Recycling and disposing of non-biodegradable plastic packaging waste has proven to be extremely difficult from the perspective of sustainable development. It takes a lot of work, energy and recycling single-use plastic packaging is inefficient. As a result, we need to find alternatives that satisfy our needs while protecting society and the environment as quickly as feasible. Therefore, the fundamental principle should be the selection of ecological and biodegradable materials [1].
Research on sustainable alternatives has been stimulated by worries about the effects petroleum-based polymers, notably in the packaging industry, have on the environment and human health. The bio-based and biodegradable polymer poly(butylene succinate) (PBS) is examined in this work as a potential laminating and film-blowing material. By employing a tiered spray-coating approach with 1, 3, 5, and 10 NC layers in between blown PBS sheets, nanocellulose (NC) from minimally processed hemp stalk waste was used to create a three-layer laminate structure.
Biodegradable materials must replace single-use petroleum-based plastics. PBS moderate oxygen barrier and water vapor resistance, however, need improvement. NCC is investigated in this work as a functional coating material to enhance the barrier performance of PBS. According to earlier research, cellulose nanofiber coatings and nano-fibrillated cellulose (NFC) can greatly improve barrier qualities, lowering permeability and enhancing sustainability. This study is a continuation to ascertain other properties of the material, such as the self-extinguishing properties of the material or the effect of microorganisms on a packaged product.

Adhesives allowing the bonding of different materials have become an essential element of contemporary functioning. Currently, over 13 million tons of adhesive substances are produced each year, with formulations based on ethylene-vinyl acetate copolymer (EVA) and polyurethanes constituting the majority. (1) However, limited adhesion to non-polar surfaces and the lack of recyclability pose a significant challenge in the light of sustainable development strategies. The growing awareness of society and new legislative requirements somewhat compel the production to align with the principles of a circular economy. (2)
The main aim of this study is to determine the relationship between the chemical structure of the terpolymer and its thermal and mechanical properties and their adhesive performance. Appropriately selected process conditions allow for the production of terpolymers with physicochemical parameters that meet the requirements of components used in the production of hot melt adhesives.
The selection of specific comonomers has a significant impact on the melting temperature, degree of polymer crystallinity, and affinity to polar surfaces. The morphology of FPO, evaluated using atomic force microscopy (AFM), indicates changes in the crystalline structure of the polyolefin through the introduction of functional branches. Based on rheological and strength tests, the relationship between the level of functionalization and adhesive strength was determined.

In the scope of the continuously intensifying environmental, social and economic problems, the need for technological advances is more urgent than ever, in a global-scale. Regarding the sector of plastics, new and more strict landfill regulations are voted, while more waste reduction programs appear, in an attempt to better meet the goals of circular economy. With this in view, an effort of developing polylactic acid (PLA) biocomposites from wood waste is herein investigated. A bio-based and rather green polymer like PLA, can serve as a matrix for incorporating high-value lignocellulosic materials, extracted from wood waste to enhance thermo-oxidative stability and/or mechanical properties. The melt compounding is herein conducted in a twin-screw extruder, while the key-parameters, such as temperature profile and shearing rates are optimized to ensure minimal thermo-mechanical degradation of both, matrix and fillers. The effect of the different filler type (lignocellulose fibers, cellulose nanofibers, lignin) is evaluated in terms of biocomposite characteristics, such as filler dispersion (scanning electrochemical microscopy, SEM), thermal stability (differential scanning calorimetry, DSC and thermogravimetric analysis, TGA), tensile properties and viscoelastic behavior. Additionally, a strategy to stabilize the biocomposites against hydrolysis is developed for long-term applications. The impact of anti-hydrolysis additives along with any synergistic effect of the fillers on PLA durability is monitored throughout accelerated ageing. The most effective PLA formulation will be used in a larger-scale production, which will contribute to the development of sustainable materials for the construction industry, while reducing environmental impact through waste valorization and use of renewable resources.

