SPE Library

The most recent developments in grafting technology for polyolefins have been applied on an industrial scale to help solve challenges in performance and processing of these ubiquitous materials. Through the use of solid phase grafting, the unique properties of each polymer can be retained while reducing undesirable side reactions. This approach has been applied to a wide range of polyolefins to address key performance needs; specifically the creation of Polyolefin Alloys. These grafted side chains of LDPE / PS, LDPE / SAN, PP / SAN modify the properties of the bulk polymer. This paper will illustrate the resulting properties when incorporated into blends of other polyolefins, ABS, PLA, and PC blends. The use of solid phase grafting technology also allows for the facile addition of MAH to a range of polyolefin backbones. The effectiveness of the method results in polyolefins which retain a high MFI, a high percent of MAH functionality and low volatility / residual MAH levels. HDPE, PP, POE, EBA, LLDPE grafted with MAH have all been successfully prepared and tested. These novel graft polyolefins exhibit excellent performance in a wide range of thermoplastic compounds and composites. In addition, a new approach to incorporating low MW functional additives into the polyolefin melt has been developed. Porous granules which can adsorb up to 80% by weight are now available in a variety of polymers including LLDPE, PP and EVA. The porous polyolefin carrier absorbs the liquid additive and allows the resulting dry granule to be metered into the compound as with any other solid additive. The result is a much better match of melt viscosity with more thorough mixing and incorporation into the compound. A wide range of liquid additives and additive blends have been successfully incorporated into polyolefin compounds including; Crosslinking of PE through the Monosil process; Vinyl Silane / peroxide, Addition of Boron based HFFR, Addition of MAH, Silicone oils and gums Antistats, anti-fog, slip aides and other low MW additives.

Plastics are a major focus of sustainability efforts around the world, due to their ubiquity and the volume of waste they generate. Many companies are proactively applying environmental goals throughout the plastics lifecycle, from R&D through application development, manufacturing and disposal. While they may not produce plastics, additive manufacturers nonetheless are playing an important role in reducing environmental impacts and advancing environmental objectives. Examples include promoting the increased use of recycled plastic content by formulating additives such as performance modifiers specifically designed to optimize recycled content. Or by replacing or removing ingredients which could negatively affect recycling streams or cause concern with regards to migration or extraction. Further, additive manufacturers are addressing the challenge of excessive packaging by developing products that maintain desirable properties, such as barrier performance, while using thinner walls or film gauges. Used in food packaging, innovative additives can avoid the need for preservatives in the food itself to support the Clean Label trend, while extending shelf life to reduce waste. This paper will describe how Milliken is adding sustainability considerations to its goals for the research and development of additives for virgin and recycled resins, as well as expanding its portfolio with products specifically tailored to meeting environmental goals across the plastics lifecycle.

Circular economy will change our way to design plastic products to provide greater durability, reuse and high-quality recycling. The European Union will considerably reduce landfill, introduce economic incentives to put greener products on the market and drive investments and innovation to circular solutions. In addition to improve design to make plastic products easier to recycle, collection and sorting will be expanded and viable markets for recycled and renewable plastics will be created [1]. Recycling of plastics will grow and the quality of recyclates has to be improved to replace pristine polymers. Additives such as stabilizers, repair additives, compatibilizers and odor neutralizing agents play an important role to enhance and to maintain the quality of recyclates [2]. Stabilizers for recyclates fulfil the same function as in virgin material namely to protect the polymer from oxidative degradation during processing and to maintain the properties during use. Consumed stabilizers of the first application have to be replaced at least and/or adjusted to the requirements of the second application. For example a recyclate from a short-time packaging application is not sufficiently stabilized for a long-term service life. Moreover, there are structural differences between virgin and recycled polymers. Recycled plastics show usually predamage through oxidation from the first service life e.g. an increased carbonyl and carboxyl group content versus virgin material is found in polyolefins. Moreover the oxidized molecular structures act as initiator sites and prodegradants accelerating recyclate degradation during processing and use [3, 4]. Furthermore, recycled plastics are often mixtures from different manufacturers and formulations with various additives and may contain more or less impurities. Specific recyclate stabilizers were developed in the past, however mainly as a variation of standard virgin stabilizer systems. Selected combinations of phenolic antioxidants, phosphites and antiacids in optimized ratio prove that the best cost/performance stabilizer combination for recyclates is different from the one for virgin material. Now a new generation of improved recyclate stabilizer systems combines antioxidants and selected alditols [5]. These systems may act in several ways: interaction with carbonyl groups, hydroperoxide decomposition and metal deactivation, thus addressing the potential weaknesses of recycled plastics. The newly developed stabilizer systems for polyolefins show excellent processing stability of PP and PE recyclates and outperform alternative stabilizers in long-term thermal stability. For commercialization of the technology an industrial partnership is established.

