Effect of Diatomite on Properties of Tannic Acid/Starch/Polyvinyl Alcohol Composite Adhesives for Wood
Diatomite enhanced tannic acid/starch/polyvinyl alcohol(PVA)adhesives(DTSP)were prepared,and the effect of diatomite addition on the performance of DTSP adhesives was investigated.The chemical structure of the DTSP adhesive was characterized by Fourier transform infrared spectroscopy(FT-IR).The results showed that diatomite crosslinks by forming hydrogen bonds with hydroxyl groups in starch-based adhesives through silica hydroxyl groups.The cross-section of the cured adhesive layer was analyzed by scanning electron microscopy(SEM),and it was observed that the DTSP adhesive had a rougher surface than the TSP adhesive without added diatomite,indicating the DTSP adhesive layer formed the stable and toughness cross-linking network.By testing the curing and bonding properties of the adhesives,when the diatomite was added at a level of 3%,the DTSP adhesive had the best overall performance,with a wood-wood tensile shear strength of 3.16 MPa,and a tensile shear strength of 1.37 MPa after soaking in water for 24 hours,the curing time was shortened by 20 minutes and the solid content was increased from 26.15%to 36.25%,compared with the TSP adhesive.The moisture absorption rate and saturated moisture absorption rate were decreased,and the contact angle was also improved from 70.2° to 85.7°.
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