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.

Poly(lactic acid) (PLA) has great potential in the plastic packaging industry due to its biodegradability, versatility, and good performance. PLA compounding with different biobased materials to enhance the flexibility and biodegradability of PLA-based packaging materials has attracted growing attention. Fungal biomass (FB), as a biological and eco-friendly by-product stream from fermentation processes, can be a valuable blending component in PLA-based biocomposites. Therefore, in this study, 10 and 20 wt% of fungal biomass (FB), defatted fungal biomass (DFB), and fungal cell wall (FCW), as promising biobased materials, were added to PLA plasticised with 10 wt% triethyl citrate (TEC) to fabricate biocomposites using the melt compounding technique. Our research focused on how the addition of fungal biomass and its fractions affected the mechanical and thermal properties, as well as the structure of PLA-based blends. These additions did not increase the strength of the biocomposites, but they did improve flexibility compared to regular plasticised PLA. The crystallisation of plasticised PLA samples blended with FB and DFB began at lower temperatures than neat PLA, plasticised PLA, and plasticised PLA blended with FCW. The addition of fungal biomass and its fractions, particularly at 20 wt%, accelerated the biodegradation of PLA-based composites. Neat PLA and plasticised PLA degraded slowly in soil and retained most of their mass, whereas PLA-based blends containing FB and its fractions degraded significantly faster. It can be concluded that fungal biomass is a promising candidate for improving the flexibility of PLA blends and facilitating their biodegradation in a natural soil environment.

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, 13 C-NMR, and 1 H-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.

The influence of beta-tricalcium phosphate (ss-TCP) particles on the early cell attachment of MC3T3-E1 osteoblast precursor cells is investigated on a poly(3-hydroxybutyrate)/poly(3-hydroxybutyrate-co-4-hydroxybutyrate) polymer blend. MC3T3-E1 cells adhere to both polymer blends, with and without ss-TCP. In both cases, the cells show a typical cell morphology and focal adhesions on the polymer surface. The ss-TCP does not significantly improve the cell adhesion and hydrophilicity of the polymer films. Further, ss-TCP does not alter the degradation behavior of the poly(3-hydroxybutyrate)/poly(3-hydroxybutyrate-co-4-hydroxybutyrate) blend when exposed to phosphate buffered saline solution for up to 70 days. However, the results confirm that the polyhydroxyalkanoate blends used in this study are non-cytotoxic and maintain structural integrity over time. These findings highlight the blend's promise for usage in long-term biomedical applications, particularly in bone tissue engineering, because of their stability in isotonic medium.

In this study, a bio-based resin containing glycerol, isosorbide, and 2,5-furan dicarboxylic acid was used to produce a glass fiber reinforced composite. The thermomechanical properties of the resin were examined through dynamic mechanical analysis, thermogravimetric analysis, and differential scanning calorimetry, and were compared with those of commercially available unsaturated polyester resin and epoxy resin. Glass fiber composites were prepared using the synthesized bio-based resin, commercial unsaturated polyester resin, and commercial epoxy resin. Tensile tests, flexural tests, and aging tests were performed on all three types of composites and the results were compared. The findings suggest that the bio-based resin exhibits superior thermomechanical properties compared to the commercial resins. Bio-based resin demonstrates a high storage modulus of 4807 MPa and a loss modulus of 72 MPa at 25 ℃, along with a high glass transition temperature of 173 ℃. The flexural and tensile properties of the bio-based resin were better than that of the commercial resins. The composite produced from bio-based resin shows a flexural strength of 334 MPa and a tensile strength of 256 MPa. Aging results indicate that the synthesized bio-based resin was fairly stable at elevated temperatures. The outcome of this work shows that the bio-based glass fiber reinforced composite is a promising composite for high temperature applications.

