THE PLASTICS INDUSTRY
In the past green business evolution among business organizations has gone through “three waves of change” (Makeower, 2009, p. 12). In the 1960s businesses started being green with the notion “Do no harm” and companies started minimizing the environmental impacts (Makeower, 2009, p. 12). In the 1960s, companies mainly focused on pollution control that included stopping illegal activities such as “spewing smokestacks and drainpipes” (Makeower, 2009, p.12). In the 1970s, the U.S. Environmental Protection Agency and similar agencies were formed in the United States and in the other countries with standard laws about pollution of air and water (Makeower, 2009, p. 9). The second wave occurred in the 1980s and emphasized “Doing well by doing good” as companies realized that taking a few proactive steps could reduce costs and enhance a company’s image (Makeower, 2009, p. 10). Later, companies started being concerned about issues like pollution prevention, waste reduction, and energy efficiency. Then in the 1990s came the third wave: “Green is green” (Makeower, 2009, p. 12). During the third wave companies paid more attention to the environmental issues. As stated by Makeower (2009), “Companies recognized that environmental thinking can do much more than improving the bottom line i.e. it can help grow the top line through innovation, new markets, and new business opportunities”. In September 1996, the ISO 14001 environmental management system was issued and applied, establishing “a baseline set of rules for how companies should be organized environmentally” (Makeower, 2009, p. 10). According to Makeower (2009), “as companies scrutinized their operations, they understood how much of their environmental impacts were affected by their external stakeholders hence Supply-chain Environmental Management became the watchword after that the concepts of industrial ecology, zero waste, and carbon-neutrality emerged” (p. 11). Today companies are finally concerned about the “S-word, sus
DYNAMIC PROPERTIES OF CROSSLINKED POLYOLEFIN FOAMS
The material of choice in the foam industry for many years was Ethylene-Vinyl Acetate copolymers (EVA). This dominance was based on its flexibility, adhesion performance, and foaming window. In the last ten years, ethylene- ?-olefin inter-polymers (or Polyolefin Elastomers (POE)) have been integrated in foam formulations as a means to increase processability and cost efficiency. In recent years, the discovery of INFUSE™ Olefin Block Copolymers (OBC’s) has increased the benefits of using ethylene-?-olefin inter-polymers in foam applications. This paper shows that the characteristics that make INFUSE™ OBC’s of interest in Crosslinked (XL) foam systems are increased softness, improved shrinkage, and compression set resistance at elevated temperatures. The paper also shows that OBC foams long term fatigue behavior departs from that of EVA and POE foams with the same cure state. The room temperature data allowed one to draw the following conclusions: (i) OBC foams showed a more elastic response than EVA and POE as demonstrated by lower final strain and faster recovery after dynamic testing; the elastic response of OBC foams was attributed to its block architecture, and (ii) short chain branching based materials (OBC and POE) seemed to recover faster than the long chain branching based EVA foam.
GLASS FILLED POLYBUTYLENE TEREPHTHALATE WITH ENHANCED SURFACE AESTHETICS
Typically glass filled semi-crystalline polymers like polybutylene terephthalate (PBT) have poor surface aesthetics especially in gas assist molded high gloss surfaces like oven door handles but are still preferred due to their mechanical properties. Such surface issues have a tendency to show up more in dark colors like black which is one of the preferred colors for oven door handles. SABIC-IP has developed a new glass filled PBT based product to provide with improved surface appearance on gas assist molded in black colors. Higher gloss readings and lower glass fiber counts were observed on the surface of molded products.
SURFACE ENERGY EFFECTS OF PC/SAN/MWCNT BLENDS WITH THE ADDITION OF A REACTIVE COMPONENT
Carbon nanotubes (CNTs) have been shown to be a versatile filler that influences several properties favorably. One such property of concern is the electrical conductivity of multiwalled CNTs (MWCNTs) which can be transferred into insulating matrices by filler percolation. In melt-mixed co-continuous poly(styrene-co-acrylonitrile) (SAN)/ polycarbonate (PC) blends containing different types of MWCNTs, a selective localization of the CNTs in the PC phase is found. This was independent of the polymer phase in which the CNTs were first incorporated. This localization will be explained using the wetting concept. In the presentation we will show the effect of adding a reactive component.
