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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Biconstituent Fiber Spinning Modeling by Using Phan Thien– Tanner Multimode Constitutive Equation
A one-dimensional model (1) for fiber spinning simulation was developed based on traditional transport phenomena equations, a Phan Thien–Tanner multimode viscoelastic model and a crystallization kinetic model.In order to solve the coupled system of differential equations a finite difference scheme and a Crank-Nicholson solution algorithm were implemented. The results of simulations were validated using data from other researchers and our experimental data from fiber spinning of Polypropylene and biconstituent fibers of Polypropylene and Polyamide 6.
Influence of Cavity Materials on the Cooling Time of Molding
The laws for optimal heat exchange in molds for injection molding of thermoplastic melts have been known for a relatively long time, more than 30 years. But from time to time we can read and hear that someone has achieved shortening of the cycle time and hence the cooling time of molding also by two-digit percentages. Based on the general equation of the cooling time of molding, for the necessary quality of molding, thus for the given process parameters (melt and cavity temperature), properties of thermoplastic melt (deflection temperature under load, thermal diffusivity) and geometry of molding the cooling time is constant. The only way to reduce the cooling time and thus the cycle time as well is the choice of proper materials for mold parts forming the cavity. Materials with low thermal properties offer great opportunity for shortening the cooling time, but their advantage is restricted to relatively small parts.
The Proposal for Classification of Injection Molding Procedures
During our investigations of the state of the art of injection molding of materials and substances we found out that there are at least 235 procedures which can be classified as injection molding of the living and the nonliving. The aim of this study is also to present these procedures in a logical order. We use two systems of codes. The aim of the first code (31 digits) is only for the proper classification of procedures into the main groups. The second one is a code with 7 digits which are for practical use. We made this description by dividing the necessary criteria into 5 main groups. The basic criterion is the injection pressure. Full description of all the 235 procedures demands an international cooperative project, which must unify the academia and the industry.
Thermoplastic Polyurethane Nanocomposites of Reactive Silicate Clays
End-tethered thermoplastic polyurethane-clay nanocomposites were prepared by bulk polymerization method; polyether and polyester polyols of molecular weight 2000 were used to form the soft segments by allowing reactions between the isocyanate groups in chain extended polymers and the hydroxyl groups in organic modifier. The mechanical and thermal properties of the resulting composites were investigated to study the effects of clay content and the nature of polyol. Composites based on polyester polyol showed better nanoclay dispersion and much improved mechanical properties. Up to 78% increase in tensile modulus, 125% increase in tensile strength, and 100% increase in elongation at break were observed with polyester polyol based nanocomposites at 5 wt% clay loading.
Application of CAE Technique in Process Optimization and Part Quality Control of Injection Molding
In injection molding, many factors affect the molding process and the final quality of the products. The production problems on materials properties, design of products, and design of molds can be solved with the help of CAE systems, but it is still relied on the experience of the operator concerning the process setup and parts quality control. In this paper, application of CAE technique in studies of relationships between process parameters and quality indexes of the part, process modeling, process parameters optimization and part quality control are introduced systemically.
Nanocomposite Systems Based on Unsaturated-Polyester and Organo-Clay: A Fundamental Approach
Unsaturated-polyester (UP) resins are bicomponent systems comprising an UP alkyd, usually dissolved in styrene monomer. This gives rise to numerous possible approaches in synthesizing UP nanocomposites. UP-resin/organo-clay nanocomposites and UP-alkyd/organo-clay nanocomposites were investigated. The effects of various mixing processes and parameters, using several organically modified clay types were studied. This methodological approach provides a basis for understanding the structuring processes involving the formation of the UP/clay nanocomposites and establishing materials-processingstructure interrelations.
