Publications by authors named "Sonia Molina Boisseau"
Article Synopsis
- Researchers developed rubber materials using a diene elastomer and tailored nanocellulose fillers, achieving better mechanical reinforcement.
- The nanocellulose was derived from freeze-dried cellulose nanocrystals and microfibrillated cellulose with high specific surface areas, modified for better compatibility with the rubber matrix.
- Enhanced materials showed significant modulus increases and maintained flexibility; in some cases, the stress-stiffening behavior resulted in ultimate stress increases of up to 7 times compared to the unfilled matrix.
Article Synopsis
- Aqueous suspensions of microfibrillated cellulose were processed and freeze-dried to create highly porous aerogels with a surface area of 100 m²/g.
- The aerogels underwent gas-phase esterification with palmitoyl chloride, leading to a variety of cellulose palmitates with degrees of substitution (DS) ranging from 0 to 2.36.
- The low DS samples (0.1-0.4) showed that the cellulose microfibrils were hydrophobic and esterified only on their surface, maintaining their inner structure.
In this exploratory work, the comparison of the utilisation of different non-conventional technologies (ultrasound and microwave irradiations) for the depolymerisation of a complex industrial starch-based waste into reducing sugars was investigated. Reducing sugars could then be converted into higher value-added compounds such as higher alcohols. The experiments were performed on three different starting materials named as 'Potato flour', 'Wet potato sludge' and 'Dry potato sludge'.
View Article and Find Full Text PDFA phenomenological modeling approach was developed to try to understand the reinforcing mechanism of starch nanocrystals in a nonvulcanized natural rubber matrix. Natural rubber was not cross-linked to maintain the biodegradability of the biosourced materials. Nonlinear dynamic mechanical experiments highlighted the significant reinforcing effect of starch nanocrystals and the presence of the Mullins and Payne effects.
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- A novel synthetic method for surface esterification has been developed using palmitoyl chloride on high crystallinity cellulose substrates, monitored by solid-state CP-MAS (13)C NMR.
- The degree of grafting varied based on experimental conditions and the specific cellulose type, influencing the structural and morphological changes observed through scanning electron microscopy and X-ray diffraction.
- The process results in fully grafted surfaces while keeping the cellulose core intact, allowing for high substitution rates under specific conditions that yield distinct X-ray diffraction patterns.
The insoluble residues obtained by submitting amylopectin-rich native starch granules from waxy maize to a mild acid hydrolysis consist of polydisperse platelet nanocrystals that have retained the allomorphic type of the parent granules. The present investigation is a detailed characterization of their molecular composition. Two major groups of dextrins were found in the nanocrystals and were isolated.
View Article and Find Full Text PDFNanocomposites films have been processed from a filler and a matrix having the same nature, i.e. waxy maize starch.
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- Waxy maize starch nanocrystals were used as a reinforcing agent in a glycerol-plasticized thermoplastic starch matrix, differing from previous studies on natural rubber due to the polar nature of the matrix and similar chemical structures of the filler and matrix.
- The study examined the effects of varying glycerol and filler content, as well as aging, on the material's reinforcing properties through tensile tests, dynamic mechanical analysis (DMA), and X-ray diffraction.
- Strong interactions between the starch nanocrystals and the matrix, primarily due to hydrogen bonding, improved the material's reinforcement and reduced recrystallization during aging in a humid environment.
The surface of waxy maize starch nanocrystals obtained from sulfuric acid hydrolysis of native waxy maize starch granules was chemically modified using two different reagents, namely, alkenyl succinic anhydride and phenyl isocyanate. The occurrence of chemical modification was evaluated by FTIR and X-ray photoelectron spectroscopies. Contact angle measurements from which the surface energy of the materials under investigation was deduced showed that chemical modification led to more hydrophobic particles.
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- The study used response surface methodology to analyze how five factors (temperature, acid concentration, starch concentration, hydrolysis duration, and stirring speed) affect the hydrolysis of waxy maize starch with sulfuric acid.
- The aim was to optimize conditions for creating starch nanocrystals that are small in size, produced quickly, and yield a high output.
- Results showed it was possible to achieve a 15 wt% yield of starch nanocrystals in just 5 days with sulfuric acid, compared to only 0.5 wt% yield from a traditional hydrochloric acid method that took 40 days.
Colloidal aqueous suspensions of starch nanocrystals were prepared by submitting native granules from A-type amylopectin-rich waxy maize to a hydrochloric acid hydrolysis. The insoluble residue contains polydisperse and more or less individualized platelet nanocrystals corresponding to the lamellae formed by the association of amylopectin side branches into parallel arrays of double helices. After 2 weeks of hydrolysis, 5-7 nm thick lamellae still connected by alpha(1-->6) linkages were seen edge-on using transmission electron microscopy.
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