Vinyl esters are thermosets that have a large variety of applications, such as adhesives and corrosion resistant coatings. Majority of commercial vinyl esters are produced from fossil-based raw materials. Utilization of fossil resources causes several problems. In addition to their negative effect on environment, their global distribution is uneven, which leads to a dependency on fossil imports that may be impacted by political instabilities in exporting countries. Since thermosets have excellent properties and are used in many applications, biobased alternatives should be developed to alleviate aforementioned issues. Biomass is continuously produced in nature, and significant amounts of unused residual biomass are generated in industries, agriculture and forestry, which can be utilized in biorefining to give precursors for thermosets.

Furfural, a promising renewable platform compound, is derived from the dehydration of pentose sugars. Traditionally, it is produced from pentosan-rich byproducts of the food industry, such as corncobs or sugarcane bagasse. Furfural serves as a precursor for other furan derivatives, such as furfuryl alcohol. However, the use of furan as a building block for vinyl ester resins remains relatively unexplored.

In the current work, two furfural-based dimethacrylate monomers were developed. These compounds can be utilized in the production of novel vinyl ester resins. Cured resin specimens showed promising properties compared to their petroleum-based counterparts, such as comparable mechanical properties. Other aspects related to application of furans in vinyl ester resins are discussed in the presentation.

Awareness of the environmental impact of non-biodegradable and fossil-based plastics drives interest in renewable alternatives like cellulose and its derivatives. These materials offer good mechanical properties at relatively low densities due to the strong intermolecular interactions between cellulose chains. However, these interactions also result in a melting point above the degradation temperature of cellulose, precluding conventional thermoplastic manufacturing processes, such as melt-processing [1].
Cellulose chemical modification into dialcohol cellulose (DAC) fibres [2] reduces cellulose crystallinity, creating a processability window between the decreased glass transition and the degradation temperature. Previous studies demonstrated that DAC can be melt-processed using water in relatively large amounts as a processing aid [3,4,5], yielding a quite rigid material with moisture-sensitive mechanical properties. Aiming at tailoring the thermomechanical and viscoelastic properties of DAC, in this study, a set of less volatile plasticizers (i.e. urea, glycerol, sorbitol, isosorbide) were exploited (Fig. 1). Results showed enhancements in the processability and reduction of DAC-based materials inherent sensitivity to external conditions. To further expand the range of thermo-physical properties, DAC was blended with starch, an abundant bio-based and biodegradable polymer, melt-processable in the presence of suitable plasticisers (Fig.1).
This work reports on the melt-processability (assessed by in-line melt viscosity), surface morphology (scanning electron microscopy), thermal stability (thermogravimetric analysis), crystallinity (X-ray diffraction), mechanical properties (tensile tests), viscoelastic behaviour (dynamic thermo-mechanical analysis) and molecular mobility (assessed by dynamic frequency sweep and stress relaxation tests) of the different DAC-based formulation, to discuss achievements and challenges for the exploitation of these fibres.

Increased sensibility of the consumers requires alternatives to bovine leather across the apparel and textile sectors, possibly also avoiding oil-based materials. Plant-based materials obtained by incorporating dried and milled fruit peels in a polymer matrix are a promising option.

Powdered vegetables are composed of biopolymers such as cellulose, hemicellulose, pectin, lignin, aliphatic polyesters, and starch [1]. To reach the required mechanical properties the powder must be connected to the polymer network and not used as filler. Most current polymer binders for this application are hydrophilic, resulting in water sensitive materials.To provide at the same time water processability and hydrophobicity, we prepared semi interpenetrated networks [2] by free radical polymerization of HEMA (2-hydroxyethyl methacrylate) and the crosslinker MBA (N,N-methylene-bis(acrylamide)) in water solution containing linear PVP (Polyvinylpyrrolidone). The hydrogel network obtained by polymerization is physically embedded by linear PVP forming the so called semi-interpenetrated network (semi-IPN) [2]. One focus of the work is assessing the durability and reusability of the leather like material as function of crosslinking and composition. We are also working to upscale our synthesis by replacing HEMA with Dopamine which has demonstrated strong adhesive properties in wet conditions, similar to HEMA.

