María Guadalupe Lomelí-Ramírez - Academia.edu (original) (raw)

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Papers by María Guadalupe Lomelí-Ramírez

Research paper thumbnail of Study of the Interaction of Portland Cement and Pinus Wood for Composites using Bragg Sensors in Optical Fibers

Research paper thumbnail of Bio-composites of cassava starch-green coconut fiber: Part II—Structure and properties

Carbohydrate Polymers, 2014

Development of any new material requires its complete characterization to find potential applicat... more Development of any new material requires its complete characterization to find potential applications. In that direction, preparation of bio-composites of cassava starch containing up to 30 wt.% green coconut fibers from Brazil by thermal molding process was reported earlier. Their characterization regarding physical and tensile properties of both untreated and treated matrices and their composites were also reported. Structural studies through FTIR and XRD and thermal stability of the above mentioned composites are presented in this paper. FT-IR studies revealed decomposition of components in the matrix; the starch was neither chemically affected nor modified by either glycerol or the amount of fiber. XRD studies indicated increasing crystallinity of the composites with increasing amount of fiber content. Thermal studies through TGA/DTA showed improvement of thermal stability with increasing amount of fiber incorporation, while DMTA showed increasing storage modulus, higher glass transition temperature and lower damping with increasing fiber content. Improved interfacial bonding between the matrix and fibers could be the cause for the above results.

Research paper thumbnail of Chemical and Mechanical Evaluation of Bio-composites Based on Thermoplastic Starch and Wood Particles Prepared by Thermal Compression

BioResources, 2014

The present work inspects the preparation of bio-composites of cassava starch with particles of e... more The present work inspects the preparation of bio-composites of cassava starch with particles of eucalyptus wood through the application of a novel method of thermal compression. Bio-composites with different amounts of wood particles (5 to 30%), with particle sizes of 4 and 8 mm, were obtained. Chemical and mechanical evaluation of these samples was carried out using optical microscopy, infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and the moisture absorption effect. The effect of the amount and size of the wood particles was tested by comparison with a thermoplastic matrix sample. Results from these evaluations demonstrated that the thermocompression method produced bio-composites with a distribution of particles in the matrix that contributed to an increase in their tensile strength. This mechanical property is also enhanced by interfacial adhesion between the matrix and particles, as confirmed by SEM. Furthermore, the maximum amount of particles in the bio-composites (30%) showed the maximum resistance to moisture absorption. Temperature and time parameters contributed to the formation of diffraction patterns V H and E H as a consequence of the structural disruption of native starch. Finally, FTIR showed the chemical compatibility between the starch, glycerol, and wood particles.

Research paper thumbnail of Study of the Interaction of Portland Cement and Pinus Wood for Composites using Bragg Sensors in Optical Fibers

Research paper thumbnail of Bio-composites of cassava starch-green coconut fiber: Part II—Structure and properties

Carbohydrate Polymers, 2014

Development of any new material requires its complete characterization to find potential applicat... more Development of any new material requires its complete characterization to find potential applications. In that direction, preparation of bio-composites of cassava starch containing up to 30 wt.% green coconut fibers from Brazil by thermal molding process was reported earlier. Their characterization regarding physical and tensile properties of both untreated and treated matrices and their composites were also reported. Structural studies through FTIR and XRD and thermal stability of the above mentioned composites are presented in this paper. FT-IR studies revealed decomposition of components in the matrix; the starch was neither chemically affected nor modified by either glycerol or the amount of fiber. XRD studies indicated increasing crystallinity of the composites with increasing amount of fiber content. Thermal studies through TGA/DTA showed improvement of thermal stability with increasing amount of fiber incorporation, while DMTA showed increasing storage modulus, higher glass transition temperature and lower damping with increasing fiber content. Improved interfacial bonding between the matrix and fibers could be the cause for the above results.

Research paper thumbnail of Chemical and Mechanical Evaluation of Bio-composites Based on Thermoplastic Starch and Wood Particles Prepared by Thermal Compression

BioResources, 2014

The present work inspects the preparation of bio-composites of cassava starch with particles of e... more The present work inspects the preparation of bio-composites of cassava starch with particles of eucalyptus wood through the application of a novel method of thermal compression. Bio-composites with different amounts of wood particles (5 to 30%), with particle sizes of 4 and 8 mm, were obtained. Chemical and mechanical evaluation of these samples was carried out using optical microscopy, infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and the moisture absorption effect. The effect of the amount and size of the wood particles was tested by comparison with a thermoplastic matrix sample. Results from these evaluations demonstrated that the thermocompression method produced bio-composites with a distribution of particles in the matrix that contributed to an increase in their tensile strength. This mechanical property is also enhanced by interfacial adhesion between the matrix and particles, as confirmed by SEM. Furthermore, the maximum amount of particles in the bio-composites (30%) showed the maximum resistance to moisture absorption. Temperature and time parameters contributed to the formation of diffraction patterns V H and E H as a consequence of the structural disruption of native starch. Finally, FTIR showed the chemical compatibility between the starch, glycerol, and wood particles.

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