The increasing demand for recyclates and the shortage of food-grade PET flakes pose challenges for batch quality and color consistency.

Repi offers various additives for recycling PET, which can be used, for example, to prevent the material from darkening.

16:9

Messe K-Kunststoffmesse

kunststoffe-international.com

kunststoffe.de

Recycling

Umweltmanagement

Kunststoff Werkstoffe

Polyethylenterephthalat

Thermoplaste

Kunststoff-Recycling

Kunststoffverarbeitung: Verfahren

Kunststoff-Aufbereitung

Kunststoff-Rezyklat

Additive

Compensating for Darkening in Recycled PET

The quality of recyclates is seen as too low. Improvements are possible by using additives, as was shown by the exchanges during the Forum Plastic Recyclates.

Quite clearly, the central theme of this year’s conference  was additives for recycling materials.

Streifinger, Florian

Kreislaufwirtschaft

Additives Are Decisive

ABS is a material for esthetically and mechanically demanding applications in the automotive industry, electronic housings, household appliances, and medical technology.

ABS is particularly in demand for electrical and household appliances.

Acrylonitrile Butadiene Styrene: Recycling Successes and Challenges

ABS / ASA-Kunststoffe

Right Combination of Mechanical  and Esthetic Properties

At the trade show, Chinese additives manufacturer UniteChem unveiled its expanded range of light stabilizers.

Polyethylen

Stabilisatoren

Polypropylen

Stabilizing Polyolefins

Clariant launched new additives at K 2022 to support plastics sustainable evolution.

New light stabilizer supports more sustainable agricultural films.

Anti-Scratch Additive and Light Stabilizer

The use of TPE materials with recycled content increases the sustainability of vehicles. They are also used more and more in the interior.

The selection of high-quality recyclate enables their use in demanding automotive applications.  

Recyclate Reduce the CO2 Footprint in Seals and Interior Applications

Thermoplastische Elastomere

Soft, Elastic and Recycled

Automakers have formulated ambitious plans for their vehicles. We discussed this topic with Frank Schumann from Trinseo.

Batterien

Energiespeicherung

Elektromobilität

Mobilität

Lichttechnik

“Nothing Speaks against the Use of Recyclates for Demanding Components”

The many different additives in plastic compounds make their composition extremely complex. Special stabilizers help to prevent the generation of volatile organic compounds (VOCs) resulting from the interaction of components in subsequent, long-term automotive applications. 

Stabilizer Reduces VOC Emissions from Polypropylene with No Drawbacks in Processing 

Compound

Weichmacher

Not for Sensitive Noses 

Emerald‘s high performance antioxidants, plasticizers, nucleating agents, epoxy resins and modifiers are the key components you need to ensure lasting performance and optimize processing characteristics. Today‘s toughest, most flexible plastics rely on Emerald‘s innovative chemistry and expertise. Featuring:

Emerald Performance Materials  

https://www.emeraldmaterials.com

Antioxidantien

Beschichten von Kunststoffen

Chemisches Bearbeiten (Auftragen)

Oberflächentechnik

Beschichten von Metallen, allgemein

Duroplaste

Farbstoffe

Harze

Holz

Kautschuk / Elastomere

Klebstoffe

Chemisches Fügeverfahren

Verbindungstechnik Verfahren

Lackieren

Pigmente

Pultrusion

Silikone

Verarbeitungshilfmittel

Verbundwerkstoffe / Werkstoffverbunde

Vernetzungsmittel

Plastic recycling: Kreyenborg uses infrared technology for the reduction of unpleasant odors in plastics.

Everything fresh: the two-stage IR-Fresh process removes unpleasant odors from recyclates.

Infrarotstrahler

Kunststoffverarbeitung: Maschinen und Komponenten

Materialhandling

IR-Fresh Minimizes Odors in PCR Granulates

In November 2021, four members of the Feddersen Group announced certification with ISCC Plus. With K.D. Feddersen Holding, now further companies of the group followed.

Further Companies of the Feddersen Group Certified

All over the world, many polyurethane manufacturers are aligning production and assortment as well as upstream and downstream processes to the circular economy.

