Cellulose Nanocrystals from Lignocellulosic Raw Materials, for Oxygen Barrier Coatings on Food Packaging Films

Abstract

Cellulose nanocrystals (CNCs) are unique, renewable top-down nano particles from which coatings with improved gas barrier properties and new functionalities can be prepared. In this paper, the potential for obtaining such high performing nanocrystals from low-cost lignocellulosic by-products or raw materials is proved by a comparison study on CNCs obtained both from cotton linters and kraft pulp, by means of the ammonium persulfate (APS) process. Morphological and chemical characterization of the nanocrystals obtained, as well as the main functional properties of the poly(ethylene terephthalate) coated films, showed quite similar characteristics and performances of CNCs obtained from pure cellulose raw material (cotton linters) and the nanoparticles produced from a potential discard of paper making processes (kraft pulp). In particular, the gas barrier properties of the coating produced with CNCs obtained from kraft pulp were very promising, providing oxygen and carbon dioxide permeability values hundreds of times lower than those of equal thickness in comparison with common barrier synthetic polymers, over a broad range of temperatures. The results obtained are relevant not only for the outstanding performances achieved, but also because they evoke a possible positive example of industrial symbiosis in the packaging field, merging together the requirements and needs of the paper and plastic industries and addressing the way towards a better management of waste and materials.

Fast Production of Cellulose Nanocrystals by Hydrolytic-Oxidative Microwave-Assisted Treatment

“…Polydispersity index (PDI) is a measure of the width of particle size distribution. A value below or equal to 10% refers that the sample is monodisperse [2,45]. The higher polydispersity indexes of the CNCs obtained ( Table 2) were thus indicative of a more complex morphology and bi-or multi-modal distributions.…”

Recent Strategies in Preparation of Cellulose Nanocrystals and Cellulose Nanofibrils Derived from Raw Cellulose Materials

“…Sulfuric acid is the most typically used as it produces a negative surface charge on the particles which leads to more stable suspension. In general, the hydrolysis process needs the sulfuric acid concentration to be 60-65%, reaction temperature to be [40][41][42][43][44][45][46][47][48][49][50] ∘ C, and reaction time to be 30-60 min. However, the yield of CNCs is very low (less than 30 wt.%) due to the excessive degradation.…”

Chitosan nanocomposite films incorporating cellulose nanocrystals and grape pomace extracts

“…Nanoscale dimensions, high inherent rigidity, and high surface area‐to‐volume ratio make CNC one of the most promising renewable and biodegradable nanofillers for reinforcement of a polymer matrix . Over the past several years, studies have investigated the use of CNC as a strengthening agent to enhance functional properties of various polymer nanocomposite films, including chitosan films for food packaging …”

“…6 Over the past several years, studies have investigated the use of CNC as a strengthening agent to enhance functional properties of various polymer nanocomposite films, including chitosan films for food packaging. [7][8][9][10] Active packaging refers to the incorporation into packaging material of active compounds such as antioxidants or antibacterial agents that provide specific functionalities not present in conventional packaging systems. It has been one of the most innovative developments in food packaging in recent years.…”