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.

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Various topics related to sustainability in plastics, including bio-related, environmental issues, green, recycling, renewal, re-use and sustainability.
Agile Formulation of Recycled Polymers
Dr. Mark Sullivan and Hannah Melia, December 2023

Polymer recyclates have a variation in properties that can affect the end properties of recycled polymers. In this session, Dr. Mark Sullivan and Hannah Melia of Citrine Informatics will present a case study to show how AI can be used to rapidly reformulate recycled polymers to maximize the use of recyclates while consistently meeting end customer requirements. Learn from Citrine's experience from more than 10 years working in machine learning for materials and chemicals development.

Biodegradation Studies and Experiments for Materials in the Marine Environment - Part 3
Dr. Micheline Labrie, August 2023

In 2022, the University of Massachusetts Dartmouth established a state-of-the-art research and product development facility to advance the science, standards, and products related to biodegradability of plastics in the marine environment. The primary objective of the Biodegradability Laboratory is to test and develop new biodegradable materials suitable for use in various industries, such as textiles, packaging, and other sectors that contribute significantly to marine plastic pollution.  This webinar will offer an overview of the laboratory's first year, highlighting the challenges, successes, and insights gained during the setup and testing of two Columbus Instrument's respirometry systems. A 60-channel and 80-channel aerobic Micro-Oxymax system were used to develop a standard operating procedure in adherence to the ASTM D6691 standard method. An overview of the full suite of instrumentation, equipment, and assays included in the standard operating procedure, biodegradation experiment setup and monitoring, and critical lessons learned will be covered.

Biodegradation Studies and Experiments for Materials in the Marine Environment - Part 2
Linda Amaral-Zettler, July 2023

The Marine Biodegradation Standard Test Method ASTM D6691 “Standard Test Method for Determining Aerobic Biodegradation of Plastic Materials in the Marine Environment by a Defined Microbial Consortium or Natural Sea Water Inoculum” is currently under revision at the ASTM International and ASTM D7081 “The Standard Specification for Non-Floating Biodegradable Plastics in the Marine Environment”, withdrawn in 2014, is being reworked into a new standard specification “Specification for Non-Floating Biodegradable Products in the Aquatic Environment WK75797” and broadens the scope to include fresh and marine waters. ASTM D6691 optimizes conditions (temperature, surface area, nutrients) to accelerate the biodegradation test at 30°C, but new ISO test methods broaden this temperature to include more realistic temperatures encountered in the marine environment from 15°-25°C, and allow for the use of films in addition to powders for testing. This talk will provide a brief overview of existing ASTM and ISO/CEN marine degradation and biodegradation test methods and specifications and share experiences using open and closed respirometry systems followed during ISO Round Robin Marine Biodegradation Testing and subsequent follow-up experiments.

Biodegradation Studies and Experiments for Materials in the Marine Environment - Part 1
Dr. Jo Ann Ratto, June 2023

Marine debris continues to be an immense problem, thus eliciting the global emphasis on pollution prevention. Biodegradable polymers have historically been studied as a solution to reduce solid waste for the military. However, biodegradation is a challenge for most materials in the marine environment. A tiered approach to evaluate polymers in the marine environment will be reviewed. The Tier 1 method utilized an optimized environment, sample preparation and conditions to evaluate biodegradation by respirometry. A Tier 2 test used weight loss as a function of time to evaluate actual items in the marine environment, and a Tier 3 test had items positioned in the deep sea for weight loss studies. Toxicity as well as disintegration were also studied for all samples that underwent biodegradation testing. Overall, this tier 1 approach was a valuable screening method for polymers while tier 2 and 3 were real-life test methods for determining the fate of polymers in the marine environment. Sample data will be displayed to show the types of materials that biodegrade in the marine environment.

Design for Sustainability — A Case Study with Appearance Nylon
Bruce M. Mulholland, March 2023

Material selection during the design phase can dictate a final part's ability to be recycled or not. This paper looks at an appearance part that transformed three different material solutions into a single material solution such that the final part was now recyclable and produced at lower cost. A look at the technical challenges and solutions to achieve this result is included.