Comparative Deformational Characteristics of SEBS Thermoplastic Elastomers and Vulcanized Natural Rubber
Three Poly (styrene-b-ethylene-co-butylene-bstyrene) (SEBS) thermoplastic elastomers (TPEs) are studied mechanically and compared to cross-linked natural rubber system. It is observed that subtle alterations in the mid-block of the TPEs affect the mechanical properties significantly. The stress relaxation at room temperature is reduced in systems where the ratio of ethylene to butylene segments in the mid-block is greater than one. The cyclic behavior of these systems also shows significant elastic hysteresis. Differential Scanning Calorimetry suggests that these TPEs crystallize at low temperatures, similar to the observed behavior in a vulcanized natural rubber. Simultaneous WAXD/SAXS measurements on a deformed sample highlight deformation at the nanometer and the molecular length scales. In-situ WAXD at different strains also provides evidence for strain-induced crystallization occurring in the selected systems. Strain-induced crystallization in these TPEs accounts for the retention of their highly elastic behavior. Results from Deformation Calorimetry further reinforce the evidence for strain-induced crystallization in certain systems.
Production of Conductive Multiphase Polymer Systems via Selective Localization of Carbon Black under Chaotic Mixing Conditions
Selective localization of conductive fillers such as carbon black (CB) in multiphase polymer system was exploited to reduce the percolation threshold and to obtain conductive composites. Polypropylene (PP) filled carbon black compound was mixed with polyamide 6 in a chaotic mixer. Double percolating fibers of PP/CB compounds were responsible for conductivity of the blend at low mixing strains. At higher strains, the PP fibrils, containing carbon black, formed droplets. However, the conductivity was not compromised due to selective localization of carbon black particles at or near the interfaces of the closely spaced PP droplets. At even higher strains, the blend turned into insulator as the PP-droplets distributed more uniformly in the blend and carbon black particles migrated to the interface of PP and PA6-phase.
On the Three-Dimensional Modeling of Polymer Processes
The accurate modeling of polymer processes for prediction or design purposes requires many considerations. These include defining the problem, determining the necessary physics the model should include, determining the equations needed to be solved, determining the rheological parameters important in the particular problem being solved, running rheology experiments to determine these parameters, deciding on the best" rheological model to represent the rheological data creating a 3-D representation of the flow domain volume on which the equations are to be solved determining and specifying all necessary boundary conditions obtaining or writing a 3-D flow code which incorporates all the preceding information running the program and finally determining and displaying the output data for which the modeling process was performed. Each of these considerations is discussed to some extent in this paper."
On-Line Morphology Control Features of Continuous Chaotic Advection Blenders
Blending has been typically regarded as a mixing process, so the variety of producible structures in melts and attainable physical properties of plastics have been constrained. In contrast, a variety of polymer blend morphologies have been deliberately constructed in situ with novel blenders based on chaotic advection. Operation of a continuous chaotic advection blender is described that allows on-line control of blend morphology development or of the arrangement of particulate additives in polymer melts. Notably, features allow efficient structure-property-composition optimization, the production of extrusions with periodic or graduated properties, and assembly of functional devices.
New Generation of TPUS; Short-Term Characterization and Applications
TPU or thermoplastic polyurethane belongs to the thermoplastic elastomers or TPE family. TPUs combine the processability of thermoplastics and the flexibility of elastomers. TPU could be tailored to cover a wide range of hardness (about 70D to 80A) by changing its chemistry, such as the chemical components or molecular weight, or the type and content of additives. Traditionally, adding plasticizer to TPU resin produces the softer grades down to shore hardness of 60A. A new trend in producing soft TPU grades is to manufacture them free of plasticizers. This is achieved by controlling the TPU chemistry.In this work, Elastollan® C75A15HPM (which is plasticizer free) is compared to Elastollan® C75A15W (which has plasticizer). Different methods are used to characterize the short-term properties of these materials. Tensile, thermo-mechanical, tear, melt-viscosity, and surface properties are discussed. The relation of these properties to processing and application is described.
