Melt-spun polyhydroxyalkanoate monofilaments were successfully processed into woven and knitted textiles using industrial machinery, demonstrating their feasibility for textile applications. The filaments, composed of P(3HB)/P(3HB-co-4HB), exhibited an average tensile strength of ∼138 MPa and an elongation at break of ∼55%, with crystallinity of ∼30%. Cyclic loading of the filaments revealed pronounced hysteresis during the first cycle, which diminished in subsequent cycles. However, a relaxation time of 120 s was sufficient to reset the molecular conformational changes that occurred during the previous cycles. Furthermore, the incorporation of beta tricalcium phosphate (β-TCP) particles during melt spinning reduced tensile strength but improved thermal stability, enhancing processability. These findings highlight the potential of P(3HB)/P(3HB-co-4HB) monofilaments for sustainable textile applications requiring mechanical resilience and thermal robustness.

The upstream applications of post-consumer polypropylene (PCPP) demand long-term oxidation stability to prevent deterioration of its properties. This study explores the potential to replace a commercial antioxidant (AO), Irganox 1010 (I1010), with greener alternatives, quercetin and tocopherol. The emphasis was placed on evaluating their influence on thermal stability, including oxidation resistance and degradation behavior during multiple processing cycles. The rPCPP exhibited inferior thermal properties, with an oxidation induction time (OIT) of 1.2 min and an oxidation onset temperature (OOT) of 205°C. Incorporation of the selected individual AOs improved these properties. The combination of quercetin and tocopherol (QT) exhibited the best results, increasing OIT to 43 min and OOT to 260°C. After five reprocessing cycles, the melt flow rate (MFR) values for the QT system remained unchanged, whereas I1010-stabilized and the non-stabilized rPCPP increased by 183% and 376%, respectively. Similarly, the carbonyl index (CI) value increased by four times for rPCPP and two times for I1010, whereas the QT remained nearly unchanged. The observed enhanced stability of QT is attributed to the synergistic effect. This effect was further supported by the DPPH assay. All the findings demonstrate the effectiveness of selected natural AOs, particularly QT, as a sustainable alternative to conventional stabilizers.

This study reports the synthesis of a stable and homogeneous nanocomposite of cellulose nanocrystals (CNCs) and vinyl acetate (VA) monomer via a semi-batch water-based emulsion polymerization technique, targeting a total solid content (TSC) of 50 wt.% to meet industrial requirements such as smaller storage volume, and easier transportation. The semi-batch approach enabled a consistent distribution of the reactants and improved scalability for industrial applications. CNCs were successfully incorporated into a polyvinyl acetate (PVAc) latex formulation at concentrations of up to 3.22 wt.% relative to VA monomer. Fourier-transform infrared spectroscopy indicated the consumption of hydroxyl groups on the CNC surfaces. The nanocomposites containing 1.93% CNC demonstrated the most promising performance, reducing the water sensitivity of pristine PVAc and lowering both the water vapor transmission rate (WVTR) and permeation. Nevertheless, the increased CNC content induced an uneven surface topography and a broader polymer particle size and distribution, as observed by polarized light and scanning electron microscopy. Mechanical testing revealed a general reduction in the tensile properties relative to neat PVAc, although the 1.93 wt. % CNC sample exhibited the least decline. The resulting nanocomposites exhibited an extended shelf life and colloidal stability, indicating their potential for industrial applications.

A new bio-based unsaturated polyester resin was blended with a bio-based reactive diluent and evaluated. Furan-based monomers were selected as the main monomers in both the resin and the bio-based reactive diluent to enhance thermomechanical properties and address solubility issues typically seen in bio-based resins and diluents. The resin was synthesized from 2,5-furan dicarboxylic acid, isosorbide, and glycerol, and the resulting polymer intermediate was then end-capped with methacrylic anhydride to introduce reactive sites for cross-linking reaction. The resin was then mixed with either different percentages of bio-based reactive diluent (2,5-bis(hydroxy-methyl) furan methacrylate) or with styrene to study the thermomechanical and rheological behavior of obtained resins. FT-IR, 13C-NMR, and 1H-NMR were used to determine the chemical structure of the bio-based reactive diluent. The thermomechanical properties of resin containing bio-based reactive diluent or styrene are characterized and compared by DMA, TGA, and DSC. The synthesized resin had good solubility in the bio-based reactive diluent but not in the styrene. The different mixtures of resin and bio-based reactive diluent showed glass transition temperatures ranging from 166 °C to 174 °C, which was higher than the commercial fossil-based unsaturated polyester resin used as a reference in this study. With thermal and mechanical properties comparable to commercial petroleum-based thermosets, these bio-based resins are promising candidates for high-performance composites, coatings, and other thermoset-based applications.

