Insoluble Regenerated Cellulose Films Made from Mildly Carboxylated Dissolving and Kraft Pulps

Abstract

Research has been undergoing for years on the development of renewable and green polymers to replace petroleum-based plastics. Herein, inexpensive and sustainable films were made by applying some mild etherification reactions on kraft and dissolving pulps to obtain carboxymethylated fibers (CMFs). CMFs were subsequently dissolved in alkaline solutions then cast, immersed in an acid bath, washed, and dried to form regenerated cellulose-based films, which do not dissolve in water. Pulps were chemically analyzed and films were characterized by Fourier transform infrared (FTIR), X-ray diffraction (XRD), nuclear magnetic resonance (NMR), field emission scanning electron microscopy (FE-SEM), and UV–vis, and their physical and strength properties were measured. It was found that kraft pulp films were denser, stronger, more transparent and crystalline, had a smoother surface, and were more water absorbent than the dissolving pulp films due to their higher hemicellulose content. Overall, low cellulose carboxymethylation as a scalable method is promising for making biodegradable, recyclable, insoluble, transparent, and strong films that can compete with cellophane and various plastic products used in packaging.

Modified Hairy Nanocrystalline Cellulose as Photobactericidal Nanofillers for Food Packaging Application

“…To make films of CMF, a previously reported protocol by Moradian et al was followed. 14 Briefly, CMF with the carboxyl density of ∼1 mmol g −1 (2 g) was dissolved in DI water (50 mL) and, after adding NaOH (2 g) and mixing, dopes were made and then degassed by centrifugation at 1000 rpm for 5 min. Afterward, the solution was casted in rectangular molds and immersed in a sulfuric acid bath (10 wt %).…”

Microspheres and Nanorods Produced in the Dissolution of Mildly Carboxylated Cellulose Fibers in Alkaline Solutions

“…To make lms, CMF was dissolved in an alkaline solution, casted in molds and regenerated in a 10% sulfuric acid bath, then washed and dried. More details about lm making and measuring the undissolved portion of CMF were described in our previous study (Moradian et al 2021). This CMF contained 6.5% of undissolved ber particles; an image of a piece of undissolved tracheid cell wall shows S2 parallel micro brils (Fig.…”

“…Carboxymethylation reaction was performed as reported previously (Moradian et al 2021) to produce 1.3 and 2.5 mmol/g (DS: 0.25 and 0.56) carboxyl charge densities. Brie y, two set of 20 g ground pulp and 220 g isopropyl alcohol were put into two glass bottles and placed into two 45 ℃ water bath while stirring (150 rpm).…”

“…The carboxyl content was calculated by conductometric titration as reported previously (Moradian et al 2021). DS was measured by the following Eq.…”

Reversible Photo-, Thermal-, and pH-Responsive Functionalized Wood with Fluorescence Emission

“…The added functional materials have poor miscibility with wood, and may deteriorate the original properties of wood itself, such as mechanical and processing properties [ 15 , 16 , 17 ]. At the same time, most added functional materials are expensive and have certain toxicity, which will greatly increase the cost and may pollute to environment and cause harm to the human body [ 18 , 19 , 20 ].…”