Improved dispersibility of nanofibrillated cellulose via simple microwave-assisted esterification

Nanofibrillated cellulose (NFC) has been successfully esterified by lactic acid (LA) in the presence of HCl catalyst in an aqueous medium using a simple microwave heating process. The degree of substitution (DS) of ester groups on modified NFC (mNFC) was quantified through a systematic characterization consisting of titration, NMR, and XPS, revealing a consistent trend in the levels of DS in mNFC. The reaction parameters of the microwave heating process including the ratio between NFC and LA (1:10), amount of catalyst (5 wt%), energy input and time, have been optimized, achieving a DS of 0.66 in mNFC with a typical power of 800 Watts in 1 min only. The TEM and XRD results confirmed that the structure and characteristics of the nanofibrillated fibers were preserved following the process. Finally, the improved dispersibility of mNFC with high DS in low polarity solvents and polylactic acid (PLA) matrix was validated

THERMOPLASTIC STARCH/WOOD COMPOSITES: INTERFACIAL INTERACTIONS AND FUNCTIONAL PROPERTIES

Thermoplastic starch (TPS)/wood composites were prepared from starch plasticized with 36 wt% glycerol. The components were homogenized by dry-blending, extruded and injection molded to tensile bars. Tensile properties, structure, deformation, water adsorption and shrinkage were determined as a function of wood content, which changed between 0 and 40 vol% in 7 steps. The modification of TPS with wood particles improves several properties considerably. Stiffness and strength increases, and the effect is stronger for fibers with larger aspect ratio. Wood fibers reinforce TPS considerably due to poor ma-trix properties and strong interfacial interactions, the latter resulting in the decreased mo-bility of starch molecules and in the fracture of large wood particles during deformation. Strong interfacial adhesion leads to smaller water absorption than predicted from additivity, but water uptake remains relatively large even in the presence of wood particles. The shrinkage of injection molded TPS parts is very large, around 10 %, and dimensional changes occur on a very long timescale of several hundred hours. Shrinkage decreases to a low level already at 15-20 vol% wood content rendering the composites good dimensional stability

Life cycle assessment of bacterial cellulose production

Purpose Bacterial cellulose (BC), obtained by fermentation, is an innovative and promising material with a broad spectrum of potential applications. Despite the increasing efforts towards its industrialization, a deeper understanding of the environmental impact related to the BC production process is still required. This work aimed at quantifying the environmental, health, and resource depletion impacts related to a production of BC. Methods An attributional life cycle assessment (LCA) was applied to a process design of production of BC, by static culture, following a cradle-to-gate approach. The LCA was modeled with GaBi Pro Software using the ReCiPe 2016 (H) methodology with environmental impact indicators at midpoint level. The functional unit was defined as 1 kg of BC (dry mass), in 138.8 kg of water. Results From the total used resources (38.9 ton/kg of BC), water is the main one (36.1 ton/kg of BC), most of which (98%) is returned to fresh waters after treatment. The production of raw materials consumed 17.8 ton of water/kg of BC, 13.8 ton/kg of BC of which was for the production of carton packaging, culture medium raw materials, and sodium hydroxide (for the washing of BC). The remaining consumed water was mainly for the fermentation (3.9 ton/kg) and downstream process (7.7 ton/kg). From the identified potential environmental impacts, the production of raw materials had the highest impact, mainly on Climate change, Fossil depletion, Human toxicity, non-cancer, and Terrestrial toxicity. The sodium dihydrogen phosphate production, used in the culture medium, showed the highest environmental impacts in Human toxicity, non-cancer and Terrestrial ecotoxicity, followed by corn syrup and carton production. The static culture fermentation and downstream process showed impact in Climate change and Fossil depletion. Conclusions Per se, the BC production process had a small contribution to the consumption of resources and environmental impact of the BC global life cycle.This study was supported by the Portuguese Foundation for Science and Technology (FCT) within the scope of the strate gic funding of UIDB/04469/2020 and UIDB/00511/2020 units and MultiBiorefinery project (SAICTPAC/0040/2015-POCI-01-0145- FEDER-016403). This study was also supported by The Navigator Company through the I&D no. 21874, “Inpactus-–Produtos e Tecno logias Inovadores a partir do Eucalipto”, funded through the European Regional Development Fund (ERDF) and the Programa Operacional Competitividade e Internacionalização (POCI) is greatly acknowl edged. The work by Belmira Neto was fnancially supported by Base Funding—UIDB/00511/2020 of the Laboratory for Process Engineer ing, Environment, Biotechnology and Energy—LEPABE—funded by national funds through the FCT/MCTES (PIDDAC).info:eu-repo/semantics/publishedVersio