Effect of Reactive and Non-Reactive Coupling Agents on Mechanical Properties of Recycled Polyethylene Terephthalate Filled With Ground Tire Powder
Aboulfazl Barati, March 2023

Accumulated used polymers and tires cause several ecosystem issues in landfills. A practical method was proposed to reuse recycled polyethylene terephthalate (rPET) and ground tire rubber (GTR) powder by melt composite process. A composite material was developed in this work using GTR for reinforcement and rPET for matrix. The effect of two non-reactive (styrene-butadiene-styrene (SBS) and styrene-ethylene-butadiene-styrene (SEBS)) and three reactive (ethylene-methyl acrylate-glycidyl methacrylate (EMA-GMA), ethylene-glycidyl methacrylate (EGMA) and SEBS grafted with maleic anhydride (SEBS-g-MA) coupling agents on the mechanical properties of the composite material were evaluated. Mechanical tensile and impact strength properties were evaluated to determine how coupling agents affect composite behavior. All reactive coupling agents improve the mechanical behavior of composite materials, whereas non-reactive ones have little effect. EMA-GMA and EGMA are more reactive with rPET than SEBS-g-MA. Using 10 wt% of EMA-GMA in the composite of rPET/GTR (4:1) increases the tensile strain and impact strength (950% and 23%, respectively) and decreases maximum tensile strength and Young’s modulus (16% and 35%, respectively).

Reactive Extrusion for Upcycling Post-Consumer Polypropylene and Its Use as a Compatibilizing Agent
Olivia Ferki, March 2023

Polyolefins functionalized with reactive side groups are known to provide improved properties to blends of incompatible resins including processability, homogeneity, and mechanical properties. However, experimentation and use of compatibilizers are limited to virgin based grafted resins, which incurs additional costs for processors. Thus, there is increasing interest in upcycling post-consumer polyolefins to higher value secondary feedstock streams that offer interfacial adhesion of polymer blends. In this work, we propose a melt grafting strategy to achieve reactive functionality and apply the method to post-consumer polypropylene with the purpose of demonstrating recycled polyolefins capabilities as compatibilizers. Experiments are performed using a semi-batch co-rotating micro-conical twin screw extruder at various screw speeds and temperatures. The torque and grafting percentages are controlled by varying the concentration of dicumyl peroxide and maleic anhydride. The functionalized polypropylenes are characterized using spectroscopy and thermal analysis techniques to determine the grafted content and resulting processing behavior. The reactive extrusion process is compared with that for functionalizing virgin polypropylene, and the scale up and economics are discussed.

Film Recyclability Study Using a Micro Blown Film Line
Jin Wang, Ph.D., March 2023

The Association of Plastic Recyclers (APR) has published several methods for evaluating the recyclability of polyethylene plastic films. Although the methods are developed for lab-scale process equipment, a large amount of film is typically required for a complete evaluation. To accelerate screening of new film structures and compositions, we have developed a small-scale workflow based on a LabTech Micro Blown Film Line. It only requires 200 grams of materials to blow a film for film properties characterization. In this paper, we will present three case studies to demonstrate this workflow. First case study is the effect of paper label residuals in the post-consumer recyclate (PCR) on the film properties. Second case study is on the recyclability of a PVOH coated film. And the third case study is on the effect of compatibilizer (RETAINTM 3000 Polymer Compatibilizer from Dow) on the recyclability of an EVOH containing multilayer film. The advantages of this workflow are: 1) low materials consumption (200 grams vs > 4 lbs per formulation); 2) fast elimination of formulations that cannot be used in the blown film process; and 3) film properties that provide some indication or ranking of the formulations with different recycle content. Although this workflow may not have high resolution of film properties for complicated film formulations (such as those using a small amount of compatibilizer), it accelerates recyclability assessments for blown film.