In wind turbines, polyurethane offers three major advantages over materials such as epoxy resins and improves two key criteria of the turbines. 

Polyurethane (PUR): Worldwide Demand for the Polymer Is Growing

Polyurethan-Schaumstoffe (PUR)

Halbzeuge und Zwischenprodukte

Kunststoff-Halbzeuge

Polyurethan

Sustainability at Every Turn

Due to the climate change, new fields of development and sustainability topics have come into focus along the added-value chain.

Polyamide continues to be one of the most important technical plastics in the automotive sector, where it enjoys widespread use. This not only applies for classical internal combustion vehicles, but in terms of volume will also be the case for electric vehicles.

Polyamides: Electromobility and Sustainability Boost Developments

Polyamide

Technische Kunststoffe

Dual Change with Polyamides

Consumption and manufacturing capacities are growing most in North America and China. In Europe, companies are working on specific paths.

PE films with monoaxial and biaxial orientation help to replace multi-material compounds for packaging.

Polyethylene (PE): Shaping New Trends in Power Generation and Packaging

Verpackungsmaterial

Logistik

Rohre, Profile

Metall Werkstoffe

Kunststoff-Rohre

Rohre, allgemein

Resilient through Changing Markets

Asahi Kasei has decided to invest in Circularise B.V., a startup company in the Netherlands that provides digital product passports and mass balance bookkeeping software.

Asahi Kasei Supports Supply Chain Traceability

Overview: Additives for Plastic Recyclates

The requirements for recyclates and their quality are increasing. In particular, improvements can be achieved with suitable additives. Meanwhile, the number of suppliers and products has increased clearly, and several recyclate-optimized systems are available. Important options are stabilizers, compatibilizers, and additives for odor improvement. An overview of the variety of products and their suppliers.

The quality of recyclates can be improved very well by means of suitable additives. An overview of the variety of products and their suppliers.

Even though 35 % of the plastic waste collected in Europe in 2021 was recycled, its weight of 5.5 million t only covered 9.9 % of total demand [1]. In spite of investments in chemical recycling, mechanical recycling of plastics will continue to be the preferred option for the utilization of plastic waste. After all, it is the most sensible in terms of energy consumption, and availability is higher. In Europe, an increased shift away from landfilling and thermal utilization towards material recycling is inevitable in order to meet the political targets regarding recycling rates, e.g. for packaging. Already now there is a lack of high-quality recyclates.

Of course, functioning collecting systems as well as sufficiently good cleaning, sorting, and separating procedures are important preconditions for suitable material flows. But equally necessary is also the analytical assessment of recyclates in terms of contamination, composition, aging condition, as well as the associated variations in material flows and the subsequent corresponding formulation using selected additives. The only exception involves production wastes, as they are mostly returned directly to the production process in minor quantities.

Frequently, plastic additives are the best option for increasing material recycling. In particular, if recyclates are to replace virgin material, and therefore require a comparable properties profile. The additives market for recyclates is aimed mainly at applications using polyolefins, i.e. LDPE and LLDPE films, HDPE hollow parts, PP, certain technical plastics such as PA and PET, as well as mixed plastics with a high polyolefin content. As always, costs of the additives play a role. However, in many cases they lead to additional benefits, e.g. higher productivity, more constant production, improved material qualities, and an extended application potential for the recyclate. In this way, the costs are partially compensated.

Basically, the entire application range of plastic additives is available for new recyclate formulations. The most widely used and demanded additive classes for recyclates have not changed during the past years [2]:

<ul><li>stabilizer systems, consisting of antioxidants, processing stabilizers, co-stabilizers, and possibly also light stabilizers,</li><li>reactive molecules, which are called chain extenders or repair systems.</li><li>compatibilizers including impact modifiers,</li><li>odor enhancers or anti-odorants.</li></ul>

Restabilization is the primary method for quality improvement of polyolefin recyclates. Without the use of antioxidants, new plastics based on polyolefin cannot be processed or used, because the antioxidants protect the polymer chains from oxidative and photo-oxidative damage. However, the stabilizers are consumed during execution of their protective function. Therefore, the recyclates must also be provided with stabilizers and anti-oxidants. Stabilizer residues from the initial application assist during processing and use of the recyclate. But at least the quantity of stabilizer used up during the initial application must be replaced. A further challenge is the transition from short-term applications such as packaging to long-term applications, because in general, the source material is not adequately suited for this purpose.

