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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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Recycling
Various topics related to sustainability in plastics, including bio-related, environmental issues, green, recycling, renewal, re-use and sustainability.
SPE Recycling Division 2021 4th Quarter Newsletter
SPE Recycling Division, December 2021
Read the 4th Quarter issue of SPE Recycling Division newsletter.
Separation of Multi-Component Parts for Mechanical Recycling
Matthias Hopp | Frederik Mühlhoff, May 2021
The recyclability of plastic components has become an important objective in the product development process of packaging and technical products. In this study an approach is taken to produce hard-soft combinations with a better recyclability by using an adhesion and, at the same time, recycling layer. This additional layer is placed between the hard and the soft component. The intermediate layer shows good adhesion to both components for the use phase of the product. At end-of-life-stage of the products, the two components can be separated by melting the intermediate layer and shearing of the parts in recycling machines. Polypropylene (PP) as the hard component and thermoplastic polyurethane (TPU) as the soft component are combined with an EBA (Polyethylene-n-butylacrylate) functioning as the intermediate layer by an overmolding injection molding process. The peel strength is investigated for the combination hard component/ intermediate layer, intermediate layer/ soft component and for the combination of all three materials. The combination without the intermediate layer shows no adhesion of the two components. For simulating a separation process the peel tests are carried out at higher temperatures. The results show a lower bond strength at temperatures around 80 °C and the failure location between the TPU part and the EBA-layer. Furthermore, the results show that with the functional intermediate layer two materials can be joined for the use phase and also separated by heating at the end-of-life-stage.
Impacts of Degraded Surface Removal on Mechanically Recycled Marine Debris
Christofer T. Owen | Cecile Grubb | John Misasi, May 2021
This study was conducted to show the effects of inclusion of highly degraded surface material in recycled ocean plastic HDPE. Two primary materials were studied, one (HDPE-SD) contains high surface degradation while the other (HDPE-MP) had the surface removed for comparison. Each material was mechanically recycled (granulated, compounded, granulated) and then injection molded to create test specimens. Optical microscopy was performed before processing to observe and measure the surface degradation. After molding, FTIR, DSC, rheology, and mechanical characterizations were done to draw conclusions about the impacts of the degraded surface on the recycled properties. Inclusion of the degraded surface was found to increase fracture elongation, zero shear viscosity and lower the melt temperature. These findings were related to the chemical structures observed via FTIR. Additionally, comparisons and insights on the challenges and benefits of recycling ocean plastics are described.
Dimensional and Mechanical Comparison of the Conventional Injection Molding Process to Imflux's Constant Pressure Process Featuring AVA Technology
Lexington Peterson, May 2021
One of the major issues the plastics industry is trying to solve today is the lack of a circular economy. Plastics do not biodegrade fast enough to keep up with the waste being generated, and therefore present ecological and environmental problems. To take discarded plastics and continuously give them new life in a variety of applications is the goal of many plastics industries. However, to reprocess recycled plastics has shown many challenges. iMFLUX’s Auto-Viscosity Adjust (AVA) technology has made doing so easier with their low, constant pressure injection molding process. This technology enables the injection molding process the ability to independently adjust parameters in real time. This research focuses on comparing the dimensional and mechanical integrity of virgin ABS and PCR ABS in the conventional and iMFLUX processes. It was determined that the conventional process had better mechanical integrity with the virgin ABS than iMFLUX, and the iMFLUX process had less deviation overall between dimensions and material transition.
Increasing the Efficiency of the Continous Depolymerisation of Polystyrene
Philipp Schäfer M.Sc. | Nils Dauber M.Sc. | Dr.-Ing. Martin Facklam | Prof. Dr.-Ing. Christian, May 2021
Unlike other thermoplastics, polystyrene can be thermally recycled into its monomer form. During the continuous depolymerization of polystyrene in the twin screw extruder, low-molecular volatile substances are gradually split off at temperatures above 400 °C. Depolymerization in a twin screw extruder offers a number of advantages for the recycling of polystyrene. The heating time in a twin screw extruder is short and high material throughputs can be achieved. The reaction products are removed directly by a vacuum system. To make the depolymerization of polystyrene more efficient and to increase process stability, the vacuum system has been optimized with regard to the vacuum dome geometry. As a result, the reaction products are removed faster and the migration of the low-viscosity melt into the vacuum dome is avoided. In addition, the constructive adaptation of the vacuum dome geometry made it possible to increase the realizable vacuum pressures during depolymerization from 400 mbar to 50 mbar and the maximum condensate yield from approx. 30 % to over 60 %. Depolymerization in a twin-screw extruder thus represents a promising process for recycling polystyrene on an industrial scale.
Cleavable Comonomers Enable Degradable, Recyclable Thermoset Plastics
Peyton Shieh | Keith E. L. Husted | Jeremiah A. Johnson, May 2021
Thermosets play a key role in the modern plastics industry. Their high density of chemical crosslinks result in excellent mechanical properties for high-performance applications, but also prevent them from being readily reprocessed once formed. We have recently developed degradable, recyclable versions of existing high-performance thermosets by incorporating small quantities of a cleavable co-monomer additive. This approach maintains the performance profiles of the parent materials while seamlessly integrating with existing manufacturing workflows.
