Improving agricultural waste pulps via self-blending concept with potential use in moulded pulp packaging

Agricultural wastes have been considered as an alternative sustainable resource for pulp production. In this work, banana stem (B), pineapple leaf (P) and rice straw (R) were used as raw materials for pulp extraction. The obtained pulps were moulded into sheets and their mechanical properties were evaluated. The sheets prepared from P and R pulps showed promising performance for moulded pulp packaging use. Having high cellulose content, slenderness ratio, and flexibility, these pulps were superior with a high degree of fibre bonds. Conversely, sheets prepared from B pulp had sub-standard properties. To improve the properties of B pulp, it was blended with either P or R pulp. Both tensile strength and Young's modulus of the blended B/P and B/R sheets were improved significantly, around 63-167 % and 55-117 %, respectively. SEM images revealed that the long and flexible P and R fibres were well-entangled with the B fibres, confirming a strong network of the blended pulp sheets. A positive deviation from the linear additivity of the blended sheet's strength was also observed. Mixing 30 % of P or R pulp with B upgraded both blended sheets to the acceptable range, showing a tensile index of approximately 44-45 Nm/g. These results indicated that pulp blending was highly efficient for enhancing properties of sub-standard pulp. Furthermore, this could possibly enable the use of all agricultural wastes as alternative raw materials for pulp and paper industries.