Biodegradable polyurethane adhesives based on polyols derived from renewable resources

The design of polymers from renewable resources is subject to increasing interest, more specifically with regard to the development of biodegradable materials in order to reduce the dependence on petroleum and its negative impact on the environment. Thanks to the versatility of polyurethane adhesives, they can be formulated by designing their properties through the selection of their reagents. This work focused on the development of potentially biodegradable polyurethane adhesives containing polyols from renewable resources, such as soya-based vegetable oils. Moreover, they were synthesised with 1,4-butanediol as a chain extender and two diisocyanates were tested, an aromatic, 4,4′-diphenylmethane diisocyanate and an aliphatic, 1,6-hexamethylene diisocyanate, which is considered more biodegradable. The biodegradable polyurethane adhesives were characterised by Fourier transform infrared spectroscopy, thermogravimetric tests, differential scanning calorimetry and gel permeation chromatography. Finally, the adhesion properties were measured in a T-peel test on leather/polyurethane adhesive/styrene butadiene rubber joints, in order to establish the amount of soya bean oil-based polyol that could be added to synthesise polyurethane adhesives satisfactorily and meet the quality requirements for footwear.