Many packaging materials contain non-biodegradable, petroleum-derived polymers, which has prompted environmental concerns. Circular economy-based solutions are sought. Due to its high starch content, potato peel (PoP), the main waste of potato processing, is a viable biomass source for biodegradable products1. To valorize PoP, this study will transform it into food packaging bioplastics.
Potato peels are a sustainable and cost-effective source of biopolymers that avoid food resource rivalry and industrial bioplastic manufacturing expenses. In this investigation, a deep eutectic solvent (DES) made of glycerol and choline chloride was used to treat potato peel powder after it had undergone acidic hydrolysis1. The plasticization effects of DES, its components (choline chloride and glycerol), and thermoplastic starch films2 as controls were thoroughly examined.
The prepared materials' structural and morphological characteristics were investigated by FTIR and SEM. Besides their mechanical properties, their interaction with water, including moisture content (MC), water solubility (WS), and water vapor permeability (WVP), was studied. TGA and DSC thermochemical analyses revealed the material's performance and biodegradability potential. Preliminary studies show that DES improves the plasticization of potato peel powder, resulting in homogenous and flexible materials. These findings show that PoP-based bioplastics have the potential to be environmentally acceptable food packaging substitutes that lessen dependency on petroleum-based polymers and increase waste value3,4.

Wood tracking reduces carbon footprints by promoting sustainable forest management, efficient resource use and supply chain transparency. It helps assess forest carbon stocks, supports sequestration strategies, and enables participation in carbon offset programs. By ensuring responsible harvesting, it minimizes deforestation and maximizes the carbon storage potential of wood products. (Bergman et al., 2014; Martinez et al., 2018; Ottelin et al., 2021)
This work explored a new approach for wood tracking by using sustainable dyes that selectively interact with wood components, ensuring stable adhesion and long-lasting marking without relying on toxic synthetic binders. The study investigated diazonium salts, previously used in textile dyeing, where textiles had to be pre-treated with the phenol Naphthol AS to enable an electrophilic substitution that forms a stable, water-insoluble azo dye directly on the fibres. Fast Red B New and Fast Black K Salt were used to investigate the suitability of the concept for wood.
To investigate the mechanism of dye formation, wood chips from oak, spruce, and beech underwent sequential water extraction and delignification to assess the role of different wood components. It was found that dye formation, measured in mg dye per g wood, is highest in oak (90 mg/g), followed by beech (20 mg/g) and spruce (10 mg/g). The significant reduction in dye formation in delignified oak and beech samples suggests that diazonium salts primarily react with the polyphenol lignin. The observed differences are likely due to variations in lignin composition and accessibility among the wood species, which will be further examined.

Itaconic acid and its esters are considered as attractive monomers for the synthesis of bio-based polymers, because the acid is available at large scale and competitive price from biotechnological processes [1]. The esters are bio-based, if the alcohol is originating from renewable resources as well. However, it is well known that itaconates are associated with low radical polymerization rates, e.g., being due to low propagation rate coefficients [2]. Moreover, depropagation is occurring at high temperatures [2] limiting polymerization rate and accessible monomer conversion. Therefore, it appears particularly interesting to conduct copolymerizations with monomers that are known for fast polymerization, and which are not prone to depropagation. These requirements are fulfilled by acrylic acid esters. Further, it is expected that (meth)acrylic acid will be available from renewable resources soon [3]. In this contribution, the copolymerization of various itaconates with different acrylates.

Itaconate-acrylate radical copolymerizations were performed at temperatures up to 90 °C up to high conversion. Based on in-line NMR spectroscopy [4] the reactivity ratios were determined to investigate the impact of the ester groups of both monomer types. While at all conditions, the itaconate monomer is preferentially incorporated into the copolymer, the type of ester group does affect the copolymerization behavior. In addition, emulsion polymerizations of itaconate systems were carried out. It is shown that rather high polymer molar masses are accessible in reasonable reaction times.

