EFFECT OF ACRYLIC AND MELAMINE-FORMALDEHYDE BASED SYNTANS IN THERMO-MECHANICAL AND HYDRODYNAMIC BEHAVIOR OF CHROME TANNED BOVINE LEATHER- A COMPARATIVE ASSESSMENT

Three different samples of cow softy leather (i.e. CSM0A0, CSM3A0 and CSM0A3) were prepared from a chrome tanned cow wet blue of Indian origin. CSM0A0 was the control sample wherein neither melamine formaldehyde based nor polyacrylate based syntan was added. CSM3A0 and CSM0A3 had 3% melamine formaldehyde based and 3% polyacrylate based syntan, respectively in addition to the other common auxiliaries used in all three samples. Other unit operations (physical and chemical) for manufacturing leather were maintained same in all the three samples. Thermal, mechanical and hydrodynamic swelling behavior of these three samples was studied, and tried to be correlated with the crosslinking densities of the samples. The hydrodynamic swelling behavior was studied in three different solvents (e.g. water, toluene and xylene) assuming definite solvent-bovine collagen interaction parameters, and crosslink densities were evaluated by applying the Flory-Rehner equation. While studying the mechanical behavior, some distinguished theoretical models (e.g. Mooney-Rivlin, Flory, and Martin, Roth & Stiehler (MRS)) were tried to be fit with the experimental results obtained in stress-stain analyses. In this process, few constants for cow Cr tanned leather were derived as value of constant A in MRS equation remained in the range of 0.9-1.0 and value of constant B in Flory’s equation remained in the range of 0.001-0.003, which were earlier not reported in the literature. From all the performed experimentations, it was found that polyacrylate based syntans formed better crosslinks (calculated crosslinking density 6.02x10-3 Mol.m-3) with chrome tanned bovine leather in comparison to melamine formaldehyde based syntans (calculated crosslinking density 2.61x10-3 Mol.m-3) and subsequently provided better thermal and solvent resistance as well the tensile strength to leather.