We investigated the melt-spinning potential of a poly(3-hydroxybutyrate)/poly(3-hydroxybutyrate-co-4-hydroxybutyrate) blend using a piston spinning machine with two different spinneret diameters (0.2 and 0.5 mm). Results from the differential scanning calorimetry, dynamic mechanical thermal analysis, and tensile testing showed distinct filament properties depending on the monofilaments' cross-sectional area. Finer filaments possessed different melting behaviors compared to the coarser filaments and the neat polymer, indicating the formation of a different type of polymer crystal. Additionally, the mechanical properties of the finer filament (tensile strength: 21.5 MPa and elongation at break: 341%) differed markedly from the coarser filament (tensile strength: 11.7 MPa, elongation at break: 12.3%). The hydrolytic stability of the filaments was evaluated for 7 weeks in a phosphate-buffered saline solution and showed a considerably reduced elongation at break of the thinner filaments. Overall, the results indicate considerable potential for further filament improvements to facilitate textile processing.

Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) is a biobased and biodegradable polymer. This polymer is considered promising, but it is also rather expensive. The objective of this study was to compound PHBV with three different organic fillers considered waste: human hair waste (HHW), sawdust (SD) and chitin from shrimp shells. Thus, the cost of the biopolymer is reduced, and, at the same time, waste materials are valorised into something useful. The composites prepared were characterised by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), tensile strength and scanning electron micrograph (SEM). Tests showed that chitin and HHW did not have a reinforcing effect on tensile strength while the SD increased the tensile strength at break to a certain degree. The biodegradation of the different composites was evaluated by a soil burial test for five months. The gravimetric test showed that neat PHBV was moderately degraded (about 5% weight loss) while reinforcing the polymer with organic waste clearly improved the biodegradation. The strongest biodegradation was achieved when the biopolymer was compounded with HHW (35% weight loss). The strong biodegradation of HHW was further demonstrated by characterisation by Fourier-transform infrared spectroscopy (FTIR) and solid-state nuclear magnetic resonance (NMR). Characterisation by SEM showed that the surfaces of the biodegraded samples were eroded.

Hydroxyapatite (HA) has shown very promising results in hard tissue engineering because of its similarity to bone and hence the capability to promote osteogenic differentiation. While the bioactivity of HA is uncontested, there are still uncertainties about the most suitable hydroxyapatite particle shapes and sizes for textile scaffolds. This study investigates the influence of the shape and size of HA particles on as spun fibers of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and HA, their mechanical and thermal properties as well as their influence on the fiber degradation in simulated blood matrix and their capability to mineralize in simulated body fluid. The key findings were that the different HA particles’ size does not affect the melting temperature and still maintains a thermal stability suitable for fiber production. Tensile testing revealed decreased mechanical properties for PHBV/HA as spun fibers, independently of the particle morphology. However, HA particles with 30 nm in width and 100 nm in length at 1 wt% HA loading achieved the highest tenacity and elongation at break amongst all composite fibers with HA. Besides, the Ca/P ratio of their mineralization in simulated body fluid is the closest to the one of mineralized human bone, indicating the most promising bioactivity results of all HA particles studied.

Volatile fatty acids (VFAs) appear to be an economical carbon feedstock for the cost-effective production of polyhydroxyalkanoates (PHAs). The use of VFAs, however, could impose a drawback of substrate inhibition at high concentrations, resulting in low microbial PHA productivity in batch cultivations. In this regard, retaining high cell density using immersed membrane bioreactor (iMBR) in a (semi-) continuous process could enhance production yields. In this study, an iMBR with a flat-sheet membrane was applied for semi-continuous cultivation and recovery of Cupriavidus necator in a bench-scale bioreactor using VFAs as the sole carbon source. The cultivation was prolonged up to 128 h under an interval feed of 5 g/L VFAs at a dilution rate of 0.15 (d−1), yielding a maximum biomass and PHA production of 6.6 and 2.8 g/L, respectively. Potato liquor and apple pomace-based VFAs with a total concentration of 8.8 g/L were also successfully used in the iMBR, rendering the highest PHA content of 1.3 g/L after 128 h of cultivation. The PHAs obtained from both synthetic and real VFA effluents were affirmed to be poly(3-hydroxybutyrate-co-3-hydroxyvalerate) with a crystallinity degree of 23.8 and 9.6%, respectively. The application of iMBR could open an opportunity for semi-continuous production of PHA, increasing the feasibility of upscaling PHA production using waste-based VFAs.

