Dependence of the mechanical properties of woodflour-polymer composites on the moisture content

• Published in: Journal of applied polymer science Vol. 68; no. 13; pp. 2069 - 2076
• Main Authors: Marcovich, Norma E., Reboredo, María M., Aranguren, Mirta I.
• Format: Journal Article
• Language: English
• Published: New York John Wiley & Sons, Inc 27.06.1998; Wiley
• Subjects: Applied sciences; Composites; Exact sciences and technology; fillers; Forms of application and semi-finished materials; mechanical properties; moisture absorption; Polymer industry, paints, wood; surface treatment; Technology of polymers; woodflour composites; Mercerization; Ester polymer; Mechanical properties; Dispersion reinforced material; Experimental study; Fumarate polymer; Esterification; Composite material; Chemical modification; Humidity effect; Dynamic mechanical properties; Wood by product; Moisture regain; Unsaturated polymer; Comparative study; Modified material
• ISSN: 0021-8995; 1097-4628
• DOI: 10.1002/(SICI)1097-4628(19980627)68:13<2069::AID-APP2>3.0.CO;2-A

Woodflour of Eucaliptus saligna with two different chemical treatments (mercerization and esterification with maleic anhydride) was used as filler of an unsaturated polyester matrix. Woodflour was treated to increase the interfacial adhesion with the matrix, to improve the dispersion of the particles, and to decrease the water sorption properties of the final composite. The objective of this study was to determine the influence of the moisture content and the woodflour chemical modification on the physical and mechanical properties of the different composites. Results indicated that mechanical properties (compression and bending tests) were severely affected by moisture and chemical modifications. In wet conditions, the composites made from treated woodflour had the lowest flexural modulus and ultimate stress. It was found that this was a reversible effect, because the original values of the compression properties were recovered after drying. Temperature scans in dynamic mechanical tests showed that an irreversible change occurred during exposure to humid environments, probably due to the hydrolysis of the polyester matrix. Essentially, the same behavior was observed for matrix and composites; however, a wood‐related transition overlapped the main transition in the case of wet composites. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 2069–2076, 1998