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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Compatibilizing Immiscible Blends from Polyethylenes and Polyamide Using Reactive Extrusion
The aim of this work was to investigate the possibilities of compatibilizing immiscible blends of HDPE – PA6 via reactive extrusion. We investigated the influence of the compatibilization on the mechanical and rheological properties, as well as the morphology of the samples was investigated. We found, that it is possible to compatibilize immiscible blends via the in situ production of a compatibilizer from a pre-cursor and a radical generator in the blends. The effectiveness of this method is comparable with the compatibilization via the addition of pre-fabricated, industrially available additives.
Effects of Surface Treatment on Hard to Bond Plastics
Difficult to bond plastics, such as polyolefins and fluoropolymers, are commonly used in various industries for some of the following reasons: the cost of the materials and their inherent chemical and thermal resistance. It can be challenging for manufacturers to find solutions to join these difficult to bond materials together. This paper will provide background information on difficult to bond materials, review techniques for quantifying the surface energy of a plastic, review the latest solutions for surface modification and introduce innovative adhesive solutions to meet the challenges of bonding these specific substrates.
High Melt Strength Polyolfins for Melt Phase Thermoforming and Extrusion Blow Molding via Electron Beam Modification
Product and Applications Development Engineers continually struggle with the task of meeting challenging performance requirements that balance physical properties and processability within even more challenging economic constraints. In this paper, we update the industry with results that will encourage the use of electron beam modification as a means of utilizing materials with desirable physical properties but historically lack melt processability due to their linear structure. It is a continuation of ongoing work with an emphasis on melt phase thermoforming and extrusion blow molding. By inducing long chain branching through high energy electron beam bombardment, dramatic increases in viscosity at low shear are achieved which increase sag time in thermoforming and hang time in blow molding. At higher shear rates, these long chain branched polyolefins exhibit strain hardening which translates into improved material distribution allowing for down gauging. LCB (long chain branched) LLDPE (linear low density polyethylene) is viewed as new polymer altogether as it has not been used as a stand alone polymer in many applications due to its inherently poor melt strength.
An Adaptive Filling to Packing Switchover Method for Injection Molding
The production of technical molded parts requires an extreme high level of efficiency, process- and qualitystability to be competitive in global markets. In manufacturing the isotropy of the internal properties is an important prerequisite for warpage-free moldings. At the same time an accurate impression of the surface and an absolute free orientation of the molecule chains of the polymer are required. Therefore, a cost effective high volume production with consistently high quality requirements can only be guaranteed by a high degree of automation and an optimal process control . It is state of the art to fill the mold cavity velocity-controlled in the injection-phase, and to compensate for shrinkage in a pressure-controlled packing-phase to fill the cavity volumetrically correct to meet quality standards. The properties of the moldings produced depend on the parameters, which are set and modified by the operator of the machine . However, these adjustments are today heavily influenced by the experience of the operator, since an accurate knowledge about the influence of the settings on individual quality features without the knowledge of the details in the process is not possible. Also, the production of plastic moldings is used to process variations which affect the stability of the process and thus the quality of the molded parts. A main problem is under- and overfilling during injection-phase. In this work a method is introduced, which enables an autonomous switch-over, which adjusts the change-over point and adapts the packing pressure based on the condition of the processed resin. Variations in the process and on the material properties are characterized by the flow behavior of the polymer melt, monitored by key ratios and corrected in situ in the same injection-cycle. The result is a significantly increased process- and quality-stability. Frequently interventions by an experienced operator for example, are no longer necessary.
Atom Transfer Radical Polymerization of Ionic Liquids with Comb-Like Initiated by Styrene and P-Chloromethylstyrene Copolymers
A comb-like copolymer of styrene (St) and ionic liquids monomer (1-vinyl-3-butyl imidazolium tetrafluoroborate) was synthesized by atom transfer radical polymerization (ATRP) with CuCl/HMTETA as a catalyst, using the copolymer of styrene and p-Chloromethylstyrene (p-CMS) as a macroinitiator, structures of these copolymers were characterized by mean of FT-IR, 1HNMR and X-ray photoelectron spectroscopy (XPS). When increasing the mass fraction of p-CMS in the copolymer, it was observed varied performances such as phase morphology, hydrophilicity and electro conductivity, which were analyzed by atomic force microscope (AFM), water contact angle and electrochemical impedance spectroscopy (EIS), respectively.
