Feedstock and processing strategies for fibrillated cellulose: performance implications in man-made cellulosic fibers, nonwovens and molded pulp products

• Feedstock composition and processing history determine fibrillated cellulose performance. • Hemicellulose, lignin type, and chain length predict fibrillation efficiency. • Molded pulp is commercially ready; nonwovens and man-made cellulosic fibers need further development. • Energy costs and scale-up barriers limit industrial adoption. • Sustainability claims require product-level life cycle assessment to be substantiated. Fibrillated cellulose, encompassing microfibrillated cellulose (MFC), cellulose nanofibrils (CNF), and lignin-containing cellulose nanofibrils (LCNF), has attracted substantial industrial and scientific interest as a bio-based platform material, yet the relationships between feedstock selection, processing strategy, and application-specific performance remain poorly integrated in the literature. This review addresses that gap by systematically analyzing how biomass source, pulping and bleaching chemistry, chemical pretreatments, and mechanical fibrillation routes collectively govern the structural, colloidal, and functional properties of fibrillated cellulose across three high-volume consumer applications: man-made cellulosic fibers (MMCFs), nonwovens, and molded pulp products. The review proposes an integrated framework for evaluating feedstock and processing routes against application-specific requirements, identifying crystallinity, degree of polymerization, hemicellulose-to-lignin ratio, and monolignol composition as candidate predictors of fibrillation efficiency and material performance that warrant systematic experimental validation. The structured synthesis of available evidence is intended as a decision-making tool for feedstock selection and process design, while also delineating where experimental evidence is sufficient and where critical knowledge gaps remain. Among the three sectors, molded pulp has reached commercial adoption, nonwovens represent an intermediate entry point, and MMCFs remain a longer-term opportunity constrained by capital intensity and process integration challenges. Techno-economic and environmental evidence assembled here suggests that fibrillated cellulose is neither intrinsically cost-competitive nor inherently sustainable, as outcomes depend critically on upstream processing choices and regional energy supply. Closing the identified knowledge gaps will require standardized characterization protocols, energy benchmarking across feedstocks, and product-level life cycle assessments, none of which currently exist in the peer-reviewed literature.