title: Biobased composites from glyoxal-phenolic resins and sisal fibers.
abstract: Lignocellulosic materials can significantly contribute to the development of biobased composites. In this work, glyoxal-phenolic resins for composites were prepared using glyoxal, which is a dialdehyde obtained from several natural resources. The resins were characterized by (1)H, (13)C, 2D, and (31)P NMR spectroscopies. Resorcinol (10%) was used as an accelerator for curing the glyoxal-phenol resins in order to obtain the thermosets. The impact-strength measurement showed that regardless of the cure cycle used, the reinforcement of thermosets by 30% (w/w) sisal fibers improved the impact strength by one order of magnitude. Curing with cycle 1 (150 degrees C) induced a high diffusion coefficient for water absorption in composites, due to less interaction between the sisal fibers and water. The composites cured with cycle 2 (180 degrees C) had less glyoxal resin coverage of the cellulosic fibers, as observed by images of the fractured interface observed by SEM. This study shows that biobased composites with good properties can be prepared using a high proportion of materials obtained from natural resources.
authors.affiliation: Instituto de Química de São Carlos, Universidade de São Paulo, CP 780, CEP 13560-970 São Carlos, SP, Brazil.
authors.forename: Elaine C
authors.initials: EC
authors.lastname: Ramires
authors.forename: Jackson D
authors.initials: JD
authors.lastname: Megiatto
authors.forename: Christian
authors.initials: C
authors.lastname: Gardrat
authors.forename: Alain
authors.initials: A
authors.lastname: Castellan
authors.forename: Elisabete
authors.initials: E
authors.lastname: Frollini
mesh_terms: D000042:Absorption; D000447:Aldehydes / Q000737:chemistry; D018533:Biomass; D003188:Composite Resins / Q000737:chemistry*; D003247:Conservation of Natural Resources; D004058:Diffusion; D005557:Formaldehyde / Q000737:chemistry*; D006037:Glyoxal / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning / Q000379:methods; D019800:Phenol / Q000737:chemistry*; D010636:Phenols / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry*; D013499:Surface Properties; D013818:Thermogravimetry / Q000379:methods
chemical_list: D000447:Aldehydes; D003188:Composite Resins; D010636:Phenols; D011108:Polymers; D005557:Formaldehyde; D019800:Phenol; D006037:Glyoxal; C011529:phenol-formaldehyde resin