Synthesis and characterization of starch-based polyurethane foams

Abstract

Starch-based polyurethane foams were synthesized by reacting a mixture of starch and polycaprolactone triol with an aliphatic diisocyanate, in the presence of water as blowing agent. Some foams were also prepared by adding a certain amount of polyethyleneglycol. The reaction kinetics is affected by the presence of starch due to the higher viscosity related to the presence of the high molecular weight polysaccharide. Starch-based polyurethanes show higher glass transition temperatures and lower thermal stability. Cellular materials with different mechanical properties can be obtained by varying the amount of starch and by controlling the relative amount of polycaprolactone triol and polyethyleneglycol in the composition.

Preparation and characterization of cross-linked starch polyurethanes

“…The development of new starch-based materials has spurred much interest in recent years (Carvalho, 2008;Wurzburg, 1997;Alfani, Iannace & Nicolais, 1998). Two distinct approaches have been tackled in this context, viz.…”

“…the preparation of ''thermoplastic starches" (TPS) by plasticization, with or without blending with another polymer (i.e., physical modification of the natural polymer), and the synthesis of chemically modified starches (Tomasik & Schilling, 2004). Given the predominant presence of hydroxyl groups in starch, as in all polysaccharides, the focus of attention for these chemical modifications has obviously been on their transformation with various reagents, including esterification and etherification (Carvalho, 2008;Wurzburg, 1997;Alfani, Iannace & Nicolais, 1998). The destruction of some or most of the hydrogen bonds induced by these reactions, is responsible for the decrease in crystallinity and in the extent of the granulate structures of starch.…”

“…The destruction of some or most of the hydrogen bonds induced by these reactions, is responsible for the decrease in crystallinity and in the extent of the granulate structures of starch. More importantly, the modifications produce distinct changes in the properties of the ensuing polymers, and give rise to a wide range of materials, including cross-linked structures, which are among the more frequently sought products of these treatments (Carvalho, 2008;Wurzburg, 1997;Alfani, Iannace & Nicolais, 1998).…”

“…Alfani et al (1998) synthesized starch-based polyurethanes using a polycaprolactone triol and an aliphatic diisocyanate. These materials showed a relatively high glass transition temperature and a thermal stability lower than that of starch.…”

Starch, Sucrose, and Rezol®IL800 as Density Modifiers for Polyurethane Rigid Foams Formulated by Recycled Polyol

“…Cellulose derivatives having OH functional groups have been used in rigid polyurethane foam formulation as modifiers. Several research works using starch as the modifier also were carried out [15][16][17][18][19][20][21] . Materials like saccharides, cashew nut shells, liquid soy bean oil, and soy flour have been used in PUF preparation [22][23][24][25][26] .…”