Novel Compatibilization Solution for PE/PA or EVOH
MiaoMiao Xiao, March 2023

Multi-materials plastic films are especially important in our daily food packaging. It can combine different polymers to achieve a range of properties, which can’t achieve by mono-material film. It can protect the food, increase the shelf life of packaged food, and reduce the food waste. However, the recycling of the multi-material packaging film faces big challenges due to the incompatibility of different materials. With the increasing awareness of plastic pollution issues, there is a clear and present need to find a way to recycle multi-material film structures to support the goals of the circular economy. Compatibilizer can help improve the compatibility of polar and non-polar components in the films by increasing the interfacial adhesion between the two phases. In the research, we developed a novel polyethylene (PE)/Polyamide (PA) or ethylene vinyl alcohol (EVOH) compatibilizer. Based on the tensile, dart impact and tear test results, with loading of this novel compatibilizer to the PA or EVOH at 1:10 ratio, up to 20% PA or EVOH can be incorporated into PE stream without scarifying too much mechanical properties and meet the Association of Plastic Recycler (APR) recognition requirements. The microscopy pictures clearly showed that the compatibilized blend has a homogeneous morphology while the blend without compatibilizer has clear 2 phases. This novel compatibilizer provides the possibility of recycle-ready multi-material film structure design and improve the sustainability of the multi-material films.

Novel Approach to Increase Sustainability Rates for PET Compounds
Yuzhen Yang, March 2023

Global plastics recycling rates are low and the market share of recycled plastics is less than 10% at the moment. People are searching for different ways to further improving the recycle rates for plastics, especially for PET. However, companies’ sustainability efforts have been hampered because recycled PET (rPET) can exhibit poor mechanical properties compared to virgin PET (vPET) due to the lower intrinsic viscosity (IV). At Kaneka, we know additives can significantly improve the prospects for recycled plastics. The newly developed IV booster MV-01 showed promising performance when used in rPET. The study shows that at low dosing level MV-01 in rPET can improve the IV to the same level as vPET even after 4 passes. In addition, the mechanical property, transparency, YI, and Haze are all well maintained. Therefore the recycle content of PET can be significantly improved after adding MV-01 to the PET compound.

Role of Renewable Resources in Polymer Industries: Materials for Sustainable Future
Ram Gupta, Ph.D., March 2023

Tim Dawsey and Ram K. Gupta National Institute for Materials Advancement, Pittsburg State University, 1701 South Broadway Street, Pittsburg, Kansas 66762, United States The current shift from solely depending on petroleum sources to seeking renewable alternatives is attributable to their fast depletion, erratic prices, and the need to reduce our carbon footprint. For instance, the polyurethane industry currently calls for renewable (and less toxic) polyols and isocyanates for their synthesis over the traditional petroleum-based ones. To tackle these issues, we have investigated the role of vegetable/fruit oils in the preparation of polyurethane foams. Different approaches such as thiol-ene click chemistry and epoxidation, followed by ring opening, were used to convert these oils into polyols. The effect of the synthesis process on the properties of polyurethanes was studied. One of the major issues in polyurethanes is their high flammability. To reduce the flammability of polyurethane foams, different types of flame-retardants (additive and reactive) were investigated during the foaming process. The effect of flame-retardants on the physicomechanical and flammability of the foams was investigated in detail. Most of the foams displayed density in the range of 30-55 kg/m3 which is suitable for many applications. The compressive strengths of these foams were higher than 160 kN/m2. Except for some high concentrations of flame retardants, most of the foams showed closed cells greater than 90%. It was found that the burning time of the foams reduced significantly after the addition of flame retardants. For example, foam prepared using sunflower oil-based polyols showed a reduction in burning time from 79 seconds to 2 seconds after the addition of 13.61 wt.% of dimethyl methyl phosphonate. The effect of various flame-retardants and the role of bio-based polyols on the properties of polyurethane foams will be discussed. Our research suggests that a variety of bio-based materials can be used for the polyurethane industries with a reduced impact on the environment.

