Characterization Of Plywoods Produced By Various Bio-Adhesives

Abstract

The increasing environmental concern and adverse health effects with the use of formaldehyde-based plywood adhesives has led to an interest in developing adhesives based on renewable resources. The main objective of this study was to explore and develop environmental friendly bio-based adhesives suitable for manufacturing plywood. Three different adhesives were prepared, one using soya meal powder and the other two using tamarind kernel powder as the major constituents. In the soya meal adhesive (SMA), water, pine oil and fresh hydrated lime were used for the preparation of the adhesive. Different methods were adopted in preparing the two tamarind adhesives, Tamarind Adhesive 1 (TA1) in which water, formalin and glucose were used and Tamarind Adhesive 2 (TA2) in which hot water and boric acid were used. These three adhesives were characterized in detail using Field Emission Scanning Electron Microscopy (FESEM) and X-Ray Diffraction (XRD). The FESEM images reveal the presence of dispersed particles in all the adhesives but the matrix of these adhesives varies. SMA shows a continuous matrix structure while the TA1 reveal agglomerated matrix structure and TA2 show more of continuous matrix with few agglomerated portions. The XRD analysis reveals the amorphous nature of all the three bio-adhesives. The XRD pattern of TA1 is similar to that of urea formaldehyde with a peak at around 20°, an indication of the presence of formalin, while the absence of such a peak in the other two adhesives is a clear indication of absence of dangerous formaldehyde. It can be concluded that the presence of dispersed particles in a continuous matrix and the absence of formaldehyde in SMA makes it superior in its properties. In spite of the presence of dispersed particles, the agglomerated matrix structure in TA1 might show inferior properties but the presence of formalin makes it similar in nature to that of urea formaldehyde. The combination of agglomeration and more of continuous matrix structure with dispersed particles and absence of formaldehyde in TA2 might make it similar in properties with SMA.