Isolation of high crystalline nanocellulose from Mimosa pudica plant fibres with potential in packaging applications

Mimosa pudica Linn (sensitive plant) is a medicinal plant of family Fabaceae. Its stem is a good source of cellulose. This research work reports isolation of cellulose nanocrystals (CNCs) from M. pudica stem fibres by combined chemical and mechanical treatments. Polyvinyl alcohol (PVA)/starch composites were prepared with incorporation of isolated CNC (1, 3 and 5 wt.%) by solution casting method. Addition of CNC in polymer composites improved its mechanical strength and barrier properties. Isolation process of CNC includes alkali treatment, bleaching and acid hydrolysis followed by homogenization. Chemical composition, thermal stability, structure, surface morphology, crystallinity and size of the freeze-dried nanocellulose were studied carefully. Fourier transform infrared analysis of raw fibre and CNC showed elimination of non-cellulosic fragments from untreated M. pudica stem fibre. Electron microscopy analysis and dynamic light scattering (DLS) confirmed the isolation of nanocellulose. X-ray diffraction showed improvement in the crystallinity of obtained nanocellulose. Increase in crystallinity indicates high Young's modulus of isolated nanocellulose which makes them proper reinforcement material in composites. Polymer composites with the addition of 3 wt.% of CNC showed the highest tensile strength and lowest water vapour transmission rate (WVTR), moisture absorption and oxygen transmission rate (OTR). As M. pudica is an abundant natural resource, it can be utilized as an efficient source of nanocellulose for different applications especially as fillers in sustainable polymer composites for packaging.

Automated summary

This research successfully isolated cellulose nanocrystals from Mimosa pudica stem fibers and incorporated them into polyvinyl alcohol/starch composites, showing improved mechanical strength and barrier properties. The isolation process included alkali treatment, bleaching, acid hydrolysis, and homogenization, leading to the enhancement of crystallinity and potential applications in sustainable polymer composites. Incorporating 3 wt.% of CNC in polymer composites resulted in the highest tensile strength and lowest water vapor transmission rate.