Life Cycle Assessment Comparing Fossil-Based and Bio-Based Plastic Gloves
Anthony Keyes, Ph.D., March 2023

This presentation provides an example of comparative Life Cycle Assessment for fossil-based and bio-based polymers that are non-compostable and compostable respectively. In this instance, fossil-based and non-compostable gloves made from polyethylene were compared with our commercial bio-based and compostable gloves utilizing ISO 14040:2006, ISO 14044:2006 and ISO 22526:2020 standards. As bio-based materials are created on a much shorter timescale than fossil-fuel reserves, some consider bio-based polymers to be a form of carbon sequestration. This means that bio-based polymers can be said to have a lower feedstock carbon emission burden than fossil-based alternatives. A major discrepancy, however, when comparing fossil-based and bio-based materials largely arises due to how biogenic carbon is accounted. This normally stems from how bio-based materials have their system boundaries drawn, where sequestration of CO2 is immediately tied to end-of-life emissions and taken as a net zero summation. This handling is the current methodology employed by the European Union Product Environmental Footprint (EU PEF) which states, “removals and emissions of biogenic carbon sources shall be kept separated in the resource use and emissions profile”. We compare this mindset to that of ISO standards and give a representative understanding where fair comparisons are possible for fossil-based and bio-based plastics, and when fossil-based materials are preferentially benefited with this tactic. In doing so, this presentation will provide the audience with an understanding on the bias LCA methods have against bio-based materials when biogenic carbon is not properly accounted for and give specific criteria which allows for a fair comparison with their fossil-based counterparts.

Using Amorphous PHA as a Biobased Performance Additive in Non-Compostable Product Formulations
Rajendra Krishnaswamy, March 2023

PHAs or polyhydroxyalkanoates are recognized for their unique ability to biodegrade in many natural environments including marine, home compost and industrial compost sites. As a result, PHAs are used in many applications where end of life is a critical value proposition. We have previously highlighted the value proposition of blending an amorphous grade of PHA (PHACT A1000P) from CJ Biomaterials in various compostable product formulations including those based on PLA, PBS, PBAT and starch. In this presentation, we will address new opportunities for A1000P in the non-compostable space. Specifically, we will highlight applications where incorporating A1000P into the formulation brings benefits that include biobased carbon content, flexibility and toughness. Examples will include enhancing the performance of products based on Acetal polymers, Nylon-11 and Nylon-12 and EVA.

Effective Processing Aid to Enhance Melt Strength of Clear PLA Without Increasing Melt Viscosity
Shusuke Yoshihara, March 2023

Combining its own technology in polymerization and polymer rheology, Kaneka North America provides the processing aid to enhance the melt strength of bioplastics like PLA. The poor melt strength of PLA causes drawdown and sagging in the melt process, leading to low productivity. The processing aid dramatically increased the melt strength of PLA at 1 % loading level. During the extrusion process, it reacts to PLA and creates a comb structure. But it didn’t affect optical properties without forming gels. It was also designed to keep the melt viscosity low so that the processing rates can be high. It worked for PHA as well. The 1% addition doesn’t impact on the certification of biodegradability. This technology could enable access to more cost-competitive and sustainable bioplastics with a broader application window. Blow molding of bottles, film blowing, fiber spinning, and foaming could be facilitated by the materials exhibiting the high melt strength.

Mechanical Recycling of Polyethylene Bottle Caps — Characterization of the Various Material States Along the Process Value Chain
M. Hassan Akhras, Paul J. Freudenthaler, Joerg Fischer, March 2023

This study provides a practical demonstration of an open-loop recycling process by creating a pilot product using a defined post-consumer plastic waste stream. The study aims to investigate the possible changes in the material property profile throughout the whole recycling process. Additionally, it also aims to generate the necessary data for the implementation of digital product passport (DPP) as a potential material traceability tool.High density polyethylene (PE-HD) beverage bottle caps were selected as the targeted input waste stream. Two collection methods, informal and formal, were employed in this case study. To ensure a high purity level of materials before entering the recycling process, both input fractions were hand-sorted after the collection step. Subsequently, materials were shredded and re-granulated before being converted into the finished pilot product, which was defined as a frisbee (i.e., flying disc).To characterize the material property profile of the different material states, several measurements including melt mass-flow rate (MFR), differential scanning calorimetry (DSC), and mechanical tests were carried out. The informal collection led to a higher material purity as the other fraction had a more prominent melting peak of polypropylene (PP), which led to a slightly higher MFR value of this input fraction. However, no significant changes in the MFR values of the other materials were observed. In terms of the mechanical properties, the tensile stiffness and strength increased after processing. In contrast, the Charpy notched impact strength of the recyclates seemed to be slightly lower than that of both input streams.