The global production of plastic reached 350 million tons in 2017, of which a large part ends up in landfill and/or incineration. Further, 1.5 to 4% of the global production of plastics ends up in marine littering every year and plastic stand for 80% of the marine littering (1). EU has set ambitious goals to reduce the littering from plastic packaging with an aim to recycle 50% plastic packaging by 2025 and 55% by 20302. Reaching these goals requires larges changes within the whole plastic industry (2) and new innovative solutions in mechanical recycling. Today, the stabilization additive packages are often not designed for recycling. When plastics are recycled the polymer will experience multiple processing steps which means polymer degradation unless actions are taken to secure enhanced stabilization. This talk will demonstrate the effect on polymer properties during four recycling steps without extra stabilization, and with multiple additions of antioxidants in the recycling process. The effects of the most used “traditional” antioxidants standing for the largest antioxidant consumption - AO1010, AO1076 and P168 - are demonstrated (3). The study demonstrates the effects on polymer properties in the two mentioned scenarios and identifies gaps-to-close related to use of traditional additives systems in mechanical recycling. For example, how much additives are needed to keep polymer properties intact in recycling and what unexpected properties are observed by accumulation of these additives and their by-products. 1 Jambeck et al. Plastic waste inputs from land into the ocean. Science (2015). 2 EuropeanCommission. A European strategy for plastics in a circular economy. 3 Maier, R. D. & Schiller, M. Handbuch Kunststoff-Additive. (2016).

Current discussions about the use plastics and the waste generated have generated great interest in plastics recycling. While this question is relatively easy to answer for monomaterials, for multilayer or composite materials there is always the question if this can work. On the other hand, to produce high quality flexible packaging, there is the need for multilayer films to protect the packed food and increase the shelf life. To have a closer look at the recyclability for such multilayer films, we wanted to take a closer look at a simple LDPE-PA6-material to see how the materials properties of this mixture can be improved. Therefore, the aim of this work was to compare the effects of compatibilisation with a pre-fabricated additive and the in-situ generation of a similar additive in the melt for LDPE-PA6-blends and to investigate the effect of mixing protocol (i.e. compounding vs. dry-blending) of the pre-fabricated additive on the resulting properties of reprocessed LDPE-PA6 films. We found, that it is possible to compatibilize LDPE-PA6-blends via the addition of maleic anhydride based compatibilizers, regardless of fabrication approach. This effect can be seen from the morphology of the samples as well as from mechanical properties. Also, the reprocessing of films from LDPE and PA6 with reasonable properties is possible when adding a compatibilizer. The best, i.e. the most balanced properties can be found when the compatibilizer is melt compounded, as this gives the best distribution. These results show that it is possible to reuse multilayer materials when considering the blend components and properly selecting a compatibilizer.

Polyethylene and polypropylene are two of the most easily recycled polymers. Recycling polyolefins can result in downcycling to simple functional polymers, true recycling for reuse in the intended application, or upcycling of the polymer into higher quality products. To take advantage of the available feedstock, and improve its utilization, stabilizers are can be added to allow the polymer to retain its original physical properties. A variety of customer based case studies on recycling and upcycling will be covered showing how additives allow for improvements in the recycle stream.

