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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Conference Proceedings
Predicting Molecular Weight and Composition Distribution for Gas-Phase Polyethylene Products
Yan Jiang, February 2020
A mathematical model was developed to simulate a laboratory-scale gas-phase ethylene/1-hexene copolymerization process using a multi-site metallocene catalyst. The kinetic scheme includes activation, propagation, chain-transfer to hydrogen, β-elimination, deactivation and reinitiation. A three-site model with 33 parameters was developed to predict number-, weight- and Z-average molecular weights, along with polymerization rate and overall hexene incorporation. In addition, the model predicts the molecular-weight and comonomer-incorporation distributions for the polymer accumulated in the reactor at the end of the batch. Statistical methods were used to rank the kinetic parameters from most-to least-estimable, based on the available industrial data. A mean-squared-error criterion was used to determine the appropriate number of parameters to obtain reliable model predictions. Parameters were estimated, using gas flow rate and composition data obtained over the course of each experimental run, along with polymer characterization data at the end of each run. Data sets not used for parameter fitting were used for subsequent model validation.
Overview of the Current Plastic Recycling Landscape
Manuel Prieto, February 2020
Trends in plastic waste management, recycling and reuse are evolving rapidly – the demand for single use plastics continues to grow and more complex plastic applications are further challenging existing infrastructure. Finding a solution requires action across all steps of the value chain (from product design to consumer education to collection to separation to recycled polymer reuse), as well as across stakeholders (from chemical companies to converters to brand owners to recycling companies to governments to investors and public figures). Chemical recycling, conversion, and decomposition technologies offer further flexibility to recover and reuse a broader set of materials and potentially provide the missing piece in the recycling equation. However, the economics of these technologies is not yet proven.
Chemical Recycling: Upcycling of End-of-Life Plastics
Carlos Monreal, February 2020
There is no time to lose in figuring out how to solve the plastic challenge and increase both the recycling rates and the recycled content in product. In parallel of this regulatory drive, many large brand owners have committed to reach 100% of recyclable packaging by 2030. Plastic Energy has developed a solution to address low-value mixed plastics that cannot be mechanically recycled. The Thermal Anaerobic Conversion (TAC) produces recycled oils (TACOIL) from end-of-life plastics. The TACOIL is then used as a new feedstock for the (petro)chemical industry to generate recycled plastics by replacing virgin oil with TACOIL. Our TAC process is a low-pressure thermal depolymerization process patented in Europe and the US. To be more specific, the shredded, densified and then molten feedstock is pumped into the oxygen free reactors at a controlled rate and temperature. The multicomponent hydrocarbon vapour produced in the reactor passes through our patented contactor vessel which finally controls the hydrocarbon chain length and quality before entering the condensation system. The TACOIL is then be subjected to various additional purification / polishing steps before being sent to the steam-crackers of the chemical industry. In addition of having two industrial plants running 24/7 more than 330 days per year for the past 3 years, Plastic Energy through its experience has managed to stabilise the output the specifications required by the chemical industry. This has led to the value-chain validation of the circularity of the Plastic2Plastic process by the ISCC+ to produce the Certified Circular Polymers. This chemical recycling process effectively upcycles the plastic through conversion to the original monomers in each process of recycling, making it safe and reusable as a food-grade product. After explaining the technical and industry experience of reach an optimal product and efficient operations, the presentation will stress some real-life Plastic2Plastic applications developed with the value-chain, and will continue on the upscaling and expansion of the capacities of Plastic Energy and the potential of the chemical recycling industry in improving recycling and creating a circular economy.
China’s Plastic Waste Import Ban: Global & Regional Implications
Jim Rounick, February 2020
China used to import large volumes of polymer waste from around the world. The sudden 2017 decision by the Chinese government to ban imports of recyclables created a supply chain gap for plastic waste processors in China. He-Ro will outline how this supply chain gap issue has been addressed by the PR China plastic waste processors & how the value chain has adapted. With additional plastic waste bans now in place in other Asian countries, will this ’new system’ created by the plastic waste processors be rolled out across Asia and the rest of the world? Will their learnings form a base for other countries to build their own supply chain infrastructure?