Effect of Nanoclay and Compatibilizer Content on Oxygen Permeability of LLDPE Nanocomposite Membranes
Layered-silicate-based nanocomposites offer great potential for improving barrier properties of polymer membranes for applications in packaging, protective clothing, geotechnical and environmental engineering, etc. In this study, organo-modified montmorillonite / linear low density polyethylene (LLDPE) nanocomposite samples with various percentages of nanoclay and maleic anhydride compatibilizer were prepared by twin-screw melt-extrusion followed by compression molding. Barrier properties are characterized through oxygen permeability measured according to ASTM D3985 standard test method. A linear relationship is observed between oxygen transmission rate and nanoclay percentage. Results reveal that both the nanoclay and compatibilizer individually contribute to the LLDPE nanocomposites oxygen permeability.
Analysis of the Cure Compatibilization Efficiency of Peroxide/Sulphur System on Devulcanized EPDM and Polypropylene Blends with Reference to Devulcanized Tire Rubber and Polypropylene Blends
The usage of waste tire rubber crumb as a dispersed phase in a thermoplastic matrix has been a topic of study for a long time. Devulcanized rubber (DR) being relatively more similar to virgin rubber is expected to perform better than ground rubber tire crumb (GRT). There have not been many studies carried out on DR like in case of GRT. The present work is an extension of the previous work  which evaluated the efficiency of peroxide (PX)/sulphur (S) system to compatibilize devulcanized tire rubber (DRT) and PP. In this work, a similar study has been carried out on devulcanized EPDM (DRE)/PP blends and a comparison has been done with the earlier work. A statistical analysis has been carried out on the key mechanical properties namely tensile strength (TS) and elongation at break (EB). SEM pictures have been taken in an effort to understand the reasons for the mechanical properties obtained. The aim behind this work is to expand the commercial worth of DR in various applications.
Development of a Custom Material Model for 3D-CFD-Simulation of Melting Processes in Polymer Processing
This paper presents a custom material model for 3D-CFD-simulations of plastification of polymeric materials in polymer processing, especially in high speed extrusion processes. The new approach enables to differ between solid phase and fluid phase in dependence of temperature. A presupposed melting mechanism is not necessary. Hence it becomes possible to simulate melting in just one single fluid domain. The model and its theoretical background are described in this paper. Trials for a custom extruder - the so-called High Speed S-Truder (HSST) - with solid-melt separation are presented. This alternative extrusion concept uses a special sleeve with hundreds of bores. It surrounds the screw and separates the emerging melt from solid material, which remains in the screw channel. The implementation of the new material model into CFD-simulations is a helpful tool to analyze and improve the complex fluid flow in this process.
Novel Development Flame Retardant Additive for Environmentally Friendly Flame Retardant PVC Compounds
Historically phthalates have been used as plasticizers in PVC to provide flexibility over a wide temperature range. In applications where higher flame retardancy is needed along with flexibility, brominated phthalates have been used to meet the requirements. DynaSil™ is a novel flame retardant synergist that has properties of flexibilizing PVC while allowing for the replacement for antimony trioxide (ATO), brominated phthalate plasticizer, and/or ammonium octamolybdate (AOM) in PVC formulations. The results show that by using the DynaSil™, brominated phthalates, ATO and AOM can be replaced without loss of flame retardant properties, sacrificing flexibility, and negatively affecting smoke properties. In addition, DynaSil™ can preserve or improve performance properties such as tensile and elongation while providing a very eco-friendly solution at reduced costs.