Stabilizers for restabilization of recyclates (with the exception of PVC) that are to be processed, as well as their long-term thermal stability, are mainly produced on the basis of phenolic antioxidants, phosphites or phosphonites, in combination with costabilizers such as acid scavengers. Hindered amine light stabilizers (HALS), e.g. low or high-molecular sterically hindered piperidines, or UV absorbers based on benzophenone or benzotriazole are used to improve the light stability.

Meanwhile, practically all additives producers and suppliers of masterbatches have recognized the potential of recyclate-adapted stabilizer systems, and offer customized products for polyolefins. In the simplest case, these are variations that have been combined like virgin material and consist of conventional phenolic antioxidants and phosphites. For example, Songwon offers products under the trade name Songnox, e.g. Songnox 21B for recycling of polyolefins. Doverphos LGP-12 from the Dover Chemical Corporation is a polymeric phosphite that is used for virgin PE material and also for PE film recyclates. Also Baerlocher uses Baeropol T blends for virgin and recycled material (Fig. 1).

But most additives producers have their own product lines for restabilization of recyclates. For example, BASF has introduced corresponding products with the trade name IrgaCycle, the SI Group with Evercycle, BYK with the Recyclobyk range, and Adeka Polymer Additives Europe has introduced ADK Cycloaid. Each product comprises recyclate-adapted stabilizing systems. Hereby, the optimized stabilizer systems for recyclates differ from stabilizer systems for virgin plastics.

At present, the IrgaCycle range (Fig. 2) comprises five products, all of which serve the polyolefin recyclate market, e.g.:

<ul><li>IrgaCycle PS 030 G is intended for dimensionally stable applications using recyclates for improved processing and long-term stability,</li><li> IrgaCycle PS 031 G is provided for LDPE and LLDPE films,</li><li>IrgaCycle PS 032 G is targeted mainly on severely damaged HDPE and PP recyclates, just like</li><li>IrgaCycle XT 034 DD, which also neutralizes contaminations such as paint residues [3].</li></ul>

The Recyclobyk portfolio, which emerged from the takeover of PolyAdd Services from BASF, comprises the restabilization of PP and of polyolefin mixtures (Recyclobyk 4371, Fig. 3), of polyolefins with polar contaminations (Recyclobyk 4374 and 4373), and a product for higher processing temperatures and long-term stability (Recyclobyk 4375) [4].

In addition to antioxidants and costabilizers, Recyclobyk 4372, and Irgacycle UV 033 D also contain light stabilizers for outdoor applications using polyolefins, such as beverage crates, containers, waste bins, and pallets, but also films. With Evercycle, dimensionally stable packaging products made of HDPE and PP (EverCycle PP-101S), and flexible packaging made of LDPE (EverCycle LD-101S) can be stabilized, and the mechanical properties of LDPE films improved (EverCycle LD-104P) [5]. With UPR-001, the ADK Cycloaid family comprises products for increasing long-term stability, e.g. of recyclate mixtures with virgin material. UPR-011 also features a nucleating agent for increasing the mechanical properties of PP [6].

Usually, recyclates – in particular post consumer recyclates (PCR) made of polyolefins – exhibit prior damage due to oxidation. Chemically, the polymer chains have an increased concentration of ketone groups, hydroperoxides, and acid groups. These groups are initiation points for further accelerated damage to the recyclate [7]. Based on this finding, and in cooperation with the Brüggemann company, the Fraunhofer Institute for Structural Durability and System Reliability LBF pursued a special approach for restabilization. Recyclate stabilizers were developed that not only contain processing and thermal stabilizers, but also components that neutralize this prior damage, and are thereby able to repair the attacked polymer chains. Furthermore, these costabilizers are able to complex contaminations due to transition metals, thereby disabling their pro-oxidative effect. These new stabilizing concepts resulted in an astounding processing stability of PP recyclates, and showed a practically linear increase of long-term thermal stability with the concentration (Fig. 4).

