Preparation of antibacterial cellulose of non-woven cotton fabric treated with curcumin/shellac based on polyvinyl alcohol/sodium caseinate blends for potential packaging purposes

Polysaccharides are renewable resources and can be used as alternative packaging materials that can serve as petroleum-based polymers. Non-woven fabrics are widely used in packaging because of their durability, ease of storage, and lightweight nature. Combining advantages of these materials offers benefits such as easy recyclability, molding simplicity, strong tear resistance and a compact design. In this research, novel antimicrobial packaging materials were fabricated by treating of non-woven cotton (NWC) fabric samples with various formulations containing polyvinyl alcohol (PVA) and sodium caseinate (SC) followed by treatment with curcumin and/or shellac followed by cross-linking via an aqueous solution of acetic acid (AC). Factors influencing formation of these formulations films were studied. The results obtained revealed that the optimal conditions for preparing crosslinked PVA/SC film with good performance properties are: PVA/SC weight ratio, 25/75 respectively; AC concentration, 0.25%; and immersion time, 10 min. The chemical structure of the PVA/SC film under optimum conditions was confirmed through FTIR analysis. Toxicity evaluations indicated that casein exhibits minimal toxicity to brine shrimp, even at high concentrations. Shellac was found to be relatively safe (10 mg/L had 0.53% mortality), PVA displayed moderate toxicity. Curcumin is relatively non-toxic at lower concentrations, and the composite D12 (PVA/SC/SH/Ag-NPs) film recorded a mortality rate of 10.3% (low toxicity) at a concentration of 10 mg/L. To enhance the antimicrobial properties, bio-additives such as curcumin, shellac, silver nanoparticles, or their binary admixtures were incorporated into the film formulations. Among the antimicrobial PVA/SC (25/75) films, the film containing curcumin/shellac at a weight ratio of 0.075/10 exhibited the best performance properties. Applying the aforementioned PVA/SC/curcumin/shellac formulation to NWC fabric sample resulted in: (a) Reduced swelling properties accompanied by an increasing in gel fraction of the treated fabric (b) Improved antimicrobial activity of the treated fabric against Gram-positive bacteria (Staphylococcus aureus), Gram-negative bacteria (Escherichia coli), pathogenic yeast (Candida albicans), and filamentous fungus: (Aspergillus niger), (c) Decreased air permeability along with an increased tensile strength, Young's and burst strength of the treated fabric, and (d) The best water vapor transmission rate compared to other treated formulations. The maximum hydrophobicity results increased the contact angle of NWC by 1219.28 and 1461.13%, respectively, after the addition of PVA/SC as in (NW1, 105.05°) and PVA/SC/CUR/SH as in (NW9, 124.31°) as compared to untreated non-woven. The successful incorporation of PVA/SC or PVA/SC/Cur/SH into NWC was evidenced by the X-ray analysis, which showed decreased crystallinity. Additionally, TGA analysis indicated that the non-woven cellulose's thermal stability was enhanced by the addition of PVA/SC/CUR-SH. The chemical structure of the treated fabric was confirmed through FTIR analysis, while its morphology was investigated using SEM analysis. These findings support the potential application of the PVA/SC/curcumin/shellac-treated fabric as a packaging material.