Developing lignin-based resin coatings and composites
2008
Phenol in phenol formaldehyde (PF) resin has been partly substituted with lignin extracted from sugarcane bagasse. In order to optimize the lignin-based resin for applications in coating and composite materials, thermal and rheological tests were performed with different wt% of lignin substitution into PF resins. Differential scanning calorimetry scans showed a small exothermic peak and a large endothermic peak, typical of resins. The T g of the resins was seen between 125 and 150°C and this transition was clearly evident when the lignin content was increased from 10 to 40wt%. Increasing the lignin content in the PF resin increases the rate of cure and the heat of reaction. Water absorption tests show that the lignin-PF resin films are effective water-barrier coatings for cardboard substrates. It is speculated that the interaction between the substrate and the lignin-PF resin has resulted in a negative surface charge which would have contributed to the reduction in the contact angle.
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