Processing - Structure - Property Relationships in Bicomponent Blown Film Extrusion Using Online Raman Spectroscopy
Crystallinity was measured in real-time using online Raman spectroscopy during blown film coextrusion of polyethylene (LDPE) and polypropylene (PP). The effect of blow-up ratio (BUR) and take-up ratio (TUR) on the crystallinity development of individual components, PP and LDPE, is reported. The kinematics of the process was found to be controlled by polypropylene, the component which freezes first. Temperature measurements revealed the appearance of double plateaus in the profile, one at the onset of crystallization of PP and the other near crystallization of PE, for some processing conditions.
Lubrication Mechanism of Poly(Vinyl Chloride) Compounds: An Understanding of Lubricant Failure at Higher Processing Temperatures
Poly(vinyl chloride) (PVC) compounds require metal lubrication and polymer to polymer lubrication for good processing performance. Much of the mechanism for PVC’s lubrication has been elucidated over the years. One point has not been completely understood, that is the “lubricant failure” at higher processing temperatures where the compound becomes more brittle. This is contrary to what might be expected with better PVC fusion (gelation). This paper discusses the mechanism involved, which is lubricant inversion, where the lubricant goes from the continuous phase to becomes the discontinuous phase.
The Influence of Painting Systems on Low Temperature Deployment Behaviour of Airbag Covers
Paint systems have influences on the low temperature Airbag Deployment of airbags. This influence is related to several items like:Type of paint which is usedMaterial properties of the paintKind of adhesion promotingPolarity modification of the substrate. (Polarity increase)Use of an adhesion promoting primerSarlink 3939DB-01 unpainted withstands the airbag deployment requirements till –35 C. In order to find out how big the influence of the paintsystems can be, Sarlink 3939DB-01 has been tested with 2 paint systems from Mankiewicz: a “Solvent Based” and “Waterborne” system, as well as with 2 other waterborne systems from other paint manufacturers. These systems have been tested in combination with an adhesive promoting primer or with a flame-treated surface, without primer.Furthermore 2 new Sarlink ® development products have been tested in comparison with Sarlink® 3939DB-01 with the waterborne system of Mankiewicz in combination with their primer system, to investigate the possibility to improve low temperature properties without changing the paint system.The following results were obtained:Both (waterborne and solvent based) paint system have a negative influence on the low temperature behavior at testing temperatures below –55C, which is regarded as representative for high speed airbag deployment around –35C.Water-borne paints used in this study outperform the solvent-based paint!Flame treatment instead of the use of an adhesive promoting primer, improves the low temperature behavior substantially.The 2 new development products outperform the 3939DB-01 in low temperature behavior, with only slightly lower stiffness for 04EW033 at 80° C. At 20° C both 04EW033 and 034 have a higher stiffness.One of the development products 04EW033 in the painted state performs even better than the Sarlink 3939DB-01 in the unpainted state and can overcome the negative effects of the paint.The findings from our investigations have been confirmed by testing at our Tier1 customers rec
Effect of Compatibilizing Agents on Clay Dispersion of Polypropylene-Clay Nanocomposites.
In this work, polypropylene-clay nanocomposites were obtained and studied by using three different coupling agents, glicidil methacrylate (GMA), acrylic acid (AA) and maleic anhydride (MA). Three different clays, natural montmorillonite (Closite Na+) and chemically modified clays Closite 20A and 30B have also been used. Nanocomposites were prepared by melt blending in a twin-screw extruder using two methods of preparation, with only one pass and two pass trough the extruder. The relative influence of each factor was observed from structural analysis by SAXS, and mechanical properties. The results were analyzed in terms of the effect of each compatibilizing agent and incorporation method in the clay dispersion and mechanical properties of the nanocomposite.