Unsaturated polyester resins, one of the most important thermosets, are invariably produced from oil-based monomers. Their application is limited in areas where high thermal stability is required due to their low T g . Besides, these resins contain 30–40% hazardous styrene as a reactive solvent. Therefore, developing bio-based solventless unsaturated polyester resin with medium to high thermomechanical properties compared to petrochemical-based counterparts is important. In order to achieve this, a series of branched bio-based unsaturated polyester resins were synthesized using bulk polymerization method in two steps. In the first step, four different intermediates were prepared by reacting glycerol (as a core molecule) with either isosorbide (diol), 1,3-propanediol (diol), 2,5-furandicarboxylic acid (saturated diacid), or adipic acid (saturated diacid). In the second step, the branched intermediate was end capped with methacrylic anhydride to introduce reactive sites for cross-linking on the branch ends. The chemical structure of the resins was characterized by 13 C-NMR. FT-IR confirmed the polycondensation reaction in the first step and the end functionalization of the resins with methacrylic anhydride in the second step. The effect of 2,5-furandicarboxylic acid and isosorbide on thermomechanical and thermal properties was investigated using dynamic mechanical analysis, differential scanning calorimetry, and thermo-gravimetric analysis. Results indicated that 2,5-furandicarboxylic acid based resins had superior thermomechanical properties compared to a commercial reference unsaturated polyester resin, making them promising resins for high-temperature composite applications. For example, the resin based on 2,5-furandicarboxylic acid and isosorbide and the resin based on 2,5-furandicarboxylic acid and 1,3-propanediol gave glass transition temperatures of 173 °C and 148 °C, respectively. Although the synthesized 2,5-furandicarboxylic acid based resins had higher viscosity (22.7 Pas) than conventional unsaturated polyester (0.4–0.5 Pas) at room temperature, preheated resins can be used for making high-temperature-tolerance fiber-reinforced composite.

The superior biocompatibility and biodegradability of polyhydroxyalkanoates (PHAs) compared to man-made biopolymers such as polylactic acid promise huge potential in biomedical applications, especially tissue engineering (TE). Textile fiber-based TE scaffolds offer unique opportunities to imitate the anisotropic, hierarchical, or strain-stiffening properties of native tissues. A combination of PHAs' enhanced biocompatibility and fiber-based TE scaffolds could improve the performance of TE scaffolds. However, the PHAs' complex crystallization behavior and the resulting intricate spinning procedures remain a challenge. This review focuses on discussing the developments in PHA melt and wet spinning, their challenges, process parameters, and fiber characteristics while revealing the lack of an in-depth fiber characterization of wet-spun fibers compared to melt-spun filaments, leading to squandered potential in scaffold development. Additionally, the biomedical application of PHAs other than poly-4-hydroxybutyrate is hampered by a failure of polymer purity to meet the requirements for biomedical applications.

Volatile fatty acids (VFAs) have become promising candidates for replacing the conventional expensive carbon sources used to produce polyhydroxyalkanoates (PHAs). Considering the inhibitory effect of VFAs at high concentrations and the influence of VFA mixture composition on bacterial growth and PHA production, a thorough investigation of different cultivation parameters such as VFA concentrations and composition (synthetic and waste-derived VFAs) media, pH, aeration, C/N ratio, and type of nitrogen sources was conducted. Besides common VFAs of acetic, butyric and propionic acids, Cupriavidus necator showed good capability for assimilating longer-chained carboxylate compounds of valeric, isovaleric, isobutyric and caproic acids in feasible concentrations of 2.5–5 g/L. A combination of pH control at 7.0, C/N of 6, and aeration of 1 vvm was found to be the optimal condition for the bacterial growth, yielding a maximum PHA accumulation and PHA yield on biomass of 1.5 g/L and 56%, respectively, regardless of the nitrogen sources. The accumulated PHA was found to be poly(3-hydroxybutyrate-co-3-hydroxyvalerate) with the percentage of hydroxybutyrate in the range 91–96%. Any limitation in the cultivation factors was found to enhance the PHA yield, the promotion of which was a consequence of the reduction in biomass production.

