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.
Polylactic acid (PLA), derived from bio-resources, is an environmentally friendly plastic which has attracted tremendous interests in both academia and industry. This paper investigates the feasibility of direct injection molding of PLA/wood fiber composites and their mechanical behavior. Response surface methodology was adopted to study the effects of molding parameters, as well as their interacting effects, on the tensile strength of the composites. Melt temperature, hold pressure, injection speed were chosen as the molding parameters studied. Additionally, the analysis of variance was applied to identify the most significant factors. The statistical model would improve our understanding of the tensile strength behavior of PLA/wood fiber composite, and provide the guidance for selecting proper molding parameters to maximize the tensile strength.
The versatile solid-state chemistry of Bismuth allows for a variety of coordination complexes and the generation of new and robust inorganic pigments as a result. Bismuth has been used in combination with a few inorganic elements, and is most readily found as complexes containing amines and amides, alkoxides, carboxylates, thiolates, and halides. Bismuth Nitrate is amongst one of the most common starting materials for synthesizing Bismuth complexes, and from this starting material the first Bismuth Vanadate pigments (PY.184) were formulated in 1985. There has been continued innovation in this pigment chemistry over the years, and in 2015 a groundbreaking Bismuth orange with a unique color index, PO.86, was launched (proprietary technology of DCC). Since their commercial introduction in 1990 (first production for Ciba, The Netherlands) into the coatings & plastics markets, Bismuth Vanadate pigments have increased in importance as their field of application has grown. These bright yellow, highly saturated pigments are characterized by their outstanding opacity/hiding power, chemical resistance, excellent weathering and durability. DCC’s 3rd innovative generation of Bismuth Vanadate pigments have expanded the limitations of this chemistry to cover a wider color gamut from greenish-yellow to orange hues. Advances such as improving the heat stability has increased the utilization of Bismuth Vanadate products in engineering resins e.g. Nylon 6. Increasing the color strength has created value in use for many customers who want to use less pigment whilst maintaining the hiding power within their system. Moreover, introducing Stir-In technology has helped to reduce operating costs by making the pigment easier to disperse, therefore reducing pressure rise in the extruder and reducing the number of extruder screen changes required during production. Improvements in our manufacturing technologies have allowed DCC to attain the most demanding and specific performance attributes such as heat stability & dispersibility. Through intensive research DCC has been able to introduce an exciting new inorganic pigment into the market, based on Bismuth and identified by a new color index: PO.86. This clean yellow shade inorganic orange has outstanding hiding power, typical of inorganic pigments and represents an excellent starting base for orange colour matches. Additionally, PO.86 is non-warping and has very good heat stability (up to 250 °C): it is therefore strongly recommended for use in polyolefin based plastics, and architectural, industrial, powder, automotive & coil coating applications. There are only a few options for formulators in this shade area (most of which are based on organic starting materials), but none of these alternatives have the same level of durability and opacity as PO.86. This paper will illustrate how Bismuth Vanadate and Bismuth Orange pigments compare to other colorants in the green shade yellow to orange shade areas, with particular reference to performance attributes such as heat stability, dispersibility, weather-fastness, warp resistance and reference how these products perform in different polymer systems. This presentation is thus ideal for those who work & formulate with color and would like to develop a greater understanding of how PY.184 and PO.86 pigments influence the plastics they work with.
