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The application of bio-based and biodegradable poly(3-hydroxybutyrate- co -3-hydroxyvalerate) (PHBV) is restricted by its high cost and brittleness. In the present work, these deficiencies were overcome by the manufacture of PHBV foams using thermally expandable microspheres (TES). Nanocellulose (Nc) and a crosslinking agent were added to PHBV-TES to control the foam structure and to improve the mechanical properties. Foams with almost perfect pores, well embedded in the polymer matrix, were obtained by a simple melt molding process. The closed-cell foams have a density 2.5–2.7 times lower than that of PHBV. The addition of Nc increased the expansion ratio, cell density and porosity and also led to a more uniform cell size distribution. The incorporation of the crosslinking agent, together with Nc and TES, increased the glass transition temperature with about 7 °C and strengthened the PHBV–Nc interactions. PHBV foams showed a 1.7–3 times higher deformation compared to PHBV and absorbed up to 15 times more energy. The fully biodegradable PHBV–Nc foams obtained in this work exhibit an advantageous porosity, good specific mechanical properties and high energy absorption, being promising alternatives for insulation, packaging or biomedical application. [ABSTRACT FROM AUTHOR]

Poly(3-hydroxybutyrate) (PHB) is a promising substitute to petroleum-based polymers in packaging and biomedical applications provided that its melt processability and degradability are improved. A new method to control the properties of PHB by using cheap calcium stearate (CS) as a lubricant and decomposition catalyst in melt-mixed PHB-CS compounds was first used. CS is composed of a metallic cation, which promotes PHB degradation, and a hydrophobic anion that improves the compatibility with PHB and processability. An environmentally friendly melt mixing technique was employed to obtain the PHB-CS compounds. Incorporation of 0.5 or 5 wt% CS reduced the melt viscosity and molecular weight of PHB, decreased the melting temperature with up to 5 °C, the crystallization temperature with more than 25 °C, and the degradation temperature with 15 and 40 °C, respectively. In small amounts (0.05 wt%), CS improved the processability and mechanical properties of PHB. In higher amount (0.5 wt%), CS slightly improved the Young's modulus, reduced the tensile strength and enhanced degradation. A better control of thermal and mechanical properties of PHB is, thus, possible by using different CS amount and processing conditions. These results are relevant for PHB application in the context of the global transition to biodegradable packaging. [ABSTRACT FROM AUTHOR]

• Valorization of waste printed circuit boards and polypropylene. • Increased impact strength compared to the recycled polypropylene without additives. • Improved fire performance of the recycled polypropylene elastomeric composites. In the last several years, the electronic waste, especially printed circuit boards have significantly increased over the world, generating one of the highest rates of solid waste. The recycling process of the printed circuit boards implies mainly the recovery of metals and glass fibers, while the reuse of the polymeric support has remained largely in the phase of research. In this paper, the non-metallic part of printed circuit boards was used as filler (up to 30%), but also to improve the fire resistance of thermoplastic composites based on recycled polypropylene and diene block-copolymers. The synergy between the elastic effect of elastomers and the reinforcing effect of the waste powder into the thermoplastic matrix was studied by mechanical and dynamo-mechanical analysis, X-ray diffraction, optical microscopy, micro-calorimetry and thermo-gravimetrical analysis. Improved mechanical properties, especially impact strength was observed. The compatibization of components considering the interactions between the ethylene-butylene blocks from the hydrogenated and maleinized styrene-butadiene block-copolymer and recycled polypropylene, respectively between the MA groups and the functionalities of the waste powder, evidenced by FTIR, was highlighted by changes in the X-ray pattern and an increased fire resistance and thermal stability. [ABSTRACT FROM AUTHOR]

• Poly(3-hydroxybutyrate) (PHB) was modified with defibrillated wood waste fibers (CF). • CF increased the thermal stability, crystallinity and glass transition of PHB. • The reinforcing effect of CF in PHB highlighted by the increased storage modulus. • The better properties are due to lignin from CF surface and CF - PHB interactions. • Combined effect of CF & plasticizer for desired stiffness/toughness of PHB composite. Wood waste fibers (CF) are low-cost modifiers which make poly(3-hydroxybutyrate) (PHB) composites more attractive for applications. In this work, biocomposites from plasticized PHB and defibrillated wood waste fibers were obtained and characterized. All the composites showed improved thermal stability, with up to 14 °C compared to PHB, a higher crystallinity and a shift of the glass transition with up to 9 °C towards higher temperatures. The reinforcing effect of CF was highlighted by an increase of storage modulus with 13 % at room temperature for the composite with 5 wt% CF and 25 % for that with 10 wt% CF. The highest increase, from 25 % to 90 %, was noticed between room temperature and 125 °C for the composite with 10 wt% CF. The better thermal and mechanical properties of composites compared to PHB are due to the presence of lignin on the surface of CF which favors PHB – CF interactions. This was also supported by the slight increase of contact angle along with the increase of CF concentration. A good interface was also highlighted by SEM: most of the fibers were well embedded in the matrix and locally covered by the polymer which also filled the lumen of CF. Doubling the amount of the plasticizer decreases the glass transition temperature, from −10 °C to −21 °C, the melting and crystallization temperatures of PHB as well, leading to more flexible composites. A decrease with 38 % of storage modulus at room temperature was also noticed when the amount of plasticizer was doubled, showing an increased flexibility. Combining the effect of CF and plasticizer, PHB composites with desired stiffness and toughness can be fabricated. [ABSTRACT FROM AUTHOR]