Fungal biomass (FB), a by-product of the fermentation processes produced in large volumes, is a promising biomaterial that can be incorporated into poly(lactic acid) (PLA) to develop enhanced biocomposites that fully comply with the biobased circular economy concept. The PLA/FB composites, with the addition of triethyl citrate (TEC) as a biobased plasticizer, were fabricated by a microcompounder at 150 °C followed by injection molding. The effects of FB (10 and 20 wt %) and TEC (5, 10, and 15 wt %) contents on the mechanical, thermal and surface properties of the biocomposites were analyzed by several techniques. The PLA/FB/TEC composites showed a rough surface in their fracture section. A progressive decrease in tensile strength and Young's modulus was observed with increasing FB and TEC, while elongation at break and impact strength started to increase. The neat PLA and biocomposite containing 10% FB and 15% TEC exhibited the lowest (3.84%) and highest (224%) elongation at break, respectively. For all blends containing FB, the glass transition, crystallization and melting temperatures were shifted toward lower values compared to the neat PLA. The incorporation of FB to PLA thus offers the possibility to overcome one of the main drawbacks of PLA, which is brittleness.

The existing recycling methods of PHA-based material are ineffective in terms of increasing resource efficiency and the production of high value end-of-life products. Therefore, in this study, a novel approach of acidogenic fermentation was proposed to recycle PHB-based composites reinforced with natural fibers such as cellulose, chitin, chitosan, orange waste, sawdust, soy protein, and starch. The inclusion of cellulose, chitosan, and sawdust improved the impact properties of the composites while other fillers had various effects on the mechanical properties. These three composites and neat PHB were subsequently subjected to biological degradation via acidogenic digestion to determine the possibility of converting PHB-based composites into volatile fatty acids (VFAs). Two different pH levels of 6 and 10 were applied to assess the effect of pH on the bioconversion and inhibition of the methanogenesis. The results showed promising PHB degradation, contributing to considerable VFA production of 2.5 g/L at pH 6 after 47 days. At pH 6, the presence of the natural fibers in the biocomposites promoted the degradation rate. On the contrary, pH 10 proved to be more suitable for the degradation of the fibers. The VFA which is produced can be recirculated into PHB production, fitting with the concept of a circulating bioeconomy.

High production costs still hamper fast expansion of commercial production of polyhydroxyalkanoates (PHAs). This problem is greatly related to the cultivation medium which accounts for up to 50% of the whole process costs. The aim of this research work was to evaluate the potential of using volatile fatty acids (VFAs), derived from acidogenic fermentation of food waste, as inexpensive carbon sources for the production of PHAs through bacterial cultivation. Bacillus megaterium could assimilate glucose, acetic acid, butyric acid, and caproic acid as single carbon sources in synthetic medium with maximum PHAs production yields of 9–11%, on a cell dry weight basis. Single carbon sources were then replaced by a mixture of synthetic VFAs and by a VFAs-rich stream from the acidogenic fermentation of food waste. After 72 h of cultivation, the VFAs were almost fully consumed by the bacterium in both media and PHAs production yields of 9–10%, on cell dry weight basis, were obtained. The usage of VFAs mixture was found to be beneficial for the bacterial growth that tackled the inhibition of propionic acid, iso-butyric acid, and valeric acid when these volatile fatty acids were used as single carbon sources. The extracted PHAs were revealed to be polyhydroxybutyrate (PHB) by characterization methods of Fourier-transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). The obtained results proved the possibility of using VFAs from acidogenic fermentation of food waste as a cheap substrate to reduce the cost of PHAs production.