Developments in End-of-Life Technologies for Multilayer and Barrier Flexible Packaging
Terence Cooper, February 2020
Flexible packaging is more economical than other formats because of its lower material and energy consumption and manufacturing and transport costs. It also provides reduced waste of packaged products, particularly food, generates much less packaging waste than rigid formats and has favorable LCAs. Consequently, its use, particularly in multilayer barrier films and pouches, has been steadily growing and replacing rigid packaging. Despite this, it is still opposed by environmental groups due to difficulties in end-of-life collection, sorting and processing and concerns about “single-use” packaging and sustainability. Because of its film and multilayer construction, and often food-waste contamination, post-consumer flexible packaging is not readily mechanically recyclable and is presently generally landfilled, so that environmental groups have pressured food and other companies to stop using it. To combat this, and to eradicate landfilling, the food, packaging and recycling industries are supporting a wide range of initiatives including: a). improved mechanical recycling systems to handle film packaging and the development and introduction of supporting collection, identification and sorting technologies and infrastructure; b). new package designs and materials facilitating mechanical recyclability by reducing polymer types and number of layers, mono-material and all-polyethylene pouches, compatibilizer incorporation, and using barrier adhesives and coatings and recyclable and biodegradable barrier materials; c). economic film layer separation and recovery methods; d). chemical recycling processes to produce monomers or valuable feedstocks; e). waste-to-energy recovery systems such as anaerobic gasification and plasma pyrolysis; and f). pyrolytic waste-to-fuel and waste-to-chemicals recovery operations. These developments are surveyed to demonstrate the wide range and intensity of current activities.
Recycled Material Standard (RMS)
Laura Thompson, February 2020
The Recycled Material Standard (RMS) is in early development stages and is ultimately meant to serve as a voluntary, market-based tool to be implemented by value chain participants and audited independently by credible third-party certification bodies. The purpose of the standard is to address some of the challenges that brands, their suppliers, and the recycling industry are facing in trying to incorporate higher amounts of recycled content into packaging or finished products. The RMS is being developed by GreenBlue for common packaging materials including paper, plastic, glass and metal, but could be employed for the same materials in markets other than packaging (e.g. the use of recycled plastic in composite lumber). The RMS will use two independent tracking system options which will be defined in separate parts of the standard: 1. The chain of custody (CoC) system will specify material management requirements within an organization in order to demonstrate that recycled content materials and products purchased, labelled and sold as RMS certified originate from recovered materials (derived from post-consumer and post-industrial sources). The chain of custody system will allow for claims to be made using either an average percentage method or credit-based claims. 2. The attributes of recycled content (ARCs) will be a certificate-based trading scheme tracked through a registration body to provide an investment mechanism for new processing capacity. Organizations purchasing ARCs will help support the development of new, additional capacity for processing recycled materials. Purchasing ARCs will also allow companies to communicate the environmental benefits associated with these materials in place of virgin raw materials.
Agilyx's Role in Commercial Recovery of Chemical Value in Post-Use Plastics
Barry Cavinaw, February 2020
Global plastic recycling rates are stagnant at roughly 10%. At the same time, plastic production exceeds 300 million tons a year and is projected to continue growing. Polyolefins account for nearly half of the world's plastics. Agilyx was established with the primary goal of dramatically increasing the world's recycling of plastics and polymers. This single focus led to innovations in polymer depolymerization technology that Agilyx deploys on a commercial scale. As Agilyx treats post-use plastics as a hydrocarbon reserve and a valuable resource, new business models emerge that support the circular plastics industry. Its 15+ years of experience working with its technology has resulted in a profound understanding of post-use polymers as well as their supply chains and variability. The company advances circular solutions for polyolefins and polystyrene using its proprietary pyrolysis technology in conjunction with vertical feedstock management. Ongoing research and development programs bolster Agilyx’s leading position in the market through continuous innovation and improvement to overall process performance, financial profiles, and the development of new product slates. Agilyx creates chemical and circular recycling pathways for end-of-use plastics through innovations, know-how, and processes that are environmentally and economically sustainable.
Technology for Ultra-pure Recycled PP
John Layman, February 2020
Consumers increasingly expect and demand sustainable products without performance and price trade-offs, and companies, like P&G, have established long-term sustainability goals that include the use of large percentages recycled resins in their products and packaging. To satisfy consumers’ expectations and achieve companies’ goals, P&G has developed a novel purification technology that converts contaminated recycled resins into virgin-like resins. The proprietary technology is based on the use of a hydrocarbon solvent at elevated temperature and pressure, and a novel combination of standard chemical engineering unit operations, such as liquid – liquid extraction, sedimentation, size exclusion and adsorbent filtrations, and devolatilization. These processes purify the recycled resins via removal of odor, volatile organic chemicals, and other organic and particulate contaminants and additives. Initial focus of the technology is on polypropylene (PP); however, purifications of other polymers are currently under development. The PP purification technology was patented by P&G and licensed to Innventure, which launched PureCycle Technologies (PCT) in September 2015 to commercialize the technology. The 70-ton capacity pilot plant started operation in July 2019, and commercialization is slated to start in 2021/22 with a ~50 kta capacity plant.