In this regard, they are clearly superior to other commercial recyclate stabilizers. Apart from constant processing, an improvement of the mechanical properties for LDPE and LLDPE film recyclates was observed (Fig. 5), as well as a substantial reduction of faults, and therefore e.g. gelling. The products introduced on this basis (Bruggolen-R-Series) are available for PP recyclates (Bruggolen TP-R2090), for PP battery housings (Bruggolen R8895), and for PE films (Bruggolen TP-R2162).

Stabilizers and Repair Systems for Polyester and PA

With poly-condensation polymers such as PA and polyesters, but also with PC and its blends, prior damage during use results less in oxidation of the chains, but rather to a reduction of molecular weight, mainly due to hydrolysis. This causes deterioration of the mechanical properties. Nonetheless, stabilizers for processing recyclates are also significant for these plastics. For this purpose, the SI Group offers EverCycle PET-102D (pellets) and PET-103D (liquid) for PET recyclates. They are claimed to improve processing stability and color, and reduce the acetaldehyde content of PET recyclates. In addition, Recyclobyk 4376 from BYK ensures higher melt viscosity and strength of PET, and also has this effect with PA.

Poly-condensation polymers exhibit functional end groups with COOH and OH polyesters, and with PA COOH and NH2. With suitable partners, these can be brought into reaction. This permits a polymer with prior damage, that has suffered a reduction of its molecular weight, to be repaired. Because the original properties such as mechanical characteristics and processing behavior are also defined by the molecular weight, prior damage can be repaired in the same way, so to speak. Popular terms for these additives are ”repair additive” or ”repair system”. They are also frequently just called “chain extenders”. Normally, these reactive molecules are difunctional. Higher functionalities lead to branching and possibly to undesirable cross-linking reactions.

Corresponding products are e.g. Stabilizer 9000 from Raschig GmbH based on a polymer carbodiimide, and Stabaxol P from Rheinchemie. Further additives for chain extension include dianhydrides or bisoxazolines. For the purpose of linear chain extension, Nexam Chemical has two products – Nexamite A94 and A99. Particularly for the linear chain extension of PA, for quite a while Brüggemann has been producing Bruggolen M1251 and M1253, based on modified PA structures. For example, by adding 2 % of Bruggolen M1251, the viscosity of a fiber-reinforced PA is increased from 2.365 to 2.930 [8]. Simultaneously, its impact resistance can be improved.

Chain extenders for polyester are frequently available in the form of masterbatches, e.g. ColorMatrix rePrize IV Builder from Avient, and Nexamite MO 992000 from Nexam Chemical. A non-linear molecular weight structure or long-chain branching is obtained primarily by means of reactive copolymers, which contain the glycidyl or MAH groups [9]. Amongst others, two suppliers of these copolymers are Vertellus with ZeMac, and BTC Europe with Joncryl ADR. But also graft polymers with MAH or glycidyl methacrylate can be used for this purpose.

In certain application cases, also a desired decomposition instead of composition can be achieved, e.g. to simplify processing of a recyclate or to obtain specific processing conditions. For example, with PA there is a demand for the production of high-molecular fiber and film materials in injection molding qualities. For this, e.g. Bruggolen M 1417 from Brüggemann can be used. Targeted decomposition also works with PP. Apart from the addition of peroxides, Irgatec CR 76 IC – a hydroxylamine ester from BASF – is also used.

Usually, polymers with different structures are not miscible, therefore do not form homogeneous blends, and consequently only exhibit inadequate mechanical properties. This already applies for mixtures of different polyolefins, and even more so for mixtures of polar (PET, PA, EVA, EVOH) with non-polar polymers (polyolefins, PS). If one wishes to avoid complex separation of the recyclate flows, but still wants to mix these incompatible polymers and obtain good mechanical properties, the solution lies in the addition of compatibilizers (so-called compatibility agents). These attach to the boundary surfaces of the polymers to be mixed, reduce the surface tension between the polymers, increase adhesion between the boundary surfaces, reduce phase separation, stabilize the dispersed phase against agglomeration in the matrix, and therefore prevent delamination in the solid body. Ultimately, this results in a finer morphology, a more homogeneous mixture, and substantially improved mechanical properties.

