Production of nanocellulose fibers from pinecone biomass: Evaluation and optimization of chemical and mechanical treatment conditions on mechanical properties of nanocellulose films

•Pinecone biomass was used as a precursor for nanocellulose production.•Optimum NaOH concentration was determined.•High purity cellulose (89%) was produced using optimized chemical treatment.•Mechanical conditions were optimized for production of high strength nanocellulose.

Nanocellulose fibers were produced from pinecone (Jack pine: Pinus banksiana Lamb) using chemical and mechanical treatments. The effects of pretreatment and mechanical grinding on the tensile strength and modulus of the cellulosic fiber sheets were studied to optimize the treatment conditions and grinding process used for the generation of high strength nanocellulose fibers. Pinecone and cellulose fibers were characterized for their chemical composition, morphology, crystallinity, and thermal properties using HPLC, FTIR, SEM, ESEM, XRD, and TGA to provide insight into the mechanism involved in the reactions. Cellulose suspensions that had different pretreatments were processed for different time periods in a Supermasscolloider to produce cellulose nanofibers. The cellulose fibers produced at the optimum chemical concentrations of 4 wt% NaOH and 5 wt% of acidified sodium chlorite solution contained approximately 89% of cellulose, 4% hemicellulose, and 6% lignin. About 67% of the prepared nanocellulose fibers showed a diameter range between 5 and 25 nm. The tensile strength and modulus of the nano fiber films prepared at the optimized grinding condition were 273 MPa and 17 GPa, respectively. The high crystalline index (70%) and improved thermal stability of the nanofibers indicate their suitability for manufacturing bionanocomposites.

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