Rheology Study of Sugar Cane Bagasse Lignin-Added Phenol–Formaldehyde Adhesives

The rheological properties of sugar cane bagasse lignin–phenol formaldehyde (PF) (30% lignin – PF) resins were studied using oscillation tests. The bagasse lignin was introduced in the classic adhesive formulation in order to supply a part of PF. Rheological qualities of optimal lignin–PF (30% lignin – PF) resins and commercial PF resin were assessed by using a rotary rheometer (ARES). Dynamic rheological measurements, performed at low strain in the linear range, are useful to characterize the network properties of resins. The results obtained showed that the time sweep indicates excellent structural stability of optimal lignin–PF (30% lignin–PF) resins and commercial PF resin. The elastic modulus is greater than the viscous one showing a remarkable elastic character of the resins, and the performed frequency sweeps show a typical spectrum of a “weak gels” structure. The time dependence at 125°C shows that the optimum cure time is 7.5 min.