In order to act as a compatibilizer, a polymer is usually necessary, which contains the structural elements of the respective polymers to be compatibilized. In very rare cases, compatibilization can be achieved by the addition of inorganic substances such as layered silicates or in the form of low-molecular reactive bonds in situ during processing. Material flows, whose properties have been improved by the addition of compatibilizers, are primarily polyolefin mixtures and blended polyolefins with contaminations due to polar polymers such as PA or polyester.

Compatibilizers for Polyolefins and Polar Plastics

Primarily, polyolefin elastomers or block copolymers are most suited as compatibilizers for polyolefin mixtures, and which are offered by the polyolefin producers for recyclates. Examples are Vistamaxx from ExxonMobil Chemical Europe, and Intune from Dow Europe. Other polymer structures are available from Kraton Polymers in the form of styrene ethylene butylene styrene block copolymers with the trade name Circular+, and as modified polysiloxane from Evonik Industries under the name Tego XP 21024 and 21025. Alternatives for compatibilization of polymer mixtures are the Kenreact products from the Kenrich company. They are produced on the basis of titanates and zirconates, and act catalytically on the molecular level and also as bonding agent. In addition, they can lower the processing temperatures of the plastics [10].

The compatibilization of polyolefins with polar plastics requires polymers with reactive groups such as anhydride or epoxy groups. These are synthesized by means of graft reactions – in most cases using maleic anhydride (MAH) on different PE, PP or styrene butadiene styrene block copolymers – via extrusion, solid phase, or solutions. Alternatively, they can also be produced by copolymerization. Apart from the polymer producers, the modified polyolefins obtained via graft reactions are offered in particular by smaller specialized small and medium-sized companies. Therefore, there is a wide range of products.

For example, the Nordic Grafting Company uses the Vistamaxx products from ExxonMobil Chemical as basic grafting material (trade name: Acti-Tech). In contrast, The Compound Company uses the Exxelor products from ExxonMobil (trade names: Exxelor, Yparex, EcoForte). Other suppliers with a comprehensive range of MAH-grafted polymers are Graft Polymer with Graftabond, Auserpolimeri with Compoline, and BYK with Scona. The products differ in their MAH content, the unreacted MAH residues, the basic polyolefin, as well as molecular weight and rheology.

Also polyolefin producers are represented in this market with MAH-grafted polyolefins, for example LyondellBasell with their Integrate products, and Dow with the Fusabond, Retain, and Elvaloy product ranges. While Fusabond M 603 and E 226 are based on MAH, Elvaloy is a copolymer with acrylates. Elvaloy AC 4327 – a butyl acrylate ethylene copolymer – is used e.g. for integrating polyesters in PE, while Retain is mainly used for improving the properties of recyclate films.

Compatibilizer versions with other polar groups of the reactive kind are ethylene acrylate maleic anhydride terpolymers, such as Lotader from SK Functional Polymer (previous products from Arkema), ethylene acrylate glycidyl methacrylate terpolymers (e.g. also from the Lotader range), as well as ethylene vinyl acetate maleic anhydride terpolymers (product example: Orevac T from SK Functional Polymer). Lotader AX 8840 and AX 8900 contain e.g. 8 % glycidyl acrylate, and therefore achieve a significantly higher functionality than conventional MAH-grafted compatibilizers.

In order to compare the effects of different compatibilizers, the Fraunhofer LBF conducted a series of tests on a sample mixture of 30 % PA6 and 70 % LDPE, whose composition corresponded to that of a co-extruded packaging film, with different compatibilizers, and the resulting mechanical properties examined. In the elongation at break test – as expected – the polymer mixture without additive exhibited only low values compared with the parent polymers (Fig. 6). In all cases, a compatibilizer additive of only 2.5 % leads to a significant increase in elongation at break. In this case, an MAH-modified PE performs best, and leaves the other structures far behind.

