Improving the Adhesion Between Hydrophobic Biodegradable Matrix and Cellulose Fibers

MIRIAN CASCO; LEANDRO LUDUEÑA; ANALÍA VAZQUEZ; VERA ALVAREZ

Advances in Materials Science Research. Volume 4.

Nova Publisher

Año: 2010; p. 287 - 306

In this work, several surface treatments were carried out on cellulose fibers. They were: alkaline-treatments (5, 10, 15 and 20 wt.% of NaOH and  10 wt.% of KOH); acetylation (treatment with glacial acetic acid for 1 or 2 hours followed by catalyzed acetic anhydride)  and esterification (treatments with stearic and lauric acids). The original and modified celluloses were characterized by DSC (Differential Scanning Calorimetry), TGA (Thermogravimetric Analysis), FTIR (Infrarred Spectroscopy), DRX (X-Ray Diffraction), SEM (Scanning Electron Microscopy), water absorption test and contact angle measurements. The analysis confirmed the decrease on crystallinity for alkaline treatment as a function of NaOH concentration together with the change from cellulose I to cellulose II, and the increase on the polarity and water absorption. Acetylated fibers showed the higher change in crystallinity and a clear decrease on polarity degree and water absorption. Esterification produced a slight increase on the crystallinity without changing cellulose I whereas the water absorption decrease and the polarity decreased until zero. All the results indicate that this last treatment took place at the surface. The most compatible fibers were used to prepare composites with 15 wt.% of them (and the untreated ones as reference). Best properties were achieved with the 2 hours acetylated fibers were a medium decrease on the polarity (good compatibility with the non polar matrix) and slight reduction on the fiber aspect ratio was found. The parameters from yield resistance mathematical models were in good agreement with the experimental behaviour.