Sustainability in Rotomolding
Denis Rodrigue, Ph.D., March 2023

In order to achieve more sustainability in rotomolded parts, several options are currently investigated. In this presentation, three possibilities are presented with typical examples produced at the lab scale (still under investigation). The first option is to use recycled resins instead of virgin ones. In this case, the recycled/virgin ratio can be change over the whole range of concentration; i.e. 0 to 100% recycled content. The second option is to add biobased fillers such as lignocellulosic fibres to get “greener” materials. In this case, the origin (wood, plants, etc.) and the particle size (mesh) are highly important. Finally, there is the possibility to use biosourced resins as the matrix. In this case, there is limitations in terms of availability and suitability of the resins for rotomolding processing, but good parts can be achieved after some optimization of the processing conditions (temperature, time, speed, etc.). Nevertheless, there is also the possibility to combine these options for specific applications (automotive, building, construction, outdoor, etc.). To get a clearer picture of the situation, typical examples will be presented and discussed in terms of physical and mechanical properties. Comparisons with petroleum-based resins is also included to determine the most interesting candidates for future developments.

circPLAST-mr - The Austrian Flagship Project on Mechanical Recycling of Plastics
Joerg Fischer, Reinhold W. Lang, March 2023

Initial situation, problem and motivation: The achievement of future EU and Austrian targets for mechanical recycling rates of plastic waste and the minimization of the EU plastic waste levy for non-recycled plastic packaging waste require significant improvements in all individual process steps of mechanical plastics recycling. For example, in order to achieve the EU target of a mechanical recycling rate for plastic packaging waste of at least 55% by 2030, the output efficiencies in the 3 essential process steps, (a) collection, (b) sorting and pre- processing, and (c) conversion & recovery, must be increased from the current Austrian status of approx. 58% for process steps (a) and (b) and approx. 78% for process step (c), to 80-85% (!) for each of these process steps.Objectives and intended outcom es: Building on the existing competences of the partners involved (11 scientific partners, 14 company partners), a further significant increase in knowledge and competence with regard to the entire recycling process loop is to be achieved through comprehensive and interactive integration and participation of the partners in the research program as an overall objective, which is indispensable for the achievement of the very demanding political target quotas. On the one hand, this knowledge generation relates in particular to necessary process and materials technology aspects and measures, but on the other hand also to logistical requirements for waste and material flow management. From this, 4 concrete main objectives including expected results are derived: (1) to identify and explore further, so far unused potentials for the mechanical recycling of plastics, (2) to define, implement and test key process steps on a laboratory/pilot scale, (3) to demonstrate the eco-efficient "marketability" of increased quantities of recycled plastics through exemplary products with improved quality and performance characteristics, and (4) to demonstrate the principle scalability of the laboratory/pilot processes to production scale (case studies).Innovation content and sustainability: The integrative and coordinated consideration of all process steps in the mechanical recycling of plastics, together with the structure and design of the research program, defined by the selected classes of material flows, plastics and products a s well as the process steps to be researched in the individual work packages and the associated effects on the material quality characteristics of the recyclates, form the overarching framework for the "conceptual" innovation content of this flagship project. Important innovation components also result from the use of digital technologies and modern, intelligent sensor technologies. This will enable the technical and the economic-ecological optimization of all process steps along the entire value chain of m echanical recycling of plastic waste from both separate collection and mixed waste. In the material flow management, special attention is paid to energy efficiency, the potential use of renewable energy technologies and the recycling of water including any additives (chemicals). The commercial implementation of the research results in future industrial practice is ensured not least by the main objectives (3) and (4) described above.