INFLUENCE OF COMPONENT WARPAGE ONTO PROCESS CONTROL AND COMPONENT PROPERTIES DURING VIBRATION WELDING
Vibration welding is a well-understood and established joining technology in the industry. In numerous studies the process understanding and process control strategies have been developed. To reach reproducible weld properties, the phase of steady-state melt formation and constant melt-down rate must be achieved during the process. More recent results demonstrate the enormous influence of the decay time onto morphology and mechanical properties of the weld seam. These results confirm the known structure-properties relationship. Industrially manufactured components always have more or less deviations from the target geometry. Typical effects as large-scale warpage, local sink marks or lateral offset of the parts results in locally different conditions during the joining process. The current strategy in case of component warpage is to increase the joining pressure to achieve complete matching between the two joint surfaces. The force-depending deformation of the joint parts during welding results in locally different joining pressures over the weld length. These different joining pressures lead to locally different weld properties. The presented project shows the effects on process behavior and the results on weld quality, local and global. Longer welding times do not help.
IN-MOLD SURFACE MODIFICATION AND IN-MOLD PRINTING DURING INJECTION MOLDING
Surfaces of plastic parts often need a pre-treatment before they can be further bonded or painted. In the presented project an innovative method of process-integrated surface modification by surface-reactive injection molding has been investigated. Before the injection cycle starts a thin modifier film is applied uniformliy (or selectively) on the mold surface. Then the high temperature of the injected polymer melt is used to initiate a chemical reaction binding functional groups to the newly created surface of the plastic part. Controlling the adhesion processes like chemical reactions in the millisecond range is especially challenging. This means that no subsequent surface pre-treatment is needed in order to save costs, time and energy. In contrast to many of the commonly used methods, the modification effect is permanent. The surfaces can be functionalized in a broad range by tailoring the type of the modifier for e.g. hydrophobic or hydrophilic surfaces. In current investigations even the modification of polyolefins could be achieved successfully. One of the most promising applications would be In-Mold Printing where fully finished surface decorated parts can be produced during injection molding. Here even two subsequent processing steps are saved compared to the common printing process of polymer parts: the surface modification for better adhesion and the printing itself are integrated in the process of injection molding. This could be realized by printing patterns of modified paint on the mold surface, e.g. by pad printing. During injection molding the paint is transferred completely to the surface of the polymeric part, which develops at this point. In-Mold Printing shortens the process chain, saves material, energy and time and opens new application fields, e.g. the integration of printed electronics to low-cost plastic products in mass-production.
EFFECTS OF COMPONENT VISCOSITIES AND DISPERSED PHASE VOLUME FRACTION ON RELAXATION BEHAVIOR FOR POLYMER BLENDS
The influences of the viscosities of the matrix and dispersed phase, and the volume fraction of the dispersed phase on the relaxation behavior reflected on the Cole-Cole plot and the imaginary part of complex viscosity curve are analyzed using the Maxwell and the Palierne models and experimental data. It is found that these three parameters have a great impact on the radii of the circular arcs of the Cole-Cole plot. Moreover, the total relaxation time of the deformed droplets increases with the increase of the viscosity and volume fraction of the dispersed phase, especially the increase of the viscosity of the matrix. In addition, it is important to found that the Cole-Cole plot is invalid to analyze the miscibility of the polymer blend when the droplets of the dispersed phase have not enough time to relax during dynamic frequency sweep test.
CHANNEL FLOW SIMULATION WITH DELAYED FOLGAR TUCKER FIBER ORIENTATION MODEL
A 2-D channel flow simulation is performed with delayed Folgar Tucker model for rigid short glass fiber orientation. The continuity and Navier-Stokes equations are discretized using Galerkin finite element method and the constitutive equation for fiber orientation is discretized using discontinuous Galerkin finite element method. Material parameters have been taken from a study conducted earlier in our group. The effect of fountain flow is included in the simulations by using a pseudoconcentration method and performing a full solution of balance equations.
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