Dwarf cavendish as a source of natural fibers in poly(propylene)-based composites

Composite materials were prepared by com pounding and hot-pressing PP or MAPP and lignocellulosic fibers extracted from the rachis of Musa acuminate Colla var. Dwarf Cavendish banana tree. The fibers were used as raw filler or after a chemical treatment expected to remove most of the extractible compounds. The resulting materials were characterized using SEM, DSC, DMA, tensile tests and water sorption experiments. All results show that the main aspect involved in the interfacial adhesion between the polar filler and the non-polar matrix is the extraction of lignin and fatty substances. This results in higher values of the degree of crystallinity and crystallization temperature of the matrix, higher mechanical properties and lower water sensitivity. Scanning electron micrograph showing the cross section of the lignocellulosic filler obtained from rachis of banana tree: (a) raw, and (b) extracted fibers.info:eu-repo/semantics/publishedVersio

Urethanes and polyurethanes from suberin: 1. Kinetic study

Within the context of a study on the preparation and the characterization of polyurethanes based on suberin, as a polyol, and conventional polyisocyanates, it was deemed necessary to carry out a preliminary study on the reactivity of the hydroxy functions of suberin. Aliphatic and aromatic mono- and di-isocyanates were tested and the kinetics of this system followed the classical second order up to conversions of about 85%. The influence of the steric hindrance and the electronic factors, linked to the specific structures of both types of isocyanates, was established.info:eu-repo/semantics/publishedVersio

Surface properties of suberin

The surface energy of suberin was determined by four different methods, namely, (i) contact angle measurements, (ii) Wilhelmy plate measurements, (iii) maximum bubble pressure, and (iv) inverse gas chromatography (IGC). The first three methods gave a gammasub value in the range 40-50 mN m-1 at room temperature. The major component of this value reflects the dispersive contribution. The IGC measurements showed a higher dispersive term, which is common with this method of characterization. The surface acid (A)/base (B) properties were also evaluated, and the results indicated that suberin has an acidic character.info:eu-repo/semantics/publishedVersio

Surface modification of banana-based lignocellulose fibres

Lignocellulosic raw materials were isolated from rachis of Musa acuminata Colla var. cavendish and characterised before and after chemical modification. The rachis was submitted to different mechanical treatments, milling and defibration, resulting in rachis powder and rachis fi bers, respectively. The chemical composition of these two samples was established and it was shown that rachis fibres exhibited higher polysaccharide and lignin contents and lower amounts of ash and extractives components, as compared with the rachis powder. The effects of solvent extrac tion, alkali treatment and chemical modification using phenyl isocyanate, maleic anhydride, alkenyl succinic anhydride and alkyl ketone dimer as grafting agents were studied. The materials were characterized in terms of chemical structure by ATR–FT-IR and 13C-CP-MAS-NMR spectroscopy, morphology by scanning electron microscopy and surface energies by inverse gas chromatography and contact angle measurements. The surface energy of these materials was found to be very close to other similar lignocellulosic materials. Finally, the water absorption of these materials before and after treatment was ascertained. The modified fibres showed considerable changes in ATR–FT-IR and 13C-CP-MAS-NMR spectra and surface properties, providing very convincing evidence that chemical grafting had occurred.info:eu-repo/semantics/publishedVersio

Multilayers of Renewable Nanostructured Materials with High Oxygen and Water Vapor Barriers for Food Packaging

Natural biopolymers have become key players in the preparation of biodegradable food packaging. However, biopolymers are typically highly hydrophilic, which imposes limitations in terms of barrier properties that are associated with water interactions. Here, we enhance the barrier properties of biobased packaging using multilayer designs, in which each layer displays a complementary barrier function. Oxygen, water vapor, and UV barriers were achieved using a stepwise assembly of cellulose nanofibers, biobased wax, and lignin particles supported by chitin nanofibers. We first engineered several designs containing CNFs and carnauba wax. Among them, we obtained low water vapor permeabilities in an assembly containing three layers, i.e., CNF/wax/CNF, in which wax was present as a continuous layer. We then incorporated a layer of lignin nanoparticles nucleated on chitin nanofibrils (LPChNF) to introduce a complete barrier against UV light, while maintaining film translucency. Our multilayer design which comprised CNF/wax/LPChNF enabled high oxygen (OTR of 3 +/- 1 cm(3)/m(2).day) and water vapor (WVTR of 6 +/- 1 g/m(2).day) barriers at 50% relative humidity. It was also effective against oil penetration. Oxygen permeability was controlled by the presence of tight networks of cellulose and chitin nanofibers, while water vapor diffusion through the assembly was regulated by the continuous wax layer. Lastly, we showcased our fully renewable packaging material for preservation of the texture of a commercial cracker (dry food). Our material showed functionality similar to that of the original packaging, which was composed of synthetic polymers.Peer reviewe

Cellulose surface grafting with polycaprolactone by heterogeneous click-chemistry

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