Influence of Macroscopic Contaminations on Mechanical Properties of Model and Post-Consumer Polypropylene Recyclates
Ines Traxler, Klaus Fellner, Joerg Fischer, March 2023

Due to insufficient sorting and recycling, macroscopic contaminations remain in post-consumer polyolefin recyclates. It is known that these contaminations affect the mechanical properties of the recyclates, as they constitute defects and thus crack initiators. However, the influences of different types and amounts of macroscopic contaminants have not yet been analyzed systematically.In this study, to close this knowledge gap, virgin polypropylene (PP) was systematically contaminated with paper, aluminum, sand, wood, in-mold labels, jute fibers and long glass-fibers. Additionally, three commercially available post-consumer PP recyclates were investigated. In a two-stage process, all materials were injection-molded into plates and subsequently milled to specimens. The specimens underwent (i) tensile tests at 50 mm/min, (ii) intermediate-rate tensile tests at 2000 mm/min, and (iii) tensile impact tests. Further, optical microscopy was used to measure the dimensions of the defects on the fracture surfaces.First, the influences of various types and quantities of contamination were evaluated. No significant effects were detected, as the matrix material was very brittle. Compared to the virgin reference grade, most samples showed lower strain-at-break values, except for those with labels and long glass-fibers, for which strain values increased. All PP post- consumer recyclates exhibited a more pronounced ductile behavior, although the contaminations incorporated gave rise to relatively high standard deviations. Second, in a comparison of various testing speeds, a greater influence of contaminants was detected in test (iii). Samples taken from a position close to the sprue had better mechanical properties than samples taken from the opposite side of the plate, as contaminants tend to flow to the end of the produced part. Finally, a non-linear relationship between the energy needed for fracture in testing methods (ii) and (iii) and the dimensions of the contamination on the fracture surface was found.

Simulated Closed-Loop Recycling of Electronics Plastic
Allison Ward, Nicolas Sunderland, Ph.D., March 2023

Mechanical recycling is one of the most economical pathways to reduce the environmental impacts of plastics. High-value, engineered plastics such as polycarbonate (PC) are being recycled at increasing quantities to the point that the supply of high-quality post-consumer recycled (PCR) polycarbonate is seen as an upcoming bottleneck to meet growing demand. There is an urgency to scale recycling of high-value, engineered plastics from the waste stream into new electronics. Accessible sources of recycled PC are still limited to select applications such as headlamps, construction sheets, and water barrels. In order to utilize material from additional waste sources, focus needs to be on addressing complicated waste types (PC with additives or PC-blends), reprocessing approaches to remove contamination (metals), and development of robust performance recycled content plastics. Mixed-plastic waste is commonly downcycled today and presents many challenges for the value chain from re-processing to the scale of e-waste collection. It is encouraging that many electronics brands have created take-back programs to increase collection rates and support scaling recycling technologies. However, today only a fraction of the electronics manufactured enter the recycling stream. Lack of volume and consistency in waste material streams present another challenge for the industry. Dell, Covestro, and MPT together investigated the effects on material properties, processing, and component quality levels through multiple rounds of simulated closed-loop recycling with positive results. A PC/ABS + talc blend was used as the base production material to add reground scrap parts and mold new laptop components. A total of three recycling loops were tested (equivalent to ~32 years), increasing regrind content by 20% each loop. Impacts of UV monocoat paint on the recycling process were also examined. Results showed the material could be recycled several times and still retain high performance. Paint had a minimal impact on the recycled material performance. Closed-loop recycling of PC and PC blends can offer an efficient pathway to recycle laptop plastic materials. The recycling process from collection, dismantling, and sorting is critical to influence the quality of e-waste to be further developed for second-life use. Laptop brand manufacturers also use a common framework of materials primarily based around polycarbonate and polycarbonate blends, creating an opportunity for scale. Circular design principals must be considered for long-term recycling success and support circular e-waste models.

An Assessment of Landfill-Bound Mixed Plastic Waste From Material Recovery Facilities (MRFs) in the United States
Victor Sanfins Cecon, March 2023

Victor received his Bachelor's degree in Chemical Engineering from the Federal University of Sao Carlos (UFSCar, Brazil) in 2019 and is currently pursuing a Ph.D. in Food Science and Technology at Iowa State University under the supervision of Dr. Keith Vorst. During his undergraduate studies, he was a visiting scholar at the University of British Columbia (UBC, Canada) for one year and an R&D intern for 1.5 years at 3M Brazil. His research focuses on the mechanical and chemical recycling of landfill-diverted mixed plastic waste with the use of several polymer processing and characterization techniques, as part of the efforts of the Chemical Upcycling of Waste Plastics (CUWP) center.

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