Reaction Model to Predict Photo Degradation Mechanism of Polyethylene Containing CB and HLAS
Iftekhar Ahmad | Mohd Danish Alhindi, April 2021
Photooxidative processes that lead to chain scission and chain linking in polymers play an important role in polymer degradation. These processes are induced by both ultraviolet and visible light absorption. Antioxidants can enhance the usable life-time of polyethylene, and some fillers can act as a UV screen and also as a chain terminating and peroxide decomposing agent in the polyethylene UV degradation. In this paper a reaction model is developed and described for UV degradation of polyethylene containing a hindered amine as an antioxidant and carbon black as filler. The degradation mechanism follows free radical initiation, propagation, termination, and stabilization steps. Reactions between free radicals and antioxidants with carbon black are considered. Mass balance on each reacting species gives the model equations that are solved using parameters that are either estimated or fitted. The model gives key parameters responsible for the degradation and stabilization.
Influence of Processing Route on the Properties of Polyolefin Blends
Christoph Burgstaller, April 2021
One of the streams from plastics waste collection is a mixed polyolefin stream, which cannot be separated completely with reasonable effort at the current technological state.  The aim of this work was to investigate the influence of the processing route, realized by different plastic processing machines, on the properties of selected polyolefin blends, made from different PP and PE grades as well as compatibilizing additives, to mimic the mixed polyolefins found in post-consumer waste.  We found, that the processing route influences the properties in regard to the shear brought into the materials – only dry-blended and injection molded blends yield lower properties than the ones which were prepared by the other processing machines. This is more pronounced when compatibilizers were added. These results show that several processing machines can be used to establish such blends, which is an important finding for mixed polyolefin stream recycling, as there not only a good mixture in the blend needs to be established, but also the processing machine has to be stable and unsusceptible to foreign materials in the stream.
Some Properties of 100% Recycled Ocean Plastic Polyolefins
Juliana Covarrubias | Christofer Owen | Evan Impink | Molly House | Nicole Hoekstra | Cecile Grubb | John Misasi, April 2021
Levels of plastic waste accumulating in the oceans are continuously rising and prompting an increase in concern on their negative environmental impacts. To help close the gap and create a circular life cycle for ocean plastics, this study begins to show the changes in chemical and engineering properties of polyolefins collected from a marine environment. Three ocean plastic polyolefins, high density polyethylene, low density polyethylene, and polypropylene, were mechanically recycled and then injection molded. The ocean plastics’ chemical characteristics were then characterized via FTIR to observed the impacts of environmental degradation. Thermal, rheological, and mechanical properties were all studied and related to the chemical structures and typical accepted values. All ocean plastic olefins were found to have properties similar to their terra-firma counterparts, however degradation was observed and is discussed in terms of the measured properties.
Styrenic Block Copolymers for Enabling Improved Performance of Post-Consumer Resins
Amit Desai | Yuliya Streen, April 2021
Improving the reusability of plastic parts, increasing the usage of post-consumer resin (PCR), and converting mixed PCR streams into high value resins are three key challenges facing the plastic recycling industry. To address these challenges, CirKular+‚Ñ¢ products were developed by Kraton Polymers to enable plastics upcycling and circular economy solutions. These products enable multi-resin compatibilization and performance enhancement of PCR resins across a wide range of applications. By leveraging the versatile chemistry of styrenic block copolymers, polymeric additives have been developed that benefit plastic recycling in multiple ways, such as improvement in properties of recycled resins and blends of virgin and recycled resins, and compatibilization of mixed PCR resin streams. In addition, these polymeric additives provide the performance enhancement at low loading levels, which in turn leads to an excellent balance of properties and low formulation cost. In this paper, several application-specific test results and case studies will demonstrate the value of these polymeric additives.
Sustainable Processing Aids to Enhance the Performance of Plastics with Recycled Content
Cristiano R. de Santi | Domenic Di Mondo | Christy Sapp | Carla Toth | Michael Pluimer, April 2021
In response to government and consumer demand for sustainable solutions to the escalating plastic waste crisis, plastic compounders and manufacturers are seeking to increase the level of post-consumer recycled content in their product formulations. The inherent variability of recycled resin streams presents challenges related to operational efficiency and product performance; thus, there is an increased need for processing aids that can assist manufacturers in their quest to balance operational efficiency with sustainability. GreenMantra¬Æ Technologies has developed and commercialized an innovative advanced chemical recycling technology that converts recycled plastics into specialty polymers and synthetic waxes that can function as processing aids in plastic production. This paper presents two case studies that demonstrate how GreenMantra‚Äôs additives enhance the manufacturing efficiency of plastic extrusion processes and maintain the physical properties of polymer systems containing 25-100% recycled plastics. Certified as containing 100% post-consumer recycled plastics, GreenMantra‚Äôs additives enhance the sustainability of the polymer system while enabling the formulation flexibility for plastic manufacturers to incorporate higher recycled plastic content without sacrificing performance. 
