Effect of functionalized lignin on the properties of lignin–isocyanate prepolymer blends and composites

摘要: Abstract Functionalization of lignin was carried out with 4,4′-diphenyl methane diisocyante (MDI) at 90 °C for 60 min. Formation the resulting reaction products confirmed help FTIR, FESEM–EDAX and DSC. Polymer blends were prepared using an isocyanate prepolymer (NCO/OH: 3.5) functionalized (up to 15 wt%) evaluated their phase miscibility, wettability, rheology mechanical properties. Under DMA run, maximum storage loss moduli observed 5 wt% content. Wettability results indicated that as content increased in blends, contact angle probe liquids on substrate while polar component surface-free energy decreased affecting wettability. FTIR spectra showed disappearance –NCO peak 2270 cm−1 supported its consumption network formation. Rheological test revealed lignin-prepolymer needed more stress flow also had viscosity recovery compared parent system. The single-lap joint shear strength higher aluminium than wood. pull-off adhesive blend ∼19% prepolymer. composites made pine needles exhibited acceptable properties specified standard (EN 312).