Composite foams made from biodegradable polymers for food packaging applications

Polymeric foams are cell structures (porous microstructures) that have been frequently made from synthetic polymers for use in the development of food packaging. Due to the problems concerning the environmental impact caused by polymers from the petrochemical industry, the foams have been more recently studied from biodegradable polymers. However, the polymer materials obtained are usually susceptible to moisture, thus conditioning the collapse of the porous structure of the material. As an alternative, the composite foams have been investigated from nanofillers such as clays, cellulose, nanoparticles, among others. This chapter aims to analyze the recent advances in the studies of composite foams.Fil: Araque Moreno, Luis Miguel. Federal University Of Piauí; BrasilFil: Alvarez, Vera Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Gutiérrez Carmona, Tomy José. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; Argentin

Biodegradable starch-based composites: effect of micro and nanoreinforcements on composite properties

Thermoplastic starch (TPS) matrix was reinforced with various kenaf bast cellulose nanofiber loadings (0–10 wt%). Thin films were prepared by casting and evaporating the mixture of aqueous suspension of nanofibers (NFs), starch, and glycerol which underwent gelatinization process at the same time. Moreover, raw fibers (RFs) reinforced TPS films were prepared with the same contents and conditions. The effects of filler type and loading on different characteristics of prepared materials were studied using transmission and scanning electron microscopies, X-ray diffractometry, Fourier transform infrared spectroscopy, thermogravimetric analysis, differential scanning calorimetry, and moisture absorption analysis. Obtained results showed a homogeneous dispersion of NFs within the TPS matrix and strong association between the filler and matrix. Moreover, addition of nanoreinforcements decreased the moisture sensitivity of the TPS film significantly. About 20 % decrease in moisture content at equilibrium was observed with addition of 10 wt% NFs while this value was only 5.7 % for the respective RFs reinforced film

On the use of nanocellulose as reinforcement in polymer matrix composites

AbstractNanocellulose is often being regarded as the next generation renewable reinforcement for the production of high performance biocomposites. This feature article reviews the various nanocellulose reinforced polymer composites reported in literature and discusses the potential of nanocellulose as reinforcement for the production of renewable high performance polymer nanocomposites. The theoretical and experimentally determined tensile properties of nanocellulose are also reviewed. In addition to this, the reinforcing ability of BC and NFC is juxtaposed. In order to analyse the various cellulose-reinforced polymer nanocomposites reported in literature, Cox–Krenchel and rule-of-mixture models have been used to elucidate the potential of nanocellulose in composite applications. There may be potential for improvement since the tensile modulus and strength of most cellulose nanocomposites reported in literature scale linearly with the tensile modulus and strength of the cellulose nanopaper structures. Better dispersion of individual cellulose nanofibres in the polymer matrix may improve composite properties

Up-cycling of agave tequilana bagasse-fibres: A study on the effect of fibre-surface treatments on interfacial bonding and mechanical properties

The aim of this study was to assess the feasibility of upcycling fibre residues from the harvesting and production of tequila to green composites. Specifically, four different surface-modified natural fibres were assessed as raw material for green composite production. Before any surface treatment, the morphology and tensile properties of agave bagasse fibres from the tequila production batches were determined by optical and environmental scanning electron microscopy (ESEM) and single fibre tensile test, respectively. Further to this, agave fibres were exposed by immersion to four surface treatments including alkali, acetylation, enzymatic and silane treatments, in order to improve their morphology and compatibility with polylactic acid (PLA). The effects of these treatments on fibres’ morphology, mechanical properties (i.e. Youngs modulus and ultimate tensile strength), interfacial shear strength (IFSS), and water absorption were assessed. Overall, surface treatments showed improvements in agave bagasse fibre properties with the best results for alkali treated fibres with an ultimate tensile strength of 119.10 ​MPa, Young modulus of 3.05 ​GPa, and an IFSS of up to ~60% higher (5.21 ​MPa) to that performed by untreated samples. These tests allowed to identify alkali treatment as the most suitable for agave bagasse fibres. These results shed light on the interfacial interaction between agave bagasse fibres and PLA and the potential to up-cycle these residue agave fibres to manufacture PLA-based green composites