SPE Library

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.

iMFLUX's Novel Low, Constant Pressure Molding Technology Overcomes Traditional Barriers to Achieving A Truly Sustainable, Circular Operation - Sponsored by SPE Recycling Division

Gene Altonen, June 2020

One of the biggest challenges facing the plastics industry today, is the need for technology solutions that enable a Circular Economy. This is especially true for injection molded parts, where operational tradeoffs are often encountered when running many sustainable materials. iMFLUX, a wholly owned subsidiary of Procter & Gamble, offers a novel injection molding technology they refer to as the “Green Curve” which uses low, constant plastic pressure to fill an injection mold. Gene Altonen, iMFLUX’s CTO, will share how this new technology addresses the key challenges molders face to deliver truly sustainable, circular solutions for their customers. Examples will be provided illustrating how this new approach to molding offers the ability to efficiently run post-consumer recycle and composites, substantially reduce energy use, and enable more sustainable part designs and materials. iMFLUX is collaborating with machine makers, material suppliers, educators, mold designers, data platforms, and sustainability industry associations to enable molders to benefit from the unique advantages this new technology provides.”

Advanced Simulation Methods for Prediction of Multi-Layer Non-Matching Fiber-Mat Applications In Resin Transfer Molding Process

Fred Yang, May 2020

The objective of this study is to use a simulation tool of resin transfer molding (RTM) process to get a comprehensive understanding of the permeabiliy measuring process. In order to varify the simulation tool’s capibility to simulate oil flow in non-matching fabric we build the mesh model of the measuring instrument cavity with the non-matching meshes in this study. This varifaciton case focuses on two properties of the RTM process, the arriving time and local pressure increasing trend in filling process. By using the simulation tools, we can observe the resin flow within the mold. The comparison between simulation and experiment result shows the reliability of simulation result. We expect that this study will help to clarify relevant issues and then reduce the trial-and-error time and materials.

Bottle-to-Bottle Recyclability for Barrier Packaging Enabled by Surface Modified HDPE

Zhenshuo Liu, May 2020

Ellen McArthur Foundation’s bold vision for The New Plastics Economy is one where plastic goods can be recycled and reused in a closed loop, a “Circular Economy”. A key hurdle to enabling closed loop recycling is the deterioration of polymer properties due to raw material contamination in the recycle stream. Mixed polymer systems, i.e. co-extrusion/multilayer packaging, use barrier materials such as EVOH or Nylon, creating significant issues during recycling. In contrast, having monolayer packaging enables the highest recyclability. Fluorinated HDPE enables monolayer barrier packaging solutions. To further understand its impact on recyclability, Inhance Technologies investigated the inclusion of fluorinated HDPE in the regular HDPE stream. Fluorinated HDPE and regular HDPE were blended at different ratios, re-extruded and pelletized. Following pelletization, bottles were molded from the regrind blends and their properties were evaluated. At all blend ratios, thermal-mechanical properties, chemical fingerprint, and sortability match those of virgin HDPE. The results demonstrate that fluorinated HDPE can be recycled as regular HDPE within the existing recycling infrastructure.

Circular Economy - New Styrenic Polymer Processing Concepts

Cassie Bradley, May 2020

Circular economy is a term describing a sustainable way to interact with all major stakeholders of the economic sphere. One basic idea is to minimize waste creation and to use post consumer waste as raw material for new products. This concept stands in contrast to the “linear economy”, based on products that end in landfill. Circular economy will play a particularly important role for all materials and goods having a short and mid-term lifetime and will have an implication on how these products are designed and recycled. Plastics food packaging are examples for goods, providing safety, protection and extended shelf-life and hence allow us to lead our modern life style. They typically have a short-term lifetime and are disposed after use. Within the challenge of “Circular Economy” however, producers of packaging, as well as upstream raw material producers are requested to provide new concepts for re-use in a true circular way, hence re-cycling rather than down-cycling or waste dumping in landfills. Plastics producers, and especially producers of Styrene-based plastics are taking up the challenge and started to “connect the dots” between municipalities, new recycling technology providers, raw material producers and customers. By promoting “chemical recycling” they are pursuing new ways to create high quality, even food grade plastics based on post consumer waste as new raw material.

Demonstration of a Preliminary Simulation Framework for Foam Blow-Molding using Commercially Available Blow-Molding Software

Bhaskar Patham, May 2020

The use of foamed polymeric precursors for blow-molding and thermoforming applications is seeing increased use in the world of application development across a wide range of segments such as automotive, appliances, and packaging. Foam blow molding holds great potential for further enhancing lightweight solutions for complex hollow structures, while adding the potential of single-material solutions offering multi-functionality, e.g., thermo-acoustic isolation or damping. Unlike in the case of foam injection-molding, fundamental processing-structure-property interrelationships are not widely researched in the area of foam blow-molding. Modelling, simulations, and predictive engineering of foam blow molding processing are still in their infancy. Any simulation framework for this purpose needs to address the complex interplay between the matrix rheology, foam morphology and morphology evolution, and the resulting processability and thermo-rheological properties of the foamed product. Here, we report a preliminary simulation framework for foam blow molding, demonstrated in the context of foam extrusion blow molding. The framework addresses several important material and processing considerations. These include: (1) the initial foam morphology; (2) the nonlinear viscoelastic characteristics of the foamed melt; (3) the derivation of constitutive parameters for the foam – arriving at a homogenized representation of the foam rheological characteristics; (4) the implementation of blow-molding simulations using these parameters in a commercially available simulation software; and (5) finally correlating the local strains in the blow molded part to its morphology.

Mechanical Properties of Electrospun Fibers from Ozone-treated Lignin

Jiawei Chen, May 2020

Ligninis a viableprecursor alternative for electrospun carbon fiber. Purification of lignin typically involves chemicals. Ozone treatment is an environmentally-friendly approach to purify lignin. In this study, electrospinning of untreated and ozone-treated lignin was conducted with polyethylene oxide (PEO) as an aid-polymerto form submicron fibrous mats. Morphology and mechanical properties of the electrospun fibers were investigated. Electrospun ozone-treated lignin fibers showedspherical shapes attached to smooth fibers, characterized as beads-on-a-string (BOAS) morphology. It was found that longer duration of ozone treatment resulted in decreased average fiber diameter while increasing bead density, changing spindle-like beads into spherical beads. Ozone treatment did not have significant influence on the strain at failure of the electrospun lignin mats. Bead formation reduced the tensile strength and the elastic modulusof the electrospun fibers. Medium ozone consistency and short reaction duration were found to be the optimum conditions where highest tensile strength and elastic modulus were achieved.