Circular economy and plastics recycling require a Polyolefin stabilization that protects the polymer during the whole cycle in the recycling process. AddWorks LXR 568, Hostanox O310 and Hycite 713 are high performance additives that protects the polymer during processing and heat exposure as well as during the washing step. Antioxidant solutions as AddWorks PKG 906 circle helps the converter and recycler to provide heat and process stability and replenish antioxidants that had been consumed during the recycling process.

The application development labs of SI Group recently invented a highly innovative technology that enables significant reduction in color of discolored polyolefins in industrial or post-consumer recycled streams. This very effective bleach-out phenomena takes place in the polymer melt in a processing extruder upon addition of a new additive system that is a subject to this presentation. The new system is composed of solid-state components and can be fabricated in a powdery form or as a non dusting formulated one-pack. The system does not change the taste and oder properties of polymers and is safe from both the manufacturing and consumer perspective.

In this paper, we demonstrate how a small amount of nanofibrils can enhance the toughness, stiffness, and transparency of polyolefins. We have studied two different kinds of toughening rubbery nanofibrils and stiffening hard nanofibrils depending on the kind of the material used for the nanofibrils, and we have observed that the properties of the nanofibril composites with these fibers were very different. It was observed that the rubber nanofibrils with ~200 nm diameter and an L/D ratio over 200 well dispersed in the PO matrix exhibited numerous outstanding properties, such as elasticity, ductility, toughness, and impact strength. It is commonly well-known that 15-25% rubber content must be compounded into the polymer matrix, to induce brittle-to-ductile transition. But with nanofibril rubbers, only 1% was needed to achieve the brittle-to-ductile transition. These results indicate that the dispersed rubber nanofibrils are much more effective than the conventional spherical rubbery phases in toughening of polyolefins. This has another significant implication that the ductility can be improved without any sacrifice to the stiffness, unlike the case of using a large amount of rubber over 15%. In other words, the toughening of polyolefins can be achieved with less than 1% nanofibril rubber without losing the stiffness. The increased stiffness with added nanofibrils was also studied. When PET or PBT nanofibrils were added in the PO matrix, the nanofibril composites exhibited a much higher stiffness. Unlike the case of using a brittle matrix such as PS or PLA, the increase in the ductility-related properties was marginal in the relatively ductile matrix such as PP or PE. The transparency change of PO materials with included nanofibrils was also studied. Like in the case of Sorbitol, the added nanofibrils decreased the crystal size significantly, to make the PO materials more transparent. But when the nanofiber content was large, then the transparency was decreased because of the large number of nanofibrils. As the nanofibril content decreased, the transparency was significantly improved.

In this paper, we demonstrate how a small amount of nanofibrils can enhance the toughness, stiffness, and transparency of polyolefins. We have studied two different kinds of toughening rubbery nanofibrils and stiffening hard nanofibrils depending on the kind of the material used for the nanofibrils, and we have observed that the properties of the nanofibril composites with these fibers were very different. It was observed that the rubber nanofibrils with ~200 nm diameter and an L/D ratio over 200 well dispersed in the PO matrix exhibited numerous outstanding properties, such as elasticity, ductility, toughness, and impact strength. It is commonly well-known that 15-25% rubber content must be compounded into the polymer matrix, to induce brittle-to-ductile transition. But with nanofibril rubbers, only 1% was needed to achieve the brittle-to-ductile transition. These results indicate that the dispersed rubber nanofibrils are much more effective than the conventional spherical rubbery phases in toughening of polyolefins. This has another significant implication that the ductility can be improved without any sacrifice to the stiffness, unlike the case of using a large amount of rubber over 15%. In other words, the toughening of polyolefins can be achieved with less than 1% nanofibril rubber without losing the stiffness. The increased stiffness with added nanofibrils was also studied. When PET or PBT nanofibrils were added in the PO matrix, the nanofibril composites exhibited a much higher stiffness. Unlike the case of using a brittle matrix such as PS or PLA, the increase in the ductility-related properties was marginal in the relatively ductile matrix such as PP or PE. The transparency change of PO materials with included nanofibrils was also studied. Like in the case of Sorbitol, the added nanofibrils decreased the crystal size significantly, to make the PO materials more transparent. But when the nanofiber content was large, then the transparency was decreased because of the large number of nanofibrils. As the nanofibril content decreased, the transparency was significantly improved.