FPUF from multistep process. The climate change, the depletion of some fossil resources and environmental degradations force the industry and research to focus their investigation on the production of more eco-friendly products in a more sustainable way. The substitution of fossil materials by renewable feedstock from biomass is driven by the development of new molecular architectures with improved or new properties. In this context, different resources such as the vegetable oils are highly investigated. The aim of this study was to synthesize new olive oil-based polyols and to analyze the effect of substitution of conventional fossil-based polyol, with the prepared thereof, in the attempt to fabricate "green" FPUFs with open cells, obtained with a chemical blowing agent (water). In this multistep process, each intermediate and the final cellular materials will be largely characterized. Figure above covers the summary description of the envision steps of the study. [Display omitted] • Biobased Polyurethane Foams with open cells have been successfully elaborated. • Renewable Polyurethane Foams have been synthesized from olive oil for first time. • These biobased polyurethanes present higher properties than commercial ones. • Morphological, mechanical and thermal properties were determined. • Different polyols intermediates have been elaborated and compared. The overall purpose of this study was to synthesize biobased polyols to replace conventional fossil-based polyols in polyurethane foams (PUF) in a multistep approach based on green chemistry, in order to bring both improved properties and sustainability. Oleochemistry has been largely used for PUFs elaboration, but for as far as we know the use of olive oil to obtain such systems had never been reported. The synthesis of the biobased polyols is based on robust approach based on the epoxidation of the double bonds from olive oil using hydrogen peroxide, followed by the ring opening of the epoxides with acetic acid or ethanol to yield polyols with different chemical structures. The chemical structures were determined and checked by NMR and FTIR. The molar masses, the thermal stability and the viscosity were also evaluated. These biobased polyols were further tested making biobased and flexible PUF (FPUFs), with open cells. In this respect, a conventional and fossil-based polyol was partially replaced by up to 35% of each synthesized biobased polyol, alone or mixed. The structural, morphological, mechanical and thermal properties of the PFUFs obtained from the mixture of the biobased polyols were superior to the ones obtained using a sole biobased polyol. Surprisingly, these biobased foams present higher properties than the conventional and fully fossil-based PUF. [ABSTRACT FROM AUTHOR]

Bacterial cellulose (BC) sponges are valuable materials for tissue engineering and regenerative medicine due to their biocompatibility and nano-sized fibrous network with interconnected open porosity. However, their instability in physiological environment and poor mechanical properties are the main issues that need to be solved in order to obtain appropriate three-dimensional scaffolds for tissue formation. In this work, a bacterial polyester, poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and a simple impregnation method were used to improve the properties of BC sponges for biomedical application. Highly hydrophilic BC was surface functionalized by amination (BCA) to improve its affinity to PHBV. PHBV uptake in BC and BCA sponges depended on the PHBV concentration and was confirmed by Fourier transform infrared spectroscopy and by the increase in density after impregnation. SEM investigation showed that PHBV was deposited on the BC nanofibrous network, in some conditions forming a tridimensional honeycomb ordered structure with uniform micrometer pores. Thermogravimetric and kinetic analyses showed a delay in the thermal degradation for the BCA nanocomposites sponges compared to the BC ones and an increase in the activation energy of degradation compared to neat PHBV. Better compression strength was obtained for BCA/PHBV nanocomposite sponges due to the increased interactions between the polymer and the aminated cellulose substrate. Swelling tests showed that BC and BCA sponges did not resist and completely disintegrated in 90 min of incubation in phosphate-buffered saline, but a good stability in this simulated physiological environment was obtained after impregnation with PHBV. The swelling degree varied between 1200% and 2400% for BC/PHBV and between 700% and 1200% for BCA/PHBV sponges, which are high enough to allow the diffusion of water and the transport of nutrients. Therefore, these easily obtained BC/PHBV and BCA/PHBV nanocomposite sponges, with improved properties, could be a promising option for tissue engineering scaffolds. • Tridimensional nanocomposites prepared from bacterial cellulose (BC) sponges and PHBV. • Surface functionalized BC (BCA) showed improved PHBV uptake and thermal stability. • A 10 to 15 times increase of the compression strength in BCA/PHBV sponges was observed. • Encapsulation of BC nanofibers in honeycomb-like PHBV structures observed by SEM. • Nanocomposites show good stability in PBS while BC or BCA sponges disintegrated in 90'. [ABSTRACT FROM AUTHOR]

Polypropylene/hemp fibers (PP/HF) composites for injection molded car parts show several advantages compared to similar composites containing glass fibers (GF), however they have low impact strength, tensile strength and modulus. Here, hemp fibers modified by alkali and alkali-silane treatment were used to reinforce a polypropylene matrix modified with maleic anhydride grafted polypropylene (MAPP) and SEBS. The addition of HF in PP modified with MAPP and SEBS has increased not only the tensile strength and modulus (by 45% and 230%) but also the impact strength. Double tensile strength and triple Young's modulus were obtained in PP composites with alkali-silane treated HF (HFs) in the presence of MAPP and SEBS. Similarly, the HFs led to a significant increase of storage modulus, with about 100% at room temperature and with about 200% at 120 °C. Moreover, the onset degradation temperature increased with 51 °C for HFs containing composites compared to neat PP. PP/HFs composites modified with MAPP and SEBS showed improved mechanical and thermal properties, being considered as a viable alternative to PP/GF composites for injection molded parts in the automotive industry. [ABSTRACT FROM AUTHOR]