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.
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.
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.
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.
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.
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.
This manuscript studies the reaction extrusion of polyurethanes based on both polytetramethylene ether glycol (C4) and polytrimethylene ether glycol (C3) polyols using a twin screw extruder. Polyurethanes (TPU) with hardness of 70A, 85A and 50D were fabricated. The two polyols showed comparable reaction kinetics with methylene diphenyl 4,4'-diisocyanate (MDI). C3 polyol polyurethanes showed slightly lower tensile stress at the same hardness level. But they showed comparable tear strength. C3 polyol TPUs needed slightly higher hard block to obtain the same hardness.
The fiber orientation distribution in a material sample was analyzed. A micro tomography reconstruction of the sample was used to derive the components of a fabric tensor from an evaluation of the global anisotropy parameter. This parameter proved to be an efficient tool for the analysis of the structure of fiber reinforced composites. The local variations of the degree of anisotropy (ratio of the maximum and minimum eigen values of the fabric tensor) from the shell to the core layers of the sample can be captured and information about the local average fiber orientation angle can be obtained.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
On-line quality monitoring of the polymer extrusion is of great importance for process monitoring and product quality control. In view of the shortcomings of the existing hardware-based sensors, a novel low-cost capacitive transducer (CT) has been designed for polymer extrusion. In this project, the developed capacitive transducer has been successfully applied for thickness and diameter prediction in polymer extrusion. Experiments with various extrusion products show that the proposed transducer features broader application and the prediction results are quite accurate and robust. Therefore, this research paves the way for on-line quality monitoring and closed-loop quality control of polymer extrusion.
Biodegradable polymers are currently a critical global research topic as they may potentially serve as replacement to conventional petroleum based plastics. One key strategy to widen its range of application potential is by improving its physical and mechanical properties. Such characteristics can be engineered by blending two polymers of desirable properties together and by inducing a cellular morphology in the pure polymer or blend with the aid of a foaming agent. This paper examines the effect of blending PLA and PHBV on their overall miscibility as well as the effect of their miscibility on the resultant foam fabricated using carbon-dioxide as a blowing agent. PLA and PHBV blends were manufactured in various compositions via compounding and foamed, and their physical, mechanical and morphological properties were characterized. The results indicated that although PLA and PHBV are immiscible, the addition of small quantities of PHBV (at 15wt%) lead to a finer and more homogenous cellular morphology.
The majority of disposable cups are made from paper plastic laminates (PPL) which consist of high quality cellulose fibre with a thin internal polyethylene coating. There are limited recycling options for PPLs which has contributed to disposable cups becoming a high profile, problematic waste. In this work disposable cups have been shredded to form PPL flakes and these have been used to reinforce polypropylene to form novel paper plastic composites (PPCs). Samples were characterised using mechanical analysis and thermogravimetric analysis (TGA). The work demonstrates that PPL disposable cups have potential to be beneficially reused as reinforcement in novel polypropylene composites.
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