Laboratory Paper Machine Evaluation of Poly-Lactic Acid (PLA) on Paper Properties of Unbleached Recycled Fibers Mixture

Today recycled paper is used to reduce the environmental impact of paper production. Starch as a dry strength additive improves the properties of recycled paper. Starch in combination with Poly-lactic Acid (PLA), a product from the biorefinery process, has the potentialto act as a promising strength additiveto further improve paper strength. In this study, PLA with molecular weight of 20,000, recycled pulp (OCC) with kappa number of 56.6, and cationic starch containing 0.43% nitrogen content were employed. Three machine conditions were run: Condition 1 – only pulp; condition 2 - pulp plus 1% starch; condition 3 - pulp plus 0.9% starch and 0.1% PLA. Selected paper properties were tested in accordance to TAPPI standards. The results showed that tensile index in the cross direction (CD) increased about 26 % for the paper made in condition 3 compared to condition 2. Tear strength of paper in condition 3 also showed a slight increase in the machine direction (MD), while it remained the same in CD, compared to the condition 2. There was no improvement seen for air and water resistance. Therefore, this study suggests that a blend of PLA – starch represents a promising approach in improving the strength properties of recycled paper.