Horticultural/hydroponics and floral natural foams from tannins

New formaldehyde-free Quebracho tannin foams were developed for horticultural/hydroponics and floral applications. These foams included in their composition a wetting agent and at least one compound able to neutralize the residual acidity derived from acid catalyst. Their densities were between 0.048 and 0.066 g/cm(3) and compression strength, between 0.07 and 0.09 MPa. Scanning electron microscopy (SEM) images showed open porosity and average cell size of 125-250 mu m. Water absorption peaked at 98% (vol) while residual pH value was 5. The new tannin foams do not result to be phytotoxic and are apt to the conservation of fresh cut flowers and as support matrices for horticulture and hydroponics. They have shown performances comparable or superior to commercial synthetic phenolic floral foam used as reference. (C) 2016 Elsevier B.V. All rights reserved.