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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3D-FE Simulation of Injection Molding - Calculation of Fiber Orientation and Crystallization
The simulation of injection molding has considerably gained in importance for mold design as well as for process design. Therefore, at IKV a 3D-simulation program based on finite elements has been developed, which has recently been enhanced through a module for the calculation of fiber orientation in short fiber reinforced parts. For reasons of numerical efficiency the simulation program makes use of a tensor model for the description of fiber orientation.Mechanical and optical properties of polymers are to a large extent influenced by morphological properties, especially by the degree of crystallization. Therefore, a model for the calculation of crystallization kinetics is currently being implemented into the simulation software.
Acrylate Elastomer Modified Polyolefinic TPEs
Soft polyolefinic TPEs are increasingly being favored over PVC based TPEs for automotive interiors. The major drivers for this change are the recycling and environmental aspects of PVC. Some strengths of polyolefinic TPEs are good low temperature performance, retention of properties after exposure to sunlight and high temperatures, low fogging, and little or no odor. The challenges in switching from PVC to polyolefinic TPEs involve attaining the desired melt processing characteristics and the mechanical and aesthetic properties at a relatively low cost. This paper will discuss Eliokem's use of a specialty acrylate elastomeric modifier in designing polyolefinic TPEs for automotive interiors and other applications
Acrylic Capping Resin Compositions
This paper describes acrylic-based resin compositions for use in co-extrusion over various substrates including PVC, ABS and CPVC. These acrylic compositions exhibit significantly improved weathering performance along with excellent impact strength when compared to existing vinyl-based compositions used in applications such as siding, windows and fencing.The acrylic-based compositions require the use of some modifiers to improve impact strength, gloss, flow and other physical properties. A comparison between the modified acrylic-based resin and PVC resin is discussed.
Adapting Finite Element Analysis to Perform Small Molecule Permeation Analysis
Until recently, there has been no extensive research done to predict small molecule permeation through polymer membranes using computer analysis. Advances have been made using finite element analysis software to help to try to predict this phenomenon. This has been successfully completed with two-dimensional models, but has not been performed on a three-dimensional model, which is necessary for products such as blow molded bottles. This paper will analyze a three-dimensional finite element analysis and compare those results to hand calculations to determine if finite element analysis software can serve as a reliable mean of analysis for permeation.
Additives for Improved Surface Adhesion in Polyolefin/Acrylate Monomer Blends
Blends of metallocene polyolefins and acrylate monomers are a new technology which provide materials with an attractive combination of physical properties. To utilize this new technology in as large a number of application areas as possible, modification of the surface adhesion properties of the cured blends is desired. A study of the effect of additives on the adhesion properties of representative blends has been carried out. The additives include monomeric, oligomeric and polymeric compositions. Functionality on these additives included groups that are expected to participate in the cure chemistry, as well as non-reactive additives. The effects of these additives on adhesion to typical inks, paints and coatings will be described.
Adhesion of Ethylene-Styrene Copolymers to Polyethylene in Microlayers
The effects of styrene content and temperature on the adhesion of ethylene-styrene copolymers (ES) to low density polyethylene (LDPE) were examined by measuring the delamination toughness of LDPE/ES microlayers in the T-peel test. Experiments on microlayers with relatively thin (8 to 18?m) ES layers demonstrated that delamination toughness was proportional to ES layer thickness. Excellent adhesion was observed between LDPE and ES. Increased styrene content led to decreased delamination toughness. Major transitions in delamination toughness and delamination mechanism were observed at the glass transition of the ES and the ?-transition of the LDPE.
Adhesion of Polypropylene to Metallocene/Ziegler-Natta Polyethylene Blends in Microlayers
The adhesion of polypropylene (PP) to blends of a metallocene and a Ziegler-Natta polyethylene (PE) was highly dependent on the density of the metallocene PE. The systems with the lowest density metallocene PE showed the highest adhesion to PP. This finding supported the hypothesis that a layer of low molecular weight, amorphous chains, originating from the Ziegler-Natta PE, formed at the PP/PE interface. The lower density metallocene PE was believed to misciblize the amorphous chains of the Ziegler-Natta PE and prevent their migration to the interface, thus improving adhesion to polypropylene.