Depolymerization Kinetics of Recycled Polyethylene Terephthalate During Melt Mixing
Akanksha Patel | Shawn Martey | Margaret J. Sobkowicz, April 2021
This article shows the effect of melt mixing parameters such as temperature and time on the macromolecular chain structure of Recycled Poly(ethylene terephthalate) using a batch mixer. The objective was to develop a pretreatment of PET to reduce molecular weight and crystallinity in preparation for microbial degradation. A depolymerization kinetic model was built to understand the irreversible structural changes caused via melt processing of RPET. Chain scission reaction occurred faster at higher temperatures, as evidenced by molecular weight calculated from intrinsic viscosity measurements.
Advances in Extrusion Blow Molding of Post-Consumer Resin
Ian P. Query, April 2021
Demand for increased recycled content in various applications has driven innovation toward incremental step change in recycled material quality. In pursuit of increasing recycled content usage in extrusion blow molding applications, considerations must be made for the preservation of mechanical properties via the prevention of thermal and oxidative degradation during both the recycling and molding processes. In order to understand the importance of timely implementation of solutions like stabilizer blends, a set of experiments was run on extrusion blow molded articles to illustrate the rate of performance decay that occurs between the recycler and the molder. This analysis proposes pathways to improve upon current recycled content utilization while simultaneously improving end-use properties.
Plastic Bag Recycling: The Obaggo Story
David New, April 2021
Dave New, founder of Obaggo Recycling, will tell the story of his journey to bring a novel plastic bag recycling solution to the mass market. He will discuss the genesis of the idea, the trials and tribulations of prototype development, and the epic search for project support and funding. A fundamentally entrepreneurial story, Dave will talk about the world of start-up accelerators, b-plan competitions, and how he navigated a vast landscape of stakeholders, cheerleaders, and naysayers.
Less is More: How to Maximize Energy Savings in Plastics Processing - Part 2 
Josh Bachman, March 2021
This is the second part of a two-part webinar. This webinar will address behavioral and organizational approaches to industrial energy management. Josh will explain how manufacturing companies can implement energy programs, both through proven best practices and through local and regional utility funding programs.
Less is More: How to Maximize Energy Savings in Plastics Processing - Part 1
Josh Bachman and Pamela Birkel, March 2021
Wasted energy is wasted profit. In these webinars, plastics engineers, plant managers, and financial managers will learn about the typical opportunities to save energy at plastics plants. In the first webinar, Josh Bachman and Pamela BIrkel will share energy savings opportunities that have been uncovered over the years. They will also share case studies of successful projects, many of which were funded by the local utility.
Taking out the Trash, Plastics Design for the End-of-Life
Eric Larson, December 2020
Nothing lasts forever. Great products might not last forever, but they usually last a long time. But no matter how great the product is, there will come a point in time where a thing no longer has any value. It then becomes waste. To be thrown in the trash. And then what? How do you design a product to account for its expected end of life? Or an unexpected end? How do you evaluate materials based on what happens at their end of life? What tools are there? How to use them? What’s next? For plastics, and for the industry.
Life Cycle Assessments: Why and How?
Chris Koffler, November 2020
The webinar will give a high-level overview of the basic process, concepts, and calculations involved in carrying out Life Cycle Assessments in accordance with the international standard ISO 14044. It will further showcase LCA studies performed for industry to demonstrate the business value that can be derived from such studies in product development and marketing. The target audience includes process engineers, product designers, product managers, sustainability professionals, and anyone interested in ways to quantify the environmental performance of goods and services.
This is Not the Wild West: Sustainability Definitions, Standards, and Regulations
Kelvin Okamoto, October 2020
With continued interest in and development of sustainable plastics, it is clear that not everyone is working with the same lexicon. Terms such as 'degradable', 'bio-degradable', 'recyclable', and 'compostable' are subject to misunderstandings, misinterpretations, or outright fraudulent claims. This webinar will address how ASTM standards are being used to create a common understanding based on science and testing. We will also address the commonalities and differences among standards, certifications, and regulations. This webinar is part of SPE's ongoing "Sustainability & Plastics" series.
Plastics & the Environment: Dispelling Popular Myths With Scientific Facts
Chris DeArmitt, July 2020

In order to make wise decisions, we must start with facts. Unfortunately, plastics have been sentenced in the court of public opinion without facts or evidence. The public have turned against plastics based on nothing more than unsubstantiated social media posts and sensationalist journalism.

As a career scientist, I decided it was time to go look for the facts. It took over a year to collect and read more than 400 peer-reviewed scientific publications. I discovered that virtually everything the public believe today is utterly untrue. This talk distills down the science around waste, litter, degradation, microplastics and more. You will be shocked to discover what the science tells us. Plus will be given free access to The Plastics Paradox book which explains how today’s policies are harming rather than helping the environment and what we should be doing instead.

Developed for a Fortune 500 company who offered over $10,000 dollars, SPE members can access it for free. The first couple of chapter is available to the public at: plasticsparadox.com.



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ANTEC 2016 - Indianapolis, Indiana, USA May 23-25, 2016. [On-line].
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