Ashori, A., Ghofrani, M., Rezvani, M.H., & Khojasteh Khosro, S.

Polymers for Advanced Technologies 26 (8): 1034–1040

2015

The aim of this work was to use waste tire rubber (WTR) in the middle layer of hybrid plywood materials. The effects
of four variable parameters, namely, WTR contents (430 and 720 g), resin contents (120 and 160 g/m2), hot pressing
(single-stage and two-stage), and arrangements of veneer layers on the mechanical, physical, and acoustical properties,
were studied. Beech (Fagus orientalis) and alder (Alnus glutinosa) veneers having 1.8-mm thickness were used in
the production of hybrid plywood panels. Rubber layers of 3- and 5-mm thickness were used in the middle layer of
plywood samples. To produce plywood panels, single-stage and two-stage hot-pressing processes were used. Bonding
of wood layers was performed using 120 and 160 g/m2 urea-formaldehyde resins, and to form the rubber layers
and bond them to wood layers, methylene diisocyanate resin (150 g/m2) was used. Overall trend showed that with
the increase in rubber content, the physical properties (water absorption, thickness swelling, and sound absorption)
of the manufactured panels were improved, while the mechanical properties (modulus of rapture, modulus of elasticity,
and impact strength) of the panels were reduced. Both physical and mechanical performances of plywood
panels were improved with increase in resin content. An increase in the WTR content in plywood improved the composite’s
acoustical property. The production process of the wood/rubber plywood did not significantly affect their
properties. The order of improvement in the physical properties of the panels is rubber content>resin
content>arrangement of layers>pressing process.