Bio-Based Diisocyanate Analysis

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Now-a-days, solvent-free, low viscosity and aliphatic partially bio-based diisocyanate(PBD) polymer based polyurethane synthesis from vegetable oil has been given more interest. This is due to low cost, environmental friendly and reducing low volatile organic compound. In this paper, we synthesized polyurethane (PU) adhesives of three different stoichiometries (NCO/OH) ratios by reacting a castor oil based polyol (OH) with PBD (NCO) of various compositions in presence of dibutylintin dialaurate (DBTDL) for the purpose of wood-wood adhesion strength. Complete Formation of PU adhesives was confirmed by FTIR spectroscopy. The effect on NCO/OH ratios on wood-to-wood bonding strength has been studied by lap shear strength measurement. The result of…show more content…
The contact angle of the film was measured with distilled water under room temperature.
2.10 Crosslink density () and average molecular weight between two crosslinks (Mc)
Crosslink density () and average molecular weight between two crosslinks (Mc) were determined by the equilibrium swelling method according to the Flory-Rehner equation (Eq. 1). Toluene was chosen as a solvent for the calculations.
Mc =-(ƥpVsØ1/3)/(ln(1-Ø)+ Ø+ƛØ2) (1) where Vs is the molar volume of the solvent, ƥp is the density of the polymer and Ø is the volume fraction of the polymer in the swollen state. χ is the polymer solvent interaction parameter.
The polymer solvent interaction parameter can be calculated by using the following equation,23
〖 χ〗_ =0.34+(V_s (〖δ_p-δ_s)〗^2)/RT (2)
Where, δp and δs are the solubility parameters of the polymer and solvent respectively in (cal/cm3)1/2. β is the lattice constant whose value is 0.34, Vs is the molar volume of solvent (cm3/mol), R is the gas constant,1.983(cal/molK) and T is the temperature

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