Surface Characterization of Polyolefins Modified by Surface Initiated Radical Polymerization
Atsushi Takahara, February 2020
Direct surface modification of polymer films by surface-initiated polymerizations has been carried out. The introduction of initiating sites on the polymer materials and successive polymerization produce surface-tethered polymer chains on the polymer surface. The surface-selective modification controls the surface properties such as wetting, lubrication, and adhesion without sacrificing the bulk performances. Among various procedures for the initiating group introduction and subsequent polymerization proposed so far, this study focuses polymer brush grafting to polymer films through surface-initiated radical polymerizations. Researches on grafting polymer chains to five different types of solid polymers, poly(methyl methacrylate)-based copolymer, Br-containing polyolefins, poly(butylene terephthalate) (PBT), poly(vinylidene fluoride-co-trifluoroethylene) [P(VDF-co-TrFE)], and poly(ether-ether ketone) (PEEK) are summarized. The surface-initiated polymerization produces thick stable polymer brush layer on polymer films with various morphologies. The polymer surfaces are homogeneously covered with polymer brushes without serious defects to change the surface properties without sacrificing the bulk performances and the morphology.
Stochastic Estimation of the Lifetime of Polyethylene Pipe with Arbitrarily Located Defects (Paper)
Byoung-Ho Choi, February 2020
Polyethylene is one of most popular materials for various piping applications. There are three failure modes for polyethylene pipes, i.e. ductile fracture with large plastic deformation (mode I), quasi-brittle fracture with slow crack growth (mode II) and mechano-chemical fracture with localized degradation (mode III), and mode II failure mode is frequently observed from field fracture samples. So, according to standard tests from ISO and ASTM, the resistance to slow crack growth of pipe-grade polyethylene resins should be evaluated. However, it is commonly observed that there is quite large scatter of test results, and many factors such as defect locations, defect sizes, loading conditions, specimen geometry etc. should be considered to analyze test results. So, stochastic approaches are required to estimate the lifetime of polyethylene pipe under mode II failure. In this study, slow crack growth behaviors of polyethylene pipe are simulated for defects with arbitrarily located defects, and the simulation results are analyzed by a continuous probability function. In many cases, it is observed that slow crack growth with mode II failure is in discontinuous manner, so the crack layer theory with new Green’s functions is applied to simulate the slow crack growth behavior from the arbitrarily located defect.
Stochastic Estimation of the Lifetime of Polyethylene Pipe with Arbitrarily Located Defects (Presentation)
Byoung-Ho Choi, February 2020
Polyethylene is one of most popular materials for various piping applications. There are three failure modes for polyethylene pipes, i.e. ductile fracture with large plastic deformation (mode I), quasi-brittle fracture with slow crack growth (mode II) and mechano-chemical fracture with localized degradation (mode III), and mode II failure mode is frequently observed from field fracture samples. So, according to standard tests from ISO and ASTM, the resistance to slow crack growth of pipe-grade polyethylene resins should be evaluated. However, it is commonly observed that there is quite large scatter of test results, and many factors such as defect locations, defect sizes, loading conditions, specimen geometry etc. should be considered to analyze test results. So, stochastic approaches are required to estimate the lifetime of polyethylene pipe under mode II failure. In this study, slow crack growth behaviors of polyethylene pipe are simulated for defects with arbitrarily located defects, and the simulation results are analyzed by a continuous probability function. In many cases, it is observed that slow crack growth with mode II failure is in discontinuous manner, so the crack layer theory with new Green’s functions is applied to simulate the slow crack growth behavior from the arbitrarily located defect.