A High Speed Extruder with Floating Screw Sleeve for Solid-Melt-Separation
The High-Speed-S-Truder with floating screw-sleeve is an alternative extrusion concept with solid-melt-separation. A 35 mm screw conveys the resin into a 60 mm screw sleeve. Inside the sleeve the material is plasticizied and discharged into the outer screw channel of the sleeve through radial bores. Only the solid bed remains inside. The development of a melt pool - and thus a decrease of the plasticizing capacity - is avoided. Due to the lower speed of the screw sleeve molten material is conveyed to a Dynamic Mixing Ring in a gentle manner. Experimental results and theoretical background will be described in this paper.
Product Advancements in ABS Metal Plating for Automotive Applications
The need for automotive exterior chromed applications with excellent surface appearance and good scratch/scuff resistance is well known. Typical exterior chrome applications (grilles and wheel covers) require no surface defects such as pits, scratches and blushes upon initial factory installation and over ten years field performance without delamination, blisters, or cracks. Initial quality often becomes a compromise between what the Tier can actually produce and what the OEM will accept for saleable vehicles. On the other hand, durability often becomes a compromise between what the OEM will warrant and what the customer judges as poor quality. Recent advancements in the field of Acrylonitrile- Butadiene-Styrene (ABS) and ABS+Polycarbonate (ABS+PC) blends by Styrolution have allowed for such a system that with the proper design and tooling considerations allows one to more closely match all of these expectations. Styrolution, the Nr. 1 styrenics supplier globally, is a joint venture created in October 2011 between Ineos and BASF is combining the expertise of two leading global suppliers. Building on a long tradition, Styrolution intends to contribute to the improvement of the Electroplating technology through material innovation, better surface adherence, reject rate reduction and manufacturing cost optimization. Examples of these contributions are presented in this paper.
Chemical Resistance Advantages of Tritan™ Copolyesters for Medical Applications - Oncology Drug Case Study
Changing fitness for use requirements for the next generation of medical devices have significantly increased the need for higher performing plastics with improved chemical resistance. For example, heightened awareness of hospital-acquired infections (HAIs) has resulted in the increased use of medical disinfectants which can cause cracking or discoloration of plastic medical devices. In addition, the continual effort to advance medicine has led to the development of new oncology drugs and oncology drug delivery devices. These oncology drugs have been found to cause cracking, crazing and hazing in certain plastics. With these trends in mind, the chemical resistance of common medical grade thermoplastics was tested against various disinfectants, oncology drug carrier solvents and actual oncology drugs. These studies illustrate that Eastman Tritan™ copolyesters exhibit excellent chemical resistance to meet the changing needs of the medical device market.
Evaluating the Interfacial Shear Strength of Basalt Fibre Reinforced Polypropylene Matrix Composites
The aim of this work was to investigate the interfacial shear strength of basalt fiber polypropylene matrix composites via two different methods. The methods applied here were the microdebond test as a direct measurement and the use of Rule-of-Mixtures models to evaluate the macromechanical properties. We found, that it is possible to yield results from both methods, which are in good accordance. Furthermore, while the assessment of the interfacial properties via the microdebond test is a direct method, the influences of preparation and handling are obvious. The calculation of the interfacial shear strength from macromechanical test needs higher effort, but therefore also more interfaces are evaluated at once. Nevertheless, both methods can be useful for application when the respective constraints are taken into account.
Effect of Molecular Structure on the Heat Seal Performance of Polypropylene Films
Three polypropylene resins (homopolymer, ethylene copolymer and elastomer based ethylene copolymer) were selected to investigate the effect of molecular structure on the heat seal performance of polypropylene films. The molecular structure of the resins was analyzed using dynamic rheological measurements and gel permeation chromatography (GPC). Thermal analysis was also performed to determine crystallinity and melting points. Heat seal test was conducted on multilayer cast films and it was found that the seal initiation temperature (SIT) and seal strength depend on the ethylene comonomer content, crystallinity, and molecular weight. The metallocene based resin having low branching content and narrow molecular weight distribution showed the lowest SIT.