The purpose of this study was to investigate the influence of aging on the properties of high-density polyethylene (HDPE) reinforced with multi-wall carbon nanotubes (MWCNTs). Nanocomposites were prepared with nanotubes at 0, 1, 3, and 5 wt%. The long-term durability of the prepared materials was evaluated by thermo-oxidative aging test. Test bodies were aged at 110 degrees C for up to 10 weeks. The nanocomposites were characterized by differential scanning calometry, thermogravimetric analysis (TGA), C-13-NMR, elongation at break, and transmission electron microscopy. The aging mainly occurred on the surface of the samples and the neat HDPE showed a strong yellowing after the aging. A strong reduction in elongation at break was seen. For neat HDPE, the elongation at break was reduced from roughly 1400-25%. When HDPE was reinforced with the nanotubes, the reduction was less dramatic.

The production of polyhydroxyalkanoates (PHA)-based plastics is expected to increase in the future as an effort to drive away from petroleum-based products. However, stating biodegradability is not enough to motivate their production, and comprehensive studies, in the context of waste management, need to be carried out. Their absence will mitigate the potential positive environmental impacts of bio-based plastics with no practical impact on waste accumulation. The chapter provides an overview of potential aerobic and anaerobic microbial methods that can be used for the degradation of PHA. Anaerobic digestion, in view of the potential value-added products generated, namely methane, hydrogen, and volatile fatty acids, and industrial operation, is believed to play a superior role in future PHA waste management strategy development in comparison to that of composting and vermicomposting. However, the composition of the final plastic materials reaching the market will influence the ease of biodegradation and clear relationships need to be demonstrated.

The usage of bioplastics could increase in the future which may cause contamination of the waste streams of conventional plastics. The objective of this study was to investigate if a small amount of biopolymer contaminating conventional polymers would significantly affect mechanical and thermal properties. A starch-based plastic was first compounded by blending plasticised starch with PLA (polylactic acid). This polymer blend was subsequently compounded with HDPE (high density polyethylene), PP (polypropylene) or PET (polyethylene terephthalate) at 0%, 1% and 5% of the biopolymer. The compounds were characterised by tensile tests, Charpy impact tests, DSC (differential scanning calorimetry) and FESEM (field emission scanning electron microscopy). Tests showed that PE and PP were not significantly affected in terms of tensile strength and modulus but the elongation at break showed a strong reduction. PET was, on the other hand, incompatible with the starch-based plastic. Already at 1% contamination, PET had lost most of its impact strength.

In this study, a commercial grade of talc is used as filler in a bimodal high-density polyethylene (HDPE) used for the pressure pipe application. The composites are characterized by thermogravimetric analysis (TGA), differential scanning calorimetry, dynamic mechanical thermal analysis, and tensile testing. The results illustrate that the presence of talc has a considerable effect on the material properties and the pipe life-length. It is presented that the thermal stability measured by TGA is enhanced, while the oxidation induction time decreases in cooperation of the talc. The nucleation behavior of talc particles during crystallization has no obvious effect on melting temperature; however, an increase in crystallization temperature is evidenced. Storage modulus as recorded from the dynamic mechanical analysis is also increased in all composites, furthermore, the temperature of the alpha relaxation is shifted toward higher temperature and finally the strain hardening modulus for the HDPE/talc composites is assessed and compared to the neat HDPE as a measure of environmental stress crack resistance.

The fabrication of smart biocomposites from sustainable resources that could replace today's petroleum-derived polymer materials is a growing field of research. Here, we report preparation of novel biocomposites using nanocellulose networks extracted from food residue (onion skin) and a vegetable oil-based bioresin. The resin was synthesized via the Diels-Alder reaction between furfuryl methacrylate and tung oil at various ratios of the components. The onion-skin-extracted cellulose nanofiber and cellulose nanocrystal networks were then impregnated with the resins yielding biocomposites that exhibited improved mechanical strength and higher storage modulus values. The properties of the resins, as well as biocomposites, were affected by the resin compositions. A 190-240-fold increase in mechanical strength was observed in the cellulose nanofiber (CNF) and cellulose nanocrystal (CNC)-reinforced biocomposites with low furfuryl methacrylate content. The biocomposites exhibited interesting shape-memory behavior with 80-96% shape recovery being observed after 7 creep cycles.