فهرست مطالب r. dehghani firouzabadi

The objective of this study was to prepare and evaluate the features of starch films containing cellulose nanofibres (CNF) and lignocellulose nanofibres (LCNF) derived from old corrugated container (OCC) by mechanical method and using super disk grinding to achieve optimal strength, solubility and biodegradability features for food packaging. The characteristics of CNF and LCNF including morphological features (diameter and its distribution) were investigated using field emission scanning electron microscopy (FE-SEM). The studied films based on starch content of 5, 10 and 15% of CNF and LCNF as reinforcement agent were prepared using solution casting method. The effects of CNF and LCNF on physical and mechanical properties, weak acid and alkali, as well as biodegradation of films under aerobic conditions (using soil) were investigated. The result showed that average diameter of LCNF and CNF obtained was 69±10 µm and 28±10 nm, respectively. The results of physical and barrier properties showed that increasing the percentage of CNF and LCNF reduced the oil absorbing. By increasing the percentage of CNF, the solubility in water, acid, and alkali films decreases slightly, but this trend was reversed for LCNF. The results of mechanical strength showed that the increase in the contribution of CNF improved strengths to burst and tear index in the films, but the improvement for the film containing LCNF was less than that of CNF film. The biodegradation process of starch film samples increased by increasing the percentage of CNF and LCNF by 20-15%. It can be concluded that the use of CNF and LCNF leads to increased mechanical strength and decreased solubility to various solvents (water, acid and alkali). Also, with using CNF and LCNF, the biodegradability features were improved and as a result, it became more practical.

Cellulose Nano-fiber (CNF) and lignocellulose Nano-fiber (LCNF) are the most abundant bio-Nano-polymers that attracted much attention in researches and applications during recent decades. Super disk grinding method has prominent characteristics compared to the other methods such as simplicity, high speed, and high yield of production and owning single-stage process.

In this study, old corrugated container (OCC) was converted to lignocellulose microfibers (LCMF) and LCNF. LCNF was produced with ultra-fine friction grinding process, as a simple, fast and one-step downsizing method. The objective of this study was to investigate the grinding method on morphological characteristics (fiber diameter and distribution) with field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectrometry (EDX/EDS) analysis, thermal gravimetric analysis (TGA), suspension stability and air permeability of films made from LCMF and LCNF.

The average diameter of LCMF and LCNF obtained was 37±10 µm and 66±10 nm, respectively. The suspension of LCMF was unstable over checking stability time (after 2 min.), while the LCNF suspension had a long-term stability. The air-permeability of LCMF and LCNF films was 42.6 and 1.26 µmPa-1s-1, respectively. With downsizing lignocellulose fibers from micro to Nano scale, specific surface and bonding area increased and higher uniformity and lower porosity obtained.

In general, the results of this study showed that the production of LCNF and its film from OCC pulp were succeeded. Further investigations on the production of LCNF and evaluation its potential to produce different products compared to CNF (free of lignin and hemicelluloses) can bring many practical and industrial benefits to further commercialization of this value-added product.