Odor Enhancers: One Size  Does Not Fit All

A frequent recyclate problem is also the presence of unpleasant smells. They occur as the result of contaminations from the previous application, e.g. as food packaging, and the decomposition of these contaminants during the usual processing temperatures of plastics. Other causes for odors are odorants and aromatic substances such as the perfumes and tensides used in cosmetics or detergent packaging, which diffuse into the plastic. Washing procedures are only partially able to remove these substances [11]. Intolerable odors severely limit possible application fields, e.g. in indoor spaces. Odors that cannot be removed by washing procedures or by means of adapted processing operations such as entrainers, are a case for additives. Basically, two concepts are pursued to control odors by means of additives: Use of reactive compounds and odor absorbers. However, there is no single additive that is suitable for all conceivable odors, in the sense of “one size fits all”. It is therefore an individual case-by-case decision, which additive works best with which recyclate. But in most cases, a reduction of odor intensity depends on the respective additive used.

Reactive functional compounds are able to react with the odor components. Thereby, they convert a volatile substance into a less or non-volatile reaction product that remains in the polymer. One example for this is zinc ricinoleate, which is sold by Evonik Industries as Tego sorb PY 88, and as a masterbatch. It can react with hydrogen sulphide, mercaptans, thioethers, and amines. But also other additives with reactive groups such as epoxides or anhydrides have a corresponding effect. Other commercial odor-inhibiting additives are e.g. Struktol RP 17, RP 53, and RP 59 from the Struktol Company of America, as well as Addisperse ON 106 and ON 108 from Aromatic Fusion.

Additive-Enhanced Outer Surface Clearly Reduces Odors

With the exception of cyclodextrines, alternatives for organic reactive compounds are inorganically-based odor absorbers such as zeolites and hydrotalcites. Thanks to their cage or layer structure, they are able to embed molecules and bind them by means of interactions. Meanwhile, many producers offer such products, for example HPF The Mineral Engineers, or Tosaf with OD7904LL EU, and Ampacet with OdorClear. So far, however, only very little is known about the basic mechanisms of odor reduction.

A particularly effective combination of additives and production method for odor reduction was developed by a Fraunhofer consortium (Fig. 7) [12]. Amongst others, strong-smelling recycled fish crates made of PS were examined. Hereby, it was shown that in a co-injection process, an additive-enhanced outer surface made of virgin material could be produced, which completely suppressed the odor in the test (Fig. 8; also see Kunststoffe international 6/22, page 28 - 31).

Particularly effective hereby was a hydrophilic zeolith as additive. Interestingly, the additive used exclusively in the outer surface is superior to a purely additive-enhanced molding. The advantage of this procedure not only lies in minimized odor with comparatively low additive concentrations, because the additive is only introduced in the outer surface. In addition, the outer surface of virgin material has a high surface quality. Moreover, the possibility exists to effectively introduce other additives in low concentrations when calculated for the entire component.

Additives are essential if recycled plastics are to be used as an alternative for virgin material in a closed circuit or in high-grade applications. In particular, recyclate-customized stabilizer systems and polymer additives in form of reactive or non-reactive compatibilizers make a decisive contribution. Additives producers are creating more and more own product lines for the important recyclate flows of PP, HDPE, LDPE, LLDPE, polyolefin mixtures, and PET. Possible solutions for achieving the respective requirement profiles by means of recyclates are increasing – also in new applications. Apart from analytical support regarding recyclate qualities, the Fraunhofer LBF with its Plastics Research Division as a neutral development partner is able to develop the technically best and most cost-effective additives solution to meet a specific requirement profile.

[1] Plastics-the facts 2022, Herausgeber Plastics Europe, zugänglich über <a href="http://plasticseurope.org/knowledge-hub/plastics-the-facts-2022/" target="_blank">plasticseurope.org/knowledge-hub/plastics-the-facts-2022/</a>

[2] R. Pfaendner, Qualität von Rezyklaten verbessern, Kunststoffe 2015, 105 (9), 164–167

[3] <a href="http://www.basf.com/global/de/who-we-are/sustainability/whats-new/sustainability-news/2021/basf-introduces-irgacycle.html" target="_blank">www.basf.com/global/de/who-we-are/sustainability/whats-new/sustainability-news/2021/basf-introduces-irgacycle.html</a>

[4] <a href="http://www.byk.com/de/produkt/additives-by-name/recyclobyk" target="_blank">www.byk.com/de/produkt/additives-by-name/recyclobyk</a>