Organic solar cells are a fascinating technology, as the active material of only 100 to 200 nm can convert sun light into electricity within an efficiency of 20%. Therebye, fluorination of the organic semiconductors, both the donor and acceptor materials, is a common strategy to reach highly efficient organic solar cells. The incorporation of fluorine lowers the energy levels and thereby facilitates charge separation and transport, leading to better photovoltaic performances. However, the stability of the fluorinated absorber materials in were rarely considered altough it is known that aryl fluorides are more reactive the alkyl fluorides, especially in combination of some inorganic transport layers or metals, used as electrodes. This work focses on the fluorine distribution in conventional and inverted solar cells based on a fluorinated donor polymer (PM6) and a fluorinated donor material (Y6), one of the most investigated sytems at the moment. Interestingly, the fluorine concentration across the absorber layer differed depending on the device architecture, in particular on the used electron and hole transport layers. Besides classical stability tests, measureing the current voltage characteristics of the solar cells, in-depth investigations using analytical transmissione electron microscopy have been carried out.

Although thermal solution RAFT (Reversible addition−fragmentation chain-transfer) depolymerization has recently emerged as an efficient chemical recycling methodology, current approaches require specialized solvents (i.e. dioxane), typically suffer from extended reaction times, and operate exclusively under highly dilute conditions (i.e. 5 mM repeat unit concentration). To circumvent these limitations, a commercial radical initiator is introduced to kinetically untrap the depolymerization and promote chain-end activation. By varying the initiator concentration, a remarkable rate acceleration (up to 72 times faster) can be observed, enabling the completion of the depolymerization within 5 minutes. Notably, a 20-fold increase in the repeat unit concentration did not appreciably compromise the final depolymerization yield, while very high percentages of monomer could be recovered in a wide range of solvents, including dimethyl sulfoxide, anisole, xylene, acetonitrile, toluene, and trichlorobenzene. Our findings not only offer intriguing mechanistic aspects, but also significantly expand the scope and applications of thermal RAFT depolymerization.

Low adhesion properties of raw lignin require its purification and modification for use in tissue adhesive formulations. This study utilized glyoxal to modify lignin, initially dissolved in a NaOH solution at pH 12. The optimal glyoxal concentration was established by evaluating quality of lignin modified with different amounts of glyoxal. After reaction, conducted at a constant temperature, pH was reduced to approximately 1.5 using HCl to facilitate lignin precipitation. The precipitated modified lignin was separated through centrifugation after being stored overnight at 4°C. Liquid from the centrifuge was considered waste, with its composition identified as NaCl, glyoxal, HCl, and water. Aim of this study was to optimize the lignin modification process while minimizing the use of glyoxal and HCl, and to explore potential waste recovery or reuse. The waste solution was repurposed for pH adjustment instead of adding a fresh acid solution to decrease use of new HCl. Properties of the modified lignin precipitated through this recycling approach were analyzed. After three recycling cycles, an increase in solution volume was observed. Water was removed from system to maintain balance, and recycling process continued. Based on analysis and calculations of accumulated NaCl, the recycling process was deemed viable for up to 24 cycles. Throughout study, lignin quality was evaluated, and a comprehensive mass balance was established. According to the mass balance, the total process loss remained below 10%. These experimental studies illustrate the potential for creating a nearly zero-waste discharge process for lignin modification intended for use in tissue adhesive formulation.

Composite materials (Fiber Reinforces Polymers) are vital for the energy transition, being key components in for instance wind turbine blades and hydrogen storage tanks. With the transition towards a sustainable world, the demand for these materials will also increase. However, the end-of-life management of these materials presents a significant challenge, as current recycling efforts prioritize fiber recovery, leaving polymeric components underutilized. For the realization of a truly circular economy high-value chemical recycling of these polymeric building blocks of these complex materials is crucial.