An Adipate Based Polymeric Plasticizer with Improved Low Temperature Properties
Adipic acid based polymeric plasticizers are the workhorses of the polymeric plasticizer market. They offer a useful combination of softening efficiency and permanence at a cost that is reasonable as polymeric plasticizers go. One property of polymeric adipates that does not quite meet the performance requirements of vinyl com pounders is low temperature flexibility. In particular the wire and cable industry requires improvement in low temperature properties to pass the lower brittleness temperature tests that resulted from post-NAFTA harmonization of the Canadian and U.S. standards for electrical insulation. In addition, while the viscosities of adipates are not high relative to polymeric plasticizers based on other chemistries, lower viscosity for equivalent molecular weights is a characteristic that would be desired by anyone handling polymeric plasticizers. The lower viscosity also accounts for processability improvements in vinyl.This paper will introduce a new adipic acid based plasticizer developed by Velsicol Chemical Corp. that lowers the brittle temperature of a vinyl com pound by 3 to 4 °C over Admex 6996®, a benchmark plasticizer of the same molecular weight. Permanence characteristics and softening efficiency are similar to the performance of the benchmark. The viscosity at 25°C is 25% lower than conventional adipates of equal molecular weight.
Advanced Sequencing and Protection of Valve Gate Systems
The control of valve gate sequencing used to be limited to timers. The growing trend is to use screw position and even cavity pressure to determine when to open and close the valve gates in a hot runner system. In some cases, a combination of control parameters may be used.Sequencing systems can also be made to protect valve gate systems from misuse. For example, the accidental application of injection pressure when none of the valve gates are open can now be avoided; as can the exposure to high temperatures when mold cooling isn’t present.This paper intends to cover emerging advancements in both sequence control and protective elements.
Advances in Techniques to Determine Extensional Rheology from Capillary Measurements
Flow through an abrupt contraction has been analyzed experimentally and theoretically through FEM simulations using the modified White-Metzner model. The results show that the 'entrance viscosity ?ENT' (entrance pressure drop divided by the shear rate) strongly depends on the shape of the steady extensional viscosity, the L/D ratio of the orifice die and it can be properly described by the newly proposed model. A Trouton Correction" was proposed and successfully tested to improve the capability of the entrance techniques to properly predict extensional viscosity at low extensional rates. It is demonstrated that the proposed improvements in this work help to more effectively evaluate extensional rheology from capillary measurements."
Advances on Filament Winding Technology to Produce Composites from Thermoplastic Towpregs and Coated Tapes
Cost-effective glass-reinforced thermoplastic matrix towpregs produced by a developed powder coating line were used to manufacture composite structures by filament winding. A conventional filament-winding equipment was adapted for processing such structures at industrial scale.To increase the filament winding production rate, a die was introduced in a powder-coating unit to allow producing pre-coated tapes (PCT) from glass fiber/polypropylene (GF/PP) towpregs. The final properties determined on the produced structures, the technological advances of the filament winding process and the work developed to optimize production at industrial scale are presented and discussed.
Amine Modified Poypropylene as Adhesion Promoting Agent. Preparation and Characterization
Polypropylene (PP) grafted with maleic anhydride (PPgMA) was modified with an excess of di-amines (DA) in the melt. The modified polymer (PPgDA) was characterized by FTIR, contact angle and wetting tension. FTIR results demonstrated that PP was modified with amine groups. Blends of PP with 0 to 100% wt of Polypropylene grafted with Diamine (PP-gDA) were prepared by melt mixing. From contact angle and wetting tension measurements it was observed changes in the surface polarity. The effect of the amine modified polymer content on the surface of cast films was characterized through contact angle and wetting tension measurements. The contact angles of water on cast film surfaces of PP/PPgDA blends decreases with increasing modified polymer content mean while the wetting tension shows an increment with the increasing of amine modified polymer.
Aminosilane Superficial Treatment of Lignocellulosic Fillers: Composite Preparation and Mechanical Properties
Composite preparation including plasticized PVC and different lignocellulosic fillers was carried out. Different contents of fillers were used (20, 30 and 40% in weight), without modification and also treated with a coupling agent, N-(-2-aminoethyl)-3 aminopropyl trimethoxy silane at three concentrations (1, 2 and 3 %). Mechanical and rheological properties of the composites were evaluated. Electronic and optical microscopy was used to analyze the dispersion. Dynamic mechanical analysis was carried out to obtain Tan ?, Hook´s and Newtonian´s modulus.
Analysis of Carpet Recycle Streams Using Differential Scanning Calorimetry, Thermogravimetric Analysis and Gas Chromatography
In order to make an injection moldable product with consistent properties from recycled carpeting, quantitation of the polymeric and non-polymeric components of the carpet feed stream is required. Feed mixtures containing nylons, polypropylene and PET as well as latex and calcium carbonate from backing material have been studied. A combination of DSC and TGA measurements is shown to provide compositional data on both polymeric and non-polymeric components in a rapid and inexpensive manner. More exact determination of polyamide components is accomplished using hydrolysis and derivatization to prepare samples for gas chromatography.