For many decades’ metallic oxides, metallic stearates have been used to scavenge acids from the 1st – 4th generation TiCl4 catalysts spanning 1955-1995. Metallic oxides and stearates form Lewis Acids which reduce antioxidant efficiency resulting in polymer degradation. New line of Stabiace hydrotalcites improve oxidation stability of polypropylene proven by OIT, MFR and tensile properties. Mitsui’s trade secret ZR Series provides same performance of Stabiace HT with addition of much less color and further reduction in PP oxidation proven by FTIR. Three polypropylene take-a ways: 1. Quality: New Stabiace HT improves the oxidation stability and physical properties. 2. Quality + Performance: Mitsui ZR Series no yellow color and 50-60% increase in antioxidant retention, increased OIT and up to 80 % less polyolefin degradation per FTIR analysis from 1-5 extruder passes at 250c. 3. Recycle and sustainability: Because the PP has much less multi-pass extruder oxidation; quality, recyclability, sustainability, odor and VOC reduction may be improved.

Polymeric products are often complex and frequently include components from several sources and suppliers. The formulation details of the polymer parts are often not known to the manufacturer. Companies in later stages in the supply chain may have even less information on components in the final formulations. Therefore, the same part number at a point in the supply chain can result in a polymer part that is not made with the same formulation, yet the apparent polymer properties may seem to be equivalent. After usage by a company or customer, a failure analysis may be required to determine the chemical details of the item. In this work, Pyrolysis-GC/MS is used in multiple modes to characterize a set of polymer parts that seem approximately similar. The results reveal significant differences in chemical composition. Similar results can be used to monitor the chemistry and part quality at the manufacturing point in the supply chain to reduce future variability in parts failure. After usage, the same techniques can be used to understand the chemistry differences and the possible reasons for the failure. This presentation demonstrates the capabilities of the Pyrolysis technique with Gas Chromatography-Mass Spectrometry. Multiple pyrolyzer modes, such as Evolved Gas Analysis (EGA), flash Pyrolysis, and Heart Cutting (HC) analyses will be performed to characterize the differences between the rubber samples.

Polymeric products are often complex and frequently include components from several sources and suppliers. The formulation details of the polymer parts are often not known to the manufacturer. Companies in later stages in the supply chain may have even less information on components in the final formulations. Therefore, the same part number at a point in the supply chain can result in a polymer part that is not made with the same formulation, yet the apparent polymer properties may seem to be equivalent. After usage by a company or customer, a failure analysis may be required to determine the chemical details of the item. In this work, Pyrolysis-GC/MS is used in multiple modes to characterize a set of polymer parts that seem approximately similar. The results reveal significant differences in chemical composition. Similar results can be used to monitor the chemistry and part quality at the manufacturing point in the supply chain to reduce future variability in parts failure. After usage, the same techniques can be used to understand the chemistry differences and the possible reasons for the failure. This presentation demonstrates the capabilities of the Pyrolysis technique with Gas Chromatography-Mass Spectrometry. Multiple pyrolyzer modes, such as Evolved Gas Analysis (EGA), flash Pyrolysis, and Heart Cutting (HC) analyses will be performed to characterize the differences between the rubber samples.

Herein, two novel hindered amine stabilizers (HAS) are formally introduced to the North American Polyolefin market. The first, a methylated oligomeric HAS, is demonstrated in the artificial and natural weathering, as well as long-term heat aging, of various polyolefin films and thin sections. Particular attention is paid to data generated in the presence of acidic species and pesticides, showing how methylated HAS resist deactivation and therefore improve polyolefin article service lives better than their more basic N-H HAS analogues. The second, an oligomeric n-alkoxy HALS, shows clear performance benefits in the presence of acidic species over methylated HALS. These two materials are recommended for use in plasticulture, artificial turf, and halogenated flame retardant applications, among others.