The RingExtruder consists of twelve coaxial screws which are arranged in an annulus. All adjacent screws are closely intermeshing and rotate with identical speed around their own axis. The mechanical agitation is very similar to the co-rotating, closely intermeshing twin screw extruders if only two screws are observed separately. The arrangement of the screws in a circle creates twelve meltpools. This leads to optimal conditions for an intensive axial and crosswise intermixing by mass transfer between the screw channels.The RingExtruder offers outstanding dispersion capabilities together with minimal introduction of mechanical energy. The screws of the RingExtruder have 12 intermeshing zones, which produce a flow pattern with a very high degree of elongation, which can be utilized for highly efficient and energy-saving dispersion. In consequence, improved product quality can be achieved and considerably lower product temperatures are obtained.Furthermore, the geometry of the RingExtruder offers a very high surface-to-volume ratio. Thus, a large heat transfer surface area is available. Special designs of the extruder barrels and the centre core allow for an extremely efficient cooling of the processing unit. Therefore, the RingExtruder allows to control material temperatures within defined limits in order to avoid degradation or the unwanted onset of pre-vulcanisation.Due to the splitting of the product flow into the twelve screw channels an enormous surface of the plasticized material with very small volumes is available. Additionally, the twelve intermeshing areas of the screws ensure a frequent material deflection and thus a high rate of surface renewal. This gives the RingExtruder an outstanding performance in degassing processes.The RingExtruder is used for various tasks in the field of compounding, reactive extrusion and devolatilization. Typical applications include the large-scale recycling of postconsumer PET, the continuous production of rubber compounds, the processing of shear-sensitive and/or highly filled materials as well as the manufacture of adhesives.
The fatigue crack growth and failure behavior of five different short glass fiber reinforced polyamide (PA) grades was investigated on specimen level using compact type (CT) specimens. By using a testing device enabling superimposed mechanical and environmental loading, the effect of environmental conditions (23°C in air and 80°C in water), matrix material (polyamide 66 and polyamide 6T/6I) and glass fiber content (30 w%, 40 w% and 50 w%) on the fatigue crack growth kinetics was determined. Tests at 80°C in water exhibited an inferior fatigue crack growth resistance. Furthermore, for PA grades with a similar glass fiber content, an influence of the matrix material was revealed. PA grades with a higher glass fiber content indicate a better fatigue crack growth and failure behavior.
In an effort to become more “green” in the plastics world, engineers are developing unique products by adding biomass materials to create bio-friendly plastics. The biomass additives may have a different aspect ratio, size, compressibility or density than the pellets and powders but they all must come together in a uniform, consistent, reliable flow into the extruder. Understanding the implications to the handling of adding a new biomass material to a blend is critical for the success of the product. Taking a scientific approach to understanding the flowability of a component and blend is critical to ensuring a successful outcome. Often, this approach results in either making a change to the equipment that the material is handled in to support the new blend, or to making a change in the material or blend (or the conditions at which it is handled) to flow through the existing equipment.
In recent decades, the engineering industry has seen a stronger emphasis on cost- and energy-efficient materials. As a result, polymers have increasingly been adopted in load-bearing applications, replacing traditional “engineering materials” such as metals and ceramics in multiple industries, from aerospace vehicles to medical devices. With this transition comes an increased need for understanding how such load-bearing polymers inevitably fail, especially with respect to cracking and fracture. Fractography – the science and art of “reading” fracture surfaces – is a powerful failure analysis tool for dealing with fractured plastic components. Fracture surface features can tell a story regarding the stress state and environment a polymer experienced during fracture, potentially eliminating hours of exploratory testing to replicate the exact failure mechanism. This tutorial will provide an overview of fracture features commonly observed for various plastics, and how those features can be related to the exact mechanism of failure. The various tools of fractography will be explored, highlighting the importance of both low and high magnification in identifying where a crack initiated and how it may have propagated. Traditional brittle and ductile fracture features will be covered, as well as more nuanced failure mechanisms such as environmental stress cracking (ESC). A deeper dive into the fractography of three commonly used commodity plastics will demonstrate the influence of composition and stress state on fracture features, as well as exhibit the value of recreation testing under controlled loading and environmental conditions.
For accelerated characterization of slow crack growth (SCG) properties of modern polyethylene pipe grades the Cyclic Cracked Round Bar Test has been developed. While many investigations on polyethylene are available with this test, only few studies have been published yet with other relevant pipe polymers such as polypropylene or polyvinyl chloride. Moreover, the increased use of non-virgin polymers for structural applications based on reprocessed or recycled resources is becoming a topic of increasing importance. The current paper presents an investigation of the general applicability of the Cyclic Cracked Round Bar Test to the mentioned polymers with a special focus on the sensibility to non-virgin materials. On the one hand the results show that this test can be used for accelerated SCG characterization of all materials. On the other it is demonstrated that the SCG resistance of non-virgin polymers is significantly lower than for virgin pipe grades.