Leverage Materials Science to Frozen Food Packaging (Paper)
Jong-Young Lee, February 2020
Polyethylene (PE) is widely used in packaging applications today due to its low cost, good processability, and superior toughness. Coextruded blown films are commonly used in PE-based frozen food packaging, with linear low density polyethylene (LLDPE) making up more than 80% of the structure. In recent years, there has been a strong desire to down-gauge the film while maintaining the incumbent packaging abuse performance. Therefore, a LLDPE resin with better abuse performance at cold temperature (< 0 °C) is needed to satisfy the market need. Much research has been done to establish the relationship between the molecular architecture of PE and the dart impact resistance (related to the toughness) at room temperature, but the knowledge at cold temperature is still very limited. Based on our study, high dart impact resistance of LLDPE film at room temperature does not guarantee high dart impact at cold temperatures. Therefore, more knowledge is needed about the cold temperature toughness of LLDPE. In this paper, we provide a fundamental understanding of the influence the basic molecular architecture (e.g. melt index, molecular weight distribution, glass transition temperature) of LLDPE resin has on the dart impact resistance at cold temperature. Dart impact resistance is measured on LLDPE blown films using an Instrumented Dart Impact instrument in a temperature controlled chamber. The results provide guidance for film converters to select LLDPE products to meet the abuse performance needs of PE-based frozen food packaging.
Leverage Materials Science to Frozen Food Packaging (Presentation)
Jong-Young Lee, February 2020
Polyethylene (PE) is widely used in packaging applications today due to its low cost, good processability, and superior toughness. Coextruded blown films are commonly used in PE-based frozen food packaging, with linear low density polyethylene (LLDPE) making up more than 80% of the structure. In recent years, there has been a strong desire to down-gauge the film while maintaining the incumbent packaging abuse performance. Therefore, a LLDPE resin with better abuse performance at cold temperature (< 0 °C) is needed to satisfy the market need. Much research has been done to establish the relationship between the molecular architecture of PE and the dart impact resistance (related to the toughness) at room temperature, but the knowledge at cold temperature is still very limited. Based on our study, high dart impact resistance of LLDPE film at room temperature does not guarantee high dart impact at cold temperatures. Therefore, more knowledge is needed about the cold temperature toughness of LLDPE. In this paper, we provide a fundamental understanding of the influence the basic molecular architecture (e.g. melt index, molecular weight distribution, glass transition temperature) of LLDPE resin has on the dart impact resistance at cold temperature. Dart impact resistance is measured on LLDPE blown films using an Instrumented Dart Impact instrument in a temperature controlled chamber. The results provide guidance for film converters to select LLDPE products to meet the abuse performance needs of PE-based frozen food packaging.
Scratch Behavior of Polymer Coatings
Mohammad Hossain, February 2020
Polymer coatings have been widely used to improve the tribological performance of various products in electronics, optics, and automotive applications. To further enhance the tribological performance, multilayer polymeric coating and/or single layer composite coating can be applied on polymer substrate. In this study, three-dimensional finite element method (FEM) modeling has been carried out to explain the scratch-induced deformation and damage mechanisms observed in polymer/composite coatings applied on polymer substrate. The stress and strain field analysis using FEM explains the mechanics behind the observed scratch behavior of coating systems. The results show that coating layer thickness and mechanical properties significantly affect the scratch resistance of coating systems. Furthermore, anisotropic behavior of composite coating can significantly influence the scratch behavior. The study provides useful insights toward designing surface damage resistant coating systems.
On Characterization of Dart Impact Resistance of Thin Plastic Films
Bikramjit Mukherjee, February 2020
We investigate the role of film/dart friction on the results of dart impact test used to characterize toughness of plastic films against impact (biaxial loading) at a high speed (~3 m/s). Utilizing an instrumented dart impact (IDI) capability, impact tests were conducted for plastic films exhibiting a wide range of dart impact values under standard test conditions. A Steel dart and a Polytetrafluoroethylene (PTFE)-coated dart were used with the former representing a high-friction interaction and the latter a low-friction one at the film/dart interface. Our results indicate that differentiation between films on the basis of their impact toughness may change dramatically depending on friction. Load-displacement curves obtained from the IDI tests, a simplistic analysis of forces, failed samples, finite element simulations, and high-speed tensile tests help us rationalize our findings about the effect of friction on impact toughness of films.
