SPE Library

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.

The SPE Library is just one of the great benefits of being an SPE member! Are you taking advantage of all of your SPE Benefits?

Not an SPE member? Join today!

Use % to separate multiple keywords.

Search SPE Library

Recycling

Various topics related to sustainability in plastics, including bio-related, environmental issues, green, recycling, renewal, re-use and sustainability.

Crystallization Behavior Of Poly(Lactic Acid) Composite Nanofibers By Annealing

Jian-hua Hou, May 2018

Poly(Lactic acid) (PLA) is a typical biodegradable and bioabsorbablesemicrystalline material and has drawn extensive attention due to its excellent biodegradability, biocompatibility and mechanical properties. The semicrystalline PLA has a low crystallinity and the crystallite is imperfect which affects the properties of PLA parts. In this study, the effect of annealing on the composite nanofiber of PLA and graphene oxide(GO) and carbon nanotubes(CNT) is investigated. Nanofibers of PLA, PLA/GO and PLA/CNT are successfully prepared. A serials of characterization on crystalline morphology on the nanofibers suggest that the addition of GO and CNT enhance the crystallization of PLA and the enhancement effect of GO is better than that of CNT. Annealing improves the degree of perfection and crystallinity of PLA nanofibers. With the increased annealing temperature, the improvement becomes more significant. The results reveal that annealing is a favorable method to tuning the crystalline of PLA and its composite nanofibers, which allows to optimize other properties for the nanofibers.

Development Of Molecular Diffusion Models For Ultrasonic Welding Of Pla

Karla Lebron, May 2018

This research focuses on the characterization of bioplastics joined using ultrasonic welding and modeling of temperature distributions and interfacial healing. Polylactic acid (PLA), which is typically derived from starch-rich crops such as corn, was studied. While the measurement of activation energy for interfacial healing at weld interfaces of PLA films has been reported, here, this information is used to predict the weld strength of rigid PLA samples welded by ultrasonics. A characterization of the mechanical properties was completed with a tensile test to determine the effects of amplitude, weld velocity and collapse distance on weld strength. From previous interfacial healing activation energy measurements based on an impulse welding method, it was also possible to predict weld strength. It was found that the most influential parameters were weld time, collapse distance and weld velocity. In general, the model predicted weld strength reasonably well with r2 values between 0.77 and 0.78.

Direct-Friction Riveting Of Metal-Cfrp Overlap Joints

Natascha Zocoller Borba, May 2018

Friction Riveting is an innovative and promising joining technology, which can potentially fulfill the industry requirements for sustainable and efficient systems. The objective of this work is to prove the feasibility of Direct-FricRiveting by inserting a metallic rivet through metal-composite overlapped plates and subsequent anchoring in the composite part, which is a challenging configuration with limited knowledge available. The case-study joint configuration used in this work comprised a Ti6Al4V rivet, which joined an overlapped AA2024-T3 upper plate with a 30% short-carbon-fiber-reinforced poly-ether-ether-ketone lower plate, material combination of high interest for the aircraft industry. Evaluation of joint formation, temperature development, microstructural and physicochemical changes in the composite, and mechanical properties were carried out for joints produced under low and high energy input. The feasibility was proved, showing satisfactory mechanical performance under lap shear testing (up to 7 ± 1 kN). Changes of polymer crystallinity and thermo-mechanical decomposition in the composite were shown not to affect the joint mechanical performance and failure behavior, while the plastic deformation at the rivet tip played the major hole. The knowledge gathered in this preliminary work will be further applied to optimize the process, contributing to the development of the Friction Riveting technology and improvement of its industrial applicability.

Synthesis Of High Hardness Polyester Resin For Powder Coatings

JUNSEOP IM, May 2018

Since powder coatings do not use VOCs, much research has been studied as eco-friendly paints. Among these powder coatings, hybrid type is widely used in home appliances and furniture. Therefore, it is very important to meet both aesthetic characteristics and mechanical properties such as gloss and hardness. However, it is difficult to maintain high gloss with high hardness because of the inorganic filler of powder coatings.