HDPE is often used in applications that include both structural and environmental loads. In this study, the effect of an oxidative environment on HDPE mechanical performance is evaluated. Thin 75 micron HDPE samples are exposed to 5ppm chlorinated water at 70C for up to 1250 hours. Changes in polymer morphology as a function of exposure time are evaluated and compared with fracture and tensile test data. FTIR data show an increase in the carbonyl group after 250 hours of exposure, while GPC data show a 20-50% loss in molecular weight after 500 hours exposure. The decrease in molecular weight is associated with shortening of the higher molecular weight chains. Essential work of fracture data and strain at break show significant loss in ductility for exposed samples. This set of data demonstrates the correlation between morphology changes and embrittlement in unimodal HDPE.
Micronized rubber powders (MRPs) have shown superior compatibility in TPOs and excellent elastomeric properties. However, it requires efforts to explore the use of MRPs in useful products and a few challenges need to be addressed. In this study, MRP-filled TPEs were compounded at various loading ratios and the effect of sizes of MRPs was investigated. In addition, the surface details of injection molded parts were studied and induction-heated molding were implemented to improve the surface finish for various applications. Finally, multiple conventional plastic processes were explored and injection-molded parts made out of MRP-filled compounds were demonstrated to discover more potential applications.
Natural insecticide, pyrethrum, and insect repellent DEET were added to poly(lactic acid) (PLA) fibers via extrusion and spraying. GPC analysis showed that the addition of DEET caused an increase in depolymerization with the increase of DEET concentration. Contact Irritancy Assay (CIA) showed that DEET-treated PLA fabrics caused the lowest percentage escape response with an escape frequency of 33.3 ± 3.3%. This was followed by the extruded natural pyrethrum-treated PLA fabrics with an escape frequency of 80 ± 6.3%. PLA fabric spray-treated with natural pyrethrum caused an escape frequency of 98.3 ± 1.7%. All treated fabrics caused repellency.
Most would agree that the mold is the heart of the molding process. From those that make them to those who use them, we all want them to last for as long as they were designed. A lot of work goes into striving toward that goal: good design, proper metallurgy selection, configuration, coatings, etc. With all that having been taken into account, why clean the mold with traditional methods that may wear out the parting line and shut-offs? This paper will demonstrate that cleaning tooling with dry ice is a safe, effective and non-abrasive way to clean common injection molds. It will provide molders, not only a way to extend the asset life of the tool, but also to improve quality, increase productivity, lower costs and improve environmental quality. This paper will focus on the first benefit of maintaining the expected life of our molds. Today, high-dollar and often complex molds, are run and maintained in varying degrees of skilled molding shops and tool rooms. Some of the cleaning methods still be utilized can contribute to tool wear.
Although tissue engineering has shown great advances in recent years, creating proper mechanical properties and cell growth microenvironments is still challenging. In this study, electrospun poly (lactic acid), PLA, nanofibrous membranes were hot embossed to develop 3D hierarchical micro/ nanostructures. Human umbilical-vein endothelial cells (HUVECs) were then cultured on these structures. The hot-embossed membranes exhibited not only superior mechanical properties (the tensile strength was 7.01 ± 0.18 MPa and the tensile modulus was 166.91 ± 15.54 MPa), but also better cell viability as evaluated through a CCK-8 assay and fluorescent dye. The grating arrays of the micropatterned fiber mats encouraged the HUVECs to proliferate. The approach proposed here—combined electrospinning and hot embossing—has great potential for biomedical applications, including for use as polymer scaffolds in tissue engineering.
Cast polyamide 6 is anionically polymerized from ε-caprolactam. Its good properties are mainly caused by the higher molecular weights, compared to standard polyamide 6. Because of sprues and post-processing, a larger amount of scrap is produced. This scrap is typically incinerated without sufficient use of its high quality properties.However, cast polyamide 6 also offers great potential for material recycling, particularly if its high molecular weight can be retained. As cast polyamide decomposes during processing as well, it is necessary to add some additives during compounding. It is the aim of the presented work, to recycle cast polyamide to highly viscous materials. This is done by adding a polyester-modified wax and a carboxylic acid. It can be shown that it is possible to get materials having viscosities of up to two magnitudes higher compared to a typical extrusion polyamide.The high molecular weight of cast polyamide can be maintained or even outperformed. While Young’s modu-lus and tensile strength remain unchanged, the used wax causes some crosslinking of the polyamide and thus also leading to higher impact strength.
