Effect of Catalyst Concentration on the Rheological Properties of Melamine Formaldehyde Resinated Cotton Fabric

摘要

Synthesis of mono through hexa substituted derivatives of Methylol Melamine Resins (MFR) were carried out at various catalyst (KH_2PO_4) concentrations of 0.5, 0.75, 1.0, 1.25 and 1.50 g. Rheological/mechanical properties of resin-cotton network were investigated to determine the effect of catalyst concentration and degree of substitution of resins on the flow property such as viscosity. Other parameters determined include percentage yield, breaking load and crease recovery properties of resinated cotton fabric. The result revealed that the yield increased with increase in catalyst concentration and attained the highest yield of 53.7% at 0.75 g and 51.3% at 1.0 g, respectively. The damaging effects of high acid concentrations were observed particularly at 1.25 and 1.50 g KH_2PO_4. Yield increased as the degree of substitution increased with hexa substitution having 48.8 and 53.7% at 0.5 and 0.75 g, respectively. Shear viscosity increased as catalyst concentration increased from 0.5 to 1.0 g with hexa and penta substitution giving the highest shear viscosity of 45 poises and 35 poises, respectively. The dry crease recovery angle increased with increased catalyst concentration up to 0.75 g and attained maximum value of 125° and 115° in the warp and weft directions, respectively at 150°C. The effect of catalyst on breaking load of sample at 150°C showed an increase from 0.5-1.0 g of catalyst concentration. The highest tear strength of 10.8 and 10.2 kgf at 0.75 g catalyst concentration was observed in the warp and weft directions, respectively. Acid damage at higher concentration was also implicated for the reduced tear strength.