Development of modified cellulosic bio–polymers from non– edible biomass for bio-plastic packaging applications

Abstract

Single-use plastic packaging has led to significant plastic pollution in the environment. Efforts are being made to develop bioplastic packaging from different biomass sources like food crops, wood, animal waste, and agricultural residues. This study investigated the transformation of non-edible biomass (NEB) namely; Mucuna pruriens, Tripsacum andersonii, Brachiaria brizantha, Chloris Gayana, Setaria sphacelate, Lagenaria siceraria, Alternnthera sessilis, and Hyparrhenia rufa into chemically modified cellulose (NEBCM) for potential application in sustainable bioplastic packaging. NEB underwent alkaline treatment at 3%, 6%, and 9% NaOH concentrations through delignification, pulping, and bleaching to extract cellulose, which was then chemically modified via acetylation, amination, and crosslinking. Solvent casting was used to fabricate NEBCM films. Bio-chemical characterization of NEB used VanSoest approach, while NEBCM was characterized using SEM-EDX, FT–IR, water absorption and thermal conductivity test. Setaria sphacelate exhibited the highest cellulose yield across 3% and 6% NaOH concentrations (44%, and 41% respectively), while Chloris Gayana, Lagenaria siceraria and Alternanthera sessilis showed lower yields, not exceeding 15%. Yield reductions were observed beyond 6% NaOH, in Mucuna pruriens (15%), Brachiaria brizantha (19%), Chloris gayana (13%), and Lagenaria siceraria (11%). Setaria sphacelate (33.5% cellulose, 20.7% hemicellulose, 9% lignin) and Brachiaria brizantha (28.9% cellulose, 32.9% hemicellulose, 7.5% lignin) emerged as promising biopolymer sources due to their favourable composition. O–H peaks shifted from 3400–3450 cm⁻¹ in NEB to 3340–3360 cm⁻¹ in NEBCM, C=O from ~1640 cm⁻¹ to 1683–1685 cm⁻¹, and 1030–1045 cm⁻¹ peaks disappeared. 1324–1325 cm⁻¹ suggested partial lignin retention, and new bands at 2154– 2179 cm⁻¹, indicated the presence of alkyne groups (C≡C). SEM-EDX confirmed improved surface morphology, from rough fibrous to homogeneous and more compact textures especially in Setaria sphacelate and Alternanthera sessilis. Thermal conductivity values ranged between 0.1744–0.3472 W/m•K, with Lagenaria siceraria demonstrating superior insulation potential. Water absorption ranged from 96.67% to 100.83%, linked to abundant hydroxyl groups; Alternanthera sessilis (100.83%), Setaria sphacelate (100.45%), and Chloris gayana (100.00%) recorded the highest values. NEBCM films showed promise as renewable polymer bases but need plasticizers and blending to improve strength and flexibility.