Antibacterial Properties of Electrospun Fibers of PCL/Clove Bud Powder
The antimicrobial properties of essential oils and other plant extracts have been known for many years and have been used against a wide variety of bacterial pathogens as well as several fungi. The purpose of this study is to investigate and compare the antimicrobial activities of various ground powdered plants such as sage, clove bud, clove leaf, lemongrass, black mustard seed, wild mint leaf, and thyme leaf against E. coli (DH5 ?). The clove bud powder showed the highest antimicrobial activity compared to the other ground plants used in this study. The minimum inhibitory concentration of the clove bud powder was measured and then its antimicrobial activity was monitored for the electrospun PCL and clove bud powder blends dissolved in a mixture of (DCM:DMF) (50:50) v/v. The antimicrobial activity of the PCL and clove bud fibers was assessed using dynamic method.
Antimicrobial Activity of PCL/ZnO Electrospun Nanofibers
PCL/ZnO nanocomposite fibers were prepared using the electrospinning process for antibacterial applications. The morphological-characterization of the electrospun nanofibers was carried out using scanning electron microscopy (SEM). The SEM images showed that the zinc oxide nanoparticles formed big agglomerates on the surface of the nanofibers. The average diameter of these nanofibers was around 390 nm. The antimicrobial efficiency of these nanocomposite fibers against E. coli (DH5 ?) was also evaluated using the dynamic method. The antibacterial results showed that the addition of zinc oxide nanoparticles reduced slightly the growth of E. coli on PCL/ZnO nanofibers.
Lightweight Styrenics for Automotive applications
The potential to light-weight Acrylonitrile-Butadiene- Styrene (ABS) and Acrylonitrile-Styrene-Acrylate (ASA) thermoplastics has been studied using various weight reduction technologies. One category includes density reduction of fixed dimensions by partially displacing polymer with gas or air. Chemical foaming agents (CFAs), MuCell® microcellular foaming , and glass bubble (GB) compounding are the most well-known technologies. The other category is the thin-wall injection molding. In both cases, acceptable balance of weight reduction and mechanical properties in finished parts has to be achieved. In this study, the changes of mechanical properties through CFAs, GBs, and thin-wall technologies are described.
Moisture Performance of Wood-Plastic Composites Reinforced with Extracted and Delignified Wood Flour
This study investigated the effect of using extracted and delignified wood flour on water sorption properties of wood–plastic composites. Wood flour (WF) extraction was performed with three solvent systems: toluene/ethanol (TE), acetone/water (AW), and hot water (HW); delignification was conducted using sodium chlorite/acetic acid solution. A 24 full-factorial experimental design was employed to determine the effects of treatments and combinations of treatments. WF/HDPE composites for testing were manufactured using extrusion and injection molding. Compared with composites containing untreated WF, composites produced with extracted WF had lower water absorption rates and composites containing delignified WF had higher water absorption rates.
Diffusion Coefficient Modeling in Polyester Barrier Materials: Applications of Infinite Series Solutions
While transport performance evaluation of new polyester resins can be accomplished through gravimetric or pressure-decay kinetic sorption experiments, estimation of model parameters can be challenging. Accurate diffusion coefficient determination is particularly difficult, as applications of the time-dependent diffusion equation yield non-intuitive infinite series solutions. Furthermore, complex diffusion processes often produce intractable models which require either short- or long-time approximations for parameter estimation. The current work circumvents such approximations by describing a modeling methodology useful for fitting complex infinite series solutions directly to experimental kinetic sorption data. Two specific modeling cases pertaining to polyester films are used to validate the methodology.
Reactive Modification of High Density Polyethylene in a UV-Initiated Process
Rheological properties of a high density polyethylene resin (HDPE) were modified by promoting long chain branching (LCB) through a novel photoinitiated reactive extrusion process (REX). Surface response methodology based on a central composite experimental design was employed with three processing variables, namely, photoinitiator concentration, polymer throughput, and extruder screw speed. The linear viscoelastic properties measured through oscillatory shear experiments indicated addition of LCB up to 0.055 branches per 1000 monomer units. The zero shear viscosity (?o) increased to a maximum of 11,600 Pa.s from a starting value of 1,900 Pa.s. Similarly, the average polymer relaxation time (?) increased from 0.05 s to 4 s. Both molecular weight (MW) and molecular weight distribution (MWD) slightly shifted toward higher values. However, the breadth of the distribution was not affected significantly.
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