Effect Of Shish Material On The Formation Of Self Induced Shish-Kebab Structure

Xiaofeng Wang, May 2018

The shish-kebab structure has been investigated for many years and it has been widely applied in many field, while the formation of the structure has still been found in limited materials. In this study, different electrospun poly(ε-caprolactone) (PCL) blended nanofibers with poly (ε-caprolactone-co-lactide) (PLCL), polylactic acid (PLA) and graphene (GO) were applied as shish materials in the self-induced crystallization and different crystalline structure were obtained. The PCL blended fibers with different internal crystalline structure led to different induced crystal lamellae morphology. By comparing with the surface crystalline structure, it seems that the formation of self-induced nanohybrid shish-kebab (SINSK) structure is regulated simultaneously by a lattice matching mechanism and a soft epitaxy effect in the crystallization process. This study might help people to explore the materials for creation of SINSK structure.

Effects Of Biodegradable Additives On The Nucleation Intensity And Growth Rate Of Isotactic Polypropylene Spherulites

Yousef Mubarak, May 2018

The effect of biodegradable additive (Biosphere) on the spherulite growth rates of isotactic polypropylene was studied by means of polarized light microscopy. It has been found that the addition of biodegradable additive to isotactic polypropylene matrix increases the intensity of the spherulites at all covered isothermal crystallization temperature in the range from 125 to 145 oC. In comparison with the neat isotactic polypropylene spherulites, much smaller spherulites were obtained at all crystallization temperatures for the isotactic polypropylene/biodegradable composite. The obtained results show that the presence of the biodegradable additives enhances spherulite growth rate at low crystallization temperatures (below 135 oC) while the effect of these additives is almost negligible at high crystallization temperature (above 135 oC).

Effects Of Different Fillers On The Thermo-Mechanical Properties And Coefficient Of Linear Thermal Expansion Of Polypropylene Composites

Manjusri Misra, May 2018

We study and report on the effect of different fillers on the coefficient of linear thermal expansion (CLTE) of polypropylene (PP) by melt extrusion technique. We examine and review the effect of some fibers such as glass fiber and carbon fibers as well as traditional mineral filler like talc. Moreover, we study the effect of new biocarbon as an environmentally friendly filler on the CLTE of neat PP and compare with the previous samples. On the basis of these results, properties and potential applications of PP composites are discussed.

Effects Of Molding Conditions On Mechanical Behavior Of Direct Injection Molded Pla/Wood-Fiber Composites

Gangjian Guo, May 2018

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.

Extending The Boundaries: Bismuth-Based Pigments For The Plastics Industry

Cristina Zanzottera, May 2018

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.

Facing Compounding Challenges Of The Future With The Ringextruder Re©

Erdmann Michael, May 2018

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.

Fatigue Resistance And Failure Characterization Of Glass Fiber Reinforced Pa Grades

Patrick R. Bradler, May 2018

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.

Flow Problems That Could Arise From Adding Biomass Materials To Plastics

Carrie Hartford, May 2018

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.

Fractography: The Science & Art Of Determining How Plastics Break

Farzana Ansari, May 2018

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.

Fracture Mechanical Characterization Of Non-Virgin Pipe Materials

Andreas Frank, May 2018

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.

Fracture Properties Of Hdpe Exposed To Chlorinated Water

Susan Mantell, May 2018

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.

From Recycled Tires To Plastic Parts: Micronized Recycled Rubbers In Thermoplasitc Polyolefins

Haikun Xu, May 2018

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.

Fully Biobased Degradable Plastic With Insecticide Functionality

Cindu Annand, May 2018

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.

Get The Wear Out

Steve Wilson, May 2018

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.

Hierarchical Micro/Nanostructures Of Poly (Lactic Acid) Scaffolds For Medical Applications

Shujie Yan, May 2018

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.

Highly Viscous Polyamides Made Of Cast Polyamide 6 Recyclates

Benjamino Rocco Formisano, May 2018

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.