How plastics helps to conquer the new challenges of vehicle electrificationbyMelanie Mennigke; LG Chem - Key Account ManagerWerner Posch; Dräxlmaier Group - Material ManagementThe need for zero emission solutions is steadily increasing and OEMs are currently developing battery electric vehicles with a focus on providing emission-free transportation, combined with lowest total cost of ownership. The main challenges for these vehicles include: range; cost and weight.Electric vehicles are no longer a trend but an established fact. In order to make the correct decision on which technological approach – BEV (battery electric vehicle) or REEV (range extended electric vehicle) - best meets the requirements of the market, the manufacturers specific boundary conditions and economic aspects have to be balanced with a multidisciplinary approach. The development of alternative drive vehicles is driven by both consumer and government demand. Consumers want fuel-efficient, low-emission vehicles, but they do not want to pay a premium to drive a more sustainable car. Governments want improved fuel economy and low emissions, and go as far as using manufacturer tax credits and consumer write-offs to incentivize alternative drive vehicle development. However, for a solution to be truly sustainable, it must be economically feasible, as well as environmentally sound.As the market grows for hybrid-powered and electric vehicle technology, plastics play an ever more important role to help reduce carbon emissions and dependence on petroleum. The challenges of using plastics in electric vehicle technology are: • Use of plastics instead of aluminum and steel for weight reduction• Use high-performance polymers and elastomers to integrate components and functions — this miniaturization reduces space and improves packaging.• Improve battery pack performance with flame-retardant and thermoplastic materials.• Prevent electrical arcs and sparks in connectors with thermoplastic materials that meet 650-volt system requirements.• Provide electromagnetic compatibility (EMC) The presentation includes proved plastics solutions for challenges described above. Examples of developed and already in serial production electric power trains (High-voltage battery systems, power electronics,...) to identify the right plastics for design and serial production which fulfil requirements such flame resistance, EMI shielding, weight reduction,... So that automakers can build hybrid and electric vehicles that meet consumer and environmental needs.
Prepared by Franklin Associates for the American Chemistry Council, this study expands upon the 2014 substitution analysis that used life cycle assessment methodology to assess the energy consumption and greenhouse gas (GHG) emissions of six general categories of plastic packaging produced and sold in North America relative to alternative packaging. The updated analysis includes other life cycle impacts - including but not limited to solid waste generation and consumptive water use, as well as updated energy and GHG results. This presentation will answer the question: if plastic packaging were replaced with alternative types of packaging, how would life cycle impacts, such as energy consumption, water use, and waste generation, be affected?
Improving long term corrosion resistance in electronic applications Electronic components have invaded the automotive environment with increasingly complex designs and functionality. In addition, the location and environment of these components continues to drive the requirements to higher performance materials. The combination of exposure to electrical potential, moisture, elevated temperature and environmental salt can affect the performance of electronic components. DuPont has developed a line of “EF” Electrically Friendly resins which will help reduce the risk of long term corrosion or performance degradation in aggressive environments.
The aim of this work was to investigate the effects of the composition and processing on the properties of PP-PET blends with and without compatibilisation. As the processing routes blend production via a co-rotating twin screw extruder as well as single screw extruder were chosen. We found, that it is possible to compatibilize PP-PET blends via the addition of maleic anhydride grafted PP. This effect can be seen from the morphology of the samples as well as from mechanical properties. In twin screw extrusion, the application of vacuum degassing shows additional property improvement due to the condensation of PET. The compatibilizer is also effective in single screw extrusion, but the effect is lower due to the missing degassing options. Nevertheless, the compatibilized blends are stable and the results show, that such mixed plastics, which can also be found in waste streams, can be reused when being properly processed.