Analysis of Extensional Viscosity Techniques for the Characterization of Fluoropolymers
Extensional flow properties of PVDF and PE having different molecular weights (Mw), molecular weight distribution (MWD), or degree of long chain branching (LCB) are investigated for film blowing application using the Rheotens melt tester. The Rheotens generates elongational flow by pulling an extruded polymer strand through a pair of toothed wheels and recording the pull down force F and the draw down ratio V. Extensional viscosity is converted from F-V relationship by two alternatives, one is the derivation proposed by Laun and Schuch (1), and the other is the more recent constitutive equations proposed by Wagner et al. (2). These methods are evaluated by comparing the resulting extensional viscosities to other methods including the Cogswell’s entrance pressure drop in a converging flow (3).
Analysis of Flow in Single Screw Extruders
In the analysis of flow through a single-screw extruder, it is generally assumed that the kinematic condition, rotating barrel around a stationary screw (B), generates the same flow distribution as the kinematic condition, rotating screw inside a stationary barrel (A). Recently this assumption was questioned.This paper addresses the issue of kinematic reversal in detail. The steady state creeping flows in a single-screw extruder under kinematic conditions A and B will be investigated by theoretical analyses, and 3D numerical simulations using the CFD software, POLYFLOW. Both analytical and numerical results indicate that kinematic conditions A and B result in the same flow field. Apparent differences appear only when a flat plate approximation (FPA) is used. However, these differences are solely due to the fact that the FPA does not take channel curvature into account. When channel curvature is properly accounted for by using cylindrical coordinates, conditions A and B produce the same velocity distribution.These results indicate that the FPA should not be used with deep flighted screws because it introduces serious errors. Similarly, the analysis of both kinematic conditions by using the FPA inevitably leads to erroneous results. The error introduced by using the FPA analysis with a moving screw is even greater than with a moving barrel.
Analysis of Low Levels of Polyvinylpyrrolidinone in Polysulfone by FTIR and Pyrolysis GC/MS
FTIR and Pyrolysis GC/MS are two analytical techniques which we used to investigate the detection of polyvinylpyrrolidinone (PVP) as a low level impurity in polysulfone (PSO). These analyses are demonstrated to be convenient and rapid alternatives to time-consuming methods such as solvent extraction, when PVP is thought to be present as an impurity in PSO.FTIR analysis was performed by comparing the intensity of the IR absorption stretches of PVP and PSO. We selected absorbances at 1680 cm-1 and 1586 cm-1 for PVP and PSO, respectively. These absorbances were selected because of their relatively high intensity, and because they are well resolved from each other and from other strong absorbances. It was thus possible to detect and quantitate PVP in PSO to a level of 0.5%, with very good linearity of response. A significant advantage of this method is that it allows for rapid and non-destructive monitoring of the two blended polymers.Pyrolysis GC/MS was also used to investigate low levels of PVP in PSO. Comparison of the levels of certain unique and well resolved pyrolysis products (such as 2- pyrrolidinone from PVP and phenol from PSO) permitted detection and approximate quantitation of PVP in PSO, with a practical detection limit of 0.05%. EI+ ionization was used to produce a mass spectrum of the components of interest, which could be reliably identified by comparison to standard library reference spectra.
Analysis of Melt Instabilities of Poly-(Vinylidene Fluoride) in Shear and Extensional Flows
The melt instabilities of polyvinylidene fluoride (PVDF) were studied in shear and in extension using a capillary rheometer and Rheotens melt tester, respectively. In shear, emphasis was given to wall slip and melt fracture during extrusion in capillary dies. The combined effect of the critical stresses for melt fracture and slip to the appearance of the extruded strands for different die size, and polymer molecular weight were also studied. The results shows that PVDF exhibits a different mechanism of instabilities compared to the those known for polyethylenes. Additionally, wall slip was shown to occur starting at very low shear rates.
Analysis of Parameters Determining the Friction Properties of Thermoplastics in Injection Molding
Frictional forces must be overcome during ejecting of parts molded over deep cores. The friction properties between the molding surface and the part are important for the design of the ejection system. Prototype equipment and test methods were already developed and proposed to characterize the friction properties in as-molding conditions.A factorial design of experiments was devised to establish the hierarchy of the parameters that affect the static friction in ejection. Two thermoplastics (PC and PP) and steel surfaces were considered. The parameters under study included: surface roughness, direction of machining with respect to the test direction and testing temperature.
Analysis of Silicone Polymers at Trace Levels by Pyrolysis Gas Chromatography/Mass Spectroscopy
Silicone polymer release liner surfaces on paper, for self stick stamps and labels, become contaminants in paper recycling. Low print adhesion is one major problem limiting the inclusion of silicone release liners in recycling feed stock. A very sensitive method of analysis of silicone polymer during and after recycling employs pyrolysis GC/MS. The analysis provides a measure of siloxanes, ignoring inorganic silicon compounds such as silicates. The method also distinguishes between linear and branched polysiloxanes by different pyrolysis products. High sensitivity, to ppb, may be possible using single ion monitoring or selected ion data collection of mass spectra.
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