During this presentation we would like to present our recent experimental work on the chemical recycling of epoxy-based composites, including strategies such as Cope elimination and oxidized acid digestion. These methods aim to recover both fiber and matrix materials while minimizing environmental impact.

Additionally we also emphasize education through internships, research projects, and specialized courses, preparing future engineers and scientists to drive innovation in sustainable materials. By integrating hands-on experience with cutting-edge research, we aim to equip the next generation with the skills needed for the energy and material transition.

By advancing scalable recycling solutions, we move closer to closing the loop on composite material life cycles and mitigating the long-term waste problem associated with FRP-based renewable energy infrastructure.

Micro- and submicron capsules have gained significant attention in various fields,1,2 but have not yet been investigated to improve the recycling/environmental degradation of rubber. A big challenge of rubber recycling is dispersing a devulcanization aid (DA), which breaks rubber crosslinks, due to the dense rubber network. When using the DA shielded by a capsule, the DA can be better dispersed before rubber curing. Challenging here is the high shear force encountered during processing that the capsules have to endure which can severely impact requirements in capsule stability.
This study investigates the stability of silica capsules depending on their size within a rubber matrix. Silica capsules were prepared, in micro (4-7 µm) and submicron (300-700 nm) sizes by inverse miniemulsion using sol-gel chemistry from silica precursors, tetraethyl orthosilicate and (3¬-Aminopropyl)trimethoxysilane. Characterization was done by using Scanning Electron Microscopy, where they show a difference in shell morphology.
Subsequently, capsules of both sizes were incorporated separately into a rubber matrix using an internal mixer. It was shown that submicron-sized capsules stayed intact, while microcapsules broke under the high shear forces encountered in rubber processing showing that the stability of the silica capsules is dependent on their size. This research provides valuable insights for the development of a capsule-enhanced rubber system in which the shielded DA is well dispersed within the rubber matrix. The capsules are designed to release the DA after the first lifecycle of a rubber product, which yields an active DA able to break down rubber crosslinks and facilitate rubber recycling.

Polylactide, thanks to its properties, is gaining more and more interest in the plastics industry. One of its advantages is biodegradability, which allows for the environment-friendly management of PLA waste [1]. However, the long time of the process and the need to provide appropriate conditions make mechanical recycling a better solution. Unfortunately, repeated processing of PLA due to shear forces, high temperatures, and moisture leads to the destruction of polymer chains, resulting in the deterioration of processing and mechanical properties of material [2].

This work presents multifunctional reactive additives for polyester recycling, using PLA as a model polymer. The synthesis of additives began with the Activator ReGenerated by Electron Transfer Atom Transfer Radical Polymerization (ARGET ATRP), obtaining a copolymer composed of a certain number of methyl methacrylate (MMA) and glycidyl methacrylate (GMA) units. After polymerization, some of the epoxy groups were opened with functionalized poly(ethylene glycol) (mPEG), primary and secondary antioxidants. During the reactive extruding, the epoxy groups from GMA react with the terminal carboxyl and hydroxyl groups of the PLA. During recycling, an increase in viscosity and improvement of mechanical properties were observed. Moreover, the incorporation of mPEG into the additive chain improved its miscibility with PLA. The optimal amount of additive giving the best performance was selected. The results were compared with the data obtained for similar triblock copolymer additives synthesized using flexible macroinitiators [3, 4].

The research was funded by POB Technologie Materiałowe of Warsaw University of Technology within the Excellence Initiative: Research University (IDUB) program.

