Effect of hot calendering on physical properties and water vapor transfer resistance of bacterial cellulose films

Abstract

This work investigates the effect of hot calendering on bacterial cellulose (BC) films properties, aiming the achievement of good transparency and barrier property. A comparison was made using vegetal cellulose (VC) films on a similar basis weight of around 40 g.m-2. The optical-structural, mechanical, and barrier properties of BC films were studied and compared with those of highly beaten VC films. The Young's moduli and tensile index of the BC films are much higher than those obtained for VC (14.5-16.2 vs 10.8-8.7 GPa and 146.7-64.8 vs 82.8-40.3 N.m.g-1), respectively. Calendering increased significantly the transparency of BC films from 53.0 to 73.0 %. The effect of BC ozonation was also studied. Oxidation with ozone somewhat enhanced the brightness and transparency of the BC films, but at the expenses of slightly lower mechanical properties. BC films exhibited a low water vapor transfer rate, when compared to VC films and this property decreased by around 70 % following calendering, for all films tested. These results show that calendering could be used as a process to obtain films suitable for food packaging applications, where transparency, good mechanical performance, and barrier properties are important. The BC films obtained herein are valuable products that could be a good alternative to the highly used plastics in this industry.

Breathable Nanowood Biofilms as Guiding Layer for Green On‐Skin Electronics

“…Accordingly, as seen in Figure a, of special interest is the densified biofilm where the density increases to 1.156 g cm −3 and thus WVTR lowers to 210.2 g m −2 day −1 (approaching but still larger than that of normal skin (204 g m −2 day −1 )) and OTR lowers to 93.7 cm 3 m −2 day −1 . Meanwhile, the densified biofilms also exhibit increasing transparency with the increasing density (Figure b), due to a decreased light scattering surface area according to Kubelka–Munk theory . The densified biofilm of special interest (1.156 g cm −3 ) reaches 67.2% transmittance @550 nm, enabling school badge underneath visible.…”

“…Characterizations : The lignin removal was demonstrated by FTIR (Perkin‐Elmer Frontier) and composition analysis (the lignin content was decided by acid hydrolysis using 72 wt% sulfuric acid at 121 °C according to TAPPI T222 om‐83, the contents of cellulose and hemicellulose were decided by sugar analysis on a Dionex ICS‐3000 anion exchange chromatography). The porosity (ψ) was calculated using ψ = (1 − ρ S /ρ 0 ) × 100% where ρ s is the apparent density and decided by samples' weight and volume, and ρ 0 is the cellulose density (1.6 g cm −3 ) . The S BET was obtained from N 2 adsorption isotherm by analyzing the amount of N 2 absorbed at P / P 0 of 0.01–0.3 at −196 °C.…”

Impact of embossing on liquid absorption of toilet tissue papers

“…where sample is the sample density (g/cm 3 ) and cellulose is the cellulose density (which is assumed to be 1.6 g/cm 3 ) (Costa et al 2016).…”

Getting Environmentally Friendly and High Added-Value Products from Lignocellulosic Waste

“…According to Ahmed et al [11], these physical treatments can be classified as follows: mechanical treatment (stretching, calendaring, or rolling), solvent extraction treatment, and electric discharge (plasma treatment, corona treatment, ionized air treatment, thermal treatment, steam explosion, electron radiation, dielectric barrier, and ultraviolet). The mechanical treatments promote the interactions between the natural fibers and the polymeric matrix by increasing the surface area of the fibers and decreasing the density and stiffness; therefore, a better distribution of the fibers in the polymer matrix is achieved [19]. Solvent extraction can increase the surface area and remove soluble impurities for natural fibers and fillers.…”