[5] <a href="http://siigroup.com/News/ArticleID/832/SI-GROUP-LAUNCHES-NEW-BRAND-FOR-PLASTICS-RECYCLING-AT-K-2022" target="_blank">siigroup.com/News/ArticleID/832/SI-GROUP-LAUNCHES-NEW-BRAND-FOR-PLASTICS-RECYCLING-AT-K-2022</a>

[6] <a href="http://www.adeka.co.jp/en/chemical/pickup/pickup15.html" target="_blank">www.adeka.co.jp/en/chemical/pickup/pickup15.html</a>

[7] R. Pfaendner, Restabilization – 30 years of research for quality improvement of recycled plastics review, Polymer Degradation and Stability 2022, 203, 110082

[8] Bruggolen M1251, Technical data sheet, October 2019

[9] J. Y. Jang, K. Sadeghi, J. Seo, Chain extending modification for value-added recycled PET: a review, Polymer Reviews 2022, 62, 860–889

[10] <a href="http://4kenrich.com/wp-content/uploads/2018/02/Ken-React-KPR-Global-Plastics-Summit-2015-Chicago-Multi-SlidesTitanate-Catalyst-for-PC.pdf" target="_blank">4kenrich.com/wp-content/uploads/2018/02/Ken-React-KPR-Global-Plastics-Summit-2015-Chicago-Multi-SlidesTitanate-Catalyst-for-PC.pdf</a>

[11] M. Roosen, L. Harinck, S. Ügdüler, T. De Somer, A. G. Hucks, T. G. A. Belé, A. Buettner, K. Ragaert, K. M. Van Geem, A. Dumoulin, S. De Mester, Deodorization of post-consumer plastic waste fractions: A comparison of different washing media, Science of the Total Environment, 2022, 812, 152467

[12] C.C. Höhne, A. Menrath, R. Pfaendner, E. Metzsch-Zilligen, B. Lok, Der Gestank soll drinnen bleiben, Kunststoffe 2022, 112(8), 44–47

Fraunhofer-Institut für Betriebsfestigkeit und Systemzuverlässigkeit LBF Bereich Kunststoffe

https://www.lbf.fraunhofer.de

Ausgabenartikel

Fig. 1. The quality of films made of PE recyclates can be improved with the polymer stabilizer Baeropol T.

Fig. 2. BASF‘s IrgaCycle range enables recyclates to be restabilized, improves their processing properties, and reduces the influence of contaminations.

Fig. 3. With Recyclobyk 4371, the polyolefins used for battery housings can be sufficiently re-stabilized.

Fig. 4. Aging strength of PP recyclate from battery housings at 150 °C with increasing stabilizer concentrations: Clearly shown is how long-term stability increases continuously with addition of the stabilizer.

Fig. 5. Mechanical properties of LDPE and LLDPE recyclate films: Addition of the stabilizer clearly improves the mechanical properties.

Fig. 6. Depending on the selected compatibilizer, the improvement of elongation at break varies greatly. However, all additives used lead to a clear increase.

Fig. 7. The outer layer of virgin material was treated with odor-reducing additives. They prevent odors from the inner recyclate layer diffusing to the outside.

Fig. 8. Odor improvement by means of additives in a co-injection molding procedure (samples stored at 80 °C): Clearly shown is the effect of the outer surface. Hydrophilic zeolite additives reduce smell most effectively by far.

KU 3-23_Fraunhofer LBF_Pfaendner - Hauptartikel

Suitable additives for improving the quality of recyclates

After 25 years in the plastics and additives industry, Prof. Dr. Rudolf Pfaendner is head of the Plastics Research Division at the Fraunhofer Institute for Structural Durability and System Reliability LBF in Darmstadt; <a href="mailto:rudolf.pfaendner@lbf.fraunhofer.de">rudolf.pfaendner@lbf.fraunhofer.de</a>

Read the German version of the article in our magazine Kunststoffe or at <a href="https://www.kunststoffe.de/a/fachartikel/vitamine-fuer-die-kreislaufwirtschaft-3441896" target="_blank">www.kunststoffe.de</a>