Polyethylene (PE), a prominent member of the polyolefin family and one of the most widely used polymers in our daily lives, is produced annually in staggering amounts, reaching 150 million tons across various grades.¹ The absence of functional groups greatly restricts polyethylene's compatibility with other polymers and limits its use in certain applications. PE is also recalcitrant to chemical recycling or upcycling due to its robustness and the inherently inert nature of its constitutive C-C and C-H bonds.² Therefore, the development of general methodologies that could install functional groups into PE’s remains a challenge in Polymer Science.³
This project aims to address this significant task, by developing a metal-free route involving activation of PE C-H bonds through hydrogen atom transfer (HAT) by photochemistry.⁴ To this end, agents, hereinafter referred to as A-FG agents, are employed to undergo homolytic cleavage, releasing both a transient radical A• that activates the PE C-H bond and a persistent radical FG• that enables selective chain functionalization.⁵ The incorporation of polar functional groups along the PE backbone is a key step for various post-functionalization. Notably, this strategy provides an entry to PE derivatives exhibiting different thermomechanical properties than the parent PE, thereby enabling the production of high-value PE-based materials through post-functionalization. Ultimately, it also allowed a handle for further insertion of cleavable C-X bonds within the polymer backbone, for further PE deconstruction.

The environmental crisis caused by synthetic polymers like polyethylene (PE) arises from their resistance to degradation and limited recyclability. Enzymatic degradation offers a sustainable alternative to the traditional recycling. However, improving enzyme efficiency remains a challenge. Recent studies highlight the potential of alternative solvents to boost enzymatic activity [1], as well as the application of enzymes for polymer degradation. In our previous work, we developed an enzymatic degradation process for high-density polyethylene (HDPE) using laccase from Trametes versicolor, achieving a significant 33% weight reduction under optimized conditions [2].
Building upon these insights, this study investigates the use of alternative polyol-based biosolvents to enhance enzyme activity, a crucial step toward advancing enzymatic polyolefin degradation. Laccase activity was tested in biosolvents with varying carbon chain lengths and hydroxyl group numbers, with 1,2,3-propanetriol showing a high increase in efficiency. These results demonstrate the potential of biosolvents to optimize enzymatic processes, creating new opportunities for sustainable polymer biodegradation. Future efforts will focus on optimizing enzymatic activity to degrade polyolefins and other plastics under sustainable conditions.

This work was developed within the scope of the project CICECO-Aveiro Institute of Materials, UIDB/50011/2020, UIDP/50011/ & LA/P/0006/2020, financed by national funds through the FCT/MCTES (PIDDAC). This work is funded by national funds through FCT – Fundação para a Ciência e a Tecnologia, I.P., under the project GREEN-PATH (ref. 2023.15169.PEX, DOI 10.54499/2023.15169.PEX.). MISA acknowledges FCT for the Ph.D. grant PRT/BD/154714/2023. AMF, AFS and APT acknowledge FCT for the research contracts CEECIND/00361/2022, CEECINSTLA/00002/2022 and CEECIND/01867/2020 respectively.

Poly(methyl methacrylate) (PMMA) is one of the most used thermoplastics of its market therefore PMMA is of a relatively high value and warrants the significance of reclaiming the original monomer, in a process known as depolymerisation. Amongst current recycling technologies, chemical recycling offers the only route for PMMA recycling with monomer recoveries > 95 %, however conventional depolymerisation techniques suffer challenges due to poor heat transfer properties of the feedstock. Microwave processing on the other hand has the potential to overcome these challenges and present a low carbon route to PMMA recycling.

PMMA undergoes depolymerisation via a series of radical directed reactions with % MMA recovery dependent on the degradation temperature and mechanistic pathway. The polar group in PMMA can locally move under the influence of microwaves facilitating dielectric heating to thermally degrade PMMA volumetrically, which provides better product purity than conventional heating.

A stepwise pyrolysis approach highlighted an overall increased impurity concentration with conversion, attributed to changes in the depolymerisation kinetics. Furthermore, characterisation of pyrolytic liquid crude from a microwave processing system showed fewer by-products were produced compared to an analogous conventional pyrolysis system, indicative of changes to the depolymerisation pathway.

The influence of pyrolysis processing parameters: temperature and residence time; were also explored for their impact to the kinetics and thermodynamics of depolymerisation to understand factors leading to formation of impurities.