On the study of polyurethane ionomer - Part I

The reaction of toluene diisocyanate (TDI) with dimethylol propionic acid (DMPA) or diaminopentane sulphonic acid sodium salt (ES-200) and other additives to form the structure of anionic polyurethane (PU) ionomer molecule has been proven by FT-IR spectroscopy. In aqueous solution, the surface tension of anionic PU ionomer molecule is seen to slightly increase with increasing concentration of ES-200. This is because the adsorption of hydrophobic groups of ionomer molecules at the surface of aqueous solution becomes even more ordered. Under the same experimental Conditions, the surface tension of anionic PU ionomer molecule appears to slightly decrease with increasing concentration of DMPA, as a result of increased hydrophobic groups of ionomer molecule adsorbed at the surface of aqueous solution. The number average particle size of anionic PU ionomer molecule in aqueous solution appears to steadily increase with an increase in the concentration of DMPA or ES-200. This is because the intermolecular interaction between ionomer-ionomer molecules themselves and between ionomer-water molecules may increase the free volume of anionic PU ionomer molecule, thus causing their number average particle size to increase. Experimental results indicate that both the tensile strength and the modulus of self-cured film of anionic PU ionomer molecule appear to decrease with increasing concentration of DMPA or ES-200, as a result Of intramolecular interaction. However, the elongation of self-cured film of anionic PU ionomer molecule is seen to increase with increasing concentration of DMPA or ES-200. This may be the result Of weakening crosslinking due to strong intramolecular interaction of ionomer molecule. For the peel strength of self-cured film of anionic PU ionomer coated on the fabric (30% polyester/70% cotton), it has been found that the peel strength increases with increasing concentration of DMPA or ES-200, as a result of increased hydrophilic interaction between ionomer molecules themselves. Copyright (C) 2002 John Wiley Sons, Ltd.