Compatibilization of Poly(Vinyl Chloride) with Polyamide and with Polyolefin with Poly(Lauryllactam-Random-Caprolactam-Block- Caprolactone)
The compatibilization of various poly(vinyl chloride) (PVC) blends was investigated in this study. The blends systems were PVC-polyamide 12(PA12), PVC-polypropylene (PP), and PVC-ethylene propylene diene rubber (EPDM) with a new compatibilizing agent, random-block terpolymer poly(?-lauryllactam-random-?- caprolactam-block-?-caprolactone) or systems containing these copolymers. It was compared to previous studies using poly(?-lauryllacatam-block-?-caprolactone) copolymer. This block copolymer was specially synthesized by reactive extrusion. Observation by scanning electron microscopy (SEM) reveals that compatibilized blends have a finer morphology than that of the noncompatibilized blends. Addition of 10 weight percents of block copolymer proved to be sufficient to give a significant improvement of the mechanical properties of the immiscible PVC blends at room temperature and high temperatures which are above glass transition temperature of PVC.For polyolefins, a three component compatibilizing system including maleated polypropylene, polyamide 12, and block copolymer was used.
Three-Dimensional Mold Cooling Analysis for Injection Molding Process
Mold cooling process in injection molding is critical in order to reduce cycle time and improve the quality of molded part. In this paper, a fully three-dimensional mold cooling analysis is developed. Mold heat transfer is considered as cyclic-steady, three-dimensional conduction: heat transfer within the part is treated as a three-dimensional transient heat conduction; heat exchange between the cooling channel surfaces and coolant is treated as a cycle-averaged steady state three-dimensional heat conduction. Numerical implementation includes the application of a hybrid scheme consisting of a 3D BEM for mold region and a CVFEM for part. These two analyses are iteratively coupled in order to match the temperature and flux at the interface. The present analysis is then used to predict the temperature field for a 3D plastic part geometry.
Transient Solutions and Experimental Observations Casting Process Accompanied by Flow-Induced Crystallization
The dynamics and stability of film casting process including crystallization kinetics have been investigated using a 2-D model with finite element method (FEM). The transient solutions of extensional deformation processes such as film casting, film blowing and fiber spinning are essential for the comprehensive analysis of their dynamics, but they are found extremely difficult to obtain if flow-induced crystallization (FIC) occurs, while it is rather a simple exercise without it. Once the transient solutions of film casting process with flow-induced crystallization were obtained, the information on this transient behavior becomes extremely useful for the optimization and stabilization of the process. Experimental corroboration using isotactic polypropylene (iPP) has been achieved.
Temporal Profiles of Spinline Variables in Fiber Spinning Process Accompanied by Flow-Induced Crystallization
The transient behavior of fiber spinning process when flow-induced crystallization occurs on its spinline has not been reported yet in the literature, whereas the steady state behavior has been well understood and simulated by various researchers as well as the transient behavior without crystallization on the spinline. In this study, this particular issue has been investigated incorporating flow-induced crystallization into the mathematical model of the system and then devising proper numerical schemes to produce the temporal pictures of the system. It turns out that the difficulty for obtaining the transient solutions of fiber spinning accompanied by flow-induced crystallization lies in the extreme sensitivity of the spinline velocity toward the fluid stress level at the spinneret. With the successful transient solutions of fiber spinning with flow-induced crystallization, nonlinear stability analysis has been investigated to advance an understanding of the process.
Properties of Rapidly Formable Composite Bipolar Plates from Graphite Filled Wet-Lay Composite Materials
The wet-lay sheets consisting of thermoplastic (Poly(phenylene sulfide) (PPS)) fibers, graphite particles and carbon fibers are generated and used to compression molding bipolar plates with gas follow channels. The bipolar plates have high electrical conductivity (in-plane), high corrosion resistance, excellent mechanical properties and thermal stability. The plates have in-plane conductivity of 270 S/cm, tensile strength of 57.5 MPa, flexural strength of 95.8 MPa and impact strength (unnotched) of 84.2 J/m. All these values exceed the industry's requirements or targets for composite bipolar plates. The through-plane conductivity (around 20 S/cm) and half-cell resistance of the bipolar plate indicate that the through-plane conductivity of the material needs some improvement.
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