New Styrenic Block-copolymer Impact Modifiers for TPO Compounds
Amit Desai, February 2020
Polypropylene (PP) is commonly used in various interior and exterior parts of an automobile for several reasons, such as low cost and ability to tailor properties using additives. These compounded PP formulations are also referred to as thermoplastic polyolefin or TPO. A key additive used in these TPO compounds is an impact modifier to improve the impact resistance of the part. In this presentation, we discuss development of new styrenic block-copolymers (SBCs) as an impact modifier for TPO compounds. Typically, a combination of polyolefinic elastomer (POE) and SBCs are used as impact modifiers for TPO, which provides an appropriate balance of cost and impact performance. In these formulations, the role of the SBC is to compatibilize the POE with PP and achieve a desirable morphology (mainly desirable elastomer domain size and distribution), which results in acceptable impact performance. In this presentation, we report development of a series of polymers to further increase the compatibility of SBC with POE and PP and consequently improve the impact resistance. A few of these new polymers led to a significant increase in impact strength compared to existing formulation without significantly affecting other physical properties, such as stiffness and melt flow. We also performed morphological investigations to confirm the hypothesis of improved compatibilization leading to better impact resistance. These new impact modifiers can enable the use of TPO compounds in newer applications demanding higher performance, such as thin-walled and low-density parts.
EOS Polymer Laser Sintering: Enabling Applications Through New Materials
Cary Baur, February 2020
EOS specializes in laser sintering technology, which uses thermoplastic powder, along precise thermal control and laser power, to produce three-dimensional parts from a digital file. Our technology is widely used across many industries, from flame retardant polyamides for ductwork in commercial aircraft to PEKK - carbon filled materials for high temperature, chemically resistant, and high mechanical strength applications such as brackets and valves for oil and gas, automotive, and aerospace. Our focus is on providing machines that can utilize many materials to meet our customers' needs and a wide selection of custom materials targeted at their specific application criteria. This presentation provides an overview of how our technology works, what types of materials we use, and how we approach material development to enable new, advanced applications with our customers.
HP Multi Jet Fusion Additive Manufacturing - the Technology and Fit into Production Manufacturing (Paper)
Barbara Arnold-Feret, February 2020
Additive manufacturing and polyolefins seem to have been a match made in heaven. However, the very characteristics of polyolefins that made it an ideal material for molding and other plastics processing can made it more of a challenge in the additive manufacturing side. Where some of the additive manufacturing equipment currently on the market utilizes polyolefins as a functional building material, the polyolefin material can create a cross road in performance. These issues can affect accuracy, strength, and speed of platform issues in use. An outline of how HP deals with the processing of plastics using Multi Jet Fusion (MJF) and with explainations, details and breakdowns to de-mythicize the MJF process is presented. Understanding the process helps understand where polyolefins fit into the HP MJF printing material universe. To explain the details of the Multi Jet Fusion (MJF) process, familiarity with the mechanism of how the fusion of the plastic is done and the basics of the interface need exploration. This paper is an overview of the MJF process, why the process serves as a unique method of manufacturing and summarizes the HP materials roadmap as of January 2020.
HP Multi Jet Fusion Additive Manufacturing - the Technology and Fit into Production Manufacturing (Presentation)
Barbara Arnold-Feret, February 2020
Additive manufacturing and polyolefins seem to have been a match made in heaven. However, the very characteristics of polyolefins that made it an ideal material for molding and other plastics processing can made it more of a challenge in the additive manufacturing side. Where some of the additive manufacturing equipment currently on the market utilizes polyolefins as a functional building material, the polyolefin material can create a cross road in performance. These issues can affect accuracy, strength, and speed of platform issues in use. An outline of how HP deals with the processing of plastics using Multi Jet Fusion (MJF) and with explainations, details and breakdowns to de-mythicize the MJF process is presented. Understanding the process helps understand where polyolefins fit into the HP MJF printing material universe. To explain the details of the Multi Jet Fusion (MJF) process, familiarity with the mechanism of how the fusion of the plastic is done and the basics of the interface need exploration. This paper is an overview of the MJF process, why the process serves as a unique method of manufacturing and summarizes the HP materials roadmap as of January 2020.
Determination of Interfacial Strength in Semi-rigid Laminates
Glendimar Molero, February 2020
A testing methodology to evaluate the adhesive strength of epoxy coatings and multi-layered polymeric laminates was developed by implementing a linearly increasing normal load scratch test. Finite element methods (FEM) modeling was also carried out to quantitatively investigate the corresponding stress profile that causes delamination to occur during scratching. By including the exact material constitutive behavior, surface characteristics, and geometry of each laminate layer in the numerical framework, the delamination strength of the laminates can be quantitatively determined using numerical modeling. The determination of the delamination strength between the weakest layer is possible by normalizing geometric factors and material properties in the FEM model. This procedure can be employed to improve laminate performance through changes in formulation and processing conditions.
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