Markets trends of cost reduction, sustainability & down-gaging drive the need for new and improved products. Development of such products requires a look across the entire value chain – an Asset to Market look. An emerging trend in the materials space is related to collection and management of data that enables knowledge creation. Management of this data and the knowledge generated is critical to accelerating research. This talk will focus on what is required for rapid product development, launch and knowledge transfer across a global organization to sustain market leadership. Key examples will be presented and will cover these trends.
It is widely accepted that the manufacturing of high expansion PP foams with fine cell morphology is a challenging task due to the low melt strength and the weak rheological behavior of the linear polypropylene. In this study we present a novel method to manufacture high cell density, large expansion microcellular foam through nano-fibrilation PP/PET composites. Various studies have been conducted to improve the processability of linear PP foams. Until now, the most successful industrial approach is using the branching PP as it expressed the strain hardening response and the increased melt strength behavior. However, the commercial price of branching PP resins are still doubled or even tripled comparing with linear PP resins, which dramatically limits the branching PP’s applications. Inducing chemical cross-linking is proven to be another effective way to improve the melt strength of PP. However, the cross-linked structure causes difficulty in recycling PP resins. Furthermore, the cross-linking reaction is not evenly initiated throughout the matrix rendering non-uniform cell structure in the final foam product. Implementing inorganic/organic filler is another alternative route for enhancing the foamability. PP reinforced with those fillers has higher viscosity and better elasticity at melting state. Nonetheless, the well-recognized challenging issue is to achieve well distribution and dispersion of nano-size fibers inside the polymer matrix. Because of the large surface to volume ratio, the nano-fibers tend to agglomerate. The well-established methods usually requires complex experimental conditions and normally involves dealing with chemical hazards. By implementing nano-fibrillation technology, all above mentioned draw-backs were overcome. The nano-fibrillation technology is used to manufacture polymer-polymer fibril composite in this study. The nano-fibrillation technology can generate high aspect ratio nano-fibrils uniformly dispersed inside the polymer matrix. The processing can be briefly summarized as: (i) blending immiscible polymer matrix (A) and polymer reinforcement (B) to make polymer (B) dispersed in spherical shape (the melting temperature of polymer B should be at least 30oC higher than polymer A); (ii) applying large deformation on the polymer extrudate by either hot stretching or cold stretching; (iii) carefully choosing a temperature between the melting temperature of polymer A and polymer B to melt the composite without damaging the fibril morphology of polymer B. In this study, three kinds of PPs with different viscosity are reinforced with PET nano-fibrils via melt spinning. The study shows that the high viscosity PP is preferred to generate low diameter nano-fibrils (~200 nm) in a wide concentration range; while the diameter of fibrils in low viscosity PP decreased with raising PET concentration. The oscillatory shear behavior is studied by comparing the storage modulus (G’) and phase angle (tanδ) of the non-fibrillated and fibrillated samples. Differential scanning calorimetry and birefringence optical microscope were employed to study the crystallization kinetics of PP/PET fibril composites. The rheological properties and crystallization kinetics were significantly improved with the presence of PET fibrils. Crucially, benefit from the strengthened rheological behavior and crystallization kinetics, the batch foaming of PP/PET nano-fibril composite is able to product a high cell density polymer foams.
For a proper selection of materials for solar-thermal applications, the failure behavior of various polypropylene (PP) grades was investigated by fatigue crack growth (FCG) experiments. The four tested material grades differed in their stabilizer system. To determine the effect of environmental media (chlorinated water with a chlorine content of 5 ppm, air and deionized water) and elevated temperatures (95°C and 80°C), cracked round bar specimens were tested on an electro-dynamic testing machine equipped with a special desigend media containment.Tests at all environmental conditions revealed a significant influence of the stabilizer systems on the FCG resistance. While at all conditions the stabilization with a hindered amine light stabilizer resulted in the best FCG behavior, depending on the environmental loading different PP grades showed the worst FCG resistance. In terms of media dependence of the crack growth behavior, for all PP grades, the best and worst FCG behavior were obtained in deionized water and chlorinated water, respectively. Results received from tests under two different temperatures showed that the FCG resistance decreased with increasing temperature in all tested environments and for all PP grades.
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