Sandwich-Structured, Hydrophobic, Nanocellulose-Reinforced Polyvinyl Alcohol as an Alternative Straw Material

Abstract

An environmentally friendly, hydrophobic polyvinyl alcohol (PVA) film was developed as an alternative to commercial straws for mitigating the issue of plastic waste. Nontoxic and biodegradable cellulose nanocrystals (CNCs) and nanofibers (CNFs) were used to prepare PVA nanocomposite films by blade coating and solution casting. Double-sided solution casting of polyethylene-glycol–poly(lactic acid) (PEG–PLA) + neat PLA hydrophobic films was performed, which was followed by heat treatment at different temperatures and durations to hydrophobize the PVA composite films. The hydrophobic characteristics of the prepared composite films and a commercial straw were compared. The PVA nanocomposite films exhibited enhanced water vapor barrier and thermal properties owing to the hydrogen bonds and van der Waals forces between the substrate and the fillers. In the sandwich-structured PVA-based hydrophobic composite films, the crystallinity of PLA was increased by adjusting the temperature and duration of heat treatment, which significantly improved their contact angle and water vapor barrier. Finally, the initial contact angle and contact duration (at the contact angle of 20°) increased by 35% and 40%, respectively, which was a significant increase in the service life of the biodegradable material-based straw.

Evaluation of the Antimicrobial, Thermal, Mechanical, and Barrier Properties of Corn Starch–Chitosan Biodegradable Films Reinforced with Cellulose Nanocrystals

“…Azeredo, Mattoso [ 55 ] reported that the presence and increase in the concentration of cellulose nanofibers in chitosan-glycerol films caused a significant reduction in WVP. A similar result was reported by Chou, Shi [ 56 ], who noted that the WVP of PVOH films decreased with the addition of CNC at 2.5% ( w / w ). Meanwhile, for biodegradable films made from a mixture of cassava starch, chitosan and gallic acid, the incorporation of 7.5% ( w / w ) cellulose nanofibers generated the material with the best water vapor barrier capacity [ 39 ].…”

Nanocellulose-reinforced, multilayered poly(vinyl alcohol)-based hydrophobic composites as an alternative sealing film

“…The details on the steps and parameters of polymerization of PEG-PLA used in this study are listed in the previous article. 18 The second part was the preparation of multilayered PEG-PLA and PLA hydrophobic composites. PEG-PLA (1 wt%) and neat PLA (1 wt%) were separately dissolved in chloroform.…”

How APTMS Acts as a Bridge to Enhance the Compatibility of the Interface between the Hydrophilic Poly(vinyl alcohol) Film and the Hydrophobic Stearic Acid Coating

“…Three water drops (5 μL each) were tested at different selected locations on the films. Prior to testing, the films were maintained under constant conditions at three different relative humidity (RH) levels: 33%, 57%, and 75% …”

“…Prior to testing, the films were maintained under constant conditions at three different relative humidity (RH) levels: 33%, 57%, and 75%. 13 Water Solubility (WA). To measure the water resistance of the PVAbased films, a humidity chamber (RHP 80, Huanrui Test Equipment Co., Ltd.) was utilized.…”

“…However, the sensitivity to moisture hampers the extensive adoption of PVA-based films. , To address this challenge, researchers have explored different approaches, including physical blending and chemical grafting. , Despite these efforts, the hydrophobicity of PVA-based films still falls short in comparison with films made of polyethylene (PE) and polyvinyl chloride (PVC). Then, researchers have turned to hydrophobic coating materials, such as nanocellulose, alkyl ketene dimmer, epoxidized soybean oil, and other hydrophobic components, to improve the hydrophobicity of PVA-based films. − Among these materials, stearic acid (SA) has demonstrated the potential to improve the hydrophobic and barrier properties of PVA-based films. − However, a new issue arises in the form of incompatibility between hydrophilic PVA and hydrophobic coating. The resulting phase separation between the PVA film and the hydrophobic coating negatively impacts the tensile strength, film-forming performance, and overall physical and practical properties of the films.…”