Today, various plastics utilized in single-use and disposable applications generate significant amount of wastes which negatively impact the environment. By applying proper technologies, however, these plastics can be repurposed to reduce their environmental footprint and impact on society. Additionally, providing plastics with a second long term life can positively contribute to the circular economy. This paper will discuss how polymer stabilizer technology and application can be used to enable the recycling and repurposing of polyolefins by maintaining their desirable properties.

Today, various plastics utilized in single-use and disposable applications generate significant amount of wastes which negatively impact the environment. By applying proper technologies, however, these plastics can be repurposed to reduce their environmental footprint and impact on society. Additionally, providing plastics with a second long term life can positively contribute to the circular economy. This paper will discuss how polymer stabilizer technology and application can be used to enable the recycling and repurposing of polyolefins by maintaining their desirable properties.

Much attention has been given to stabilization packages for polyolefin pressure pipes over the past couple decades, however corrugated and conduit pipes have generally been ignored with respect to more robust stabilization packages. Certain groups such as the Florida Department of Transportation and the American Association of State Highway and Transportation Officials (AASHTO) have set rules establishing oxidative resistance in HDPE corrugated pipes, but few others have followed this example. A discussion of the simplicity and importance of pipe resin stabilization as well as examples from stabilized pipes will be covered.

Much attention has been given to stabilization packages for polyolefin pressure pipes over the past couple decades, however corrugated and conduit pipes have generally been ignored with respect to more robust stabilization packages. Certain groups such as the Florida Department of Transportation and the American Association of State Highway and Transportation Officials (AASHTO) have set rules establishing oxidative resistance in HDPE corrugated pipes, but few others have followed this example. A discussion of the simplicity and importance of pipe resin stabilization as well as examples from stabilized pipes will be covered.

Use of plastics and particularly polyolefins is increasing rapidly globally due to their low environmental footprint, their versatility and durability, and competitiveness in use cost. The polyolefin industry is continuously evolving in response to global megatrends of population and environment, particularly in response to regulatory and consumer preferences regarding reduction of single-use plastics. In this presentation we will provide an update regarding polyolefin markets, a view regarding sustainability trends in polyolefin applications, and recent developments in the area of catalysts for PP which are improving product performance and plant operations. Innovation in process design and catalysis, combined with operational excellence, is driving LyondellBasell's unique technology portfolio to deliver differential performance, creating value for the user and positioning them for long term success in response to a constantly changing environment.

Several nitrogen-containing ligands have been tested as internal modifiers of the Amoco CD commercial catalyst for propylene polymerization, among them 2-phenyl indole. The ligand forms an indolenine complex with TiCl4 at room temp. with a hydrogen and a double bond migration, from the 2-3 to the 1-2 position of the indole framework. Chemical and analytical evidence indicates that the Indolenine.TiCl4 complex coordinates exclusively on the 110 lateral cut of MgCl2, which has two open coordination sites on each Mg (1). During catalyst activation at above 105oC the complex undergoes ortho-metallation (2). To our knowledge, this is the first example so far in Ziegler-Natta catalysis of an organometallic complex, (a polymerization catalyst itself), coordinating on the MgCl2 support. Reaction with Et3Al (3) reduces the titanium to Ti(III) and the double bond migrades back to the 2-3 position. Titanium looses all the chlorides with formation of a single Ti-Et bond. The organotitanium complex occupies now only a single coordination site on Mg. The second coordination site on this Mg atom becomes now available for additional TiCl4 coordination! Indeed, fresh TiCl4 attaches on the newly created vacant coordination sites (4) boosting substantially catalyst activity (up to 100%, especially in the gas phase), with retention or even improvement of polymer extractables. There are now two types of active sites on the catalyst system: a. Originating from the complex, and b. From the TiCl4. Both polymerization sites are activated with Et3Al. These transformations occur only on the 110 lateral cut of MgCl2, which constitutes about 15% of the total surface area. The other 85% is represented by the 106 cut, which may be occupied by standard modifiers (phthalates, diethers, succinates, etc.), and by TiCl4 dimers or oligomers.