This study reports the development of polylactic acid (PLA)-based biocomposites modified with microwave-acetylated lignin and reinforced with regenerated cellulose fibers, targeting enhanced mechanical and thermal properties. Lignin acetylation was performed using a catalyst-free microwave-assisted method, yielding improved compatibility with the PLA matrix. Composite blends with varying ratios of PLA, lignin, impact modifier, and fiber loading were processed via extrusion, 3D printing, carding, needle punching, and compression molding methods. Mechanical characterization revealed that composites with higher cellulose fiber content and lignin incorporation demonstrated enhanced impact strength and energy dissipation capabilities. Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR) and thermogravimetric analysis (TGA) confirmed the successful modification of lignin and its influence on thermal stability and char residue formation. Scanning electron microscopy (SEM) provided insights into microstructural changes, such as improved interfacial bonding and reduced fiber pull-out with increasing lignin content. These findings underline the potential of lignin-cellulose PLA composites as a sustainable alternative to traditional materials in automotive and other high-performance applications, combining lightweight design with environmental benefits. 

We present a systematic study of thermoplastic polypropylene (PP) composites reinforced with wood fibers (WF) derived from Norway spruce industrial residues (FibraQ) as scalable, sustainable alternatives to conventional polymers. The wood fibers retain a characteristic softwood monosaccharide profile and display robust morphological integrity and uniform dispersion across loadings from 20 to 50 wt%. Mechanical characterization demonstrates a linear increase in tensile modulus and strength with increasing WF content, counterbalanced by reduced ductility and impact toughness due to increasing fiber network density. Thermal analyses confirm enhanced stability and elevated Vicat softening temperatures upon WF addition. Importantly, these composites exhibit outstanding closed-loop mechanical recyclability: after three industrially relevant processing cycles, PPWF retains >90% of initial stiffness and >94% tensile strength, significantly outperforming neat PP and previously reported biocomposite systems. Our study provides the first direct quantitative comparison of recyclability and structural retention for industrially relevant PPWF composites. These advances offer a pathway for integrating renewable residues into high-performance, durable, and circular materials platforms beyond the capabilities of conventional polymers.

This study investigates the morphology and thermo-mechanical properties of cross-linked polyethylene (PEX) pipes for potential use in high-temperature borehole thermal energy storage systems. Particular attention is given to a novel type of PEX pipe produced through photoinitiated cross-linking (PEX-e). Two formulations, PEX-e1 and PEX-e2, were analyzed and compared to peroxide-cross-linked polyethylene (PEX-a) and non-cross-linked bimodal polyethylene (PE100) pipes. The degree of cross-linking was evaluated via gel content, while cross-link density and molecular weight between cross-links were determined using dynamic mechanical analysis (DMA). Phase composition and molecular mobility were explored through 1H static nuclear magnetic resonance (NMR), and the melting and crystallization behavior was assessed by differential scanning calorimetry (DSC). Oxidative stability and degradation were examined by using Fourier transform infrared (FTIR) spectroscopy, oxidation induction time (OIT) measurements, and thermogravimetric analysis (TGA). Both PEX-e formulations achieved satisfactory cross-linking degrees and exhibited remarkable OIT values. However, significant differences in cross-link distribution were noted, with PEX-e2 showing a less uniform dispersion of cross-links, which resulted in a lower storage modulus. FTIR analysis indicated that oxidation products were formed in PEX-e1 during cross-linking, highlighting the need for further optimization of the formulation and processing conditions.

The textile industry faces an urgent need for sustainable alternatives to petroleum-derived fibers, with bio-based and biodegradable polymers emerging as promising candidates. In this work, we demonstrate the successful melt-spinning of polyhydroxyalkanoate (PHA) monofilaments, specifically P(3HB)/P(3HB-co-4HB), into woven and knitted textiles using standard industrial machinery. This is relevant, as PHA processing into textile-grade fibers has remained a major challenge due to its thermal sensitivity and mechanical limitations.

The resulting monofilaments exhibited tensile strengths of ~138 MPa and elongation at break of ~55%, with crystallinity around 30%. Mechanical testing under cyclic loading revealed pronounced hysteresis during the first cycle, which diminished in subsequent cycles; importantly, a short relaxation period of 120 s was sufficient to reset conformational changes, demonstrating recoverability under repeated stress. Beta tricalcium phosphate (ß-TCP) particles were incorporated during melt-spinning. While this reduced tensile strength, it significantly improved thermal stability, thereby expanding the processability window for melt spinning.

Thermoset resins are reactive polymers capable of forming covalent cross-linking, and are important constituents in many products, which are used every day for many purposes. Automotive, transportation, construction, boats and vessels, sporting goods as well as tanks and pipes used in the chemical and pulping industry are important applications for thermoset composites, but industrially used thermosets have so far mainly been of non-renewable source and very few commercial biobased thermosets are available today. There are a vast number of biomolecules reported in the scientific literature, which have been used in the synthesis of biobased thermosets, such as plant oils, lignin, and various sugars. 

The possibilities to synthesize and produce thermoset resins from renewable biomolecules will be reviewed, and our previous and on-going research in this field will be presented. Our research has focussed on free radical crosslinking cured thermoset resins, where carbon-carbon double bonds are the reactive crosslinking site. Different molecular architectures have been synthesised, and the resins have been reinforced with natural fibres, such as flax, hemp and viscose. The synthesized polymer architectures include star-shaped lactic acid oligomers from penthaerithrytol and methacrylate end groups, branched lactic acid oligomers with glycerol and functionalised with methacrylic and allylic groups, as well as various concepts based epoxidized soybean oil.

The synthesis strategies, the properties and characteristics, as well as performance as a biocomposite for structural composite applications will be discussed and presented.